Q: what's the max run on AES snake?

[cajonezzz]

Hey guys, our studio is getting geared up to record live acts in an adjacent space, and to do a little FOH and monitor mix, without using a split, we're thinking of sending back out of the main capture PT rig, via AES... BACK to the live room venue ( approx 300 ft away, maybe a little less)

basically thinking we can bus all the necessary tracks back out via AES on SENDs in Ptools, then, with an HD rig in the live room, build a FOH MiX and headphone mixes to feed an Aviom headphone system.

I'm thinking latency won't be a problem via AES, but not sure what the limitation of AES is ( distance).

anyone done similar?

cz

[roonsbane]

Things to consider.

I know a Boston area classical engineer who invested a lot of money on a Mogami AES snake. I would estimate 150' long. This was probably over $400. He tried it on one session with a full orchestra and never tried it again. I believe he was feeding it from an 8 channel troisi A/D. He thought it sounded terrible! I remember he thought the image had gotten blurry and strange. I would not run AES beyond 20'. I would not run ADAT lightpipe beyond 10' and the shorter the better in both cases unless lightpipe is converted to glass. Then I would want to run word clock separately and word clock should be kept short as well according to the aardvark word clock generator manual. I believe it says 50'.

I hope this helps.

Cameron

[Roland]

Originally Posted by cajonezzz

Hey guys, our studio is getting geared up to record live acts in an adjacent space, and to do a little FOH and monitor mix, without using a split, we're thinking of sending back out of the main capture PT rig, via AES... BACK to the live room venue ( approx 300 ft away, maybe a little less)

basically thinking we can bus all the necessary tracks back out via AES on SENDs in Ptools, then, with an HD rig in the live room, build a FOH MiX and headphone mixes to feed an Aviom headphone system.

I'm thinking latency won't be a problem via AES, but not sure what the limitation of AES is ( distance).

anyone done similar?

cz

You could take the AES signals into an RME box convert that to Madi, with an optical lead that's good for 1,000m, however if I've understood you corectly you are planning to send all the signals to the pro-tools system then send them back to the FOH desk via AES? If this is the case I would suggest that you look at the split as it seems a lot safer (and I suspect cheaper) way of doing things. Sensible, passive split should cost a few hundred dollars. Remember KISS, Keep It Simple Stupid, it'll save your arse every time.

Regards


Roland

[mpdonahue]

Craig,
We regularly run 8 channels of 96kHz AES over 500' of CAT5 cable with no issues. The only caveat is that the interfaces on the send and recieve devices need to be transformer coupled, not electronically or quasi balanced like some of the cheap pro-sumer gear. I actually tested the system with 2 1000' spools of Belden Mediatwist and found it worked reliably at 44.1 but not 96k.
Use the search function and you will find a thread about AES over CAT5 from about a year ago.
All the best,
-mark

[David Rick]

Originally Posted by roonsbane

I know a Boston area classical engineer who invested a lot of money on a Mogami AES snake. I would estimate 150' long. This was probably over $400. He tried it on one session with a full orchestra and never tried it again. I believe he was feeding it from an 8 channel troisi A/D. He thought it sounded terrible! I remember he thought the image had gotten blurry and strange. I would not run AES beyond 20'.

Clearly he ended up with a jitter problem. Long cable lengths cause dispersion of the digital signal which turns into jitter. In a conventionally-designed DAC, the sonic result is the image blurring you describe. But if he'd run it to hard disk and played it back later, the jitter probably wouldn't have mattered. It takes much more jitter to foul up the actual data bits than it does to make a DAC clocked from that data sound really horrible.

One solution is a more carefully-designed DAC. The Benchmark DAC1, for instance is completely immune to interface jitter, right up until the point that it actually clocks in the wrong data. DAC's with cascaded PLL's can also do a very good job of suppressing the interface jitter, especially if the final PLL uses a VCXO. The Lavry converters are a good example of this.

One thing you should NOT do on location is make the DAC your clock master. Feeding that clock down 150' of cable will add jitter to the ADC's clock reference, and the audible effects of that are permanent.

David L. Rick
Seventh String Recording

[Plush]

AES spec for max length is 300 meters, so your run is well within the boundaries of normal usage.

[huub]

Have succesfully ran AES over a 50 meters non-digital multicore..
A/B'd it with analog, heard no difference.. (Was using nice converters on both ends)
Bot trucks were clocked from same source, but used src on aes input, so was re-clocked I suppose..

BTW, if you use impedance converters/xlr-bnc converters (one unit that does that), you can use bnc/coax cable which is soooo much better and more reliable for long distance...

huub

[klaukholm]

We regularly run 100' aes mogami snakes from our Prism to our Pyramix station.