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Cannot get Buffalo III to lock to Exa2ui I2S source
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Joined: 12/20/2012(UTC) Posts: 7  Location: Oslo
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I am working on a 4 channel DAC using standard TP components (TP supplied transformers, Placid HDs, Buffalo IIIs, the latest Tridents and Legatos) and the Exadevices Exa2ui as a USB to I2S feed. I have tried to follow the excellent integration guide carefully configuring the Buffalo III boards for stereo and using I2S as input. Unfortunately, I cannot get the Buffalo IIIs to lock to the I2S signal. The Buffalo lock LED is on when not playing music, but as soon as I attempt to play anything, the lock LED turns off and I get no music. This happens for all sample rates. Using the same setup and I2S feed, but connecting an old Buffalo II board, I have no isssues whatsoever and I get lock and no dropouts at every sample rate I have tried (44-192 kHz) even with pretty sloppy I2S cabling. This is what I have done in an attempt to resolve the problem so far: - Made sure all voltages are correct (5.25V) and that shunt currents are sufficient (60 mA)
- Tried different DPLL bandwidth settings - default and highest (SW1 5,6,7 to OFF and ON)
- Wired the I2S input carefully using CAT6 Ethernet cabling with ground return paths for each signal so that the the individual twisted pairs in the cable carry one signal and the corresponding ground return path
- Wired the I2S input using very short (1 inch) direct cabling
- Tried both Buffalo III boards
- Tried supplying the digital sections both with a convential scheme (DVCC Trident getting 5.25V from the Buffalo board and Exa2ui getting a 3.3V feed from the I2C header) and my planned setup with a separate Placid HD powering the DVCC and the Exa2ui board through individual 3.3V Tridents and with shared ground connections to allow current to flow (I have confirmed that this works fine with the Buffalo II board by the way)
I am at a loss what could be the problem and what I can do to resolve it so I really could need some help. Thanks in advance for any input you may have. Edited by user Thursday, December 20, 2012 8:22:44 AM(UTC)
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Have you set the DIP switch Input remapping to OFF? |
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Rank: Member
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Joined: 12/20/2012(UTC) Posts: 7 Location: Oslo
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Originally Posted by: Corpius  Have you set the DIP switch Input remapping to OFF? Yes, but thanks for the suggestion.
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Other I2S sources working ok?
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It's hard to make out in your picture so...
What are your current DIP switch settings, and what jumpers do you have installed. Also, how have you configured the volume pads (using pot or jumper)?
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Rank: Member
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Joined: 12/20/2012(UTC) Posts: 7 Location: Oslo
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I do not have any other I2S sources unfortunately, but as mentioned, the same I2S source with sloppy 20cm long I2S cabling is rock solid at all sample rates with a Buffalo II board I have. As for jumpers and switch setttings, I believe I have followed the integration guide carefully: - JPCM1-3 jumpered
- JDSD1-2 open
- J1-12 jumpered
- No external volume control with ADC 3.3V and PB4 holes jumpered
- All switch settings OFF with exception of SW2 5 set to ON (SPDIF autodetect=bypass)
- I have also tried setting SW1 5,6,7 to ON (DPLL bandwidth=highest)
Any obvious mistakes? Read somewhere that someone had similar issues with Buffalo II and removed the firmware chip which "solved" the lock problem. Is that something that could/should be tried with the Buffalo III?
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For a 4 channel DAC you should only jumper J1-J4 and J7-J10. Leave all other jumpers open. |
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Rank: Member
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Joined: 12/20/2012(UTC) Posts: 7 Location: Oslo
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Originally Posted by: Corpius For a 4 channel DAC you should only jumper J1-J4 and J7-J10. Leave all other jumpers open. Well, it is a 4-channel DAC but with two stereo Buffalo III boards, so I believe my jumper settings are correct.
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Make sure you are actually getting signals going to the DAC. Does it lock?
Are you certain you have a good ground return? It's hard to make out from the picture.
Are you certain you have not transposed(miswired) a signal?
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Rank: Member
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Joined: 12/20/2012(UTC) Posts: 7 Location: Oslo
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Yes, I am as sure as I can be that I get signals to the DAC, that I have not mixed up the cabling and that I have a good ground return. I have two DAC boards that I have wired multiple times using multiple wiring approaches. My "cleanest" and preferred approach for the permanent build is the CAT 6 cabling where each of the twisted pairs (almost wrote pears  ) in the cable transmit one signal and with the other lead of the pair acting as signal ground. I have also tried wiring directly with 1 inch leads (as show in one of the pictures) where the ground return is coming off the I2C header. I am sure that is not optimal, but it worked without a hitch on the Buffalo II board. I have also examined my wiring multiple times and measured all connections to make sure I have good contact and no shorts. A couple of things to note (mentioned before, but perhaps worth repeating): - The lock LED is on when "idle", but turns off immediately when playing music. I think I have heard a split second of music so the DAC seems to be losing sync
- The Buffalo II board works perfectly with exactly the same I2S source, power supplies, output module, cabling etc. As soon as I swap the BIII board with the BII board I have no issues whatsoever
Could there be a compatibility issue of some sort? Any thing I could try to measure or document? (I have a simple Fluke scopemeter, but nothing that can analyse I2S signals I am afraid) I really appreciate your feedback and help. Edited by user Thursday, December 20, 2012 4:26:49 PM(UTC)
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Well you could just check that the signals look good at the DAC. That is that they look clean.
The DAC locks on the bit clock... so it seems odd that that should change when music is playing.
There is no real difference between the buffalo II and III in regard to the signal handling as long as they are configured equivalently.
You may need to make sure that for some reason the VD voltage is sagging when music starts to play. But that does not seem very likely. Just thinking of things I would check.
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I guess the other thing to check out be the output voltages from the Tridents and AVCC module (very, very carefully).
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Joined: 12/20/2012(UTC) Posts: 7 Location: Oslo
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I will do the recommended checks. I have only tested with the latest Tridents but I believe I have an older set as well that I can assemble and test. Will probably take me a few days due to other commitments.
Thanks once again for your support.
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Rank: Administration
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Joined: 10/24/2006(UTC)
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Location: Nashville, TN
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Well testing the ones you have in place would be the best place to start, as you want to see how they are doing with the load.
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Rank: Member
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Joined: 12/20/2012(UTC) Posts: 7 Location: Oslo
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It just had to be a big screwup on my part with two Buffalo IIIs not working and the Buffalo II working perfectly with the same power supplies and I2S data input. I really thought I followed the integration very carefully, not to mention the numerous rereads and rechecks. But I made one vital mistake. I somehow assumed that the boards were delivered with the switch settings to all OFF and failed to actually check that this assumption was correct. Reading another support thread, I saw Brian mention that the switches were set to all ON when delivered. Realizing this, I confirmed my mistake, reversed all my switches and voila 100% signal lock and beautiful sound emerging. Sorry for making such a stupid mistake and let me use the opportunity to thank everyone that offered suggestions. Edited by user Saturday, December 22, 2012 10:12:57 PM(UTC)
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Cannot get Buffalo III to lock to Exa2ui I2S source
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