ESS Sabre Reference DAC (8-channel)

[BrianDonegan]

Originally posted by gentlevoice
... thought some of you might know about ADCs as well... (see two posts above this for my question)?

Would you know about this Dustin? Or maybe where to ask/search?

Regards,

Jesper

You will have much better luck starting a thread so everyone will see your question. It's also better then dragging threads off topic.

[EDIT] Didn;t mean that to sound so rude, sorry.[/EDIT]

[Terry Demol]

Originally posted by gentlevoice
... thought some of you might know about ADCs as well... (see two posts above this for my question)?

Would you know about this Dustin? Or maybe where to ask/search?

Regards,

Jesper

Probably worth starting a new thread.

Currently the best ADC's chips are from AKM (123dB DR / 110dB
THD) Cirrus (120dB DR / 110dB THD) TI (124dB DR / 108dB THD.

All pro audio ADC's that are exceeding this are using gain ranging
IP architectures for example Lavry Engineering, Stage tech, Prism
etc.

I believe current lowest distortion ADC is discrete 1 bit design by
Bruno Putzeys (and others), see grimmaudio. It is a DSD ADC and
requires DSD -> PCM conversion, but appears to be as good as it
gets linearity wise. DR is similar to chips.

I'm not sure what is used in the Dcs ADC.

Do some searching and you will find all this.

cheers

Terry

[JC951t]

Hi Terry,
Sorry, but personally, I don't feel that great specs
alone equals good sound.

[gentlevoice]

Thanks for your comments & suggestions :-)

Yes, I know that I am intervening in a thread that has another purpose. As I wrote I hoped that somebody - in an otherwise very interesting and high quality DAC thread (flattering ;-)) - would know about ADCs.

And Terry thanks for your comments - I will look at it.

I look forward to seeing the progress of your endeavors.

Regards,

Jesper

[borisov57]

Hi Jesper,

I have made two ADCs based on TI chips, but only for measurement purposes. If I were you, I would choose TI or CS ADC and try different input preamps/buffers for maximum sound quality.

Good luck

[wildmonkeysects]

It's been a while since I've delurked, however this has my attention! I am looking forward to the Buffalo boards.

Qs for Dusty:

a: Do the internals of the Sabre chip clock off rising and falling edges of Xti; or just the rising edge? ie, which edges matter?

2: About the internal analog stage thermal signature: what load minimizes the chip thermal shifts with signal swings? It is likely a parabolic function, but there may be a sweet spot, a particular resistive load, that will minimize internal thermal tails. It will not nesc be the minima for DNR or SFDR, but it may sound good. I'm guessing something like 550 to 650 ohms across the differential outputs in stereo mode. Current out mode is not nesc the sweet spot.

In regards to "thermal tails", I mean in the broader sense: active devices, including pure digital applications will have shifting threshold voltages with thermal shifts, and a chip is awash in isothermal fronts or waves "sloshing"around...the time constants correlate with audible frequencies, typically 1 to 10 kHz depending on chip geometry. This is a recipie for a PWM heater, with time constants of audible consequences for small but significant time and amplitude shifts.

I will have fun fine tuning when I have the HW in hand.

Cheers,

WMS

[Terry Demol]

Originally posted by wildmonkeysects
It's been a while since I've delurked, however this has my attention! I am looking forward to the Buffalo boards.

Qs for Dusty:

a: Do the internals of the Sabre chip clock off rising and falling edges of Xti; or just the rising edge? ie, which edges matter?

2: About the internal analog stage thermal signature: what load minimizes the chip thermal shifts with signal swings? It is likely a parabolic function, but there may be a sweet spot, a particular resistive load, that will minimize internal thermal tails. It will not nesc be the minima for DNR or SFDR, but it may sound good. I'm guessing something like 550 to 650 ohms across the differential outputs in stereo mode. Current out mode is not nesc the sweet spot.

In regards to "thermal tails", I mean in the broader sense: active devices, including pure digital applications will have shifting threshold voltages with thermal shifts, and a chip is awash in isothermal fronts or waves "sloshing"around...the time constants correlate with audible frequencies, typically 1 to 10 kHz depending on chip geometry. This is a recipie for a PWM heater, with time constants of audible consequences for small but significant time and amplitude shifts.

I will have fun fine tuning when I have the HW in hand.

Cheers,

WMS

WMS,

In the absence of Dustin, I would hazard an educated guess and
say that 0 ohm dac OP load is optimal for THD -and- thermally
related distortion.

AFAIK, most DEM coding schemes equalize bit share time and
therefore thermal shifts of junctions, but only if the OP currents are
always the same when on.

Once the OP is allowed to voltage swing, an 'on' dac bit will not
necessarily have the same current all the time depending where the
OP voltage is.

Having said the above this dac must have a pretty smart dem coding
scheme as specs with max recommended OP voltage swing are
still super linear.

cheers

T

[peufeu]

Hello,

I wonder if the offer for samples is still up ?

I resurrected the Ethernet DAC project after a long pause, and plan to have a massive DAC shootout in 2-3 months, time to build everything. I would like to include this one since it looks very promising. Project includes low jitter, oversampling in the FPGA, etc.

[Russ White]

Thanks to Brian, I have in my hands a built up Buffalo prototype. The boards took longer than expected because the PCB house made a mistake and they had to be redone. But they are here now and look good.

I have not had a chance yet to listen to it (just got it last night), and I found some firmware changes I need to make before it will work. But perhaps tonight it will be playing music. A brief examination electrically seems to checkout.

I will post some pics soon.

Cheers!
Russ

[fierce_freak]

Sounds great, Russ. I look forward to your impression