Single rail, active I/V for TDA1543, TDA1545A

[tingtong5]

Hi guys,

I've been looking for a schematic like this and am glad I run into this.

I plan on using it as the I/V stage for my Monica2 DAC (tda1545A).

Before I start building it (I read the whole thread of course) I would like to ask if thee is any more to tell (experiences/modifications) that was not yet written in this thread?

I got the advice (from an expert) to use a 10R resistor between the collector of Q1 and the emitor of Q2 to prevent oscillation. The same guy also advised to change D2 to a red LED as well.

Does it make any difference if one uses a small or bigger red LED ?

Rbroer, do you still sell circuit boards for this I/V convertor?

Regards,

Ronald

 

[rbroer]

I got the advice (from an expert) to use a 10R resistor between the collector of Q1 and the emitor of Q2 to prevent oscillation.

It won't hurt, so try it with and without and let us know your results.

The same guy also advised to change D2 to a red LED as well.

Afraid for saturation of Q3 ? Your same worrie should apply then to D3.
You will end up with less output voltage margin, unless you increase your supply voltage. In this case I would suggest something like >= 18Vdc

Does it make any difference if one uses a small or bigger red LED ? Dunno about your LED's. My stock of RED ones do 1.5V @ 1mA, and my GREEN ones do about 1.7V @ 1mA

Rbroer, do you still sell circuit boards for this I/V convertor?
Never sold any, I build this on VERO boards as you should have seen earlier in this thread.

I actually might have this built circuit lying around somewhere. I built it into a cd player for my brother. Player's laser died and I got the player back and I think I salvaged some parts, including the I/V.
Drop me a PM if interested, then I'll try to locate it.

Groeten,

 

[tingtong5]

It won't hurt, so try it with and without and let us know your results.

Ok I will

Afraid for saturation of Q3 ? Your same worrie should apply then to D3.
You will end up with less output voltage margin, unless you increase your supply voltage. In this case I would suggest something like >= 18Vdc

I was planning on using 18 Volts.
Yes worried about saturation..
Since I would like to have 2Vrms output I plan on raising the I/V resistor to 5K6. I wonder if 18V will still be sufficient in that case.

Does it make any difference if one uses a small or bigger red LED ? Dunno about your LED's. My stock of RED ones do 1.5V @ 1mA, and my GREEN ones do about 1.7V @ 1mA

Ok...

Never sold any, I build this on VERO boards as you should have seen earlier in this thread.

Sorry, I misunderstood.

I actually might have this built circuit lying around somewhere. I built it into a cd player for my brother. Player's laser died and I got the player back and I think I salvaged some parts, including the I/V.
Drop me a PM if interested, then I'll try to locate it.

Thanks a lot Already send you a PM

 

[tingtong5]

I build the circuit and first impression is:
- colouration of passive 2K2 I/V conversion on TDA1545 is gone
- better bass (more dynamic?)

So thats good and I am very happy with these results Also I do have decent output now (I used 5K6 for I/V resistor).

On the other hand is seems to sound a little on the "cold" side. I used normal carbon resistors, will it make a difference to change those for say DALE resistors?

Rudolf if you read this, do you happen to know where to get/order DALE resistors in holland?

I also wondered why you choose for diodes instead of LED's for D2 and D3 ?

Regards,

Ronald

 

[tingtong5]

Nobody any opinion about substituting both diodes to led's ?

 

[Mazuki]

For those of you who built this I/V for the TDA1543, what is the value of the Vref resistor? Specifically, 8XTDA1543. Or does it not matter anymore?

 

[hollowman]

This issue may have been covered before ... how can one utilize TDA1545's (or TDA1543's) Vref? It, according to Philips datasheet, is supposed to be connected to the positive (+) input of the I/V opamp. However, Rbroer's Single rail, active I/V does not have "differential" inputs.
Thx for any info anyone can provide!

 

[CeeVee]

Have a look here, ive done one for the PCM 1738, it's working and producing gorgeous sound.

http://www.diyaudio.com/forums/showthread.php?t=130568&page=19


Many thanks to Rudolf

 

[hollowman]

Have a look here, ive done one for the PCM 1738, it's working and producing gorgeous sound.http://www.diyaudio.com/forums/showthread.php?t=130568&page=19

I have two units that use the PCM1738: Musical Fidelity DAC, and a Pioneer DVD-A/SACD. So your project is interesting.
Please note that to avoid confusion, let's keep all PCM1738 comments on your thread (not unless one specifically correlates to TDA1545 or 1543): this thread is for TDA1545 and TD1543 only. I think there is a dedicated Rudolf I/V thread for the TDA1541, also.

 

[CeeVee]

.. let's keep all PCM1738 comments on your thread ....

Absolutely hollowman i'll follow this one here and the PCM1738 there.