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Old 11th September 2005, 02:12 PM   #1
A 8 is offline A 8  Sweden
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Default Balanced PCM1704 PCB

I am looking for pcb's that are well designed using 2x BB PCM1704 per channel in balanced mode.

Ideally a diy board with very good pcb quality but a cdp or commercial dac will do.

Any suggestions?

Thx/
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Old 13th September 2005, 04:19 AM   #2
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I've been trying to find exactly the same thing: differential 1704 with balanced analog out. With no luck, unfortunately...

My Denon 1650SR has dual differential topology with single ended analog out, and it certainly has potential, but still far away from NOS 1541A. Mainly because of sheer complexity and very poor single sided PCB - ground topology. I believe strongly in differential 1704 and simple analog, balanced filter/buffer.

I recon, whoever comes first with this KIT design, will make some serious money... like sonic frontiers did with their DACís with 1702Ö


Extreme_Boky
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Old 13th September 2005, 04:23 AM   #3
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REALLY????????? How much money?

"I know that sound..........and I love it." - Marcus Lycus


Jocko
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Old 13th September 2005, 04:46 AM   #4
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I'm currently working on a pcm1704 based dac that Iíve thought of modding to be balanced output

The first prototype I guess you could call is just about done, Iím just waiting on some new pcm1704 chips to arrive as the ones I got are suspected dead (and if replacing them doesnít fix it Iím screwed )

Schematic, Board, Assembled pic 1, and 2

Iíve got plans to extend it to balanced by just an add-on board (main board, and add-on) that sits on top of the current analog section and tap into the data lines to feed another 2 pcm1704's and just by tying the INVERT pin of them low their outputs are then inverted to have your balanced output
Also a redesign of the analog psu from the quick and nasty lm78/9** I tacked onto the current one to lm317 for the opamps +/-15v and AD826 and LT1027 setup for the dac's psu that has been reported to work very well (I think I seen it done like that on a levison dac with pcm1704's)

This is all still just work in progress so far,
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Old 13th September 2005, 06:21 AM   #5
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I don't get it. What's the benefit of two PCM1704 per channel? Why not just take one output and convert to balanced? I would think this is better that two converters that are not matched.

You don't get any more bits of resolution. Maybe 3dB of SNR. What am I missing?

Click the image to open in full size.

jh
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Old 13th September 2005, 06:52 AM   #6
A 8 is offline A 8  Sweden
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If there are no diy dacs out there one could always get a used commercial player and use the board.

Besides the Denon are there others?

Again the board quality and layout needs to be good, particulary the ground scheme and groundplanes.
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Old 13th September 2005, 08:57 AM   #7
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Quote:
Originally posted by Extreme_Boky
I've been trying to find exactly the same thing: differential 1704 with balanced analog out. With no luck, unfortunately...

My Denon 1650SR has dual differential topology with single ended analog out, and it certainly has potential, but still far away from NOS 1541A. Mainly because of sheer complexity and very poor single sided PCB - ground topology. I believe strongly in differential 1704 and simple analog, balanced filter/buffer.

I recon, whoever comes first with this KIT design, will make some serious money... like sonic frontiers did with their DACís with 1702Ö


Extreme_Boky

As a fan of the TDA1541, you should look out for a Sony DAS-R1. Balanced S1's.
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Old 13th September 2005, 09:57 AM   #8
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Quote:
Originally posted by A 8
If there are no diy dacs out there one could always get a used commercial player and use the board.

Besides the Denon are there others?

Again the board quality and layout needs to be good, particulary the ground scheme and groundplanes.

There are quite a few out there. Aside from the Assemblage DAC2.6/2.7/3.0 all the ones I can think of are a bit on the expensive side but if you plod through google you may find some relatively inexpensive ones coming out of China.
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Old 13th September 2005, 01:17 PM   #9
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Quote:
Originally posted by rfbrw

if you plod through google you may find some relatively inexpensive ones coming out of China.

Can you be more specific or name any of those inexpensive ones?

I am certainly interested.



Carlos
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Old 13th September 2005, 04:40 PM   #10
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Quote:
Originally posted by carlmart



Can you be more specific or name any of those inexpensive ones?

I am certainly interested.



Carlos
Alas, I won't be much use to you.
Aside from the Lite DACs, and I'm not sure of their configuration, I came across the others in passing and as I wasn't actually looking for them, paid them no real attention.
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