Preamps/Dac and digtal/analog

[[DANGERDAN]]

Sarppp fella's im back for hopefully another draw dropping argument because i love to argue xD.
I want to discuss Preamps/Dac and how they affect sound, whats good bad etc. I also want to discuss the technology between our old analog and the new digital.

Il start of with my experience so far that's made me want to look into this, I was researching about DAC/preamps and how it affects sound because i am trying to understand it all better and try and find the best possible way to get the best sound, The preamp is basically the docking station for connectivity but also serves a important job of preamping the signal from the source but generally its only just upping the volts from the 200mv to a preferred level of about 1v.
So we have Preamps and dacs everywhere its just not noticed our tvs output are generally preamps/dac our computer 3.5mil outputs are preamps/dac, pretty much anything that has a headphone or rca output from a audio source is a preamp/dac (dac is subjective to digital source).
Whats interesting is the quality of sound each one has and that it actually is different.
Ok on to the question, what i have done is using my xonar d2x sound card i decided to use it as the preamp and used a 3.5mil jack to rca to connect the sound card to the main in jacks in my marantz amp to bipass the preamp built into my integrated.
To my amazement there was less amp power needed and was also a increase in quality, I made sure of my findings and compared the soundcards pre amp to the marantz pre amp switching back and fourth and there was less volume amplification needed from the marantz.

So my question is when you are connecting the sound card to the preamp in the marantz does the preamp ignore the previous preamp and adjust the voltage to its own and would it be possible that my sound card has a better preamp than the one in my old marantz.

Thanks again guys sorry for the long post and we will get into analog/digital a bit later.

[Nanometer]

That's actually a great question. And then quick answer is no. What comes out of your audio jack comes out of a preamp first stage, then second stage to the power amp which is how the sound is boosted to an audible level. The marantz takes the analog signal and takes note of the input amplitude(which is also the voltage variation) and sends it out through another power amp. The voltage amplitude is important because you can not only control the amplitude on the preamp, but also from the device that the signal is being sent from(ipod,computer etc.)

Should you select a codec such as Music PLIIz the sound is reconfigured using the preamp computer, split to its appropriate channels, and then sent back to the op-amp and then to the power amp.

If you are an electrical guy, the preamp computer is where all the operational amplifiers are located. The amplifier itself contains no operational amplifiers, but instead contains power amps which take a large amount of power in order to boost the signal. An amp is one of the more important components, because of the quality of your sound comes from a quality power amp.

Digital is a different story because the signal is no longer a signal, but a digital stream of 0s and 1s. The process is similar in the preamp and amp processos, but the way the sound is encoded is completely different.

Yes, it is possible to have a better op-amp/ preamp in your sound card, but I would say that is highly unlikely. The days of computer sound cards are over, and digital is in ;)

[STEvil]

How did you determine the different power requirements?

Turning the dial more or less on amped vs non-amped source just means the volume dial is acting in part as a gain on the source.

[[DANGERDAN]]

How did you determine the different power requirements?

Turning the dial more or less on amped vs non-amped source just means the volume dial is acting in part as a gain on the source.

Windows Sound level on 30, WMP on Full, Marantz amp on 40 notch and left there no other settings touched when comparing the two.
When switching between the main in and using the marantz preamp there is a distinct sound pressure level difference, the sound card plugged in direct was a lot louder and had a fuller sound.

@nanometre, thats exactly what i thought so just to clear it up, if there was say a difference source being plugged into the preamp of my marantz for eg a different model sound card and if that sound card could produce the same typical type of sound but different voltage output would the preamp in the marantz still calculate it and put out the same level.

If you get my question :).
Thanks.

[EniGmA1987]

the most popular high-end DAC chips seem to be:

Sabre32 ES9018
PCM1704UK
WM8741

Might want to do some research on each of those and figure out why they are so much better than other ones, and why they sound different.
Also you should look into sampling rate on DACs, oversampling, etc. Is oversampling in a DAC good, or is it not?

I think the saber32 chip takes the input signal, and then internally uses a much higher sample rate to do its thing, then samples back down to what the signal is supposed to be and outputs it.


Once you have learned all about the DAC stuff in changing digital to analog, you should look into the preamp stage of things and see how that affects sound. There are many different kinds of preamps, the use of op amps is the most common. And a cheap op amp can have a HUGE effect on your sound. I think I remember the "diamond output stage" being the most true representation of the original sound.



Also if you wanted to learn a little bit more, you can look into alternate forms of preamp technology that IMO sound much better. Rather than voltage signal adjustment, there is such a thing as current signal instead. Not found in many devices, usually restricted to high end stuff. think of if you have ever worked on a decent audio mixing console. When you send the signal from a group of channels into different VCA busses, and then turn one of the VCA sliders down, the sound doesn't just drop in volume, but it changes as well. And alternately, if you push the slider up, the sound increases, but also changes. When you bring it down things tend to get "softer", and when you bring it up the sound tends to get "harder", even so far as to being "harsh". This is because the VCA is a voltage control attenuator, it lowers the sound level by lower the voltage. Lower voltage means those op amps sound different. That is why I prefer to adjust the signal level with current changes rather than voltage changes. There seems to be less noticeable change in sound.

[STEvil]

;4761595']Windows Sound level on 30, WMP on Full, Marantz amp on 40 notch and left there no other settings touched when comparing the two.
When switching between the main in and using the marantz preamp there is a distinct sound pressure level difference, the sound card plugged in direct was a lot louder and had a fuller sound.

@nanometre, thats exactly what i thought so just to clear it up, if there was say a difference source being plugged into the preamp of my marantz for eg a different model sound card and if that sound card could produce the same typical type of sound but different voltage output would the preamp in the marantz still calculate it and put out the same level.

If you get my question :).
Thanks.

No, the marantz receiver (and no receiver that I can think of) have auto-gain hardware.

Your output source puts out a set voltage, if you change the output source you change the voltage. If you change the voltage then what was "40" on the volume dial is no longer 40.

For example usually on Creative PC sound cards one output is amplified for headphone use where the other output is non-amplified. As Enigma said, voltage levels can change the way something sounds. You need to see what is "right" for your setup.

[[DANGERDAN]]

Ok so you say there's no auto gain with any preamp/integrated that sounds fine, but what happens when say my sound card is putting out a set volt of say 800mv and the preamp in the marantz is designed to increase the volt to the standard 1v. Presuming 200mv is the output of a unamplified source would the signal output from 800mv go higher than 1v when it reaches the preamp, or does the preamp not amplify it ontop of the current source.

On top of that why is it when my preamp is bipassed via main in jacks that the sound pressure level is increased yet no settings were changed only the removal of the main preamp, wouldn't it be the other way around ? or if anything the same level of sound ?.

Thanks. xD

[[DANGERDAN]]

Ok im just going to cry literly i :banana::banana::banana::banana:ing cant believe what i have done, Plugging my headphones into the marantz amp with the direct input from the sound card into the main in jacks gives a totally insane improvement for my headphones.
The improvement is near night in day where there is a whole lot more sound separation where i actually now can understand the term (fuller sound) Sounds i never heard before i can now hear. Who knew a sand shaker or whatever you call it could sound so good hahahahaha.

Im going to be going crazy now for the next few days i only wish my 2k speakers could sound like this xD, amp amp amp i want want want.

:D:D:D:D:D:D:D:D:D

[STEvil]

Does it increase incoming voltage signals? If so then maybe it is the gain-matching taking place by the onboard hardware (because it would have to have it to do that) that may be changing the sound. As said before, changing the voltage of the signal can change how the output will eventually sound.

Stepping up from 200mv to 1v is much larger than stepping up from 800mv to 1v, and depending on where you set your windows volume controls the sound card could be outputting anywhere from 200mv to 2v.. or more. As you've found out you need to find what is best for your system :)

[[DANGERDAN]]

I read that no matter what volume you have on the sound card that the voltage is constant all the way through and no matter what you connect to it the voltage is the same, Its speccd at 2vrms output for my sound card.

[EniGmA1987]

sound cards don't output a set voltage, the voltage changes as the signal level changes. Unless it uses some other form of volume control other than "standard", which I dont think it does. I dont know of a single piece of computer hardware that uses anything but normal volume control that adjusts voltage. If it was a set voltage on your sound card, you wouldnt be able to change the sound level on it at all.

As STEvil said, the level you have it set to in Windows will affect greatly how much voltage comes out.

[[DANGERDAN]]

oh thats interesting i think i understand, i just tried turning down the volume on the marantz amp and i forgot that the preamp is removed so it wouldnt do any good. The volume is now controlled by the preamp aka the sound card xD.
I tell you what i like the sound from the sound card as a pre amp a lot more than the marantz cheap built in one, I looked into the DAC and it uses TI Burr-Brown PCM1796 which seems to be the family from one of enigmas suggested three he posted.

Yum

[EniGmA1987]

they are very different beasts. The PCM1794 is an advanced segment DAC, similar to the PCM1730 which I'm STILL putting together. They work in similar ways to Delta Sigma DACs and it runs a single ended supply.

The far superior PCM1704 is a Sign Magnitude DAC. These are true multibit DACs unlike the Delta Sigma or Advanced Segment DACs. It also runs from a differential powersupply. However this chip is mono and requires a digital filter before hand to split a stereo digital signal into two mono signals. The DF1704 is the logical choice. So you need 2 PCM1704s and a DF1704 and things get very expensive but in the end the price is usually reflected in the sound quality.


delta sigma DAC's resolve greater detail and present a crisper image. The 1704 seems to present a smoother aand more relaxed sound.

also:

The 1704 is a DAC only, and requires a separate digital receiver of some type, as well as a digital filter. then, it also requires a very good I/V stage (specifically tuned to its needs) and an output stage.




PCM1796
Architecture: Advanced Segment

PCM1704
Architecture: Sign-Magnitude

may be somewhat similar names, doesn't mean they are similar ;)



and a bit of info on the Saber32 ES9018 chip:


The ESS 9018 is a very sophisticated, inclusive DAC chip. It features an innovative onboard SPDIF receiver, a unique upsampling/oversampling method, and programmable digital filters. The ESS can be used in either voltage or current output mode, and requires a very specific following output stage to achieve maximum performance.

[[DANGERDAN]]

Interesting, there are quite a lot of bur-brown DAC's around i can see.

[Bobsama]

At least for computers, D/A converters are so suggested since they provide better quality interconnection and significantly reduce line noise. Using the mini-TRS connection is asking for trouble as you're also broadcasting significant electrical noise from inside the PC chassis. While an audio chip may measure 90 dB SNR, it's in actuality much noisier. That's the reason desktop computer specs are for a steel or aluminum chassis and why I/O shields are needed; they contain electrical noise to inside the box.

Regardless, IIRC, most headphone outputs can't provide consistent power from 20hz-20khz.

[[DANGERDAN]]

Ah yea i see, well for those who followed my RF83 thread as you remember i was having trouble with the bass but now i am a solid believer in preamps because now she is pumping.
The woofers have so much more excursion is not funny, i was like man those beast's are going to tip themselves over.
The suspension rubber looks different as if its been loosened must be from the heavy movement giving it a workout xD, The preamp in the marantz must be really bad but the amp itself is pretty darn good with another preamp. Im still looking into research on what effects can happen with a preamp is connected to a preamp (voltage wise).

[STEvil]

depends on the preamps and what voltage you are feeding. Could suffer horrible sound quality, blown preamps, feedback, or nothing at all.

[[DANGERDAN]]

Me and a mate seem to agree on a theory that if you have a preamp connected to a preamp that the one preamp last to be connected before the main amp is the one that has control of the signal, because that amp will take the signal ignore any previous voltage and use its own to further push the signal.
But there could be a problem with that because the signal is being carried through by the voltage push and so too that will have a effect on the sound but i do believe the theory sounds good and that most of the effect would still come from the last preamp as that will provide its own regardless of any previous power.

xD

[EniGmA1987]

This is my opinion and thoughts and I have no real proof of it, but my thouts on the matter are this:


A pre-amp is looking for a signal to be somewhere within a certain voltage range, the average mic level signal in some cases, or an average line level signal in others. So if you have a signal going into a preamp which allows you to control the volume by adjusting the voltage and amps up the signal at the output, then send that signal out that is much higher than average and go into a second pre-amp, the sensitivity will be way off since the pre-amped incoming signal into the second pre-amp will have higher voltage that the pre-amp is not calibrated to. This can cause problems such as distortion, burn out some components in the second pre-amp, or other things of that nature. *could* cause those problems, depending on just how "hot" the signal is out of what the 2nd pre-amp is designed to be taking in.


Just my opinion on the matter.

[STEvil]

sending high voltage ouput (from a pre-amp or line-level source) to a pre-amp causes oscillations.

Chaining amplified signals causes each pre-amp to add its own "signal" to the source as it passes through. Each one causes a distinct sound and when you compound these effects you cannot always easily remove them even with multiband crossover networks and/or equalizers..

You cannot send a signal from one point to another and expect the destination to not care what the source being sent is quality wise.

[[DANGERDAN]]

Thats perfect and exactly what i was looking for and makes a :banana::banana::banana::banana: load more sense, So there must be a input voltage limit on the marantz pre amp ?? because that would explain why there's more volume on the soundcard direct instead of the two preamps in series giving more volume.
As you said when the amp is bi passed whatever was on the the windows sound setting would be different in actual SPL.

[STEvil]

Most pre-amps are built to work with about 200mv up to 4 volts, some only up to 2. As to why there's "more" sound direct it could be either a circuit disabling the pre-amp (or not, causing oscillations) or just something to do with how you are hooking things up.

[Donnie27]

;4761957']Ok im just going to cry literly i :banana::banana::banana::banana:ing cant believe what i have done, Plugging my headphones into the marantz amp with the direct input from the sound card into the main in jacks gives a totally insane improvement for my headphones.
The improvement is near night in day where there is a whole lot more sound separation where i actually now can understand the term (fuller sound) Sounds i never heard before i can now hear. Who knew a sand shaker or whatever you call it could sound so good hahahahaha.

Im going to be going crazy now for the next few days i only wish my 2k speakers could sound like this xD, amp amp amp i want want want.

:D:D:D:D:D:D:D:D:D

Same thing I tried to explain to one of the Experts using a Headphone Tin Can AMP. Right now, everyone near me that I know, are using those older receivers HP Out can blow up any cans connected to them. I don't just mean for their Ear shattering Volume levels that even STEVil would love but for the PURE STEREO bliss.

The one (HP Out) on my JVC 709 is a no brainer since it is being fed straight from a Prelude with a Burr Brown Opamp and etc.... The one that fools everyone is an X-Fi Platinum connected the Harmon Kardon 730. Everyone thinks there's a better sound card installed.

@STEVil my 730's Pre AMP is decoupled from its AMP. Why does Tone Control and Filters still work?

[[DANGERDAN]]

I went through looking at all the receivers/preamps and all of them really only accept 200mv rca input, this was the same for all marantz/pioneer/denon etc so im guessing that's that standard so there cannot be complications.

So this would explain the lower volume when both preamps are connected as my inbuilt may still be able to push more than 2v and get more SPL out of my speakers but its still a crappy preamp compared to my soundcard.

@ donnie
Yea well it sounded crappy to begin with that's why i never used it but when the preamp was bipassed it was like magic, it makes sense because the amp will be giving more impedance in the HP out jack then if it was just coming straight out of the sound card.
Also what do you mean by tin can amp ?? do you literly mean a amp in a can lol ?

Is there a standard impedance for HP outputs ? i would like to know what my HP impedance is.

[STEvil]

@STEVil my 730's Pre AMP is decoupled from its AMP. Why does Tone Control and Filters still work?

I dont understand the question, you need to give a system layout because obviously something is still connected if what is "decoupled" is still working.

[Donnie27]

;4766144']I went through looking at all the receivers/preamps and all of them really only accept 200mv rca input, this was the same for all marantz/pioneer/denon etc so im guessing that's that standard so there cannot be complications.

So this would explain the lower volume when both preamps are connected as my inbuilt may still be able to push more than 2v and get more SPL out of my speakers but its still a crappy preamp compared to my soundcard.

@ donnie
Yea well it sounded crappy to begin with that's why i never used it but when the preamp was bipassed it was like magic, it makes sense because the amp will be giving more impedance in the HP out jack then if it was just coming straight out of the sound card.
Also what do you mean by tin can amp ?? do you literly mean a amp in a can lol ?

Is there a standard impedance for HP outputs ? i would like to know what my HP impedance is.

Sorry about that Tin Can comment, it is a generic term for Mini HP Amps like the Cmoy (http://tangentsoft.net/audio/cmoy-tutorial/). My bad, I should just said Cmoy-like and or others like it. I listened to at least 10 similar mini amps and they pale in comparisons to Headphone outs on many of the Old School receivers.

When I did use the Pre-AMP, the Harmon Kardons Filters worked very nicely.

STEVil
Patch Cords or Metal Couplings that connect the Pre-AMP Out to the Main AMP In. My Front Channel or Main Speakers out on my Sound card is connected/Patched straight to the Main AMP In on the Harmon Kardon.

http://www.harmankardon.com/resources/Brands/harmankardon/Products/ProductRelatedDocuments/en-US/OwnersManual/HK730%20om.pdf

Page #6 middle top row.

[STEvil]

why wouldnt the tone controls/filter work, then? They're part of the output side of the amp, not the preamp.

[Donnie27]

why wouldnt the tone controls/filter work, then? They're part of the output side of the amp, not the preamp.

I got the answer I was looking for. The others are Power AMPs clean like my old Phase Linear. The AMP/s (twin) in the HK 730 is an integrated AMP.