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Old 23rd March 2010, 11:24 AM   #1
markusA is offline markusA  Sweden
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Default Another go @ choosing the right DIY DAC

I've been reading though other threads but I'm not getting the info I'm looking for.

What would be the best sounding DIY dac with no output stage? I don't wan't any OP-amps if I can do without them.

My intended use
DAC -> Pot -> Tube buffer

I've come across three interesting dacs
K & K Audio - Lundahl Transformers, audio DIY kits and more
DDDAC 2000
The Buffalo II Digital-to-Analog Converter

but I'm sure there are others out there as well.
What's your favourite? And Why?
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Old 23rd March 2010, 12:50 PM   #2
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With any voltage out dac you will have DC on the output pins. You either need caps or trafos to connect to the outside world. Doing without opamps is not a problem, for instance, the CS4398 outputs close to 2VRMS all by itself.

Best, Bill
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Old 23rd March 2010, 02:00 PM   #3
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I vote for the DDDAC 1543 Mark II. This is a wonderful project...is not expensive..better by far than my other DAC's by a good margin. I have built the Mark II as a DAC as well as a USB DAC. I have found that ripping cds with EAC and playing them back using Foobar and ASIO drivers through the DDDAC 1543 Mark II is better than the Mark II as a DAC connected to a transport and of course far better than listening to a cd player through your system.

I suggest that the project it be built using 24 dac chips...That would mean two 12 chip modules.

I implemented my 1543 Mark II using a Jung/Didden super regulator for each board. I thought this made a nice difference. Lately, I put a B1 buffer after the 1543 Mark II and noticed some more improvement.

Doede Duama is very helpful...I can't imagine a better sounding topology
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Old 23rd March 2010, 02:12 PM   #4
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Different strokes for different folks, my Mark II is in my junk box. Didn't push any buttons for me, even fed I2S directly.

But that's just my opinion, and you know what they are like.
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Old 23rd March 2010, 02:41 PM   #5
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Oh Well...
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Old 23rd March 2010, 02:53 PM   #6
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Quote:
Originally Posted by Bill Fuss View Post
With any voltage out dac you will have DC on the output pins.
Not always to the point you may have to worry about. I'm quite liking a board a did with a WM8524 and it is spec'ed to max 1mV DC. I haven't seen the specs on a ESS9022 to know how they do for DC offset.
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Old 23rd March 2010, 03:16 PM   #7
markusA is offline markusA  Sweden
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It's natural that there will be differences in opinion.
The DDDAC 1543 is on my list of interesting kits so I appreciate the opinions both positive and negative.

Bill Fuss> There's a 0.1uF cap on the input of the buffer. Is that enough to kill the DC?
Will the pot suffer from the dc? It shouldn't be that bad? I'm going with a 10kohm LDR pot...
What would you recomend instead of the DDDAC? I'm not skilled enough to take on the design process so I need some sort of kit.
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Old 23rd March 2010, 04:39 PM   #8
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Quote:
Originally Posted by markusG View Post
There's a 0.1uF cap on the input of the buffer. Is that enough to kill the DC?
Will the pot suffer from the dc? It shouldn't be that bad? I'm going with a 10kohm LDR pot...
Yeap, it is gonna kill the DC. And any low bass too. Actually anything below 3-400Hz will suffer.
But, hey, if you add a tube, magically the sound will be better...

PS: The voltage output DAC's have an OpAmp inside anyway. The current output DAC requires an I/V stage (that ususlly I don't see it done right with tubes).
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Old 23rd March 2010, 04:57 PM   #9
kevinkr is offline kevinkr  United States
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Quote:
Originally Posted by SoNic_real_one View Post
Yeap, it is gonna kill the DC. And any low bass too. Actually anything below 3-400Hz will suffer.
But, hey, if you add a tube, magically the sound will be better...

PS: The voltage output DAC's have an OpAmp inside anyway. The current output DAC requires an I/V stage (that ususlly I don't see it done right with tubes).
I prefer current output dacs because it allows me to choose how to do the I/V conversion. My preferred device for differential dac I/V at the moment is a THS4131. I don't use dacs with unbalanced outputs so I can't comment on that.

I'm a tubeophile and would definitely agree that it is extremely hard to do a good tube I/V converter. I've done several and thought they were somewhat inferior sounding to a good solid state I/V. Someday I may try again or I might just use a transformer for I/V conversion - I currently use transformers to go from balanced output to unbalanced output with LM4562 and THS4131 - works quite well.

Another way to consider is discrete transistor based I/V - there are several purportedly good ones including one from TPA.
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Last edited by kevinkr; 23rd March 2010 at 04:59 PM.
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Old 23rd March 2010, 05:27 PM   #10
markusA is offline markusA  Sweden
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SoNic_real_one> Thats odd? I must be missing something? It seams to me most all tube amps have a cap in series and 0.1uF is a pretty common value? I've seen the measured curves and there's no dip below 400Hz? The pot is out in front of the cap.
Looking at a typical high pass filter and the imput impedance being in the Mohm range due to the cathod follower it should put the fc <2Hz?

Now, I'm a n0ob and I'm bound to miss things. Maybe this is one of those times?

kevinkr> Balanced is good, my entire cirquit is fully balanced.
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