Top notch electronics guru's needed

[Waterlogged]

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).

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.

[Johnny87au]

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

[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.

[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?

[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.

[Waterlogged]

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).



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.

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.

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.

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]) that I could have done this with but when I opened it. . .well. . .lets just say it isn't pretty.

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?

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.

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.

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.

[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.

[Holst]

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.

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
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.

[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.

[Holst]

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.

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

[Waterlogged]

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.

[Waterlogged]

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 . . .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?

[Holst]

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

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

[Waterlogged]

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.

[Waterlogged]

OK, slight correction here on the CIC6124E chip.

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



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

[Waterlogged]

Anybody?

[Holst]

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.

[Waterlogged]

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?

[Waterlogged]

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







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.

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!". 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.

[Waterlogged]

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. 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). That just leaves me to worry about the µPC1230H2 power amps. Well, that's it for this update...back to the grind.

[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

[Waterlogged]

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

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.

Would you believe this came to just over $50?


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.


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.

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.

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

[Waterlogged]

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 ). 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?

[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)

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.

[Waterlogged]

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)

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. 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.

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

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

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.

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.

Well, I was about to post up a image that I'd spent a fair bit of time on (about 3hrs) of the 0.12µF circuit until I noticed it was epic fail. 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.

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

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.