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Ultimate Twin TDA1541a Non-oversampling DAC with tube buffer & reclock set.......

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S

SamL

Member
Joined 2004
tube-lover said:
Hi samL,

sure pls visit the groups buy forum that I will continous a very very low profit project which was a single End Dac. which can operate use single chip or parallel chips. ( IV resistor must change).

This dac still can use transformers couple whcih change from SE to balance.

so output:
1. from OP-amp
2. from OPT.

same use isolate power transformers, compact size, lower noise, & with USB.

take a full look of the DAC protype, funish outlook will not be this.

thx

thomas
Click to expand...


:yummy:
 
J

JeroenVl

Member
Joined 2005
I/V resistors

Hi,
Could somebody tell me what I should do with the I/V resistors on the DAC board (R28, R39, R47 and R48).

According to post #83 I should remove these when using the Opamp board and according to post #113 I should increase them from 22R to 100R parallel when using the tube board (but I think I also saw somebody suggest 75R parallel).

My question is what should the resistors be when using the tube output board with only one tda1541 and what should they be when using the two tda's in parallel.

Thnx,

Jeroen
 
W

WT

Member
Joined 2002
Dear Jeroen

When you use opamp output board, you don't need R IV since there are opamp IV on board already.

When you use tube output board, for my taste, I prefer around 20-47 ohm R IV. Currently, I use 33 ohm as RIV. The higher value, the higher ourput you get but also more distorsion. This will depend on your gain on your preamp and power amp as well. If your system has less gain, you might need higher value like 47ohm or even higher.

If you use only one TDA1541A you might need to use higher value resistor. You can start trying from 22 ohm and see if the gain acceptable. If it is too low, increase it until it's loud enough for your system.
 
S

scintillaman

Member
Joined 2007
Hi All

I am new here. Not much of a DIY but this is where a lot of great items start. I am very interested in Thomas's Dac. I will keep watching with much interest. Can't wait to it actually available for purchase. Can anyone give me any idea what kind of output level and impedance can be expected with balance output.

Thanks

Carlton
 
S

sugano

Member
Joined 2003
circuit and manual

Hi Thomas,

Hope you still remember me? You delivered the kit and some extra parts in person to me at Jordan MTR station in your greenish Toyota?

Anyway, I bought the complete kit from you long time ago and I still haven't finished building, well it's almost finished but my PC hard drive died before I could finish the kit.

I lost all information on building the kit because of the dead hard drive so could you please e-mail me the circuit and manual again when you could?

Thank you,
Peter Sugano
 
R

riotubes

Member
Joined 2005
My experience with implementing a Synchronous Reclocking Circuit

I don't know if any of the v2 builders are following this thread at this point, but I wanted to report back on a transport/dac interface that has seriously elevated the performance of this dac.

I built a reclocking circuit designed by John Swenson based on a 11.2896 MHz Tent clock which sends the master clock back to the transport, and then takes BCK, LRCK and SDATA out of the transport via Left Justified Format back to the tda1541 dac, converts the signal to i2s, reclocks/resynchs it using the same Tent clock and sends it to the 2x3 header on the dac board that has traces to the dac clock input pins. So this is a synchronous reclocking circuit...not asynchronous.

The results for me were amazing. The interesting twist is that the "transport" is a squeezebox. The jitter at the Dac pin is virtually non-existent according to Jonh's attempt at measuring a similar circuit in his own dac (and below his scopes lower detection threshold of 10ps). The jitter on the dac input pins is basically limited to the jitter on the output of the Tent clock. Guido publishes this to be about 3ps depending on power supply noise, and mine probably measures a bit higher because I have not yet replaced the SB's stock psu. This is the best digital I have yet to hear in my system. The results are amazing.

I became interested in this project after reading several posts by Guido Tent on the virtues of synchronous reclocking and at the same evaluating ways to integrate computer audio.

I posted more about the mods to the tda1541 dac and SB here:
http://www.audioasylum.com/forums/pcaudio/messages/2/24319.html

All the credit goes to John Swenson who designed this circuit and who generously posted the schematic over at slim devices' audiophile forum.
 
xaudiox

xaudiox

Member
Joined 2006
ferdsaudio.com
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