jkeny said:
The Skpre has an input Z of 6.75K, so the Sabre will be in voltage mode.
Are C1 and C11 ceramics, by the way?
Sorry Dan,
I don't know the answer to C1 & C11 type. I don't have a Buffalo myself - just looking into it for a friend & gathering info together here. It's becoming a useful thread so far, with the info posted.
Final question - did you compare the SKPre to an IVY or other IV analog stage here?
I don't know the answer to C1 & C11 type. I don't have a Buffalo myself - just looking into it for a friend & gathering info together here. It's becoming a useful thread so far, with the info posted.
Final question - did you compare the SKPre to an IVY or other IV analog stage here?
SKPre Balanced Mode
Do you have a diagram of how to set up the SKPre to use balanced to SE mode? I have a pair of built boards, but they are set to use SE input. Balanced to SE would be nice because the SKPRE sounds very good.
Thanks,
Do you have a diagram of how to set up the SKPre to use balanced to SE mode? I have a pair of built boards, but they are set to use SE input. Balanced to SE would be nice because the SKPRE sounds very good.
Thanks,
Sorry for getting off the Buffalo mod topic... Double thanks for the SKPre thread. Will try this and compare to the IVY.
Thanks,
Thanks,
Spartacus said:Hi John,
Dan here, from the SKA forum. This is what I'm using for the Analog supply to my Buffalo:
Q2 is an MPSA14 darlington. Way, way better than LM317s. This is currently feeding Greg's Mini-reg to provide a nice and clean 3.3V Vref.
The clock: a separate supply with an AD797 based reg feeding a 66MHz oscillator from Guido Tent.
I'm using a Twisted Pair DIR to convert S/PDIF to I2S. Didn't make a jot of difference to the sound, but enabled 192K to work.
Analog stage is an SKpre symmetrical discrete opamp for balanced to SE conversion. The output offset is trimmable, so no coupling caps needed. Superb.
Next up ..... bypassing the LM4562 buffer and feeding the analog supply directly from the Mini-reg. Not at all convinced this will help, but worth trying.
Dan
I'd only bypass the LM4562 if the reg used here has lower output impedance, most of the VBE/cap multiplier based regs output impedance is too high imo for the AVCC, main reason I used separate Paul Hynes shunts and removed the LM4562's
Is there any cicuit or details for Gregs mini reg? these look nice and compact
t. said:
The above circuit is a pre-regulator for the mini-reg, which itself is a feedback reg with low output Z, and 100dB+ wideband line rejection. I'm not sure how Greg, would feel about sharing the circuit .... best contact him at SKA audio.
The other thing to remember is that when the Sabre is running in Voltage out mode, its modulation of the power supply will be low, making regulator Z less important.
Dan,
This makes me wonder about wildmonkeysects surmising about the possible analog configuration of - "Just" a very clean Avcc and use V out. He also wondered if the Vout config with an optimal load (unknown what this is) and - there is probably a sweet spot for the external load where the Sabre's thermal modulation is minimal
On another site a Sabre user experimenting with different configurations used a peltier to cool the chip and found a clearer sound but was afraid of condensation damaging the chip.
but bad PSRR so a clean supply is necessary
This makes me wonder about wildmonkeysects surmising about the possible analog configuration of - "Just" a very clean Avcc and use V out. He also wondered if the Vout config with an optimal load (unknown what this is) and - there is probably a sweet spot for the external load where the Sabre's thermal modulation is minimal
On another site a Sabre user experimenting with different configurations used a peltier to cool the chip and found a clearer sound but was afraid of condensation damaging the chip.
soundcheck said:
Correct link:
http://www.diyaudio.com/wiki/index.php?page=Dac+Buffalo+Modifications
😉
TheShaman said:
I'm torn between my Plan A (see quote) and Plan B, which involves keeping LCBPS/LCDPS for rectifying and pre-regulation and adding SuperTeddyRegs (one for every rail).
Any input that would help me make this choice is appreciated!
TheShaman said:
The only issue with plan B that i can see is whether you will have enough drop out voltage. Using the LCDPS and bypassing the LM regs is an option ... that's probably what i would do.
Spartacus said:
I was thinking 9V transformers for VA/VD and 18V ones for the I/V.
SuperTeddy should be fine with 4V dropout I think (Teddy states 3V is the minimal).
My 2 cents - if you can get the performance from one regulator then I would avoid using a pre-regulator & the possible interactions there might be when using two regs. in series.
I haven't heard of the sigma regs before & just looked into them - can't find any specs on their noise, PSRR, impedance - have you got a link?
I haven't heard of the sigma regs before & just looked into them - can't find any specs on their noise, PSRR, impedance - have you got a link?
jkeny said:
You're probably right.
jkeny said:
There are plenty of technical details on the relevant pages of the AMB.org website (check Tech Highlights for example).
There were also some solid numbers, if I'm not mistaken, on the HeadWize forum but they had some hacking troulbe and have been offline for some time now.
Just had a look at the circuit for the sigmas. Nice design. The Teddy regs will have lower noise and better rejection of high frequencies, but higher output impedance. Both will be a considerable improvement on the LM regulators.
Spartacus said:
Output impedance is one of the reasons I haven't ruled the Sigma's out yet.
In this aspect perhaps a JSR-03JSR-03 would be a better option.
In addition, I'm a bit troubled by the lack of load-regulation on the SuperTeddys.. They'd match well with the constant-current draw of the Counterpoints but I'm not so sure about VD (VA is negligible) or alternative I/V stages like the IVY II implemented in Buffalo 32S (to which I might upgrade at some point).
- Status
- Not open for further replies.