Turtlerock Forum

hey gentlemen (and ladies)

is stuff specifically for aes digital signals or can i use it for spdif and other things?

from memory SPDIF requires 75Ohm cable...?

ill let someone else confirm, but im pretty sure :)

yep it's only good for AES, not SPDIF.

i think it's theoretically possible to use it for analogue signals, but when i experiemented with that years ago it sounded all wrong. maybe someone could bring some science to the table and explain it... but i suspect that the capacitance is quite different.

[quote="wez"]yep it's only good for AES, not SPDIF.

i think it's theoretically possible to use it for analogue signals, but when i experiemented with that years ago it sounded all wrong. maybe someone could bring some science to the table and explain it... but i suspect that the capacitance is quite different.[/quote]

According to Jim Williams of Audio Upgrades and Bob Ohllson ( Motown Legend ) AES cable is far superior to any mic multicore - just check the capacitance figures - I just got me a shitload of Gotham stuff to wire me studio.

that's interesting. i vaguely recall someone suggesting years ago to just buy 110 digital and use it for everything (except SPDIF of course). so maybe it's a good thing... but my (very unscientific) listening tests at the time left me feeling that it didn't sound quite right for analogue. i wish i could be more specific about what i didn't like, but it was a while ago... i have an inkling there was something about the LF that didn't work for me. whatever it was it was probably very subtle (or maybe not... most days i can't remember where i parked my car, so my half-arsed years old recollections about a couple of cables may not be entirely reliable ;-)

but it sounds like we may need to do some new listening tests! report your results here.

cheers, wez

usually AES EBU specified cable has slightly lower capacitance between conductors per metre. All else being equal this would make it a better audio cable. Most other things are pretty much equal between good quality audio and good quality digital cable. But is it cheaper?

Rob

So how do you get away with passing AES audio down video cables... ie... BNC type cables? Our whole facility passes audio around this way, either as dedicated stereo pairs or embedded in the video signal. It's just regular, run of the mill video cable.

thanks for the replies guys, as far as cheaper? its free as it was pulled out of a studio that we're moving...

not running spdif down it is actually a bummer cause it would have been handy for that

could be useful for audio, its decent quality mogami stuff, and i have enough to do two of the runs i wanted to do

Kris wrote:So how do you get away with passing AES audio down video cables... ie... BNC type cables? Our whole facility passes audio around this way, either as dedicated stereo pairs or embedded in the video signal. It's just regular, run of the mill video cable.

i would assume you're talking about 75 ohm cables... the voltage drop using bad or long cables is much more of an issue with SPDIF than AES. how long are your cables? but look, you can run SPDIF down those skinny $2 RCA things you get with a cheap stereo and it might work OK. it might work most of the time. or you could spend a bit of time and money and have it work perfectly. all of the time.

which is why i choose the latter - 110 ohm mogami 3080 for AES/EBU, 75 ohm whatever the model is WITH the proper 75 ohm BNC and RCA connectors for SPDIF, mogami 2549 for balanced audio etc etc. is it essential? that's up to you, and you'll know whether or not it is for you. how many dodgy cable/connection-related issues have i had to chase down in the last 5 years since i got serious with this? none. not a single one. it's just one less thing for me to worry about, and to me that's money well spent.

but if your system works kris, that's cool. there's plenty of discussion on the interweb about why the correct impedance is important for digital cable and frankly i'm over reading up on it... to steal someone else's term, my 'little scientist' inside has to choose carefully what to care about these days. so i care about using the right cable, i just don't care to think about it too much.

as with many 'digital' problems, you don't know that something is wrong until you basically lose signal, usually because the voltage drops too low (so again, more of a problem with SPDIF than AES). so using the right cable is all about avoiding the problem in the first place (and the right connectors - not much point using the correct impedance cable and then wacking any old connector on it). apparently you can even use standard CAT5 cable for AES, anyone tried that? so if you actually haven't encountered any problems using the 'wrong' cable, then you probably can move on to some other esoteric issue to keep you awake at night (jitter anyone?).

(of course jitter is one of the issues you might have with mismatched cable... but i don't think i've got the strength for another round of that topic).

sample rate is another issue too, you're more likely to experience problems at 96k and beyond.

sorry this reply is a bit all over the place but so am i.

Kris wrote:So how do you get away with passing AES audio down video cables... ie... BNC type cables? Our whole facility passes audio around this way, either as dedicated stereo pairs or embedded in the video signal. It's just regular, run of the mill video cable.

You use an impedance matching transformer (at either end if you want to go back to 110 ohms).
In fact, a lot of broadcast equipment comes with AES/EBU connections via 75 ohm BNC. This allows use of video routers, VDAs etc. instead of installing seperate circuits just for AES/EBU. Neutrik makes suitable impedance matching transformers. http://www.neutrik.com/fl/en/audio/204_654550159/AES_EBU_Impedance_Transformer_productlist.aspx

Martin wrote:thanks for the replies guys, as far as cheaper? its free as it was pulled out of a studio that we're moving...

not running spdif down it is actually a bummer cause it would have been handy for that

could be useful for audio, its decent quality mogami stuff, and i have enough to do two of the runs i wanted to do

If you put impedance matching transformers at either end it will work fine for your SPDIF signals. Just connect the XLR end to the AES/EBU 110ohm cable and the BNC end to the SPDIF equipment.

http://www.neutrik.com/fl/en/audio/204_654550159/AES_EBU_Impedance_Transformer_productlist.aspx

As far as using it for analog - ain't nothin' wrong with that. I use the Canare AES/EBU cable for analog all the time.

Wez, my post was a genuine question, not a shot at your post. I know zero about this sort of stuff so was asking to learn. We have tech people that do that stuff for us.... as for how much cable.... kilometers, quite literally. You should see the Kone wiring panels at another facility in town that I work with. Absolute chaos but the techs know every inch of it.

hey kris, not sure what you mean... i was just trying to answer your question. did my reply come across as something else?

i was just editorialising about the merits of good cable, certainly wasn't having a go at anyone... it was written in the friendly spirit of helping each other out that makes this form the beautiful thing it is. never occured to me that someone might be taking a shot... i'm oblivious to that.

it was late though and i didn't really check my grammar (or logic, coherence etc), and we all know how careful you have to be about that on the internet.

anyway... otto explained it, thanks otto!

actually now i re read my post it does come across as a bit of a rant... here i am saying how much i don't care about this stuff anymore then i write a minor thesis on the subject. what can i say, i'm an enigma.

but it was a very friendly non-specific rant, albeit one that veered OT a little bit. i was just trying to give my 2 volts worth vis a vis digital cables and the joys thereof.

cool cool.

well now that the dramas are sorted the upshot is i've got a good milk crate sized container full of the stuff which should meet some needs quite well, might use it for the non-mission-critical type tie lines around the place, and use new stuff for digital signals or to preamps etc