ESS Sabre Reference DAC (8-channel)

Thanks for the PDF, jcx.

The transformer I am using does have THD numbers above 0.001% for the low bass.

http://www.jensen-transformers.com/datashts/10kbdpc.pdf

I doubt that low bass distortion will have any affect on the transparency of the sound of this DAC part. Listening room standing waves will distort the sound much more than that.

My opinion is that the transparent sound is mostly due to the jitter rejection capability of the part. This DAC chip can even make 16-bit redbook sourced material sound remarkably clean and lifelike. Circuit changes that affect the -120db level aren't what is making the CDs sound so good. The Sabre8 part has the capability to nullify the bad effects that come with SPDIF data transission.

Of course, the 24-bit-depth material sounds good too! :D
 
Russ White said:



Its the IVY. :)

There is another circuit in the works (basically a discrete IVY) but I am still adjusting the secret sauce. :) The circuit is tested but there is no PCB yet.

Cheers!
Russ

Russ,

WRT new I-V, Is this the fully differential discrete closed loop design
you posted sim results to on another forum some time ago?
That looked like a decent design.

The thing with ESS Sabre is it has very low OPZ (200 ohms) and very
high current OP in stereo mode. So a virtual ground configured I-V
will have a lot of work to do and needs to be designed well to
achieve the Sabres 120dB THD. Doing it closed loop as you did is
certainly possible and the I-V should easily better this figure.

I prefer zero feedback, current conveyor I-V designs and this is
where the Sabre is a -real- challenge. That 200 ohms and 8mA
swing will send most current conveyor circuits into significant
non linearity.

I have one open loop design simmed which does < 120dB THD at full
OP but it took some pretty heroic design measures to get there.

T
 
Terry Demol said:


Russ,

WRT new I-V, Is this the fully differential discrete closed loop design
you posted sim results to on another forum some time ago?
That looked like a decent design.
T


Hello Terry,

Yes it is very similar to that circuit. I have tweaked it a little and made it more bullet proof, adding short circuit protection etc, and giving it enough current drive to be able to drive headphones etc. It can easily drive a 25ohm load to 2VRMS. So even low impedance cans would be fine.

This way I can control the volume in the DAC.

I like both closed and open loop designs, but I must confess, I am aiming for low THD and high damping factor right now. I am sure I will try lots of I/V circuits in the future. So keep me posted if you have success with your endeavor.

I will update the thread in the Pass Labs section when I have it complete. The circuit itself is tested. It works, and very well.

Cheers!
Russ
 
Sum up of features and formats

Hi,

Can you guys please help me sum up the current features and the acceptable input formats of the DAC-module that Russ & co are working on? As I understand it the DAC-module will always work in a 2ch mode and:

- accept a standard SPDIF input from any old CD-player (16-bits @ 44.1 kHz)
- accept USB input data via a separate USB-to-I2S board, 24-bits @ 96 kHz?
- accept SACD DSD input data, 1 bit @ 2.8 MHz?
- higher PCM rates, 192 kHz?
- ...?

Regards,
Dex
 
Re: Sum up of features and formats

DexterMorgan said:
Hi,

Can you guys please help me sum up the current features and the acceptable input formats of the DAC-module that Russ & co are working on? As I understand it the DAC-module will always work in a 2ch mode and:

- accept a standard SPDIF input from any old CD-player (16-bits @ 44.1 kHz)
- accept USB input data via a separate USB-to-I2S board, 24-bits @ 96 kHz?
- accept SACD DSD input data, 1 bit @ 2.8 MHz?
- higher PCM rates, 192 kHz?
- ...?

Regards,
Dex

Hi Dex,

The USB module we have supports 44.1 and 48khz 16bit I2S output. The ESS DAC we are doing will accept that.

It will accept DSD.

It will also accept 16/24bit PCM or SPDIF up to 192khz.

Cheers!
Russ
 
Dougie085 said:
So even if your feeding the I2S into the Opus no 24bit? Gotta have the metronome in place and then it will do 24bit 192khz?


No it has nothing to do with the DAC. The DAc can do 192/24 no problem. :)

It is just a limitation of the PCM2707 USB module. That module can only output 44.1 or 48khz. :)

The Buffalo DAC will easily do 192/24 either PCM(I2S LJ/RJ) or SPDIF.
 
Dougie085 said:
Ok I get that part but what I'm asking is that with the Metronome will it do 192khz? And also will the PCM2707 do 24 bit or only 16bit? Sorry if we're frustrating you :) I just was thinking with the USB module I would be able to do 24bit at least.


The metronome can convert the 16bit to 24bit yes. but there is no need, since the ESS DAC already basically does the same thing (only better). Just feed it the I2S out of the USB module.

Cheers!
Russ
 
USB

Hi All,

Yes you could just use the SPDIF output from your computer and drive it into Russ's board for a 24 bit, source, but I think everyone knows this. I am curious as to who has made USB do 192kHz and 24 bit depth from the computer since that is was we did for the demo boards. Anyways, how are the design's going?

Dustin