Author Topic: The Best DAC is no DAC  (Read 3096 times)

Offline PingPing

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The Best DAC is no DAC
« on: February 05, 2016, 08:47:31 AM »
Hi, I have been reading about feeding 128/256/512 DSD to a board that converts it to I2S (Amanero or JLSounds board) then take the I2S left and right channels and feed through a DC Block then through a LPF which removes the HF carrier/noise.  This removes the need for a dac and the opamps.   

The following are a couple of other forum threads...
No-Dac and No-USB
best dac no dac

It seems that it can be a simple (reasonably simple) implementation and the results appear to be very good!   
Anyone have any thoughts about this approach/implementation?

Offline PingPing

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Re: The Best DAC is no DAC
« Reply #1 on: February 06, 2016, 11:04:49 PM »
Nobody interested?   Has anybody tried any of these approaches?

Offline stevenvalve

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Re: The Best DAC is no DAC
« Reply #2 on: February 06, 2016, 11:27:00 PM »
I think zenelectro is the one to comment, we will see.

Offline zenelectro

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Re: The Best DAC is no DAC
« Reply #3 on: February 08, 2016, 11:43:09 AM »
Hi, I have been reading about feeding 128/256/512 DSD to a board that converts it to I2S (Amanero or JLSounds board) then take the I2S left and right channels and feed through a DC Block then through a LPF which removes the HF carrier/noise.  This removes the need for a dac and the opamps.   

The following are a couple of other forum threads...
No-Dac and No-USB
best dac no dac

It seems that it can be a simple (reasonably simple) implementation and the results appear to be very good!   
Anyone have any thoughts about this approach/implementation?

The title suggests you are getting rid of the DAC, but you are just moving the DAC further up the chain.

Whatever the logic chip is that drives I2S output - this is now your DAC. A 1 bit DAC - with all it's advantages and disadvantages.

Advantages - less complexity, no digital filters, perceived more direct signal path.

Disadvantages - 1 bit audio has a huge amount of noise to filter. Even modern DAC's with a few bits have much less HF noise and so the analog stages have an easier job.
Jitter and isolation also have to be addressed. Then there is the OP drive. The I2S OP logic gate is your driver and has certain limitations.

So it's an easy intuitive solution just to low pass a DSD stream and get pretty good sound but to do it really well is a whole other kettle of fish.

How to do it really well? The whole circuit gets more complex, has some additional 'digital' filtering, jitter reduction and a few other things but it
then moves beyond a simplistic DIY project.

cheers

T

Offline PingPing

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Re: The Best DAC is no DAC
« Reply #4 on: February 08, 2016, 02:30:26 PM »
Where is the DAC ... there is Digital in to Digital I2S out then through an analogue DC block LPF... No DAC or have I missed something?

 I believe, the key part to this is ensuring that it is in a 128(Min)/256/512 DSD pulse bit format before it reaches the Digital I2S out :)

If you tried this, I would love to know your implementation of it :)
« Last Edit: February 08, 2016, 02:33:50 PM by PingPing »

Offline zenelectro

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Re: The Best DAC is no DAC
« Reply #5 on: February 10, 2016, 02:47:46 PM »
Where is the DAC ... there is Digital in to Digital I2S out then through an analogue DC block LPF... No DAC or have I missed something?

 I believe, the key part to this is ensuring that it is in a 128(Min)/256/512 DSD pulse bit format before it reaches the Digital I2S out :)

If you tried this, I would love to know your implementation of it :)

Read my post. The I2S OP is the DAC - a 1 bit DAC.

cheers

Z

Offline PingPing

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Re: The Best DAC is no DAC
« Reply #6 on: February 13, 2016, 11:40:40 PM »
Has anyone tried this or are thinking of trying it :)