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Hey guys,
I was just wondering if you'd considered other input types such as AES/EBU and/or the Firewire interface.
Regards,
Byron
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You can use AES/EBU now. Just connect the AES + and GND to the D1 and GND inout terminals.
Firewire is not likely (by us), but you might be able to find a Firewire->I2S converter somewhere.
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Brian, I'd like to conect an AES/EBU input to the Buffalo. I don't quite get what you stated in your reply:
"You can use AES/EBU now. Just connect the AES + and GND to the D1 and GND inout terminals."
AES/EBU has 3 leads, +, -, GND. WHere exactly do I connect these to:
+ to D1, GND to GND, what about - ?
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AES/EBU is a differential signal. The easiest way to implement it is to use it as a single-ended signal, by leaving out one half of the differential pair (not connecting - in this case). A better way to do it is to make a little circuit like we have at the AES/EBU input of the S/PDIF MUX module. This uses a transformer and voltage divider, outputting a single-ended signal to feed to the Buffalo. Brian Donegan attached the following image(s):  AESEBU.png (15kb) downloaded 528 time(s).You cannot view/download attachments. Try to login or register.
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Brian,
I need to run a long digital cable so I am wanting to implement an AES EBU input to the B2.
I am confused by this drawing. My understanding is that AES EBU is a balanced signal on pins 2 and 3. Pin 1 is ground preferably the case and not circuit ground. Do you mean to imply using 1/2 of the AES signal unbalanced into a transformer? This would seem to remove the benefit of CMRR and also destroy the characteristic impedance of the line. Perhaps you meant to use the balanced pair on pins 2 and 3 into the transformer?
By splitting the termination you are attenuating the signal. Is this to feed the lower level SPDIF input on the MUX? Could the output of a 1 to 1 transformer directly feed D1 on the B2 DAC with 110 ohm termination to ground, or is it preferable to attenuate and use the SPDIF input?
Lastly there is already some other termination on the D1 input probably part of the I2S usage, and it isn't AC coupled as is the SPDIF input. Should I provide a small cap on the secondary of the transformer similar to the input side or is there no voltage on the D1 pin and so no need to protect the transformer from saturation? What value R or network should be added to provide proper termination of 110 ohms?
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The Rane audio site has some helpful interfacing ideas. Most involve 1:1.21 transformers not 1:1 transformers, followed by passive attenuation T networks. What is the expected P to P level of the SPDIF input to the Buffalo 2? 3 volt or 0.5 volt? What is the value of the AC coupling cap used on the buffalo 2 SPDIF input? I already have a good 1:1 pulse transformer so I am thinking of using it fed from pins 2 and 3 of a balanced AES3 digital signal. The secondary would be grounded and the high side fed through a T pad converting 110 to 75 ohms and providing 18 DB of attenuation. 90 ohms series 23 ohms to ground and 54 ohms out. I would leave the 75 ohm termination resister in place on the Buffalo 2 so the input could be easily returned to a SPDIF input, or possible even switched. The other option would be 1:1 transformer AC coupling into D1. What is the expected P to P voltage on the D1 input? What is the existing network on the D1 input? Which input would you recommend? Edited by user Sunday, December 19, 2010 8:52:11 PM(UTC)
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D1 requires TTL input. The transformer circuit the Brian posted is indeed balanced. Disregard the numbers as they do not correspond to XLR pin numbers. Any good 1:1 HF signal transformer should work fine. The input is balanced (differential, refenced only to each other) and the output is single ended (refenced to gnd). When using this circuit you would utilize the "SPDIF" input and not D1 on Buffalo II. Edited by user Monday, December 20, 2010 7:28:44 AM(UTC)
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Also if you like, you could simply use the MUX, and use I2S into the Bufallo II. Your choice.
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