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JohnG  
#1 Posted : Monday, December 18, 2017 10:43:28 PM(UTC)
JohnG

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Im wanting to use 2 Buffalo IIIs for 4 channels. Would I set them up just like Dual Mono, except set the DIP switch to Stereo and then connect the DACs to their separate I2S signals?

Thanks, John

Possum  
#2 Posted : Wednesday, December 20, 2017 9:08:42 PM(UTC)
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It depends what your 4 channels are.

If you are doing quadrophonic you would not set them up like Dual Mono (which requires left and right channels on each DAC to be shorted) - you would simply be building 2 stereo DACs (1 for front LR and another for rear LR)

If you are doing a 4 way xover for a single channel you either need 4 DACs in mono mode (all configured for either left or right channel) - or you have to somehow remix the stereo input signal so L&R signals are actually all left or all right side signals
JohnG  
#3 Posted : Thursday, December 21, 2017 12:11:07 AM(UTC)
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Thanks. It's stereo with an active 2 way crossover on each side - for a total of 4 channels.
Possum  
#4 Posted : Wednesday, December 27, 2017 1:27:56 AM(UTC)
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In that case, you would setup the same as quadraphonic - except one dac is receiving bottom-end stereo input and the other the top-end signal in stereo.

BTW you can do this with a single BIII if you like, as it allows up to 8 channel operation - whereas the BIIISE is designed for stereo applications (it combines the outputs into 2 channels)

The more channels connected in parallel the better the error correction. The improvement between a single stereo DAC and dual-mono (or tri-mono in my case using a 3 way digital xover) is pronounced if the rest of your system can reveal it.



JohnG  
#5 Posted : Wednesday, December 27, 2017 6:15:01 AM(UTC)
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Thanks. I tried it, but the volume control on the DAC with firmware doesn't control the volume on the other DAC. My read of the manual is that the volume control across the DACs only works with the Dual Mono DIP switch setting. So, I need to order a second firmware chip (Ive lost mine) and run them independently.

For volume control, I could use a dual gang pot to control both DACs. I might also try hooking both wiper pins up to the same pot. Until I get the firmware, Im using volume control in a miniSharc with is upstream of the DAC
Possum  
#6 Posted : Wednesday, December 27, 2017 11:52:53 AM(UTC)
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OK. It helps to have the full context....

Dual pot will work of course - or you can simply ditch the on-board firmware and control both DACs with an Arduino via their I2C connectors.

I now exclusively use an arduino rather than the onboard firmware for precisely this kind of flexibility. My last tri-mono build is fully Wi-Fi controlled via an arduino, and my current build uses an Alps motorised pot and infra red remote control to adjust the volume of multiple dacs.

Of course, the arduino can control many dac features aside from volume control

Brian Donegan  
#7 Posted : Thursday, December 28, 2017 6:19:21 PM(UTC)
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You can control volume on multiple DACs from the supplied pot by simply attaching the center pot pin to the second DAC's center pin (firmware on both boards). They do not need to be in Mono mode.
JohnG  
#8 Posted : Wednesday, January 3, 2018 11:15:38 PM(UTC)
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Thanks. I just placed an order for a new firmware chip, as Ive lost track of my second one.
JohnG  
#9 Posted : Monday, March 5, 2018 6:53:26 PM(UTC)
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I set it up like this - which may be useful for others. I have a miniSharc from miniDSP preceding the DACs, and have 2 configurations:

One config is for my LXmini speakers - which needs 4 channels of output. So, Channels 1,2 from the miniSharc output goes via I2S to one DAC and Channels 3,4 goes via I2S to the other Dav. Each DAC has a Legato, and I use the balanced outs to go to the amps, for a total of 4 channels.

The next configuration is for a standard stereo output. Again, Channels 1,2 go to one DAC and 3,4 to the other. But, in the miniDSP config, I invert channels 2 and 4. This creates the Dual Mono. Then, I take the SE output from the Legato to balanced in on the amp (choose one of L or R to be positive and the other to be negative and be consistent).

Both BIII are in stereo mode, with firmware and volume and no I2C cable between them. The back panel has 6 output xlr's: 4 for the LXmini and 2 for the stereo.

Now, I change the configuration in the miniSharc and don't have to re-wire anything or flip dip switches.

meo  
#10 Posted : Tuesday, April 3, 2018 6:48:22 PM(UTC)
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Hi JohnG,
Does it work ok? I want to do a similar setup, multiple DAC's on I2S.
I asume you connect all dac's to the same master, bitclock and LR clock? Does this work, in other words can you connect multiple dacs to the clock lines without problems by the higher load, lower impedence, etc?
I've been looking for some time for answers to this, so I'm very curious about your expereiences!
Marcel EO
Possum  
#11 Posted : Tuesday, April 3, 2018 9:21:51 PM(UTC)
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There is no problem connecting 2 DACs to the same I2S signals. This is how you do dual mono. I have connected 3 DACs to the same clock signals without issue.
thanks 1 user thanked Possum for this useful post.
meo on 4/5/2018(UTC)
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