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I am confused. How can you possibly stack the input board onto the Buffalo board? Buffalo itself is stacked onto the Ivy board and due to tridents there is no way you can stack anything on top of it.
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If you aligned the headers you will notice they match perfectly. You can put the input board directly over BIII. (it will extend out toward the input side, not over the DAC)
You can even directly solder it - using resistor leads or similar through the holes. :)
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Ok, but that is an extremely unusal way of coupling boards. I've never seen it in 30 years I've been doing electronics. I am using sidecar so it wouldn't work for me anyway (unless I did triple board coupling). Actually no, I have seen it before. Can't remember where but I did see a commercial device using this approach. Edited by user Sunday, December 30, 2012 12:31:21 AM(UTC)
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Oh I am not saying that is the only way to do it, merely the most direct. You could also use a plain male and female set of pin headers. Edited by user Sunday, December 30, 2012 12:31:01 AM(UTC)
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I do agree that for those using sidecar at least adding (or replacing the existing cap) 22-47uf (low ESR) would be a good idea.
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One thing to keep in mind - is I designed the sidecar well after the SPDIF4. It might have been more expedient if they had come in the other order. :D
Next revision I will use this hindsight to improve the design.
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That makes sense, originally I only had cable from B3 to input board (didn't connect through Sidecar as I damaged ribbon connectors trying to install them and had to wait for Digikey delivery) and I don't recall having any lock-on issues. Problems only started once I added the Sidecar into the chain (even though the new cables were much shorter). Luckily it's easy to add a reservoir cap without modifying the PCB.
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[img]null[/img]I built the box for the Buff32s. The BuffIII with the input board presented me with some problems, but I worked it out. I stacked the SPDIF-4 Board but turned it around using the ribbon cable. My locking problem was soved by using both sides of the LCDPS one set for <5vdc for the input board and the other set for 5.45vdc for the DAC[img]null[/img] pelliott attached the following image(s):  DAC_3b.jpg (216kb) downloaded 45 time(s).You cannot view/download attachments. Try to login or register.
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Now that I managed to fix my music server motherboard, I must report that bypass capacitor didn't really help much. From my squeezebox, coax (and optical to some extent) is still glitchy. It may be marginally better than before but it's still unreliable. I will try Russ' impedance fix later, but for now inserting the resistor in the supply line to drop the voltage is the only thing that worked well.
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Originally Posted by: Russ White  OK so here is what I tried, and it worked, but its hard for me to say if it is better or not, since it was already working fine for me before.
So if one of you brave souls wants to give it a go I would appreciate it. :)
what I did was lower the reference voltage and impedance by reducing R9 - R12.
I used 2K but 1K would also have probably been fine. you could test this easily by just adding a 2-4.7K resistor in parallel with the existing resistors (this way you don't need to desolder anything).
See if that helps at all.
basically what this does is lower in the impedance into both inputs.
One other idea is to apply a bit of positive feedback (say 47-200K this will take some tweaking) from each output to each positive input on the comparator. But his is a little bit more difficult, and will actually slow the thing down - it may not handle 192Khz input if you do this.
Anyway, just some things to try if you feel like tinkering. I tried the resistor fix and it helps to some extend, but lowering the voltage still works best. Lowing the voltage of the placid to 5V also works, but this should degrade the DAC's performance right? unfortunately my DDM is behaving a bit odd and I do not trust its reading anymore. I ordered a new one and re-measure all voltages again... I'll also try bypassing the chip |
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I have no 22 - 47uF caps lying around, but I do have quite a few 100uF Panasonic FM low ESR series. I just added one of these to C13 underneath the board. This improved it performance almost to a point of no dropouts. Tomorrow I'll try lowering the voltage again back to 5V, but with the cap still in place. I have a good feeling that this will eliminate the last dropouts. The max9201's datasheet clearly states that the analog supply may range from 5 to 10V, but the digital supply needs to be 5V. This would mean that the supply voltage needs to be 5V when using a single supply and common ground, like the 4-ch spdif board does. oh btw. I also have the the parallel 4.7K resistors still in place :) Edited by user Friday, January 4, 2013 7:39:31 PM(UTC)
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7V is the absolute max on VDD. So VDD 5.5V should be perfectly fine. I have never had any trouble even up to 6V.
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Yes, you're right, but don't forget that you did never experienced the problems I and others did with the 4ch spdif board. It's worth a try to me :) |
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Originally Posted by: Erlend Sæterdal With the voltage divider at the output?
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No I did not see I have to add 270 in series and 75 ohm parallel. And I could not understand that bass signal from my TV tuner was so much more " Dynamic " than via SPDIF from CD.
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Curiouser...couriouser
i am powering the 4way at 4.25 vdc. with using input 1, i get lock with no problem for about 5 mins. If i move the interconnect to input 2 i get solid lock for as long as i listen. if i switch back to input 1 i et lock for about 1 min. Switch back to inpur 2 i get solid lock for as long as i care to listen. Now for the weird part. I have a second 4way and the symtoms are the same!!!
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Ok and I disvovered better sound on 2 than 1 . Have to say I use Vishay 1837 cap on input 1 . Now I changed it to 100 nf. Black Gate NX High Q.
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Originally Posted by: Russ White Originally Posted by: Erlend Sæterdal With the voltage divider at the output? Yes still not stabil lock with the divider. But raised the voltage to 5,5 V and still stabil lock on SPDIF. The BLack Gate cap on input is so much better. Now this dac is as good as my own. :) Edited by user Tuesday, January 15, 2013 8:21:24 AM(UTC)
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Originally Posted by: pelliott321 Curiouser...couriouser
i am powering the 4way at 4.25 vdc. with using input 1, i get lock with no problem for about 5 mins. If i move the interconnect to input 2 i get solid lock for as long as i listen. if i switch back to input 1 i et lock for about 1 min. Switch back to inpur 2 i get solid lock for as long as i care to listen. Now for the weird part. I have a second 4way and the symtoms are the same!!! Have you added the 47 uf Oscon ? I use 1200 uf. Polymer.
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