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Old 15th May 2009, 08:58 AM   #1
Tolu is offline Tolu  Germany
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Default AK4396: best solution for output stage

While I am waiting for my 1543 DAC from HK, I did some research on my Emu 0404 USB. Sound is not bad but not the crown in audio.

So I found some passive approaches for the output stage just to omit the opamps.

In the datasheet is reported that Aout+ and Aout- is 2.8Vpp each so in addition you'll get 5.6pp or 2Vrms if you're going symmetrical. That's my problem!

I need unbalanced connection and so my question arose: is there a (passive) possibility to keep the 5.6Vpp for unbalanced output?

The XLR solution could be:
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Old 15th May 2009, 09:00 AM   #2
Tolu is offline Tolu  Germany
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The unbalanced version would be that:
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Old 15th May 2009, 12:04 PM   #3
sendler is offline sendler  United States
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Default No filter needed

The AK4396 will sound it's best running direct out through the coupling cap without the analog ultra sonic filter. The ultra sonic noise spectrum of this chip is unique in the industry in not needing one. Adding the 1k resistor to the output impedance of the chip tends to choke the sound. Just take the signal out through the blocking cap from one leg as you have shown in the second drawing for 2.8v and omit the filter. No output R or cap to ground. Leave the other leg open, or terminate with a blocking cap and resistor to ground which approximates the load the the + leg will see.
.
Check out the noise graphic of the AK4396 here.
.
AK4395/4396 ultrasonic noise spectrum graphic
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Old 15th May 2009, 01:29 PM   #4
Tolu is offline Tolu  Germany
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What cap (µF) do you propose?
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Old 15th May 2009, 06:12 PM   #5
sendler is offline sendler  United States
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Default Dayton foil caps are the best

Quote:
Originally posted by Tolu
What cap (�F) do you propose?
.
The Dayton film and foil caps are by far the best sounding for low level signal coupling that I have tried but any top level cap will sound much better than the stock output.
.
http://www.parts-express.com/dayton-film-capacitors.cfm
.
I parallel 8 to make 4uf.
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Old 15th May 2009, 06:34 PM   #6
Hurtig is offline Hurtig  Denmark
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You should never use the output of the DAC-chip directly. These are normally very sensitive to the load (Even though the Zout is low).
Also, you should never use onle the 1 of the outputs of a differential DAC, to have a simple solution to the single-ended output. You have to use a differential-to-single-ended converter.

Doing as above, you will never ever discover the potential in a DAC like the AK4396.
Look at page 34 on the AK4396 datasheet:
AK4396 datasheet

This is the simple approch to diff-single-ended conversion, using a single op-amp. I must emphasis, that this is NOT the best solution, but it is way better the above!

The best solution is a discrete design, prefferable with no negative feedback. Search the forum, and you will find many of these.

AK4396 is actually a great chip, and if you give it the right invironment, you will discover that the TDA1543 is like driving an old VW Buggy. Not worth the time, even though it's quite funny.

And be aware, that when you listen to AK4396 (or similiar) based DAC-systems/CD-players that do not sound that good, it's not because of the DAC-chip. Typically it's because the analog stage is made completely wrong.
Funny thing we discovered in the 4 years of developing our DAC is, that most of the thing people call "Digital sound" (As in negative), actually has nothing to do with the digital parts. It's all in the analog stage. The reason that you still hear these issues after 25 years of improvement in DAC-chips is, that most CD-players is still equipped with the same low grade op-amps as in the early 80's.
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Old 15th May 2009, 07:50 PM   #7
Tolu is offline Tolu  Germany
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Hi Hurtig

is fig. 17 (3 opamps) so much better than fig.16 (1 opamp)? What are the differences?

I am trying my 0404 USB at the moment with Foobar2000 on my old Dell Notebook. The bad thing are the irregular crackles. Is this normal for EMU 0404 USB or is it a PC problem?
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Old 15th May 2009, 08:11 PM   #8
Hurtig is offline Hurtig  Denmark
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Hi Thomas
I don't know anything about the EMU 0404 USB. But I really do not like the idea of connectiong the computer to the stereo. Computers are a noise-nightmare.
If you do connect, galvanic isolation would be wanted. But almost any USB DAC/Soundcare do not have this feature, and will result in noise entering the stereo. This could very well lead to the symptoms that you mention.

About the 2 different schematics in the AKM datasheet. No, the 2nd one is not better. I just gives you balanced output to. But it is still an op-amp, follow by another op-amp. Not that good.
You could get OK results from trying different op-amps. But it's still an op-amp and sounds just like it.
I would go for a discrete analog stage using NO negative feedback.

If you do choose an op-amp, my suggestion is the old fashion NE5534. If you can get the "A" version it's even better.
I have seen many people change from NE5534 (5532) to newer and "better" devices, only because of the better specifications in the datasheet. People who actually run a blind-listening-test, tend to go for the NE5534. For an op-amp it's not that bad, and sonically it will run down most of these new "racing-op-amps".
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Old 15th May 2009, 08:59 PM   #9
sendler is offline sendler  United States
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Default Ever tried it?

Quote:
Originally posted by Hurtig
You should never use the output of the DAC-chip directly. These are normally very sensitive to the load (Even though the Zout is low).
Also, you should never use onle the 1 of the outputs of a differential DAC, to have a simple solution to the single-ended output. You have to use a differential-to-single-ended converter.

Doing as above, you will never ever discover the potential in a DAC like the AK4396.
Look at page 34 on the AK4396 datasheet:
AK4396 datasheet

This is the simple approch to diff-single-ended conversion, using a single op-amp. I must emphasis, that this is NOT the best solution, but it is way better the above!

The best solution is a discrete design, prefferable with no negative feedback. Search the forum, and you will find many of these.

AK4396 is actually a great chip, and if you give it the right invironment, you will discover that the TDA1543 is like driving an old VW Buggy. Not worth the time, even though it's quite funny.

And be aware, that when you listen to AK4396 (or similiar) based DAC-systems/CD-players that do not sound that good, it's not because of the DAC-chip. Typically it's because the analog stage is made completely wrong.
Funny thing we discovered in the 4 years of developing our DAC is, that most of the thing people call "Digital sound" (As in negative), actually has nothing to do with the digital parts. It's all in the analog stage. The reason that you still hear these issues after 25 years of improvement in DAC-chips is, that most CD-players is still equipped with the same low grade op-amps as in the early 80's.
.
Have you ever tried the AK4396 running direct out?
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Old 15th May 2009, 09:44 PM   #10
Hurtig is offline Hurtig  Denmark
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I have not tried the AK4396 running directly from the outputs, but I did try on some similiar IC's from AKM and Crystal. They all tend to be quite sensitive to the load, and to have optimum performance, you must use the signal from both + and - outputs, since the signal will contain common mode signals.

If you want to achieve the best performance, there is no shortcut. I know a lot of people say they get extreme results from old Philips DAC's like the TDA1543 often running with no oversampling and very bad analog stages. I still believe it to be a case like people who like the performance of an old VW beatle, just because the did some bodywork on their own.

Face it.... Solutions like that will never get you high end performance. If you like it, it's probably because you like that it destroys the dynamics of the music. Some people actually thinks of this as "Musicality". But it's not.
Campare it to a high end DAC, and you will notice all the things that are missing in the music.

I did listen to a few TDA1541/43 based DAC's, of which at least one of them has been called "High End".
But sorry to say... They all sounded terrible. For background music it's OK, since there is absolutely no dynamics. But again... That's not the idea of High End. Who would call an old taperecorder High End today?? Quite funny, because these old DAC's does remind me of the sound of a taperecorder. He he he... wow... That's High End (In the early 80's....)
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