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Please forgive me for jumping in on this thread but I am having an issue with the output wiring for a dual mono Buffalo IIIse - if this should be a separate thread then please tell me and I will copy it across. I understand the principle from the integration guide that the opposite channel on each DAC (eg on the Left channel DAC, the right side) outputs in anti-phase to the other. However, whenever I try to use both L+R outputs across both DACs the sound I end up with sounds like it has been EQ'd to hell and back. Clearly I have something wrong with the way that I am wiring up the phases. When I configure the DACs for dual mono and just use the single output from each DAC (eg for the Left channel DAC just use the left channel output and connect to the left I/V stage) then this sounds fine. It would therefore appear that I've got the actual configuration correct. However, as soon as I try to link the outputs following the attached diagram the problems start. It clearly sounds like something is wrong but I can't see where and having done it three times and ended up with the same thing I think I must be going mad. Would someone mind checking over the wiring diagram and let me know if this is correct and if it is I will go and try a fourth time - gibber ;-) https://picasaweb.google...IktzE-GA?feat=directlinkFor reference I am using a third part balanced tube stage (tube-i-zator) Many thanks, Crom
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Hi Crom. Just to clarify I should ignore the two IVY III boards to the right of the DAC boards in your linked picture? You are connecting the R and L DAC boards direct to the R and L inputs of tube-i-zator? Correct, the left DAC board left channel will be in phase, the right channel of the left DAC board will be anti phase. The right DAC board will be opposite; that is the right channel DAC right channel will be in phase, the left channel anti phase. Using jumpers or I2C control? Only thing I can think of is the newer March 2013 and after boards were shipped with different firmware in the chips. The dip switch settings will be opposite of the pre March 2013 DAC chips. I re-did your color code. Edited by user Monday, June 3, 2013 6:09:18 PM(UTC)
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Hi SCompRacer, thanks for the speedy response. Yes, please ignore the IVY boards - sorry, should've made that clear. I also didn't make it clear that I have 2 x Buffalo IIIse. It's the large arrows on the diagram that I'm working to. I have 2 tube-i-zators so that I can achieve a balanced output along with dual mono.
All dipswitches were set to on position by default. The only change to those is on the L DAC board I have set dipswitch 3 (Switch bank 2) to off (my firmware is from Jan 2013 - before the latest update) and have the firmware chip in that DAC (L) but not in the other (R). I have connected the 3 (but not the 4th - 3.3v supply) I2C connectors between DACs and jumpered R7 (from memory) on the 'slave DAC' which is my R channel. I have IP_S on both boards jumpered and ADDR on the slave DAC jumpered.
If all that's correct then I must be going mad. I'm going to give it another go from scratch!
Cheers,
Crom
BTW, I've been doing lots of reading of your posts over the past months - great work and thank you!
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Thanks for the kind words! Did you connect a ground from each channel? While the BIII board (and I presume BIIISE) were shipped with all the dipswitches ON, earlier pre March 2013 firmware manuals said default was most dipswitches were to be turned OFF. Dipswitch block SW2 switch 3 should be ON for dual mono. OFF is for a single board which will result in phase issues with dual mono. If you use a 4 channel input board if won't work with some switches set to ON. It might be worth revisiting the dipswitch setting once you get the phase thing fixed. I kept an old manual so I don't get more confused than I am sometimes. ;) EDIT: The BIIISE is not in the older manual so I am making dipswitch setting assumptions for the BIIISE based on the old firmware for the BIII DAC. Edited by user Monday, June 3, 2013 6:55:54 PM(UTC)
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Oh, forgot to expound on DPLL settings. With SW1: switch 5, 6 and 7 ON, DPLL is highest which can allow more jitter through. Suggested default is all three are set to OFF, where the DAC attempts to set DPLL. Just saying, it's worth it to explore. EDIT: Again, these dipswitch settings are based on pre March 2013 firmware and older manual for BIII. Edited by user Monday, June 3, 2013 7:01:53 PM(UTC)
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Thanks for your help here - I am slowly losing the will to live with this one :-( I stripped it all down and rewired it from scratch. I tested the L dac board in stereo mode and it works perfectly. Beautiful stereo image...the usual :-) Dipswitch 3 (SW2) was ON for single board stereo mode and I have to assume that this is correct as it's been working in one board mode for months (although re-reading the integration guide which firmware the instructions are written for could be a little clearer on that point - sorry Leon, don't take this the wrong way as your work is invaluable!!) Anyway, I then tried wiring up the left channel using this contraption: http://i1282.photobucket...tchannel_zpsbe6875f0.jpgI checked the short circuits but it's fine and does for testing. I flicked the dipswitch across to the OFF position and got the weird fazing / eq mess I had before. I then thought I'd try to switch the dipswitch back to ON. No change, same noise mess. I then thought I'd try to leave the dipswitch in the dual mono setting and just wire the single L board for stereo...works beautifully. So, this leads me to believe that the boards are somehow refusing to make the switch into dual mono mode. Any ideas?
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I assume you are powering the DAC down before and after changing the switches...
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Hi Brian, thanks for your time on this one. I hadn't because the integration guide said that I didn't have to. I shall try it now ;-)
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The switch settings are only read at startup.
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OK, I tried power cycling with no change. The only thing I noticed is that when I went from stereo mode (switch on) to dual mono (switch off) the music was replaced with very loud distortion from the left speaker. I obviously had the speakers down low when switching so no problem but just wondered if that meant anything. to get rid of the distortion I reset the DAC by touching the reset terminals on the 'master' dac. I have noticed this happening before and a reset immediately clears the distortion back to the usual eq'd noise.
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Reset with reset the registers in the DAC chip, but will not reboot the firmware chip that sets the registers.
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Gotcha, thanks for that. Still nothing approaching decent sound here. Is there anything else that would stop the DAC from issueing the 'go into dual mono' state (simplistic, I know!) because I can't get over the fact that even though the switches were set correctly and I powered down/up it still sounds fine in stereo mode (ie wired normally) but not when wired in parallel?
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One thing I've just noticed is that when the DAC is turned on, the lock lights on BOTH dacs flash and then stay locked (same as they did when using a single board). The slightly odd thing is that when not playing anything the mute light comes on (as normal) but ONLY on the slave DAC...not on the master dac board. Is this normal behaviour or should they work in tandem like the lock lights?
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What are you using as local regulators on the Buffalos? I get the feeling the chip is not powering up in time to receive the setup commands from the firmware chip. Edited by user Tuesday, June 4, 2013 4:15:43 PM(UTC)
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Hi Brian,
I've got a set of tridents and also a set of Paul Hynes' miniregs. I have swapped both sets in and out with no discernible difference.
I have, however, just stuck an oscilloscope across the analogue outputs and put some test tones through. I can categorically say that both DACs are acting as standard stereo perfectly ;-) Left channel is outputting to left side of both DACs and right channel the other side. Both sides are in phase according to the marks on the PCB. This does explain why I was having such phasing issues when trying to connect the L & R sides together!!
So, your hypothesis about the chip not powering up fast enough could be a possibility...but how do I test for this?...or speed it up a bit?!
Power supply to both boards is rock solid 5.25v and voltage coming out of regs is pretty much spot on except for the AVCC 'double trident' which measures 3.43v from one side and 3.42v on the other.
Cheers,
Crom
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A few further tests in case they are any help:
I swapped out the firmware chip from the main DAC with the spare - no change.
I checked that the I2C connections were actually connected between the dacs and the connections checked out. I then powered the DAC down and disconnected the 3 I2C leads. Upon powering up the DACs - no change. The DACs definitely don't seem to be getting the whole dual mono thang. I've checked that there is 3.3v coming out of the non-connected I2C connector but how could I test to see if the correct signal is being sent up the I2C lead?
Thanks for your help so far,
Crom
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Hi Brian,
Any more thoughts on how to proceed with this?
I'm going to try to swap the master and slave DAC board around tonight to see if it makes a difference.
Cheers,
Crom
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Did you place the jumper at the port expander?
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...and, did you add the Address jumper?
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Hi guys, The addr jumper is definitely in place (only jumpered on slave - Right channel - board. The master DAC - L channel - it's open). The port expander...I'm not so sure. Is that the 24 pin IO connector marker 'Ext-IO' on the board? If so, I did see a reference to this in the BIIISE integration guide which referred to dual mono being B3 (pin 12 of this connector). I looked into this and page 74 of the integration guide says that off means that the switch is open. I took that to mean that to achieve dual mono the dipswitch (S3 from switch bank 2) should be off - which it is - and that the switch (b3 on the ext-io port) should be open - which it is because there is no connector on it. Are you saying that what I should be doing is to switch dipswitch 3 (switch bank 2) to OFF position and then close Ext_IO pin 12? If so, should pin 12 be jumpered to ground or VDD(3.3v)...or something else? And...do I just need to do this to the master DAC board or both? Cheers, Crom Edited by user Wednesday, June 5, 2013 7:40:21 PM(UTC)
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