Best and final TDA1541A output stage

studiostevus · 1st June 2010, 07:19 PM

I will start building my first 1541-based DAC soon, based on the currently running GB from dvd-project.

I am still very much in doubt though on the ideal output stage for the tda 1541A (esp. with 2 dac chips). I quick google gives sooo many options I got lost...

Let's make a poll on the view of the community!

oshifis · 2nd June 2010, 12:24 PM

Thorsten Loesch's "Adagio" comes from Audio Note DAC and it is very similar to the "Lampizator", so...?

Sandor · 2nd June 2010, 01:38 PM

Thorsten's Adagio uses a 20 ohm I/V resistor, a step-up transformer and a SRPP gain stage (E182CC).
The last published Thorsten's circuit has a 50 ohm I/V resistor, a choke loaded common cathode stage (ECC88), and no transformer.
The Lampizator uses a 100 ohm I/V resistor, a SRPP with a high gain tube (6N2P), and no transformer.

You could include in the list the good, and popular, "less simple I/V" from Rudolf Broertjies, as well as the Joko Homo's and Pedja Rogic's circuits.

I have tried all the above circuits and the best to me is the Adagio.
Regards.

Paul

studiostevus · 2nd June 2010, 02:08 PM

Quote:

You could include in the list the good, and popular, "less simple I/V" from Rudolf Broertjies, as well as the Joko Homo's and Pedja Rogic's circuits.

I don't think I still can. Maybe a moderator can include these in the poll?

studiostevus · 19th July 2010, 08:31 PM

Alright... I hoped this poll would be more conclusive.
Lampizator seems definately out.

Remaining are Thorsten, discrete and 'other'....
Are there any qualification as to what discrete sounds like vs. tube? (e.g. clearer, softer, more bass, etc?)

SoNic_real_one · 19th July 2010, 11:40 PM

I did vote for OpAmp. A decent OpAmp will have signal/noise, distortion way smaller than TDA's own. And there are fast enough OpAmps out there for the I/V stage (even for 4x OS).

gripracer · 20th July 2010, 12:38 AM

how about just a resistor and step-up transformer? then if you need gain, add a triode.

SoNic_real_one · 20th July 2010, 04:13 AM

The resistor can have bigger noise factor than an OpAmp input. DAC current output might not be loaded correctly by a resistor - OpAmps give zero impedance for an I/V stage.
Transformer has less bandwidth (lower end) than an OpAmp. And more, more distortion (hysteresis anyone?).

gripracer · 20th July 2010, 06:37 AM

yes, opamps may measure better, but they certainly wont sound better than a resistor and transformer.

qusp · 20th July 2010, 12:03 PM

I dont know about that, I love iron as well, but you have to spend some serious money on output transformers to beat a good opamp circuit for IV. I generally prefer discrete SS and thats how I voted, it can measure right up there too, much better than trannies. I do like the simplicity of transformer output, but there is no denying the numbers are usually pretty bad and its not suitable for all dacs either IMO

View Poll Results: What's the best output stage for TDA1541A based DAC
Opamp	10	20.83%
Discrete Solid State	15	31.25%
Lampizator-style	8	16.67%
Cathode Follower	0	0%
Thorsten-style	6	12.50%
Other	9	18.75%
Voters: 48. You may not vote on this poll

1st June 2010, 07:19 PM	#1
studiostevus diyAudio Member Join Date: Oct 2009 Location: The Hague	Best and final TDA1541A output stage I will start building my first 1541-based DAC soon, based on the currently running GB from dvd-project. I am still very much in doubt though on the ideal output stage for the tda 1541A (esp. with 2 dac chips). I quick google gives sooo many options I got lost... Let's make a poll on the view of the community!

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2nd June 2010, 12:24 PM	#2
oshifis diyAudio Member Join Date: Mar 2004 Location: Budapest, Hungary	Thorsten Loesch's "Adagio" comes from Audio Note DAC and it is very similar to the "Lampizator", so...?

2nd June 2010, 01:38 PM	#3
Sandor diyAudio Member Join Date: Mar 2004 Location: Milan	Thorsten's Adagio uses a 20 ohm I/V resistor, a step-up transformer and a SRPP gain stage (E182CC). The last published Thorsten's circuit has a 50 ohm I/V resistor, a choke loaded common cathode stage (ECC88), and no transformer. The Lampizator uses a 100 ohm I/V resistor, a SRPP with a high gain tube (6N2P), and no transformer. You could include in the list the good, and popular, "less simple I/V" from Rudolf Broertjies, as well as the Joko Homo's and Pedja Rogic's circuits. I have tried all the above circuits and the best to me is the Adagio. Regards. Paul

19th July 2010, 08:31 PM	#5
studiostevus diyAudio Member Join Date: Oct 2009 Location: The Hague	Alright... I hoped this poll would be more conclusive. Lampizator seems definately out. Remaining are Thorsten, discrete and 'other'.... Are there any qualification as to what discrete sounds like vs. tube? (e.g. clearer, softer, more bass, etc?)

19th July 2010, 11:40 PM	#6
SoNic_real_one diyAudio Member Join Date: Jan 2008 Location: Virginia	I did vote for OpAmp. A decent OpAmp will have signal/noise, distortion way smaller than TDA's own. And there are fast enough OpAmps out there for the I/V stage (even for 4x OS).

20th July 2010, 12:38 AM	#7
gripracer Banned Join Date: Mar 2009 Location: Atlanta, GA	how about just a resistor and step-up transformer? then if you need gain, add a triode.

20th July 2010, 04:13 AM	#8
SoNic_real_one diyAudio Member Join Date: Jan 2008 Location: Virginia	The resistor can have bigger noise factor than an OpAmp input. DAC current output might not be loaded correctly by a resistor - OpAmps give zero impedance for an I/V stage. Transformer has less bandwidth (lower end) than an OpAmp. And more, more distortion (hysteresis anyone?).

20th July 2010, 06:37 AM	#9
gripracer Banned Join Date: Mar 2009 Location: Atlanta, GA	yes, opamps may measure better, but they certainly wont sound better than a resistor and transformer.

20th July 2010, 12:03 PM	#10
qusp Sometimes a square peg fits a round hole just fine diyAudio Member Join Date: Oct 2009 Location: Brisbane, Australia	I dont know about that, I love iron as well, but you have to spend some serious money on output transformers to beat a good opamp circuit for IV. I generally prefer discrete SS and thats how I voted, it can measure right up there too, much better than trannies. I do like the simplicity of transformer output, but there is no denying the numbers are usually pretty bad and its not suitable for all dacs either IMO

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