Top notch electronics guru's needed

First I'll start off by saying this subject matter is way over my head so I need anyone that responds to keep things layman simple (in other words. . .talk stupid:p:).

I'm looking to build a 5-10W (or whatever else would be more appropriate for the speakers) amplifier with a 5 or 7 band graphic equalizer that works on 12VDC.

There are a number of constraints though and they are:

• If at all possible, I'd prefer it fit into a FDD bay (height and width wise), if not, I do have 1 full Optical bay at my disposal.
  
• Depth must be kept to 2.25" (57mm) or less.
  
• Must have an on off switch and volume control.
  
• Would really prefer to do this with a pre-made breadboard (or several) if at all possible but I can go custom if absolutely necessary.
  
• All parts must be able to be procured locally (Radio Shack and a local electronics store that's poorly organized/labeled). I may also have other electronics retailers locally that I'm not aware of yet.

What I need is A) someone to tell me if this is possible in the first place and B) someone to work up the schematics and parts list for me, if it is.

The speakers I'm using for this project are Infinity 3032cf Reference series and the bands I'm looking for in the EQ are 50Hz, 200Hz, 800Hz, 3KHz, 12KHz (5 band) + 120Hz and 8KHz (7 band).

Any help will be greatly appreciated and props will be given when the project this is going into is completed/unveiled. :up:

WL i know this isnt helping but you should hit up rob on guru3d, hes there guru audio lab person and im pretty sure he will have a answer :)

You should be able to buy kits that will get you 80% there. Then its just about packaging it up in the correct way and wiring it all together.
Radioshack should have a kit for the amp.
As for the equaliser thats a bit more tricky but something like this - http://www.quasarelectronics.com/sma...-equaliser.htm should work ok.

Personally I would take the easier route by finding something that already does what you want (car stereo, or audio seperate) and then remove the parts I want and repackage them.

Tbh you are going to want a 30 watt amp at least! Otherwise you will run into clipping quite easily and that can damage speakers.

Depth may be an issue for the filtering caps and any reason you want it in your computer?

Scythe makes an ~8Wx2ch integrated amp that'll fit inside a 3.5" bay. It's the Kama Bay AMP mini.

Anyways; choose an appropriate amp for your speakers. That of course will depend a lot on their nominal load and efficiency. High-efficiency speakers don't necessarily need big amps, but you won't get far with small amps on low-efficiency speakers.

Apologies for my tardiness guys, I've been a bit busy doing further research on this.

I need to make some small amendments after reading your posts and doing my further research. It seems I have a wasted band that I chose and that would be the 50Hz band. The speakers response range starts @ 85Hz so anything below that is kind of wasted. Here are the full specs on the speakers (as I know them).

http://img440.imageshack.us/img440/810/speakerspecs.jpg

So the new bands are 120Hz, 480Hz, 1kHz, 3kHz, 12kHz (5 band) + 240Hz and 8KHz (7 band). I also realized that an on-off switch is more or less pointless but I will need to keep the volume control.

Quote:

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Originally Posted by Holst

You should be able to buy kits that will get you 80% there. Then its just about packaging it up in the correct way and wiring it all together.
Radioshack should have a kit for the amp.
As for the equaliser thats a bit more tricky but something like this - http://www.quasarelectronics.com/sma...-equaliser.htm should work ok.

Personally I would take the easier route by finding something that already does what you want (car stereo, or audio seperate) and then remove the parts I want and repackage them.

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A look through the RS site didn't reveal any kind of amp kit, only this, which seems a bit under powered and uses 9V. :shrug:

That link to the Eq is neat, too bad it's mono. :( It did give me some ideas so I did some further searching to see if I could find something a bit more useful. I did find some links I need to read a bit more completely.

As for repackaging something already available, most everything is either too expensive or has a fair amount of extra crap that I would need to figure out how to get rid of yet keep all the functionality in tact which is kind of beyond my current skillset. I also happen to have beside me a Pyrimid 10 band, 200W Geq (that has now for some inexplicable reason, just crapped out on me[no smoke]:shrug:) that I could have done this with but when I opened it. . .well. . .lets just say it isn't pretty.http://deephousepage.com/smilies/shudder.gif

Quote:

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Originally Posted by Panther_Seraphi

Tbh you are going to want a 30 watt amp at least! Otherwise you will run into clipping quite easily and that can damage speakers.

Depth may be an issue for the filtering caps and any reason you want it in your computer?

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This is for a portable MP3 server, so the emphasis is on being 100% complete, portable and compact. Normally, I wouldn't bother going this far for something like this because WMP has a pretty decent Eq already and there are a host of third party software Eq's as well but, there is my problem, this isn't going to be a windows system. It's going to be a Ubuntu system and from looking around, there is only 1 half way decent music player that has a Eq built in and it's a bit flaky from the little bit I've been playing with it. During my writing this post, I just discovered another Linux music player (Banshee) that seems a bit better than the one I had found (Audacious) but I still like the idea of doing this via hardware better yet.

In the course of my research, I found this amp that I may have access through a couple local outlets, would this be a better choice? The case I'm using is aluminum so I could substitute that for their heatsink thereby making the unit much smaller for it to be stuck somewhere out of the way.

Quote:

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Originally Posted by Bobsama

Scythe makes an ~8Wx2ch integrated amp that'll fit inside a 3.5" bay. It's the Kama Bay AMP mini.

Anyways; choose an appropriate amp for your speakers. That of course will depend a lot on their nominal load and efficiency. High-efficiency speakers don't necessarily need big amps, but you won't get far with small amps on low-efficiency speakers.

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That Scythe is also sitting beside me ATM. With the speakers I'm using, they cut out around 60% knob volume (with WMP and Realtek HD Audio manager cranked up). The unit is also too big (even stripped down) to be of any use. :mad:

I don't know how or if any of these cheap ones are, but I've used a few EQ back in my obnoxiously loud stereo days. They all run 12VDC so if you can put up with the size, they should do fine.
http://shop.ebay.com/i.html?_nkw=car....c0.m270.l1313

I would just check their THD levels, should be less than .5% or better for clean sound. Not sure about the amp, most...even smaller ones, are pretty big, but maybe that's something you can do fairly easily with some simple circuits.

Seems like there are a few amp circuits floating about, but I've never attempted one myself. Might be fun to try sometime though:
http://www.ecircuitcenter.com/Circui..._Amplifier.htm

There are also some kits like this floating around:
http://cgi.ebay.com/Kit-88-10W-10W-S...d#ht_649wt_905

Not sure how any good they are, but they look smaller in size.

Quote:

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Originally Posted by Martinm210

I don't know how or if any of these cheap ones are, but I've used a few EQ back in my obnoxiously loud stereo days. They all run 12VDC so if you can put up with the size, they should do fine.
http://shop.ebay.com/i.html?_nkw=car....c0.m270.l1313

I would just check their THD levels, should be less than .5% or better for clean sound. Not sure about the amp, most...even smaller ones, are pretty big, but maybe that's something you can do fairly easily with some simple circuits.

Seems like there are a few amp circuits floating about, but I've never attempted one myself. Might be fun to try sometime though:
http://www.ecircuitcenter.com/Circui..._Amplifier.htm

There are also some kits like this floating around:
http://cgi.ebay.com/Kit-88-10W-10W-S...d#ht_649wt_905

Not sure how any good they are, but they look smaller in size.

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I think buying one of those equalizers will be the best bet.

With some effort you will be able to repackage them into the space you have available.
Without any electronics knowledge it will be hard (and probably expensive) to build what the OP wants from components.
I "could" have a go at building this myself but it would take me ages. Somebody will more skills than me may be able to draw you a circuit that will work without testing.. but not me. I would have to build it and then figure out what I did wrong and fix it :D
Much easier to buy a commercial solution and repackage it especially as these equalizers are pretty cheap. It would be easy enough to remove the lights and switches and mount them into a drive bay.

OK well, a bit more research has revealed a very nice little 40w (20w+20w) audio amp that looks like it might work.

As for the GEq, I see some that are pre-made that are nice but I think I'm still going to try a custom build on this. I work for a school district and am on decent enough terms with the tech teacher in the building I'm in (though he's not very well versed in electronics per se). He can however point me to his sources and resources which may be helpful. I also picked up a pair of books over the weekend on the subject and I've learned by reading the first one that I've actually mislead you guys a bit as I already know a lot of the elemental basics. . .so I'm not quite as uneducated about this stuff as I thought, but I still have a long ways to go before designing an actual control circuit like this. I'll continue to read (and hopefully learn something) and talk to my tech teacher and see what I can come up with.


Martin, YGPM.

Quote:

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Originally Posted by Waterlogged

OK well, a bit more research has revealed a very nice little 40w (20w+20w) audio amp that looks like it might work.

As for the GEq, I see some that are pre-made that are nice but I think I'm still going to try a custom build on this. I work for a school district and am on decent enough terms with the tech teacher in the building I'm in (though he's not very well versed in electronics per se). He can however point me to his sources and resources which may be helpful. I also picked up a pair of books over the weekend on the subject and I've learned by reading the first one that I've actually mislead you guys a bit as I already know a lot of the elemental basics. . .so I'm not quite as uneducated about this stuff as I thought, but I still have a long ways to go before designing an actual control circuit like this. I'll continue to read (and hopefully learn something) and talk to my tech teacher and see what I can come up with.


Martin, YGPM.

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:D

If you have the time to spend and somebody to help you then you should be ok :)
I found quite a few circuit diagrams on the net that will get you most of the way there. Then its just a matter of getting your head around how it works and finding the components.

Good luck and let us know how you get on :)

Well, after a bunch of selective reading, I think I have enough of a grasp to try repackaging the 200W Pyramid GEq. I've already started stripping away the crap I don't need and haven't screwed anything up. . .yet.;) Got rid of the LED's and the Fader and I'm now working on getting rid of the "boost" switch so that it's on full time. Once I get that accomplish, I can set my sights on backward engineering the traces and coming up with a PCB of my own.

I've also been playing message tag with the teacher, so I haven't gotten anywhere on that front, and my impatientness with that situation is what drove me to start with the Pyramid.

I'll keep you guys in the loop as much as I can. . .things are starting to get fun.:hehe:http://undergroundfreakz.com/s/contr.../FIREdevil.gif:smoke:

Guys, I need some help here. I ran into a brick wall trying to get info on the last chip. The number on it is CIC6124E and it's a SIP-9 package type chip. I've Googled the hell out of this thing and there are tons of these chips available still (some from '86 :rofl:. . .tells you how old this GEq is that I'm ripping apart ;)) but, the closest I got to getting any info on this chip is this (link) but it's incomplete (and probably inaccurate). I can't seem to find a free (without any kind of registration) PDF anywhere for this one. If there's anyone that has info on this or has access to a PDF, can you help me out please?

I had a quick google as well but didnt find any more info.

In the past I have had some success getting hold of PDFs from chip manufacturers by emailing them.

Best not to tell them exactly what you are doing, but if you imply that you want to purchase some of these chips you should be able to get hold of a PDF with the info you need :D :D

EDIT - Can you not just use a multimeter to work out the PCB layout by following the traces? Or is it too complicated?

I haven't gotten very in depth as far as that section of the board yet in regards to the traces but I do have a fairly solid idea what it did (note past tense;)). I'm fairly certain it was used to control the LED's as all the LED leads that I removed are right in front of the chip and 5 of the 9 pins traces go to where the LED leads tied into the board. The other 4 pins all seem to tie in someway or another into the 2 20W Power amp chips (1 for each channel).

This board is a mess, the bottom is all traces and they used 23 wires on the top to jump from one place to another on the board in addition to the normal top side components.

You wouldn't happen to know who uses a squarish looking C with IC inside of it as their logo, would you? That seems to be the only kind of manufacturer ID on the chip.

OK, slight correction here on the CIC6124E chip.

This is a scan of the area and I've numbered/labeled everything.

http://img442.imageshack.us/img442/1...c6124earea.jpg

I've also included a .doc with the relevant info. I really believe I can leave this out of the repackage, what are your opinions?


If the .doc doesn't look right, you may need Open Office, that's what I used to create it.

Edit: Added a PDF for better compatibility

Anybody?

I dont know.

From your description it may just be driving the LEDs.. but it may be doing other things as well.

What you really need to do is make a breadboard circuit and try and get it working using your existing PCB and components as a pattern.

Once you have a working circuit you can then remove the bits you dont need and make a new PCB that will fit your size requirements.
If you start removing things without understanding what they do you will get stuck and wont know what your missing.

Can you take a pic of the entire thing (just for my own interest)

A pic of the IC logo might help as well.

It'll have to be later tonight, need to go make money for the bills now. ;)

I am tempted to pull it from the board now just to see if everything still works the way it should and should accomplish the same thing as the breadboard idea, no?

OK, so here are scans of the full PCB (top and bottom) and a pic of the chip itself.

http://img651.imageshack.us/img651/5047/pyramidpcb.jpg

http://img573.imageshack.us/img573/5910/topan.jpg

http://img19.imageshack.us/img19/3016/cic6124echip.jpg

I got restless when the forum went down so I pulled the chip from the board and everything still works fine, afterwards I also removed the 2 caps and resistors directly behind the chip without any ill effects as well. :up:

I did give myself a scare though, when I powered it up after removing the chip there was an awful transformer hum coming from the speakers and I thought "OK, that's not good. . .put it back in". Well, I put it back in and the hum was still there and I thought "great! Just screwed the whole thing up!:brick::mad:". Then I had a thought to try another PSU and the hum went away. . .pulled the chip again and sound was clear. Seems 1 of the little 12v power bricks I got from P-PC's doesn't like this project while the other one does, also tried with a normal 350w PSU with good results.

Later today, the boost switch (upper left hand corner) will be removed and jumper wires will replace it where they are needed.

OK, so I've slowly been plugging away at this and have made a bit of headway as you can tell form the pic. I've managed to completely remove the switch and everything else in the immediate area by means of relocation or simple removal due to no longer being required. The speaker outs (Yellow and White wires by power amps) were moved to their current locations after a couple of steps between the amps and their locations by the switch became redundant by removing the switch. Also relocated 12v+ to a location closer to the switching transformer due to a redundancy there as well.

Added some Enzotech heat sinks to the power amps (kind of regret that now as they're gong to be a headache to get off) when I noticed how hot they were getting during some testing.

The quad op-amps turned out to be a blessing in disguise. The chips on the GEq are NEC C324C's and I took them off to try some early layout ideas on a breadboard and noticed that underneath them, LM324 was silk screened on the board. Checked out the data sheets on both and for all intents and purposes, they're the same. :D That means I can get replacement chips at Radio Shack if I screw something up there (which I'm not expecting to happen but, the safety net is nice to have;)).http://www.xtremesystems.org/forums/...es/elefant.gif That just leaves me to worry about the µPC1230H2 power amps. :para: Well, that's it for this update...back to the grind. :cord:

http://img19.imageshack.us/img19/3048/top2dl.jpg

now that the gurus are all here. when soldering do you guys recommend the glasses like these?
http://www.amazon.com/Slot-Replaceab...sr=1-3-catcorr

or something like this?
http://www.amazon.com/Jumbo-Helping-...=pd_sbs_misc_3

Quote:

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Originally Posted by trans am

now that the gurus are all here. when soldering do you guys recommend the glasses like these?
http://www.amazon.com/Slot-Replaceab...sr=1-3-catcorr

or something like this?
http://www.amazon.com/Jumbo-Helping-...=pd_sbs_misc_3

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Those in the first link give me headaches and I wind up looking cross eyed for a while after taking them off. The second one looks OK but I don't like everything so close together. I have a separate iron stand and helping hands w/mag as well as a bigger magnifying glass.




OK guys, got a update worth putting up for y'all.

So I got a partial list together and went to the "unorganized" electronics store on Monday and walked out a bit poorer than I was expecting to (think I'll suffer through excessive choice overload @ 1 of the online retailers next time). Got all but 2 of the resistors I need and got a few of the Mylar caps too. What he didn't have in stock, I (foolishly) had him order. :brick:

Would you believe this came to just over $50? :eek:
http://img96.imageshack.us/img96/1214/goodies1.jpg

Sunday night I came across a link to a PDF that I sorely needed in regards to the µPC1230H2 power amps. It had the schematic of the chip and a couple of cross ref #'s (ECG1389 & NTE1389). I highly recommend that if you do any kind of electronics work, you D/L this PDF, it's pretty well stocked. It may someday save your bacon like it did mine.

PDF Download link (Enjoy ;))

Looking through the shelves of stuff at the store, I noticed a bunch of stuff from NTE sorted by part # in bins and thought "NAAAAH! He wouldn't possibly carry those.". . .well, he did and I helped myself to 2 of the 3 he had. :D:rocker::eleph:
http://img26.imageshack.us/img26/5893/goodies2.jpg

On the way home from work, I stopped by Radio Shack and picked up what they had in stock of LM324's and a PC board that should be large enough for everything to fit on.
http://img829.imageshack.us/img829/3407/goodies3.jpg
Tomorrow, I need to hit the Shack close to my house and see if they have 4 more LM324's so I have the correct amount and I'll start poking through the online giants tonight for the ceramic disc and electrolytic caps I need. . .I don't feel like getting soaked again. :shakes:

Well, that's it for the update. Now I need to start figuring out the best way to lay all this crap out. :rofl:

Guys, I need some help here. I've got a few (probably stupid) questions regarding caps. If you look at post #20, you'll see 2 very large caps near the amp circuits, these are 1000µF 16V caps that measure ~13mm Ø x 16mm H. I've been scavenging a bunch of old dead (or useless) electronics and I came across a 270W SPI power supply that had something go very wrong in it (it scrambled my brand new FC-5 a bit so that it thought full voltage was 16.1V :eek:). Anyway, I found it has some caps (which I've already pulled) that are exactly the same ratings (1000µF 16V) but they are only 8mm Ø x 19mm H, is this going to matter at all or is the only important thing the ratings?

Second Q is about voltage. I need 2 2.2µF 16V caps for one of the bands and I came across some 50V versions...will this affect the band at all?

Third Q is about µF's and their affect on bands. This GEq is kind of old and it has some 0.12µF 16V caps (purple cap under the 5th slider from the right next to the black cap in pic in post #20) for another of the bands. I can't seem to find these new anywhere and was wondering what kind of affect I might run into if I swap the 0.12µF for a 0.1µF?

As long as the cap rating is the same it "should" work ok.
The "should" is there because the ESR (quality) rating may be different, which may then affect sound quality (I doubt I would notice but somebody who uses a GEq might)

You should be ok using the 50v cap in the place of a 16v one.. however it will be much bigger.

Without knowing what the 0.12uf cap does its hard to say if you can swap it for a 0.1uf one. However I would avoid doing so unless you have no choice.

Have you thought about making a PCB yourself by etching one? This might be easier and more space efficient than using breadboard.

If you are planning on more projects like this one then its well worth scavenging as many electronic components from old stuff as you can, buying new components is expensive unless you buy 100's
You can also get bags of random resistors/caps and other things on ebay for good prices if you keep an eye out.

Quote:

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Originally Posted by Holst

As long as the cap rating is the same it "should" work ok.
The "should" is there because the ESR (quality) rating may be different, which may then affect sound quality (I doubt I would notice but somebody who uses a GEq might)

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Well the Pyramid GEq I have is from the mid to late 80's so I'd have to guess that the ESR of todays caps is a bit better. :shrug: I'm certain everything I've scavenged so far is a minimum of 5-7 years newer than the GEq and most of it is post 2000.

Quote:

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Originally Posted by Holst

You should be ok using the 50v cap in the place of a 16v one.. however it will be much bigger.

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Actually, the 50v is smaller than the 16v (4mm x 7mm compared to 6mm x 11mm). :eek:

I'm also planning on swapping out 8 100µF 10V for some 100µ 16V I pulled from a pair of dead ECS MoBo's. They're the same diameter but half the height of the 10V jobs which should help keep this on the compact side height wise.

Quote:

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Originally Posted by Holst

Without knowing what the 0.12uf cap does its hard to say if you can swap it for a 0.1uf one. However I would avoid doing so unless you have no choice.

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Well, I was about to post up a image that I'd spent a fair bit of time on (about 3hrs:shakes:) of the 0.12µF circuit until I noticed it was epic fail.http://img825.imageshack.us/img825/7484/facepalmw.gif This will have to wait until tomorrow, I need to get some sleep. I will say however that I'll pull the ones I have if I have to, it's just that I'd prefer some longer leads if possible.

Quote:

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Originally Posted by Holst

Have you thought about making a PCB yourself by etching one? This might be easier and more space efficient than using breadboard.

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Yep, I actually have all the stuff here that is needed. It was meant for another part of this same build that didn't materialize due to size limitations I just couldn't get around. Just don't know if I want to commit to that undertaking yet though. I actually find breadboards easier to work with.

Ahhh, the 1980's bit explains alot. The cap size, the old looking design and the ancient components from manufacturers that went bust long ago also the lack of PDF documentation :D :D

The modern caps should be ok even if they are smaller, but just because the caps on the board are old dont assume they are lesser quality. This was probably an expensive bit of kit when new.

Get it working on the breadboard and then transfer to an etched board if you want to neaten things up.

OK, so here's an image showing exactly how the 0.12uF cap is being used. I lit the PCB from the bottom so you can see all the components and traces at the same time.

The way the circuit is setup, it starts @ the 120KΩ on the right, signal then splits and goes to the LM324 pin 12 & the 332 Mylar cap, signal from the Mylar cap goes straight to the 0.12 cap, the other part of the signal comes out pins 13/14 and splits up, 1 path goes through a 560Ω resistor to the 0.12uF cap and the other through a 5.6KΩ to the ground rail. The 0.12uF cap then goes to the 1KHz slider.

http://img109.imageshack.us/img109/4...apfinal.th.jpg

if you want to upgrade those lm324, might want to consider something like OPA4134

Most of those capacitors are what actually do the filtering and amplification. I hope I am not preaching to the choir, is that of only two circuits classes.

For reference, Impedance is the frequency dependent variant of resistance, basically the point of your EQ system.

The basic setup for most EQs I have seen (I have only made one as a test for very limited frequency bands)
Involves piping the sound through a number of RC circuits with calculated impedance to match your goal EQ frequencies, then running that through an op amp with a voltage follower loop. Afterwards, the influence of this RC filter is moderated by a potentiometer (the impedance of which is simple its resistance)

I can attach a PDF of a simple lab we did last semester, it is written in very simple language and may be helpful for you to actually do, just to get an idea for what is going on.

Quote:

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Originally Posted by oohms

if you want to upgrade those lm324, might want to consider something like OPA4134

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Actually, I am looking to replace 1 of the LM324's. Only half of it is used and I don't see the sense of wasting prime real estate on half a chip that does nothing. I'm looking at getting a single LM358 to replace it, from the documentation I've found, it looks to be a dual op amp from the same family. :shrug: Can anyone confirm this? If this is the case, I've already got a NTE cross ref number for the chip that I can likely get locally, it'll give me an excuse at the very least to go back to the store where I got all the goodies I posted earlier and find out how my "ordered items" are coming along. ;) Thinking I'll go with Digikey for future purchases as overwhelming as the site can be.http://img207.imageshack.us/img207/3521/smileypanic.gif They've obviously got a huge selection and decent prices from the looks of things and I can order only what I need which will also lower costs a good bit.

Quote:

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Originally Posted by cdolphin

Most of those capacitors are what actually do the filtering and amplification. I hope I am not preaching to the choir, is that of only two circuits classes.

For reference, Impedance is the frequency dependent variant of resistance, basically the point of your EQ system.

The basic setup for most EQs I have seen (I have only made one as a test for very limited frequency bands)
Involves piping the sound through a number of RC circuits with calculated impedance to match your goal EQ frequencies, then running that through an op amp with a voltage follower loop. Afterwards, the influence of this RC filter is moderated by a potentiometer (the impedance of which is simple its resistance)

I can attach a PDF of a simple lab we did last semester, it is written in very simple language and may be helpful for you to actually do, just to get an idea for what is going on.

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Thank you. You've confirmed something I thought I recalled finding on the net when I started this project but have been unable to find that link again (forgot to bookmark it and don't remember the search phrase used:brick:).

Quote:

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Originally Posted by Waterlogged

Actually, I am looking to replace 1 of the LM324's. Only half of it is used and I don't see the sense of wasting prime real estate on half a chip that does nothing. I'm looking at getting a single LM358 to replace it, from the documentation I've found, it looks to be a dual op amp from the same family. :shrug: Can anyone confirm this?

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Anyone?

LM358

LM324

Please note that the PDF's also list a LM324A and LM358A which are a bit different and are not the chips being used.

OK, so I went back to the electronics store where I got most of the goodies for this project so far for the NTE928M (LM358) and I can definitely say...soakage! :mad: $4.44 (before the 8.75% sales tax) for a chip I can get for under $ .50 from Digikey. I also talked briefly with the guy that ordered my stuff and he thinks it "should" be in sometime next week...another reason to shy away from there, it'll be almost 3 weeks since I ordered it when I get it.:rolleyes: Anyway, I got the chip home, pulled it out of the bag and noticed that those w**kers over at NTE didn't even actually make the chip. I can clearly make out the TI logo and LM358P underneath the NTE printing when I hold it at a certain angle to the light. :shakes:

You can barely see "LM358P" hiding under the NTE printing here.

http://img155.imageshack.us/img155/4852/nte928m.jpg

Some clever pic taking reveals the truth behind the manufacturer ;)

http://img411.imageshack.us/img411/3069/nte928m2.jpg

Anyway, I'm seriously toying with the idea of doing a custom circuit board for this and have gone so far as to resurrect my Shuttle SS51G with Windows Millennium on it so I can use my trusty IMSI TurboCAD 7.0 that has tons of electronics parts drawings already drawn up that I can use to help lay it out. I'm also considering going SMD as much as possible for the custom board as it'll help miniaturize the board even further. It'll mean reordering almost everything from scratch from Digikey but, I think it could really be worth the added cost/headache(?). I'll just keep going through the motions with what I've currently got/have coming and use this one as a valuable learning curve "experiment" or "proof of concept" run.

Waterlogged, on post 31, it is ok to use the LM358.

I recomend mouser.com for parts, it has a very advanced search function, and all the parts have data sheets.
http://www.mouser.com/

Quote:

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Originally Posted by pby5cat

Waterlogged, on post 31, it is ok to use the LM358.

I recomend mouser.com for parts, it has a very advanced search function, and all the parts have data sheets.
http://www.mouser.com/

---

Thanks for the confirm pby5cat. :up:

I actually plan to use them as backup for whatever Digikey doesn't have. I had a good chuckle when I was getting the NTE928M, I noticed a bag on one of the shelves that still had a Mouser sticker on it, I had to keep myself from laughing out loud.

Geez, I'm a bit bored ATM and got to thinking that if NTE "repackages" the LM358 chips from TI, then maybe they do it from other Manu's as well...I soon found my answer. ;)

This is the 20w Power amp chip. It clearly says "µPC1230H2" (just like my original chips :D).
http://img517.imageshack.us/img517/83/nte1389.jpg

Looks like NTE may be nothing more than an industry parasite...it doesn't really matter to me as long as they keep making chips I need available. :p:

just make sure to have adequate cooling for the amp chips. it's looking like you've ended up with alot of parts that have increased capabilities. you CAN overdrive amp chips to a certain point as long as you have the right cooling... kinda like going water cooled for computers.

infact, that being said... if the amp chips are just the right size, you might want to consider doing your board just right to allow for say... a small water block for a MOBO power regulator and use that for your chips if your tower is WC'd. you wouldn't have much worries about cooling flow in such a cramped space and you wont have degraded performance over time from heat soak.

just a couple ideas to throw at ya ;)

Quote:

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Originally Posted by skuldarin

just make sure to have adequate cooling for the amp chips. it's looking like you've ended up with alot of parts that have increased capabilities. you CAN overdrive amp chips to a certain point as long as you have the right cooling... kinda like going water cooled for computers.

infact, that being said... if the amp chips are just the right size, you might want to consider doing your board just right to allow for say... a small water block for a MOBO power regulator and use that for your chips if your tower is WC'd. you wouldn't have much worries about cooling flow in such a cramped space and you wont have degraded performance over time from heat soak.

just a couple ideas to throw at ya ;)

---

:rofl:

You know what, I'm one step ahead of you on that. I had the thought last week and have already found a block that'll work...was just a bit afraid to mention it for fear of ppl thinking I'd completely lost my senses...but then again, I'm putting a GEq in a computer sooooo...maybe I have lost my senses. :nuts: I even PM'd a buddy to tell him about what I was thinking about doing and that "I may need help". :ROTF:

@Waterlogged: THIS IS XS!! watercooling things that make heat doesnt make you weird.:D

Quote:

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Originally Posted by pby5cat

@Waterlogged: THIS IS XS!! watercooling things that make heat doesnt make you weird.:D

---

Well. they are only 20W a piece but...point taken. ;)

http://img511.imageshack.us/img511/6331/xssmall.gif
:rofl:


Got a new quest for this project. . .to incorporate a 12V DC PSU. I spent the better part of Sat poking and prodding around the transformer area to see what kind of requirements I was facing and I've got to say, I don't think they're too bad. I used one of these power bricks (Link) for the testing and all worked well but. . .it's too damn big to fit into the build. It is also far more powerful than what's needed which is the most important thing I learned from the testing. The test equipment was a Kill-A-Watt P4460 (Link) that was used to measure amp draw from the wall and a Klein MM1000 DMM for voltage. The peak numbers I saw were .61A draw from the wall, 8.6mV draw from where the power hits the PCB to the transformer in and 147.8mV through the transformer. These are absolute worst case numbers as I had the volume all the way up on the computer and on Youtube and I also had full gain on every band on the GEq (which will be unrealistic in everyday usage as I dislike a lot of 2K+ bands added to my music, too sharp). I'm thinking I can get away with something that will have 120V in (I can tie this into the normal power supply at the AC in terminal connectors) and have 12V 1A output and still have a fairly decent safety margin, would this be correct?

If so, this is where I need your help. I have an old USB HDD enclosure that bit the farm a while ago but the wall wart is still good. It has plenty of power per my guess work (12V 1.5A) but when I went to test it, well, it made the nastiest buzz in the speakers so that one is a no-go. It was while I was poking around looking for something similar that it occurred to me that I would probably be better off trying to put this on the the circuit board as well. Well, I've seen lots of diagrams on how to do this kind of thing but I have no clue if the power I'm going to get out of any of them is going to be clean enough for my needs. What I need is a design that is known to give super clean power at the ratings I actually need (i.e. no hum, buzz or static when I test it)...any takers? Typical diagram and parts list is all that's needed this time as I've gotten a bit more used to reading them since I started this topic. ;)

So the input voltage of the GEQ is 12 volts?

To reduce the noise on that HDD power supply, put a 100uF+ cap across 12v to ground. make shure the cap is rated for 15+ volts, and if it is an electrolytic cap you match the palority.

What about your computer powersupply? ATX spec requires less then 120mVpp noise, and any good manufacturer runs at about 80mVpp

For low a noise PS you need a Linear power supply, which has a ripple of 4mVpp. A switching PS for your needs is about 120mVpp. Follow the link for a small linear PS, please check the dimensions in the data sheet, under case type B. http://www.mouser.com/ProductDetail/...V7BK3RezC40%3d

You can also use a DC to DC converter, which has a 75mVpp. the link is a 12volt in, 12 volt out. http://www.mouser.com/ProductDetail/...F6h9ilfp77c%3d

Quote:

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Originally Posted by pby5cat

So the input voltage of the GEQ is 12 volts?

To reduce the noise on that HDD power supply, put a 100uF+ cap across 12v to ground. make shure the cap is rated for 15+ volts, and if it is an electrolytic cap you match the palority.

What about your computer powersupply? ATX spec requires less then 120mVpp noise, and any good manufacturer runs at about 80mVpp

For low a noise PS you need a Linear power supply, which has a ripple of 4mVpp. A switching PS for your needs is about 120mVpp. Follow the link for a small linear PS, please check the dimensions in the data sheet, under case type B. http://www.mouser.com/ProductDetail/...V7BK3RezC40%3d

You can also use a DC to DC converter, which has a 75mVpp. the link is a 12volt in, 12 volt out. http://www.mouser.com/ProductDetail/...F6h9ilfp77c%3d

---

Hi pby, Thanks for taking the time to post but, it may be kind of moot now unless that same kind of setup will fix the new problem? I just knew someone was going to post as I was writing up the post below (damn that Murphy:shakes:).


OK, so I found a wall wart that supplied clean power (old M$ Sidewinder joystick PSU) that is rated @ 12V 1.3Aand quickly found out...it's not enough juice. :down::( Volume was noticeably reduced and didn't sound quite as good as it has with the power brick. I then decided that I would try it with the NeoHE550 that's in my daily driver (the one I'm posting this from) and got this.

http://img703.imageshack.us/img703/3960/geuv.mp4

At video start to :10, computer is completely idle

At :10 to :20, I'm moving the cursor around.

At :24 mark, new noise is "reload every" doing a reload of the LC section page.

At :35 mark I open Ubuntu's system monitor and leave it open until the end of the vid.

Is this EMI or RFI? Can I filter these noises out and use the regular PSU to power the GEq? It would make this a lot easier if I can. :yepp:

For reference, this (Link) is the PSU I will eventually be using in this build. It's the most powerful that will fit in the space I've been able to make for it. There is also an iStarUSA PSU (Link) that is a bit more with the same specs if that would be any better?

If you have an oscilloscope, put the probe on the 12volt and the clip on ground. post a picture of the screen showiing the noise. Make shure to include volts/div and time/div settings in your post.

Try a 100+uF capacitor like i talked about above, across the 12volt to ground, and see if the noise goes away with your computer PS.

I think the PS you linked are made by the same OEM. outside of the labels, everything is identical as far as i can see. The Istarusa should be better, due to the company making server stuff.

EDIT

A 7812 regulator would work. It takes 12 volts in and spits out 12 volts, but it is a regulator so it has ripple and noise suppressors and corrects for voltage fluctuations. you will need a .33uF filter input cap and 1uF output capacitor. Preferably tantium or polymer, somthing non electrolytic. The regulator and caps should be about $2. This chip will output 1Amp in free air, and up to 2.2Amps heatsinked or waterblocked. The mounting tab on the top is connected to ground, so use a grey or pink thermal pad and electricly isolate the screw head, so you dont ground out your water loop. http://www.mouser.com/ProductDetail/...jep01a5GgKU%3d\

Updated DC/DC conveter speced at 65mVpp noise http://www.mouser.com/ProductDetail/...2bzmSVcZJv4%3d

No scope. . .anyway, I've got to take a step back from this for a couple reasons.

1. I find myself switching from "filter" to "separate PSU" on a almost hourly basis. I need to stop and figure out what will be the best decision for the project before I commit anymore time to this "power issue".

2. Yesterday, I went to replace the toilet and linoleum and found out I need to replace the sub floor as well. :rolleyes: I already had a trip planned to FCPU today and as soon as I get back from that, I commence demo on the bathroom. It may be a day or so before I'm back. ;)

I would be tempted to go the filter route.

I think it will be just as hard to build a separate PSU that will give the clean supply you need as it will be to clean up the pretty good 12v from the PC PSU.

A filter will be smaller and safer (as you wont be running mains power into the EQ)

Yes go with the filter idea.

First, try the 100+uF cap across the 12volt to ground right at the PCB connects. This should be an easy 10 min test. If it isnt better i would go with the regulator.

Quote:

---

A 7812 regulator would work. It takes 12 volts in and spits out 12 volts, but it is a regulator so it has ripple and noise suppressors and corrects for voltage fluctuations. you will need a .33uF filter input cap and 1uF output capacitor. Preferably tantium or polymer, somthing non electrolytic. The regulator and caps should be about $2. This chip will output 1Amp in free air, and up to 2.2Amps heatsinked or waterblocked. The mounting tab on the top is connected to ground, so use a grey or pink thermal pad and electricly isolate the screw head, so you dont ground out your water loop. http://www.mouser.com/ProductDetail/...jep01a5GgKU%3d\

---

I am an electrical engineer, and i have electrical test equipement so id like to help if i can. PM me if you think of someway my equipement can help.

Tried the cap (all the way to 2200uF), didn't seem to work.

Both you gentlemen have a PM. ;)

pby5cat, per my last PM to you, I finally got the chance to set the system up on the test bench (you have no idea how excited I was to be at this point of the project with all the sub systems :eleph:) with the 270W PSU and the highest wattage spike I saw was ~116W. This was while playing a CD and with everything but the actual HDD's I plan on using (had 1 3.5" SATA instead of 2 2.5"). Unless this is some sort of false sense of security it's trying to give me, I think the 270 is going to be fine. I also didn't seem to have any of the static, crackle or other noises with the 270W PSU that I got from my 550W NeoHE. :shrug: I'm gonna play with it some more to make sure on that though. ;)


Anybody know how much power a GPU fan header supplies? The card in question is a Zotac 8400GS (ZT84SEH2P-FSR). The fan it comes with is "rated" @ .11a according to the label but, I'm sure the header is capable of more than that, just don't know how much more. :shrug:

Congrats on the test.

The physical fan header could probaly do 1amp safely, but the fan speed controller circuitry has an uknown current rating.

Atleast .11A is safe.

Quote:

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Originally Posted by pby5cat

Congrats on the test.

The physical fan header could probaly do 1amp safely, but the fan speed controller circuitry has an uknown current rating.

Atleast .11A is safe.

---

Thanks pby5cat. . .guess that rules that idea out. :poke: I was planning on tidying up the wiring a bit by putting that 10w item on the fan header but, that doesn't look like that's going to be a good idea after all.:( Probably for the best anyways, I've been playing with it some more and it seems my current custom cabling system is messing with the colors...I've found the appropriate connectors and pins @ Digi but I'm now thinking to get my order @ Mouser instead (they have some DMM fuses I need that Digi doesn't have). Just a matter of finding them @ Mouser now.

I've also had it with the local shop, I "ordered" some Mylar caps and some ¼w resistors from there on Jan 31 and haven't gotten a single phone call from them yet...not the way you should run a customer based business IMO. :down: I'll be getting the stuff I didn't get from them likely from Mouser when I make my order.

I'm half surprised you haven't hit up DIYAudio.com for this project. somma them guys n gals are geniuses. lots of old-hands and engineers over there from all walks of audio design and implementation.

Quote:

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Originally Posted by defect9

I'm half surprised you haven't hit up DIYAudio.com for this project. somma them guys n gals are geniuses. lots of old-hands and engineers over there from all walks of audio design and implementation.

---

defect9. . . . .where the hell was this post when I started this topic?:mad::slapass::p:

First time I've heard of that site. I poked around some and wow...those folks are a little scary the way they debate the finer points of electronics (like metallized vs foil foil caps). Kind of like the way some of the LC guys debate pump or fan noise. :eek:

I'm pretty happy with the way things have turned out though, I just have a major decision to make on if I go ahead with the original plan to prototype using the breadboard and then do the real one or dump that idea and go to one of three plans.

Plan one is to go ahead and finish getting the parts I need to finish the breadboard and use that as is.
Plan two is to build a custom board and use the parts that were to go on the breadboard.
Plan three is to drop all the through hole parts and replace everything possible with a custom SMD board design. I'll still need the power amp chips I got but mounting them on SMD pads isn't going to be a problem and should actually make them sturdier for mounting the water block.

I'll probably have to price out each option to make the decision though. :rolleyes:


Got two questions for anybody that can answer it. 1. Is dropping from a 0.12uF aluminum electrolytic cap to .1uF aluminum electrolytic cap going to make a noticeable difference for the one channel? I'm thinking that I likely won't be able to tell the difference. 2. I've been lining up Nichicon KW series for the aluminum electrolytic caps, would these a good choice?

The change from .12uF to .1uF could change the center fequency of that channel slightly, but most likey unnoticable.

Use Nichicon FM series due to lower impedence, then fill in with FC or HE series if need be.

Quote:

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Originally Posted by pby5cat

The change from .12uF to .1uF could change the center fequency of that channel slightly, but most likey unnoticable.

Use Nichicon FM series due to lower impedence, then fill in with FC or HE series if need be.

---

I can't find Nichicon FM or FC series...did you mean Panasonic? Also, is lower impedence the only reason to choose a general purpose cap over the audio grade (KW's) caps? Not trying to be a smartass, I'm genuinely curious why a general purpose would be recommend over a cap that was made for the purpose I planned to use it for.:confused::shrug:

1 more Q about the 0.12uF, would changing from an Aluminum Electrolytic to a Polyester Film affect the way the band sounds any? I'm asking because I found them in Polyester film.

Oh im sorry, all the "F's" are panasonic. The lower the impedance, the more current can go though the cap and lest impact the cap has on the circuit. The impedence is called the ESR, Equivelent Series Resistance. So when mobo companies say they use Low ESR caps in the CPU power circuitry, they are increasing the effeciency and lowering heat dissipation of the caps and inducters. Say if a normal cap is .8ohms and u have the CPU using 80Amp split between 8 phases, thats 10A per cap. so P=IV each cap has to deal with 8 watts. If that ESR was .08 ohms, the cap dissipates 0.8 watts.

Electrolytic to film is about the bigest change possible in caps. The films mostly have a lower ESR. When it comes to sound the ESR changes with frequency. Im not shure if you would know the difference, try both?

while you're pricing out options, consider something like this for your amp stage, as it's primarily all SMDs except the things that would be far too expensive to SMD. You can run it off the computer PSU directly, or off a meanwell switching psu (which is basically what your computer psu is, only the meanwell is obviously smaller). sounds amazingly clear and clean, even with floorstanders. and even running the bugger for hours on end with punishing music through 3-way floorstanders, it gets barely hotter than room temperature.

I still haven't found anything right for your EQ though. considered mentioning some of the smaller car-based EQs you could gut, but probably no better than what you've already found. just incase, here's the ones i found. option a option b

Oh, and polyester film is generally considered to sound way better than electrolytic when comparing same capacitance. basically consider electrolytic to be the least desireable in the audio path, but an excellent choice when used in a PSU filter for its polarity properties (or something like that, i'm no guru).

Quote:

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Originally Posted by pby5cat

Oh im sorry, all the "F's" are panasonic. The lower the impedance, the more current can go though the cap and lest impact the cap has on the circuit. The impedence is called the ESR, Equivelent Series Resistance. So when mobo companies say they use Low ESR caps in the CPU power circuitry, they are increasing the effeciency and lowering heat dissipation of the caps and inducters. Say if a normal cap is .8ohms and u have the CPU using 80Amp split between 8 phases, thats 10A per cap. so P=IV each cap has to deal with 8 watts. If that ESR was .08 ohms, the cap dissipates 0.8 watts.

Electrolytic to film is about the bigest change possible in caps. The films mostly have a lower ESR. When it comes to sound the ESR changes with frequency. Im not shure if you would know the difference, try both?

---

OK, I somehow understood what you said :ROTF:...it's just...I can't find impedance values for the KW's on the PDF (Link), they have an "impedance ratio" though but, I can't compare it to the Pana's. On top of that, none of the series you listed go as low as I need them to for 3 of the cap values...but the KW's do. :shrug: That was one of the 2 reasons I was looking at them, the other being they were "audio grade" which from what I understand (maybe mistakenly), are supposed to have decent impedance.

The GEQ has the following AE caps:

• 0.12uF 16V
• 0.22uF 16V
• 0.47uF 16V
• 1uF 16V
• 2.2uF 16V
• 4.7uF 16V
• 47uF 10V
• 47uF 16V
• 100uF 10V
• 1000uF 16V

The original plan was to replace all these with 50V Nichicon KW's but now I'm not sure.

Quote:

---

Originally Posted by defect9

while you're pricing out options, consider something like this for your amp stage, as it's primarily all SMDs except the things that would be far too expensive to SMD. You can run it off the computer PSU directly, or off a meanwell switching psu (which is basically what your computer psu is, only the meanwell is obviously smaller). sounds amazingly clear and clean, even with floorstanders. and even running the bugger for hours on end with punishing music through 3-way floorstanders, it gets barely hotter than room temperature.

I still haven't found anything right for your EQ though. considered mentioning some of the smaller car-based EQs you could gut, but probably no better than what you've already found. just incase, here's the ones i found. option a option b

Oh, and polyester film is generally considered to sound way better than electrolytic when comparing same capacitance. basically consider electrolytic to be the least desireable in the audio path, but an excellent choice when used in a PSU filter for its polarity properties (or something like that, i'm no guru).

---

The topic started off as something of a moving target. This is because I wasn't sure which direction I really wanted to go in on this project due to my lack of knowledge on the subject. I finally settled on consolidation reconstruction (shrinkage of the PCB to be more precise) of the GEQ I have here with newer components (there will be some selective theft along the way unless I can find replacements for the transformer and slider pots). This guarantees that I get a working product in the size I need the first time without trial and error (well, we'll see about the error part later;))

If that's true about the film's, why don't I replace everything I can with them instead? That'll take care of the 6 lower valued caps and leave me with 3(4) AE type capes to source.

Quote:

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Originally Posted by Waterlogged

If that's true about the film's, why don't I replace everything I can with them instead? That'll take care of the 6 lower valued caps and leave me with 3(4) AE type capes to source.

---

if the electrolytics you're replacing are polar caps (having a distinct positive and negative) which most electrolytics are, the caps you replace them with must also be polar.

TBH, unless you have a really, really good system (every part of the chain, basically, with super sensitive speakers) to hear the difference, even though its considered "a big difference" in the audio world, it's only noticable in close monitoring A/B testing. also where in the audio chain it is will also affect how much difference is noticed anyway. if its tying to ground instead of as a pass-through, there will be less importance on it. still want a good cap though, and bang for buck the panasonics mentioned are great, i love em.

most times it seem to me AEs are picked for ease of sourcing and cost, and when polarity matters.

Quote:

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Originally Posted by defect9

if the electrolytics you're replacing are polar caps (having a distinct positive and negative) which most electrolytics are, the caps you replace them with must also be polar.

TBH, unless you have a really, really good system (every part of the chain, basically, with super sensitive speakers) to hear the difference, even though its considered "a big difference" in the audio world, it's only noticable in close monitoring A/B testing. also where in the audio chain it is will also affect how much difference is noticed anyway. if its tying to ground instead of as a pass-through, there will be less importance on it. still want a good cap though, and bang for buck the panasonics mentioned are great, i love em.

most times it seem to me AEs are picked for ease of sourcing and cost, and when polarity matters.

---

Crap...forgot about the polarity. That kills that idea...hmm, or does it? Looking at the current PCB, I have 3 of 10 bands that use film/ceramic caps in the RC filter circuit, 1 that uses all film caps in the RC filter circuit and the other 6 bands use film/AE caps in the RC filter circuit (ref post #20 for PCB image). I wonder if I can get away with replacing just the AE caps that are part of the actual RC filter circuit with films (these would be the 6 I suggested replacing earlier) and use the Pan's as suggested for the rest...or I could use the KW's for the lower values and the Pan's for the rest...but then again, I see that the KW's are available in lower voltages for some of the caps I need...GAHHH! Too many options! http://img207.imageshack.us/img207/3521/smileypanic.gif :nuts:

*Deep breaths*. . . . .




*sigh*

So let me see if I got this right...If I go with all KW's (like in my original plan), I likely won't be able to tell any difference in the output but I'll be using slightly more power than if I use a mix of other general purpose caps...this about right? Seeing that all the caps I'm looking at are much newer (both in actual usage and materials/design) than the ones on the GEQ I'm basing this design on, the numbers should all be a little bit better shouldn't they? I mean we are talking about a Pyramid GEQ from the mid/late 80's. I can pick up a brand new Pyamid for like $30 US so, they aren't really considered "good kit" to start with.

the difference between caps from the 80's and caps from now is mostly just age and ESR (yes this is a generalization). Caps tend to become more volatile with age. replacing them basically updates their expiration date. honestly while manufacturing techniques of caps and all other audio circuit parts have improved, circuit design is still generally the same. A filter is a filter, whether using ICs or discrete components.

What makes 'great kit' versus 'radio shack base model' is in the tolerance of the parts used, and any extras in the circuit design to combat potential problems (which is an entire book in and of itself). it costs more money (generally) to guarantee better tolerances. That's why really good kit with .1% (or better) tolerance resistors and 1% or better tolerance caps cost so damn much. It means either the technique has to be ultra-rigid and controlled, or the parts have to be more rigorously tested and binned.

if pyramid uses +/- 1% resistors and +/- 10% caps (common), by the end of the audio chain in the EQ if you got completely unlucky and the values were nearly as far off as possible, you could have differences of beyond 3db (which in the wrong area of the audio band would be noticable without direct A/B comparison). However, as even Pyramid has basic testing standards, that would only happen if their test equipment malfunctioned or their tester was drunk/high/getting fired. Yes, each one will differ based on the batches of parts. and law of averages sorta states that odds are as long as they tested it to be within standards, it won't be noticably retarded. But as long as it falls within the acceptable tolerances (which pyramid still cares about, even if it's a budget item), you're gonna get a good piece of kit. I just wouldn't expect it to be the same as something you'd pair with $4000 speakers.

As this is portable and you're not building a quiet room specifically for listening to it, you very likely wouldn't hear that subtle stuff anyway. The EQ itself will shape the sound to your liking way more than your choice in caps. additionally, if you'd be getting the new pyramid and putting everything on a new PCB for space, you're probably just as good in keeping what you already have, replacing caps, replacing pots, and shrinking the footprint. 25v caps are usually a good compromise for keeping voltage overhead in a 12v system and reducing size vs the 50v. for some reason i thought there were also 16v caps out there.

I agree with everything defect9 has been saying about the caps.

Well, I know for a fact all the resistors are 5% because I purchased exact replacements. The film caps are all "J" so their tolerance is 5%. I haven't gotten in depth with the ceramic's yet but, a couple of them say "K" on them so those are 10% and it's probably a safe assumption the rest are 10% as well (feel free to slap me for assuming ;)) The AE caps are going to be a bit trickier. They are made by a company that has "Chief" in the name (perhaps full name?) as that is the only identifying mark on them outside of temp, voltage and uF values. I've done a lot of searching and can not find anything about this company or their caps online. I'm hoping you guys will tell me that the color of the cap can help determine the tolerance value as I have 2 different colored caps (of same voltage and uF, 4.7uF/16V) on the board. The colors are a light blue and a lilac(or perhaps violet?) purple. 4 of the caps are blue, 2 of those are part of the filter circuit between the input wires and the first LM324 (the 1 that's only half used [marked #1 in pic]) and the other 2 are between the output of that LM324 and the power amp chips. The 2 purple ones are part of the 30Hz band filter circuit. Here are some pics of the caps. Maybe you guys can help me figure out tolerance values for these stupid things. I also have 2 pairs of caps that I can't pinpoint the manufacturer name/logo (looks like "CSE" to me), again can't find anything on this brand either.

Warning: First image is very large, do not open if you have a slow connection!

http://img837.imageshack.us/img837/9523/pcblarge.th.jpg http://img852.imageshack.us/img852/6308/colorsx.th.jpg http://img703.imageshack.us/img703/2478/bigcap.th.jpg

Honestly, this constantly having to fight history to find the info I need is really starting to piss me off. :mad: I'm half tempted to throw in the towel on this GEQ and get a brand new one and backwards engineer that one. With any luck, it'll likely have a similar layout with caps in values I can actually get relatively easy. Possibly save my sanity for the paltry sum of $27 + shipping. :idea: What do you think...should I?

you could always search the net for a 5-7 band schematic as well. instead of having to backwards engineer someone elses work, you simply translate the schematic onto a piece of breadboard or into some PCB software.

why physical eq instead of software eq?

BTW, you don't have to match exact tolerance for a circuit like this. tolerance is basically manufacturing value spread. 5-10% tolerance is just fine. if you're anal about being as exact as possible on the caps values, buy extra and measure them by hand with a multimeter that will read in microfarads and pick the ones that are closest to the intended value (like chipset binning, but simpler and faster).

you dont have to copy the tolerance values of the caps, u can use any tolerance you want as long as it is the same or lower.

The colors are done by manufacturers to deferential the companies cap series from each other, and to deter counterfeiters.

Quote:

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Originally Posted by defect9

you could always search the net for a 5-7 band schematic as well. instead of having to backwards engineer someone elses work, you simply translate the schematic onto a piece of breadboard or into some PCB software.

why physical eq instead of software eq?

BTW, you don't have to match exact tolerance for a circuit like this. tolerance is basically manufacturing value spread. 5-10% tolerance is just fine. if you're anal about being as exact as possible on the caps values, buy extra and measure them by hand with a multimeter that will read in microfarads and pick the ones that are closest to the intended value (like chipset binning, but simpler and faster).

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From post #6

Quote:

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Originally Posted by Waterlogged

This is for a portable MP3 server, so the emphasis is on being 100% complete, portable and compact. Normally, I wouldn't bother going this far for something like this because WMP has a pretty decent Eq already and there are a host of third party software Eq's as well but, there is my problem, this isn't going to be a windows system. It's going to be a Ubuntu system and from looking around, there is only 1 half way decent music player that has a Eq built in and it's a bit flaky from the little bit I've been playing with it. During my writing this post, I just discovered another Linux music player (Banshee) that seems a bit better than the one I had found (Audacious) but I still like the idea of doing this via hardware better yet.

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Since I posted that, I've done a little bit more playing around with Banshee and while it's a impressive improvement over Audacious, it still has a couple things I consider "problems", like when the track being played ends and advances to the next track, it doesn't highlight the new track when the program isn't selected (something the stock player [Rhythmbox] does properly). Also, the EQ preamp is touchy as hell which easily distorts the signal and you need to make a new preset to be able to manually adjust the sliders. Also, while I originally dreaded the thought of taking the route I chose, I find myself refusing to settle for a software GEQ now...something about the "unique factor" of having a hardware GEQ in a computer is now very appealing, I think it raises the build to a new level.

As for grabbing something off the net, I have a known working hardware unit here and many of the schematics I've found online are incomplete (missing parts list). The ones I find that are complete use chips that I can't get from Mouser or Digikey or I need to buy 1000 of them. That's why I've stuck with this thing for so long but it's starting to get on my nerves having to fight so hard to get info on almost all of the stuff it was made with. Starting over with something newer is very tempting , and still on the table at this point.


About the caps, thanks guys. I am still something of a noob at this and thought everything needed to be precisely the same. Any guesses as to what tolerance of the AE's might be?

I know you guys are recommending Panasonic FM's, FC's and Nichicon HE's but they simply aren't available in some of the values I need...are there any other caps you can recommend that come in the values I need?.........Hm, will SMD caps/resistors work just as well as standard through hole parts for this? (I'm guessing they will)...If so, lets concentrate on them. While they will be a headache to solder, it should allow me to more efficiently utilize the blank double sided PCB I have and make this unit as small as possible.

I found a 5 chan GEQ IC chip BA3812L, that only needs external pots and caps. When three IC are combined together it can make a 7 point stereo GEQ. http://www.datasheetcatalog.org/data...hm/ba3812l.pdf

About the Q factor mentioned in the data sheet, it controlles the bandwidth in the case of tuned or resenant circuits in ur case. http://en.wikipedia.org/wiki/Q_facto...trical_systems

Follow the equations in the data sheet to set up ur frequency points. Note that R0 and R1 are fixed, so play with C0 and C. Also it looks like C0 > C.

This chip has an output buffer but no amp, so you will need to provide an amplifier chip.

Check google shopping for the chip, its on ebay and one other company.

Operation voltage range is 3.5 to 16 volts, so 12volt is ok.

you're so gonna fry WL's brain with that lol.

Great find pby5cat. it'd be easy as pie (or cake) to add a small footprint TA2020 amp to that eq. Plus the simplicity really does lend itself well to SMD, assuming one can solder smd. last I checked, there's a way to bake SMDs onto a board with a solder designed for such a method, but I haven't googled that recently. so, instead i found a guide to smd soldering

http://www.avrfreaks.net/modules/Fre...ng%20Guide.pdf

I'm gonna be honest, at the rate this project is progressing, I'm considering making one for myself just for the funk of it, though it'd be attatched to a non-computer bound yet still 12v PSU system.

Fry?...it's been sizzling on the back burner for a little bit now. When I looked over that stuff it went

http://img534.imageshack.us/img534/9...yyeventbet.jpg

:rofl:

Sorry pby5cat, I wouldn't even know where to begin with the math to figure out the bands. :shrug:


This topic will be on a short hiatus until probably sometime mid/late next week at the earliest. I just ordered the new GEQ and will wait for it to show up. When it does, I'll crack it open and look it over to see if it's going to make life any easier for me, if so... I'll go with that design. If not, I'm going to forge ahead with the work I've already gotten done and just grab parts in the largest package SMD's I can (hopefully most of them will be 1206, though I'm pretty sure I'll need some 0805 already), for easier handling. Soldering shouldn't be too big a problem as this will be a from scratch build so it should be place the component, tack it, then solder the other side and clean up the tack if need be...sounds easy doesn't it? I'm not expecting things to go that smoothly though. ;):ROTF:

dang, and here I was about to start doing the math. I just about got the entire circuit figured out for layout too (don't ask how long it took staring at it to get to that point).

Looking forward to the continued progress of this one. It definitely falls in the realm of extreme.

OK, haven't forgotten about this. I'm being jerked around by the company I ordered the new EQ from. Ordered on 3-16 and still do not have it yet even though the CC has been charged. I've been patient and understanding but the gloves are now about to come off. This company has a 10 rating on RR over the last 6 months, well, that's about to take a serious hit for starters. . .then I get rough. :mad:

Damn buddy, sorry to hear that. Always sucks when a company that's been great for so long falls down on the job.

Maybe it's a sign. You want me to get the math together on a custom eq? can't be all that difficult as it's just a collection of duplicated filter stages with tweaked values.

Quote:

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Originally Posted by defect9

Damn buddy, sorry to hear that. Always sucks when a company that's been great for so long falls down on the job.

Maybe it's a sign. You want me to get the math together on a custom eq? can't be all that difficult as it's just a collection of duplicated filter stages with tweaked values.

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Thanks for the offer but I final got them to respond and things have been resolved (I didn't even have to get nasty with them). I'm guessing they just simply forgot/overlooked the email I sent asking about several substitute models I was interested in. Turns out they only had one that I have some minor concerns about (height) which costs more than the one I wanted, they sent it without charging me extra for the hassle I've been forced to deal with. Still not 100% happy with resolution but, it'll get me back up to speed on the project. Should have it by weeks end and then I'll start pulling it apart to discover it's secrets.

sweet, good to hear it's moving forward again.

*sigh* Preliminary testing on the unit I got has not gone well. It turns out that it's missing something very important (something which I over looked in my haste to get something shipped to me :shakes:). . .the amplifier. :shock2: I'll play with it some more but I'm pretty sure it's not going to work the way I need it to.

Currently tracking down the original unit that I wanted that has the amp in it, I just need to make sure the store that lists it in stock actually has it before placing the order. It's a different store and it's a refurb but that doesn't really matter to me at this point.

well, uh, damn again. I hope it aint a sign.

A bit late to the concert, but consider some Class D amps or the venerable Chipamps.

I don't see if you've ever found an answer to your questions about the CIC6124E, but I do have some information. Ignore it if you don't need it.

CIC was a spinoff company of Taiwan's International Technology Research Institute (ITRI)¹. ITRI is the same organization that gave us UMC and TSMC². It appears CIC was in operation from 1975 until 2004.

It's my belief this circuit may be similar to a BA6124, but I could be wrong. The BA6124 is a LED Level Meter driver³.

Good, bad or indifferent; I'm curious to know your thoughts on this post. I find your project intriguing and I hope this helps a little.

D

Notes:
1: See registration 1248161 at http://www.uspto.gov
2: http://www.itri.org.tw/eng/about/art...10&NodeId=0101
3: http://pdf1.alldatasheet.com/datashe...HM/BA6124.html

Quote:

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Originally Posted by denali

I don't see if you've ever found an answer to your questions about the CIC6124E, but I do have some information. Ignore it if you don't need it.

CIC was a spinoff company of Taiwan's International Technology Research Institute (ITRI)¹. ITRI is the same organization that gave us UMC and TSMC². It appears CIC was in operation from 1975 until 2004.

It's my belief this circuit may be similar to a BA6124, but I could be wrong. The BA6124 is a LED Level Meter driver³.

Good, bad or indifferent; I'm curious to know your thoughts on this post. I find your project intriguing and I hope this helps a little.

D

Notes:
1: See registration 1248161 at http://www.uspto.gov
2: http://www.itri.org.tw/eng/about/art...10&NodeId=0101
3: http://pdf1.alldatasheet.com/datashe...HM/BA6124.html

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Interesting info indeed. :up: It does look like what I have here, don't need the LED's so I pulled that chip out of the circuit and all is working well ATM.

As for the project, I think I'm going to give up on sourcing a new GEQ and go with what I have already. Prototype will likely be final product for the build as I just want to finish the build (ECS finally released the H67H2-I and I have one on the way:D). I have 2 builds to finish before I can get back to this so it's going to be a few more months before I'll get to it, In 2 weeks I start my "busy time" of the year at work where I start working 8hrs a day instead of 5, so project time will drop as I have 3 less hrs a day and I'm usually beat when I get home and just want to relax so that may add even more time to this project. :(

Quote:

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Originally Posted by Waterlogged

Interesting info indeed. :up: It does look like what I have here, don't need the LED's so I pulled that chip out of the circuit and all is working well ATM.

As for the project, I think I'm going to give up on sourcing a new GEQ and go with what I have already. Prototype will likely be final product for the build as I just want to finish the build (ECS finally released the H67H2-I and I have one on the way:D). I have 2 builds to finish before I can get back to this so it's going to be a few more months before I'll get to it, In 2 weeks I start my "busy time" of the year at work where I start working 8hrs a day instead of 5, so project time will drop as I have 3 less hrs a day and I'm usually beat when I get home and just want to relax so that may add even more time to this project. :(

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Thanks!

I can relate to being busy. College, work and family are eating my brains... :yepp:

I'm definitely going to keep following this thread. Thanks for the reply!

D