Very good i/v converter

[istipisti]

Hi!

I've tried some i/v converter to my (dual TDA1541A) dac, but, this is the best. Look at the schematic:



Very-very good dinamic smooth sound. The high and middle frequencies are very good too.

Adjusing:
adjust T1's emitter resistor value. Set DC 0V to the TDA1541A output

Comment:
- the output condensator is paper in oil type
(the input resistor is for protecting the DAC output when the i/v converter's T1 dies.)

This is inverting he input, and this is good! We need to invert it to the correct phase! So every TDA1541A's converter need to do this.

Sorry for my bad english...
Is there somebody wants to try this?
Istvan

[Guido Tent]

Originally posted by istipisti
Hi!

I've tried some i/v converter to my (dual TDA1541A) dac, but, this is the best. Look at the schematic:



Very-very good dinamic smooth sound. The high and middle frequencies are very good too.

Adjusing:
adjust T1's emitter resistor value. Set DC 0V to the TDA1541A output

Comment:
- the output condensator is paper in oil type
(the input resistor is for protecting the DAC output when the i/v converter's T1 dies.)

This is inverting he input, and this is good! We need to invert it to the correct phase! So every TDA1541A's converter need to do this.

Sorry for my bad english...
Is there somebody wants to try this?
Istvan

Hi

Nice circuit, reminds me of the circuits I built for MC cartridges.

I'd suggest to remove the input resistor, as you want a low input impedance, the resistor degrades performance.

You can protect the DAC by adding antiparallel diodes (I use 1A Schotkky types), so the DAC never sees mre than say +/- 0.3V at its' output. This shouldn't be a problem.

You may want to replace R6 by a current source and add some emitter resistance to T2, this improves linearity.

best

[istipisti]

Hi Guido!

Thank You. The Schotkys are good solution for the protection! The bottom resistor was current source in my first simulation, but... I believe in the "minimal concept". Maybe it is better.
I think my circuit sounding similar to the John Linsley Hood Class A.
But, we can put in some resistors and transistors and...



I think, my version is better.

[Guido Tent]

Originally posted by istipisti
Hi Guido!

Thank You. The Schotkys are good solution for the protection! The bottom resistor was current source in my first simulation, but... I believe in the "minimal concept". Maybe it is better.
I think my circuit sounding similar to the John Linsley Hood Class A.
But, we can put in some resistors and transistors and...



I think, my version is better.

Hi Istipisti,

Well, I like minimal too, so why adding 2 transistors ?

I myself have designed a tube based IV converter with less than 1 ohm input impedance to mate with PCM1704.

best

[Terry Demol]

Originally posted by Guido Tent



Hi Istipisti,

Well, I like minimal too, so why adding 2 transistors ?

I myself have designed a tube based IV converter with less than 1 ohm input impedance to mate with PCM1704.

best

Hi Guido,

All tube or hybrid cascode?

Cheers

Terry

[Guido Tent]

Originally posted by Terry Demol



Hi Guido,

All tube or hybrid cascode?

Cheers

Terry

Hi Terry,

There's many transistors around the tube, mainly for biasing

best

[PHEONIX]

Hello Guid

Does the Tube achieve low input resistance by its self or is there a transistor between the DAC and the tube.

Do you have feed back around the tube?.

Regards
Arthur

[Guido Tent]

Originally posted by PHEONIX
Hello Guid

Does the Tube achieve low input resistance by its self or is there a transistor between the DAC and the tube.

Do you have feed back around the tube?.

Regards
Arthur

Hi Arthur,

It is a mixed bag of everything, tubes intrinsically do not achieve 1 ohm input resistance.

best

[PHEONIX]

Originally posted by Guido Tent


Hi Arthur,

It is a mixed bag of everything, tubes intrinsically do not achieve 1 ohm input resistance.

best

Hello Guido

Have you ever been tempted to build an all valve I / V stage which achieves low input resistance, and it would also be nice if it was direct coupled.

Reagards
Arthur

[Guido Tent]

Originally posted by PHEONIX



Hello Guido

Have you ever been tempted to build an all valve I / V stage which achieves low input resistance, and it would also be nice if it was direct coupled.

Reagards
Arthur

Hi

All valve is possible, but I use transistors where they come in handy, e.g. biasing tubes. To me, valves are not a goal as such.

Mine is DC coupled. It has antiparallel Schottky diodes at the input to protect the DAC chip output........

best