AES Yamaha/Tascam crossover wiring

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Lerok

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Hello, unsure if this is the right place, but seems like it -

Recently I picked up an Aurora 16 and a Motu 112D, and was planning on connecting them via the AES inputs on the back, however I’ve hit a snag.

It would appear as though the MOTU uses the Tascam DB25 pin out, where the Aurora uses the Yamaha one - no problem, i thought, I can just solder myself a crossover cable using the pin out at sweetwater ( https://www.sweetwater.com/sweetcare/articles/aesebu-db25-pinout-guide/)

So I did that, and no dice - I even resoldered a second cable, and checked both with a continuity tester to make sure there were no shorts or dropped signals, nope.

The weird behavior is if it’s hooked up with a (incorrect) Tascam to Tascam db25 cable, the lynx picks up the sample rate from the motu’s clock, but if I try to use the custom cable, it doesn’t even do that...

I’d really like to avoid biting the bullet and spending another 300 on cables, so I was curious - does anyone have any ideas?

I’m stuck between a lynx and a hard place, so thank you a ton!
 

Bo Deadly

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What kind of cable and db25 connectors did you use?

AES-EBU uses a MHz bit clock. It's not super high frequency but you can be sure you need to use quality cable with the right shielding and the db25 interconnects have to be very neat without much shielding missing from the end.

Also I can imagine it might be very easy to get the pins mixed up.
 

Lerok

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squarewave said:
What kind of cable and db25 connectors did you use?

AES-EBU uses a MHz bit clock. It's not super high frequency but you can be sure you need to use quality cable with the right shielding and the db25 interconnects have to be very neat without much shielding missing from the end.

Also I can imagine it might be very easy to get the pins mixed up.

I used run of the mill DB25 connectors I had lying around - for cable, I was using Carol E2102S (3x22awg, shielded) - I was guessing there would be minimal difference from that vs higher end cable, given that the cables I'm building are only around 6in (one spot in a rack to the one below it). I have some mogami 2932 lying around with some slightly nicer DB25 connectors, if you think that could make a difference - I sanity checked my wiring/pinout a few times and everything looks up to snuff there...

Would you recommend resoldering another cable with the mogami/(I think) neutrik or switchcraft connectors? I'm new to aes/ebu audio, and may have mistakenly assumed the short cable run wouldn't make much of a difference...

For reference here is a picture of the inside of a connector, it's about as short as I can get it without brutally murdering my fat fingers.

1pG1ruS.jpg
 

john12ax7

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You should double check that the connections are not mirrored.  Also AES signals need the right impedance, it might not matter for such a short length,  but you really want to be using 110 ohm digital cable.
 

Lerok

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john12ax7 said:
You should double check that the connections are not mirrored.  Also AES signals need the right impedance, it might not matter for such a short length,  but you really want to be using 110 ohm digital cable.

I'll triple check the connections, as at this point my user error seems to be the most likely culprit - I knew 110 ohm was the best choice, but I figured over a 6in length it wouldn't be huge (also, this was kind of a "hey my lynx just arrived, lets see if I can get it working with what I have lying around" kind of project haha.

I'm strongly considering just picking up three adapters from Redco for $120, but I figured if I could save a few bucks here that's another sm57 or two in the future...
 

Bo Deadly

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The more I think about this, I think the cable use has to be just so. I would not try to make my own. I might also be a little weary about using adapters. What about this?

https://www.proaudiola.com/product-p/8-m3162-ddb-ddb-2-s-adapter.htm

Says Mogami 110ohm with metal shells. Delivery is a little slow but the price is very competitive.
 

Lerok

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Interesting, thanks for sharing that link! My current thought is to pick up one cable and reverse engineer it, see if I can get anywhere or if I'm missing something stupid, and if not just bite the bullet, ah well.

Thanks a lot!
 

Ricardus

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If it's not working you wired it wrong. Simple as that. Yes, you need to be using 110 ohm wire, and if you wired it correctly, outs are going to ins, and ins are going to outs. So ch 1/2 outs on the Yamaha end have to be going to ch 1/2 in on the Digidesign/Tascam end. Etc etc... on down the line.
 

Bo Deadly

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Lerok said:
Interesting, thanks for sharing that link! My current thought is to pick up one cable and reverse engineer it, see if I can get anywhere or if I'm missing something stupid, and if not just bite the bullet, ah well.
I would think that a really short cable should work. So you might triple check your wiring.

But it could also just as easily be that high frequency transmission line effects are responsible. At really high frequencies, a wire is not just a conductor. The inductance and capacitance and everything comes into play. The wire is actually part of a critically damped circuit. It's all highly non-trivial and it's not really something I'm knowledgeable about so I'm probably talking out of my rear little but, again, I definitely would not try to make my own cable. Don't throw good money after bad. Just buy one.
 

abbey road d enfer

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Lerok said:
The weird behavior is if it’s hooked up with a (incorrect) Tascam to Tascam db25 cable, the lynx picks up the sample rate from the motu’s clock, but if I try to use the custom cable, it doesn’t even do that...
In order to detect the sample rate, the Aurora must know where to look for it. There should be a setting in the housekeeping menu allowing to select the source.
The Tascam and Yamaha "standards" have one common connection, pins 1 and 14 carry channel 1 in both.
So whatever the cable, if the SR source is set to CH1, it should be readable.
Actually, for testing, you could wire two sub-D's with only one pair connected. I'm not sure you need to connect the shield on both sides since the connection is transformer-balanced.
I don't believe one second that the quality of the cable is at cause with such a small length. Remember the 110 ohm standard has been chosen because most of the usual audio cables have a characteristic Z of about 110r.
I have never seen a case where using an ordinary audio cable for carrying AES/EBU signals made it totally unreadable. Worst case was drop-outs and temporary lost of sync.
The available info on both units is not very helpful; since there is only one set of them, how are you telling the sub-D 25 to be outputs?
 

Lerok

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squarewave said:
I would think that a really short cable should work. So you might triple check your wiring.

But it could also just as easily be that high frequency transmission line effects are responsible. At really high frequencies, a wire is not just a conductor. The inductance and capacitance and everything comes into play. The wire is actually part of a critically damped circuit. It's all highly non-trivial and it's not really something I'm knowledgeable about so I'm probably talking out of my rear little but, again, I definitely would not try to make my own cable. Don't throw good money after bad. Just buy one.

I'm going to whip out the mogami later today and give it a shot (I measured the impedance on that to be around 109, so it should be pretty solid), my guess is that I'm stupid and wired something incorrectly, so we'll see...

abbey road d enfer said:
In order to detect the sample rate, the Aurora must know where to look for it. There should be a setting in the housekeeping menu allowing to select the source.
The Tascam and Yamaha "standards" have one common connection, pins 1 and 14 carry channel 1 in both.
So whatever the cable, if the SR source is set to CH1, it should be readable.
Actually, for testing, you could wire two sub-D's with only one pair connected. I'm not sure you need to connect the shield on both sides since the connection is transformer-balanced.
I don't believe one second that the quality of the cable is at cause with such a small length. Remember the 110 ohm standard has been chosen because most of the usual audio cables have a characteristic Z of about 110r.
I have never seen a case where using an ordinary audio cable for carrying AES/EBU signals made it totally unreadable. Worst case was drop-outs and temporary lost of sync.
The available info on both units is not very helpful; since there is only one set of them, how are you telling the sub-D 25 to be outputs?

The lynx is set to detect the sample rate correctly, but it has fairly limited controls, the motu on the other hand has a computer control panel, so I'll dive a bit deeper into that to verify that I'm not missing something (that's where I've set the outputs)...

I'm sure it's a stupid mistake on my part, so we'll see if it works again a bit later today after finals...
 

abbey road d enfer

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Lerok said:
The lynx is set to detect the sample rate correctly,
In order to detect SR it has to have a list of sources; it starts checking these sources in order of priority until it finds one it can recognize. There are so many possible source on the Aurora, it's not impossible the AES/EBU inputs are excluded.
 

cyrano

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I think the idea of buying 1 cable is a good one.

It will allow you to rule out another possibility: one (or even both) of the devices could be (partly) defective...
 

Lerok

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Just as an update, I resoldered things, being extra careful with both the pinout and the size of the shieldless portion of the cable, and for some messed up reason it works perfectly.

I'm guessing either the cable I was using had a short inside it, or I messed up, which is equally likely given that I was soldering at 2am.

Anyways thank you a ton, saved me from having to shell out 300 on cables from yamaha :)
 

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