Best I/V for multiple tda1541a, no tube no transformer

[fastvideo]

I plan to build a external dac with 2x or 4X or 8X TDA1541A.
The more I read the more I am confused about how the I/V stage effect the sound. And there is no specific I/V stage that is highly recommended.


I have my rotel rcd855 works very well with daul tda1541a, opa1611 opamp for I/V and output stage. Tried to put 4X tda1541a inside, but result is not good.

Need suggestion for the I/V and output stage for multiple TDA1541A.
Any working schematic ?
Please I perfer using no tube or transformer.

 

[Nazar_lv]

I like this schematic I/U for 1541 and others
it is dynamically linear I/U stage with feedback only in audio band 0-20kHz, but for multiple 1541 cap/res values should be converted.

 

[fastvideo]

I like this schematic I/U for 1541 and others
it is dynamically linear I/U stage with feedback only in audio band 0-20kHz, but for multiple 1541 cap/res values should be converted.

What is R5 for? how should I adjust it? for multiple 1541 which r/c should be convert?
Any circuit using opa861?
thanks.

 

[Nazar_lv]

What is R5 for?

nulling output

for multiple 1541 which r/c should be convert?

R1,R2,C2,C3
write how many chips will you use, I recount it nominals

Any circuit using opa861?

861 is worst, but not bad for 1955

 

[Vikt0r]

I like this schematic I/U for 1541 and others

Surely you do love it

Nazar, if I have nothing better for I/U than THS3001 - how the schematic should look like?

BTW, the current source circuit (R5,R6,C4) for TDA1541 - what value is C4?

Thanks

 

[fastvideo]

R1,R2,C2,C3
write how many chips will you use, I recount it nominals
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I have 10 spare tda1541 on hand.
Wanted to try with 2x or 4X or 8X TDA1541A to see how good multiple tda1541 can be?

 

[Vikt0r]

Wanted to try with 2x or 4X or 8X TDA1541A to see how good multiple tda1541 can be?

Fastvideo,
your best solution would be the 2X design and selling (or gifting ) the rest to me, so I can try the 8X design

The more chips you use - the better the result would be. But not sure you will notice this difference

 

[fastvideo]

nulling output
R1,R2,C2,C3
write how many chips will you use, I recount it nominals
861 is worst, but not bad for 1955

Any update on this?
Any reason OPA861 is not good with TDA1541?
Any OPA861 working circuit with TDA1541? I have some OPA861 here and would like to test it out.

 

[Nazar_lv]

fastvideo, sorry I have no time in January, for 2x 1541 R1=750 R2=2.2k C1=1500p C2=3900p
for 4x 1541 R1=390 R2=1.2k C1=3300p C2=7500p

Nazar, if I have nothing better for I/U than THS3001 - how the schematic should look like?

see attach, schematic by Walt Jung

BTW, the current source circuit (R5,R6,C4) for TDA1541 - what value is C4?

4.7-10u X7R 1206

Any reason OPA861 is not good with TDA1541?

low power supply voltage, not super buffer

 

[Vikt0r]

see attach, schematic by Walt Jung

What's the reason to use the provided schematic, if the current of the DAC isn't fed into the low impedance of the CFA? The 1K in series destroys the idea, in this case why not use just a resistor for I/U? It just a workaround to avoid oscillation with a cap in a feedback loop (whic is otherwise not acceptable for CFA), but a workaround which screws the goodies of the CFA applicaton in here...

 

[revintage]

Hey fastvideo,
Why go the opamp autostrada? Instead go for a passive solution with a resistor in the ballpark of 30ohm/DAC together with a FET cascoded(could be folded for DC out) stage.

 

[Nazar_lv]

What's the reason to use the provided schematic

filtering in first analog stage, good linearity

The 1K in series destroys the idea,

resistor is inside feedback loop, dynamic impedanse of this design is 1.5ohm.
From 1541 output to ground also you need capacitor 200-300pf

 

[Marlowe]

OPA861 is good

Any update on this?
Any reason OPA861 is not good with TDA1541?
Any OPA861 working circuit with TDA1541? I have some OPA861 here and would like to test it out.

I have built a Pedja Rogic's AYA II where the opa681 are used for I/V conversion and output buffer. The sound is very good to me.

I have tried various I/V stages for my NOS TDA1541A DAC for years, including passive I/V, AD844, rbroer's discrete circuit, and so on. Among these circuits, Pedja's OPA861 is no doubt the best one to me.

 

[Marlowe]

low power supply voltage, not super buffer

I don't think the lower power supply (+/- 5V) is an issue here. In my experience, the sound from the OPA861 I/V is dynamic and powerful.

 

[fastvideo]

I have built a Pedja Rogic's AYA II where the opa681 are used for I/V conversion and output buffer. The sound is very good to me.

I have tried various I/V stages for my NOS TDA1541A DAC for years, including passive I/V, AD844, rbroer's discrete circuit, and so on. Among these circuits, Pedja's OPA861 is no doubt the best one to me.

Can you post schematic of the OPA861 for I/V conversion and output buffer stage that you are using?
I am very interested to test it out, thanks.

 

[Marlowe]

I have no right to post the schematic. The same idea is also suggested by Kuei Yang Wang in this thread. Give me a mail if you are interested the detail.

 

[Marlowe]

Hi Fastvideo,

I found a diagram of the I/V stage that is archived on Pedja's site.

http://www.audialonline.com/html/archive/ayaIII/images/out.gif