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Old 26th December 2007, 02:43 PM   #1
VR2ZXP is offline VR2ZXP  Hong Kong
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Unhappy How is the best method to parallel TDA1541

Hi all, do anyone can share me your experience about TDA1541 DAC? I built a prototype of CS8414 with re-clock + SAA7220 + TDA1541AS2 x 2 by differential. The sound is warm, sweet and close to my Marantz CD-95. After that, I tried to parallel one more TDA1541AS2 to each channels, although the dynamic range and bass have much improved, the sound becames cold and sharp.

Is there any method to parallel TDA1541 to keep better dynamic and bass but also with warm and sweet sound?

There are the photos of my prototype :
http://www.fotop.net/VR2ZXP/VR2ZXP53

Please teach!! Thanks very much!!
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Old 27th December 2007, 04:21 PM   #2
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Very nice!
I'm hoping to build something like that in the new year (I currently only have a single 1541 running and hope to double it soon).

Maybe you could check your regulation (do you have seperate regulators per DAC? What regulation are you using?).
Do you have seperate regulation for the SAA7220? That chip is quite good for polluting power rails with noise.

What is the FPGA doing?

Cheers,
Phil
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Old 27th December 2007, 04:58 PM   #3
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Hi,
I would synchronize the DEM oscillators (or, better, reclock them).

Cheers

Andrea
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Old 27th December 2007, 05:08 PM   #4
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hi VR2ZXP ,

first remove the 7220 if U like the high density vocal.

second, not use differential, use CPLD will enough!

for differential dac( 1541a), U can reference for this link,


http://homepage2.nifty.com/electrart...da1541dual.htm

In my opinions, use transformers couple for balance was the best method, more stable, better bass & vocal was better than capacitors output stage & higher density MF!



thx

thomas
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Old 27th December 2007, 05:16 PM   #5
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Quote:
Originally posted by philpoole

What is the FPGA doing?

It is not a FPGA. It is a CPLD.

As to its function, perhaps the answer lies in the silkscreen.
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Old 27th December 2007, 05:20 PM   #6
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thanks rfbrw



sorry type wrong words.

thanks

thomas.
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Old 28th December 2007, 12:49 AM   #7
VR2ZXP is offline VR2ZXP  Hong Kong
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Quote:
Originally posted by philpoole
Very nice!
I'm hoping to build something like that in the new year (I currently only have a single 1541 running and hope to double it soon).

Maybe you could check your regulation (do you have seperate regulators per DAC? What regulation are you using?).
Do you have seperate regulation for the SAA7220? That chip is quite good for polluting power rails with noise.

What is the FPGA doing?

Cheers,
Phil
Hi Phil,
Thanks very much for your reply. 10pcs of 78M, 79M regulators have been used for 8414, 7220, CPLD, re-clock and DACs. 4pcs of LM317 & 337 are for OPAMPs. Will change to use LT series in final version.
Is it a problem if I am using same regulators ( 78M05, 79M05 & 79M15 to form +5V, -5V, -15V ) for 2pcs of TDA1541 in parallel? Is it becomes better if separate it?

I got this CPLD from a China site which is for produce +L, -L, +R & -R data.

Cheers,
VR2ZXP
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Old 28th December 2007, 12:49 AM   #8
VR2ZXP is offline VR2ZXP  Hong Kong
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Quote:
Originally posted by Andypairo
Hi,
I would synchronize the DEM oscillators (or, better, reclock them).

Cheers

Andrea
Hi Andrea,
Thanks for your reply. I am using 11.2896MHz TCXO + 74HC4040 for the re-clock. Would you please comment if there are some better circuits? Which async or sync counter is the best for re-clock?

Cheer,
VR2ZXP
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Old 28th December 2007, 12:49 AM   #9
VR2ZXP is offline VR2ZXP  Hong Kong
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Join Date: Apr 2007
Quote:
Originally posted by tube-lover
hi VR2ZXP ,

first remove the 7220 if U like the high density vocal.

second, not use differential, use CPLD will enough!

for differential dac( 1541a), U can reference for this link,


http://homepage2.nifty.com/electrart...da1541dual.htm

In my opinions, use transformers couple for balance was the best method, more stable, better bass & vocal was better than capacitors output stage & higher density MF!



thx

thomas
Hi Thomas,
Long time no see, do you remember me when I checked from you about AS2 stock last time by email?
Thanks very much for your comment.
Something want to be consult from you.
1) Now my method to parallel 2pcs of TDA1541AS2 is just connected all the pins together excluding DECOU & Cosc. Those capacitors in DECOU & Cosc are separated. Is it connection correctly? What is the sound difference if same capacitors be used to both DACs in each channels? Which values of caps should be used?
2) Checked from the service manual of Marantz CD-7, OPAMPs circuit be instead by HDAM discrete circuits. What is the sound difference of this change?

Thanks again!!
VR2ZXP
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Old 29th December 2007, 01:40 PM   #10
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Quote:
Originally posted by VR2ZXP


Hi Andrea,
Thanks for your reply. I am using 11.2896MHz TCXO + 74HC4040 for the re-clock. Would you please comment if there are some better circuits? Which async or sync counter is the best for re-clock?

Cheer,
VR2ZXP
Hi,
in a external DAC it is only possible to use asynchronous reclocking, unless you slave the transport.
Your reclocking scheme resembles the one by Doede Douma, which I never tried myself.

DEM reclocking needs to be synchronous with the BCK signal, so you can take this signal and divide it to get the correct DEM frequency (4..8 fs)

There are some schematics from ECdesigns (use the last ones) that show how to sync multiple DACs.

Cheers

Andrea
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