ESS ES9008/9018 Sabre dac

[leo]

I've just tried this new input filter recommended by Russ for the IVY http://www.twistedpearaudio.com/foru...?g=posts&t=587
So far I'm liking this better than the original values, its certainly worth trying!

[leo]

[leo]

Anybody had experience with Oscon SVP caps? these seem to be polymer based instead of electrolyte fluid
Theres quite a few on this new 32bit ES9018 based dac

Reason I ask is because they are on the anolgue decoupling too, the older Oscons wasn't really suited for analogue but they wasn't polymer
I've not a lot of experience with Polymer caps

[leo]

I've been running this newer ES9018 Sabre based dac for over a week now.
There was a few things which needed sorting on the grounds but apart from that its been running in very nice

Again psu and regulation are extremely important in a dac like this, the standard supplied regs in this particular design by Twisted Pear are based around separate LT1763 and LM49710/20 used as voltage buffers for the dac chips AVCC L & R
Theres no onboard regulation for the outputstage so I first tried well filtered LM317/337 set to +/-15v, I then borrowed the Paul Hynes +/-15v Z1A/Z1N shunt regulation , these gave an immediate improvement


Its true this newer Sabre improves on the older version in some area's, I've yet to try a few more tweaks to make comparing more fair but so far its pretty impressive

[Audiocom AV]

Anybody had experience with Oscon SVP caps? these seem to be polymer based instead of electrolyte fluid
Theres quite a few on this new 32bit ES9018 based dac

Hi Leo

I have used the OSCON SVP capacitor for upgrade mods in several unit including the Benchmark DAC1, Squeezebox Transporter; results have been very good.

Best Wishes
Mark

PS: I sent you a PM on the TX2575.

[leo]

Thanks and thanks Mark

[jkeny]

Leo or anyone,
Any idea why the LT1763 V Regs are used here at IC3,4,5 below the clock - designed for battery use & so atrocious PSRR by the look of the datasheet - what are they supplying PS to, the chip, clock? I'm not sure Russ wants to answer this Q as posted on the Buffalo tweakers thread on DIYA

Any further tests with PH shunt regs?

[rolls]

Leo or anyone,
Any idea why the LT1763 V Regs are used here at IC3,4,5 below the clock - designed for battery use & so atrocious PSRR by the look of the datasheet - what are they supplying PS to, the chip, clock? I'm not sure Russ wants to answer this Q as posted on the Buffalo tweakers thread on DIYA

Any further tests with PH shunt regs?

I think they are chosen because of their "low" 20uV noise. Anagram chooses the same on their DAC EV board, you have a choice of shunts, e.g. Paul's, or of no regs....

regards Andre

[jkeny]

Hi Andre,
I can't fathom it - How does low generated noise represent an advantage compared to low PSRR (PSRR <50dB (1KHz - 20KHz) <40dB over 100KHz) which allows noise coming in from the PS, a greater source of noise, if you ask me? If this DAC was intended to run off batteries then I'd understand!

BTW, I asked over on DIYA about using protoboards with Sabre DAC but Russ put it down as sub-optimal with traces & gnd. I made the point that this would probably be more than made up for by using better & multiple PS & clock. (I'm not even sure how sub-optimal it would be)

[leo]

Leo or anyone,
Any idea why the LT1763 V Regs are used here at IC3,4,5 below the clock - designed for battery use & so atrocious PSRR by the look of the datasheet - what are they supplying PS to, the chip, clock? I'm not sure Russ wants to answer this Q as posted on the Buffalo tweakers thread on DIYA

Any further tests with PH shunt regs?

As a guess (I've not closely traced the circuit yet so could be wrong) LT1763 regs provide the 1.2v core, XO and dacs 3.3v , I'd imagine the 3.3v is then split off through CRC filtering + op-amp voltage buffer for the AVCC L&R.
My next plan is to feed the LT1763's from a PH shunt reg set to 5v, this should clean a lot of s**t up before it gets to those regs.
removing the LT1763 altogether and installing separate PH regs would probably be the best

This Buffalo32s pcb allows track cuts so external separate regs for the AVCC L & R can be used , a pair of PH regs will be used to do this duty as I did with the original Buffalo dac

The PH regs will certainly be staying for the IVY section, they are vastly superior to any other regulator combo I've tried
Also none of the LM317/337 based regs seemed happy with the SVP caps seen on the output , PH regs have no such problem with very low ESR caps