DAC to Chip Amp

davidallancole · 27th November 2007, 01:19 PM

Has anybody tried running a DAC like the TDA1543 straight into a chip amp like the LM3886? Do you think there would be any benefit?

sharpi31 · 27th November 2007, 04:20 PM

I've done this in two systems, and also used the lower output TDA1545 (always into LM3875 chips).

With high sensitivity loudspeakers (>94dB) this can be a great solution. If the available gain is sufficient, avoiding extra opamps can provide great transparency. Dynamics do suffer slightly, but this isn't usually an issue if high sensitivity speakers are used.

Obviously short, low capacitance interconnects are a must.

The best combination I have built so far is a modified Lite DAC-AH (passive I/V mod with 150R resistor) into a 10K stepped attenuator into the LM3875. There is definitely more balls with the paralleled dacs than with a single dac. The output impedance is lowered by a factor of 8 with 8 dacs, as the I/V resistor value has to be lowered.

I have tried buffers and active preamps but these always seen to add weight at the expense of resolution, detail and 'air'.

I say give it a go, as long as your speakers are fairly sensitive.

davidallancole · 27th November 2007, 04:22 PM

Sweet, thanks for the reply. I may try it one day.

BWRX · 27th November 2007, 11:07 PM

It would be interesting to try and how you configure the chip amp would depend on the output of the DAC you used. Running the balanced output of DAC into a diff amp would probably be one of the best ways to do it.

davidallancole · 28th November 2007, 03:11 AM

From what I have been reading, a lot of DACs have current outputs and then are turned back into voltage through a I/V converter. I was thinking maybe it would be possible to run this into a chip amp that is set for current feedback (current in/current out but larger current out i.e. current source amp) for use with some of the drivers from Nelson Pass's article on current source amps with fullrange drivers.

BWRX · 28th November 2007, 03:40 AM

Quote:

Originally posted by davidallancole
From what I have been reading, a lot of DACs have current outputs

Then you could configure the power op amp to be a current to voltage converter.

davidallancole · 28th November 2007, 12:40 PM

There seems to be a lot of possibilities with this. I will have to check into it in the future when I am done some other projects. A USB DAC that outputs straight to a chip amp seems to be an excellent way to build a small, tight amp.

Bgt · 28th November 2007, 01:41 PM

Quote:

Originally posted by sharpi31

I have tried buffers and active preamps but these always seen to add weight at the expense of resolution, detail and 'air'.

I have the same experience with active preamps, they miss 'air/separation/detail'.
I am experimenting with a LM4562 buffer into an UCD.

nikonf2 · 18th May 2011, 05:22 AM

what is the grounding resistor value for passive mod, 100r or 100kr?

27th November 2007, 01:19 PM	#1
davidallancole diyAudio Member Join Date: Nov 2005	DAC to Chip Amp Has anybody tried running a DAC like the TDA1543 straight into a chip amp like the LM3886? Do you think there would be any benefit?

27th November 2007, 11:07 PM	#4
BWRX diyAudio Moderator Emeritus Join Date: Jan 2005 Location: Pennsylvania	It would be interesting to try and how you configure the chip amp would depend on the output of the DAC you used. Running the balanced output of DAC into a diff amp would probably be one of the best ways to do it. __________________ Brian

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27th November 2007, 04:20 PM	#2
sharpi31 diyAudio Member Join Date: Oct 2005	I've done this in two systems, and also used the lower output TDA1545 (always into LM3875 chips). With high sensitivity loudspeakers (>94dB) this can be a great solution. If the available gain is sufficient, avoiding extra opamps can provide great transparency. Dynamics do suffer slightly, but this isn't usually an issue if high sensitivity speakers are used. Obviously short, low capacitance interconnects are a must. The best combination I have built so far is a modified Lite DAC-AH (passive I/V mod with 150R resistor) into a 10K stepped attenuator into the LM3875. There is definitely more balls with the paralleled dacs than with a single dac. The output impedance is lowered by a factor of 8 with 8 dacs, as the I/V resistor value has to be lowered. I have tried buffers and active preamps but these always seen to add weight at the expense of resolution, detail and 'air'. I say give it a go, as long as your speakers are fairly sensitive.

27th November 2007, 04:22 PM	#3
davidallancole diyAudio Member Join Date: Nov 2005	Sweet, thanks for the reply. I may try it one day.

28th November 2007, 03:11 AM	#5
davidallancole diyAudio Member Join Date: Nov 2005	From what I have been reading, a lot of DACs have current outputs and then are turned back into voltage through a I/V converter. I was thinking maybe it would be possible to run this into a chip amp that is set for current feedback (current in/current out but larger current out i.e. current source amp) for use with some of the drivers from Nelson Pass's article on current source amps with fullrange drivers.

28th November 2007, 12:40 PM	#7
davidallancole diyAudio Member Join Date: Nov 2005	There seems to be a lot of possibilities with this. I will have to check into it in the future when I am done some other projects. A USB DAC that outputs straight to a chip amp seems to be an excellent way to build a small, tight amp.

18th May 2011, 05:22 AM	#9
nikonf2 diyAudio Member Join Date: Jun 2010	what is the grounding resistor value for passive mod, 100r or 100kr?

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