from glt
After observing the lock drops I went back to the TPA site and found the chip for sale. Brian shipped it out immediately. I replaced the original chip with the alternate chip but I have not seen any improvement. I have left the DAC on for > 30 min and still observe lock drops.
I do not know how to answer your question about how it works with the original firmware since I simply replaced chips.
Thanks for your suggestions; any more ideas? - David
Yes: Alternate firmware chip....
After observing the lock drops I went back to the TPA site and found the chip for sale. Brian shipped it out immediately. I replaced the original chip with the alternate chip but I have not seen any improvement. I have left the DAC on for > 30 min and still observe lock drops.
I do not know how to answer your question about how it works with the original firmware since I simply replaced chips.
Thanks for your suggestions; any more ideas? - David
You can do the following:
- If the new firmware did not improve the dropouts, it is likely you got the wrong part. Order another one
- Use spdif
- try twisting the bitclock and GND wires together (use a longer gnd wire so you can reach the bitclock from the usb board's header).
- If the new firmware did not improve the dropouts, it is likely you got the wrong part. Order another one
- Use spdif
- try twisting the bitclock and GND wires together (use a longer gnd wire so you can reach the bitclock from the usb board's header).
If the firmware chip didn't work, I'd look at your i2s wiring. Replace what you have with cat6 twisted pairs next.
Yes, the dropout is always coincident with a loss of DAC lock, as indicated by the lock LED winking off.
With regard to the twisting of the I2S wires, if I follow glt's advice and twist the bck and gnd together, should I then twist the remaining (LRCK and D0) together, using cat6 wires? Or is there another, preferred configuration?
With regard to the twisting of the I2S wires, if I follow glt's advice and twist the bck and gnd together, should I then twist the remaining (LRCK and D0) together, using cat6 wires? Or is there another, preferred configuration?
Your PCM wires are nice and short already. I would be surprised if that is the problem. have you tried another mac or PC?
Yes I have tried another music source. My laptop is a mac G4 with OS 10.4.11 and I tried Itunes and then COG as players. I then substituted my girlfriend's laptop, an Intel dual core Mac running 10.6.x. The first try (easiest) was to use Itunes, then I downloaded the Audirvana player and tried it: using both resulted in the occasion unlock/dropout, no improvement over my G4 laptop.
I also tried a buddy's laptop that was running windows, but the laptop never recognized the USB receiver/DAC, so we never got to try his music source (JRiver).
I also tried a buddy's laptop that was running windows, but the laptop never recognized the USB receiver/DAC, so we never got to try his music source (JRiver).
There is something I don't understand: when the Buffalo are used in Stereo mode all the DAC have positive phase and all the DACB have negative phase. This make sense. In all mono mode, the DACB are still all negative phase, but two of the DAC are also negative. Why this? How are the output of the chip mapped to the output of the board?
Additionally, can somebody explain what de-emphasis does and what are the advantages and disadvantages?
Thanks,
Additionally, can somebody explain what de-emphasis does and what are the advantages and disadvantages?
Thanks,
Which configuration/firmware?
From what I gather from the TPA documents, in dual mono the phase setting is as follows:
For the left mono board:
left side DAC: in-phase; right side DAC: anti-phase
left side DACB: anti-phase; right side DACB: in-phase
For the right mono board:
left side DAC: anti-phase; right side DAC: in-phase
left side DACB: in-phase; right side DACB: anti-phase
You could program all DACs in-phase and all DACBs anti-phase and flip the wires in the output stage...
From what I gather from the TPA documents, in dual mono the phase setting is as follows:
For the left mono board:
left side DAC: in-phase; right side DAC: anti-phase
left side DACB: anti-phase; right side DACB: in-phase
For the right mono board:
left side DAC: anti-phase; right side DAC: in-phase
left side DACB: in-phase; right side DACB: anti-phase
You could program all DACs in-phase and all DACBs anti-phase and flip the wires in the output stage...
I am talking about the volumite firmware in dual mono mode. If I got it right, the eight DAC are grouped in two groups, even and odd.
What surprised me of the tp fw settings is that in dual mono I would expect to find flipped phase in four DAC and four DACB settings, (reg 13 and 19) but I see flipped phase only in two DAC settings. That what puzzle me.
I am tempted to leave everything like in stereo and not to have the wires crossed.
Thanks,
Davide
What surprised me of the tp fw settings is that in dual mono I would expect to find flipped phase in four DAC and four DACB settings, (reg 13 and 19) but I see flipped phase only in two DAC settings. That what puzzle me.
I am tempted to leave everything like in stereo and not to have the wires crossed.
Thanks,
Davide
This is because with buffalo II the DACs are remapped internally to support stereo SPDIF/PCM/DSD at the same time. So the the source of some DACs are another DAC. Thus you only should flip the phase of the source DAC or you will end up with double flip on the second (like a double negative). Try it, and you will see what I mean. Why do you care? If you do you might want to get the data sheet and study it. 🙂 There is an important reason to flip the phases on the opposite side. It makes doing dual mono easier. Because a normally stereo output stage becomes a mono output stage. 🙂
Last edited:
Is it OK to switch the I2S/SPDIF jumper while the buffalo is powered on?
I'd like to rig a switch to this jumper to make a i2s/spdif input selector.
Is this feasible?
I'd like to rig a switch to this jumper to make a i2s/spdif input selector.
Is this feasible?
REALLY?
But the source of DAC is an input. Is the phase applied at the input?
And what if I increase the quantizer where the inputs are then internally combined?
But the source of DAC is an input. Is the phase applied at the input?
And what if I increase the quantizer where the inputs are then internally combined?
The actual S/PDIF signal is fed through that switch, so you will be routing the signal around you case with an off-board switch.
IIRC, you will need to reset the DAC (could be wrong, but can't remember and can;t check from where I am at the moment).
Russ,
You are right. The register definition is crazy! 🙂. I did some of these partial DAC phase reversal tests a while back and I did not get the expected results...
However if I use normal phase (so both outputs have the same phase for each mono board), then it works fine.
Thanks Nikon1975 for asking the question...
You are right. The register definition is crazy! 🙂. I did some of these partial DAC phase reversal tests a while back and I did not get the expected results...
However if I use normal phase (so both outputs have the same phase for each mono board), then it works fine.
Thanks Nikon1975 for asking the question...
Last edited:
So, If I have to summarize I would say that:
Reg13 and Reg 19 does not define the absolute phase of the output signal, but reg 13 the input phase of the DAC and reg 19 the phase of DACBX with respect of DACX.
The data sheet is not clear at all on the matter.
D.
Reg13 and Reg 19 does not define the absolute phase of the output signal, but reg 13 the input phase of the DAC and reg 19 the phase of DACBX with respect of DACX.
The data sheet is not clear at all on the matter.
D.
- Status
- Not open for further replies.