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[Mac Kerr]

John Vaneldik wrote

Hi guys, I work for a company that does a lot of corporate work and we are starting to use Aviom Snake systems a lot. The problem we are having is that you cannot run "Com" through the digital snake of course. This is causing the Video companies (who are generally supplying the com systems) to complain about having to run another line just for com. Does anybody know of a manufacturer that produces box that will solve this problem for us. The solution is actually fairly simple (in theory): A box at one end that splits up the ear piece and mic signals and filters off the DC power (a beltpack would do this). Then a box at the other end that will put the put the audio signals and DC power back together and send it out a 3 pin XLR.

Since Doug hasn't been able to unlock this yet, I'll answer here. There are lots of products that will let you interface intercom to a digital snake. To do it you need a 4 wire adapter, which takes the single wire talk bus type system used in intercoms, and turns it into a balanced send and return. This means you need 2 channels of audio for each channel of comm, one in each direction. There are 4 wire adapters available like the Clear Com IF-4B, RTS SSA-424, Studio Technologies Model 46, Riedel IF-2104, and probably some others. The downside to all of them is that you will lose the call signal. I know the RTS, and maybe some of the others, bring out the call signal as either a GPI type signal, or as data. If you have an alternate path for these kinds of signal through your snake you will be able to get back the call light. Oddly, RTS uses audio tones for signalling, but does not pass them through the 4 wire adapter.

Mac

[Ken Freeman]

Hey John,  It looks like some of the networked audio devices will support a dedicated intercom interface in the future.  The 4 wire interface, although pricey, might be less expensive if you are just moving a channel or two and must do it in a digital snake.  A 300 foot 4 pair snake seems cheaper.  On your note about beltpacks, I have built such devices from a pair of beltpacks in the past, but things like sidetone null make them much less stable than you might expect.  I'd keep my eye on the medianumerics for this feature soon as part of a network.

http://www.medianumerics.com/html/01.2_about_rn.html

Ken

[Riley Casey]

I sure wish I'd seen this last week when I was trying to get RTS thru a digital snake using a TW12 at my end connected to my PI comm system.  We were able to null for send OR receive but not both. I just didn't think it thru ... DOHHHH!

[theo mack]

See...
Copper is still king for some things.

[Dave Stevens]

Mac Kerr wrote on Wed, 18 October 2006 17:36

The downside to all of them is that you will lose the call signal.

Which makes it not useable for concert work as that is the primary method of contacting someone.   I do some corp work where they have us disable the call lights,   but for the concert gigs  you're only on if you need to talk to the guy.

Jim @ Telex showed me a multiple Cat 5 bundle with a couple of twisted pairs, suitable for either AES3 or copper tie lines that looked pretty cool.  On my last outing we used a multi that had two coax lines and four STP lines that worked well.  Until digital snaking systems can pass signal as a dry pair there we'll still need some copper.  Some of these snake designs are tunnel visioned to be used only with consoles and make no provision for dry lines which I think is a short coming in the design.

Dave

[Mac Kerr]

Dave Stevens wrote on Mon, 23 October 2006 13:42

Until digital snaking systems can pass signal as a dry pair there we'll still need some copper.  Some of these snake designs are tunnel visioned to be used only with consoles and make no provision for dry lines which I think is a short coming in the design. Dave

They'll never be able to be a dry pair, 'cause there's no pair there. For use with comm there are alternatives. If the digital snake has some other data capability, like RS422 or GPIO, you can recover the call signal that way from the ClearCom 4 wire adapters, and the RTS SSA-324. In rereading the information on the RTS SSA-424 digital hybrid, it seems to say that ClearCom, RTS, and Telex Audiocom call signals will be transmitted as 20kHz tones through the 4 wire link. That would mean you would not lose signaling through an SSA-424. All others that I am aware of require either RS422 or GPIO to transmit the call signal.

Mac

[Dave Stevens]

Mac Kerr wrote on Mon, 23 October 2006 11:05

They'll never be able to be a dry pair, 'cause there's no pair there. For use with comm there are alternatives.

AS a dry pair Mac, not IN a dry pair...  Functionality, not topology.    For most portable work the alternatives are expensive workarounds that aren't really addressing the issue and not addressing all issues.    Some of the corp guys may have four wire converters but by and large most tours do not.  Com is not used in that way and in some cases the cost of converting the com is more than the actual number of stations and base.  In those apps there is usually always a power cable and it's larger than the whatever is transporting the digital signal and adding another 100 meters or so of pr cable is the easiest, most flexible and least expensive way to solve the problem.

Dave

[Mac Kerr]

Dave Stevens wrote on Mon, 23 October 2006 14:45

AS a dry pair Mac, not IN a dry pair...  Functionality, not topology.    For most portable work the alternatives are expensive workarounds that aren't really addressing the issue and not addressing all issues.    Some of the corp guys may have four wire converters but by and large most tours do not.  Com is not used in that way and in some cases the cost of converting the com is more than the actual number of stations and base.  In those apps there is usually always a power cable and it's larger than the whatever is transporting the digital signal and adding another 100 meters or so of pr cable is the easiest, most flexible and least expensive way to solve the problem. Dave

I don't get the distinction. A dry pair can pass audio in either direction, and can pass voltage. A digital audio path is one direction only, and cannot pass anything but data.

Yes, an SSA-424 is an expensive solution. More so when you remember you need 2 of them. Against the cost of a large digital transport system it may look less daunting. It will still probably be cheaper to run a 6 pair audio multi along with your FOH power cable for comm. Better yet, let lighting run it with their dmx multi! They're going to run comm for spots anyway.

Mac

[Hasse Queisser]

Dave Stevens wrote on Mon, 23 October 2006 19:42

Jim @ Telex showed me a multiple Cat 5 bundle with a couple of twisted pairs, suitable for either AES3 or copper tie lines that looked pretty cool. Dave

Dave, do you have any more info on this? Is Telex manufactoring this one themselves or is it third party? If so, who makes it?

[Scott Helmke (Scodiddly)]

I think in this sort of discussion a "dry pair" is going to have to be treated as an ideal to aspire to, not something that can actually be created over a data link.  It's not just line loss that puts a distance limitation on communication links, it's the speed of propagation as well.

[ProSoundWeb Community]