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Old 14th April 2002, 06:33 PM   #1
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Default Parallel DACs

I know there are some people interested in what improvement paralleling DAC chips bring to the sound.

I have paralleled PCM 1704 chips in my DAC and I must say that I was expecting more. The output is higher (comparing 1 o'clock to 4 o'clock position on volume knob) but I am not sure if the resolution and dynamics changed much. The cost and time involved in my opinion is not worth it. These were surface mount devices and I had to put one chip on top of the other. There was a gap between the legs so I had to use small pieces of wire to connect them.

From my experience I must say that using separate power supplies for digital and analog section of the DAC brings more improvement than paralleling DACs.

Any other opinions and observations?

Peter
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Old 14th April 2002, 08:26 PM   #2
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Default Re: Parallel DACs

[QUOTE]Originally posted by HPotter
[B]I know there are some people interested in what improvement paralleling DAC chips bring to the sound.

I have paralleled PCM 1704 chips in my DAC and I must say that I was expecting more. The output is higher (comparing 1 o'clock to 4 o'clock position on volume knob) but I am not sure if the resolution and dynamics changed much. The cost and time involved in my opinion is not worth it. These were surface mount devices and I had to put one chip on top of the other. There was a gap between the legs so I had to use small pieces of wire to connect them.

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Certainly costs but you near to parallel 4 to 8 units ala Accuphase to make the s/n appreciably lower. My hat off to you to do what you did.
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Old 14th April 2002, 09:14 PM   #3
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Lightbulb Paralleled DAC's

Hi Peter (Hpotter),
I can coroborate your findings. I paralled two AD1865N in my NON-OS KWAK-DAC.
Definition was less and the bass kind of boomy. Output was higher of course.
A more intelligent way of paralleling DAC's is using two DAC's in a balanced configuration for one stereo channel. You need two IV converters though. The balanced DAC gives more power or bass-slam .
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Old 15th April 2002, 01:04 AM   #4
tiroth is offline tiroth  United States
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A balanced pair will yield a 3dB S/N improvement.
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Old 15th April 2002, 02:16 AM   #5
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Correct.

Jocko
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Old 15th April 2002, 05:01 PM   #6
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Hey Harry:

Since you have lots of '1704s around, why don't you toggle the pin that controls the phase and make it balanced. You'll get much more of an improvement that way.

What grade DAC are you using?

Jocko
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Old 15th April 2002, 07:05 PM   #7
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I'm using grade K. Someone on this forum stated that paralleling DACs improves resolution, however it's hard for me to decide if this is what I achieved. The music has more "body" ,but sometimes it can be taken as boominess.
On the current board I can't use full balanced configuration, but that's what I will try in my next project.
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Old 16th April 2002, 12:06 AM   #8
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The reasons I asked are:

1.) The ungraded ones have poor low-level linearity. Perhaps putting 4 in parallel might help them, but you could save money by buying just one "K" grade.

2.) Awful lot of money to spend for no appreciable benefit.

Jocko
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Old 16th April 2002, 01:25 AM   #9
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Smile Awful lot of money to spend...

Not quite right. With the increased gain I don't have to use a preamp which usually is more than 2 grade K chips.
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Old 16th April 2002, 02:00 AM   #10
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Default *all* pins?

Hmmm:

Did you parallel/jump _all_ of the pins, including the three decouple pins? These are most likely voltage sources [ well, maybe the offset decouple has a higher source impedance...] at different potentials chip to chip...and may not be happiest "shoved" together.

WMS
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