Another TDA1541A based dac (dual differential)

Tazzz · 3rd July 2011, 10:50 AM

I've had this up and running for about a year now...

abraxalito · 3rd July 2011, 11:12 AM

Very interesting looking design, thanks for sharing. I take it its NOS and the clump of logic in the middle creates the digital inversion. Why did you opt for separate common-mode chokes on the secondary sides of the transformers rather than one choke on the primary side? Also what's the I/V stage - those discrete TO220 transistors?

studiostevus · 3rd July 2011, 11:36 AM

Interesting indeed. Can you share more on the logic circuit?

erin · 3rd July 2011, 01:14 PM

Tazzz, Is it your design, can we buy it somewhere?

Tazzz · 3rd July 2011, 04:36 PM

Quote:

Originally Posted by abraxalito

Very interesting looking design, thanks for sharing. I take it its NOS and the clump of logic in the middle creates the digital inversion. Why did you opt for separate common-mode chokes on the secondary sides of the transformers rather than one choke on the primary side? Also what's the I/V stage - those discrete TO220 transistors?

Yes, as its playing now its run in NOS but with passive sinx/x. Its much easier to dampen the Q of the filters when they can be loaded with large electrolytics.

The I/V stage is pretty much that of the "D1" Only I've changed it to draw current from the power supplies more equally and not load the sinx/x filters excessively at low volume settings.

Quote:

Originally Posted by studiostevus

Interesting indeed. Can you share more on the logic circuit?

Its similar to the i2s splitter posted by pedja rogic some years back but since I had a CPLD implementation in mind first Its implemented in another way using less flip-flops.

The rest is a clock divider and a couple of XOR gate providing a truly differential signal for the DEM pins.

Quote:

Originally Posted by erin

Tazzz, Is it your design, can we buy it somewhere?

No, its my PCB.

jazz · 4th July 2011, 08:43 AM

Hi Tazz,

I'd be very interested in your schematic's and pcb layout. I'm currently trying to do something very similar and would hope to pick up some ideas from your implementation. Would it be possible to post the schematic and or pcb layout?

regards,
Joris

Tazzz · 4th July 2011, 04:17 PM

Quote:

Originally Posted by jazz

Hi Tazz,

I'd be very interested in your schematic's and pcb layout. I'm currently trying to do something very similar and would hope to pick up some ideas from your implementation. Would it be possible to post the schematic and or pcb layout?

regards,
Joris

Sorry, no not at this moment.

savvas · 4th July 2011, 09:46 PM

Quote:

Originally Posted by Tazzz

Sorry, no not at this moment.

So what's the point of this thread ? Any further info or comparison ?

batteryman · 6th July 2011, 05:37 PM

I am about to start on a dual differential 1541a dac.
I am buffering and inverting the data to one dac and using a bifilar wound dual primary I/V transformer.

The plan is to use 3 pairs (in series) of 74hct14 hex inverters to buffer all three I2S lines borrowed from the inputs of the 7220. One dac will receive its data after only one inversion.

The transformer is here:Sowter Type 9545 DAC INTERFACE TRANSFORMER

For the time being the transformer supplies the valve output stage of an Audio Note DAC1 (I'll also try the transformers on this as well)
I

Tazzz · 7th July 2011, 05:05 PM

You don't get all the benefits from running differential if you do it that way you really should split up the I2S into left and right and use separate dacs for the different channels.

3rd July 2011, 11:12 AM	#2
abraxalito diyAudio Member Join Date: Sep 2007 Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though... Blog Entries: 46	Very interesting looking design, thanks for sharing. I take it its NOS and the clump of logic in the middle creates the digital inversion. Why did you opt for separate common-mode chokes on the secondary sides of the transformers rather than one choke on the primary side? Also what's the I/V stage - those discrete TO220 transistors? __________________ I think ideas are what you want to get rid of. I don't really like songs with ideas. - Leonard Cohen

4th July 2011, 08:43 AM	#6
jazz diyAudio Member Join Date: Dec 2001 Location: leiden, physically that is...	Hi Tazz, I'd be very interested in your schematic's and pcb layout. I'm currently trying to do something very similar and would hope to pick up some ideas from your implementation. Would it be possible to post the schematic and or pcb layout? regards, Joris __________________ oh, what a beautifull day I wanna go out and play!

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3rd July 2011, 11:36 AM	#3
studiostevus diyAudio Member Join Date: Oct 2009 Location: The Hague	Interesting indeed. Can you share more on the logic circuit?

3rd July 2011, 01:14 PM	#4
erin diyAudio Member Join Date: Nov 2006	Tazzz, Is it your design, can we buy it somewhere?

6th July 2011, 05:37 PM	#9
batteryman diyAudio Member Join Date: Jun 2011 Location: SCOTLAND	I am about to start on a dual differential 1541a dac. I am buffering and inverting the data to one dac and using a bifilar wound dual primary I/V transformer. The plan is to use 3 pairs (in series) of 74hct14 hex inverters to buffer all three I2S lines borrowed from the inputs of the 7220. One dac will receive its data after only one inversion. The transformer is here:Sowter Type 9545 DAC INTERFACE TRANSFORMER For the time being the transformer supplies the valve output stage of an Audio Note DAC1 (I'll also try the transformers on this as well) I

7th July 2011, 05:05 PM	#10
Tazzz diyAudio Member Join Date: Jun 2007	You don't get all the benefits from running differential if you do it that way you really should split up the I2S into left and right and use separate dacs for the different channels.

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