Terry Richards Apr 20, 2018:

Thanks for letting us know. It's always good to get feedback, even when it concerns PA systems :)

STEVEN DEWITT (asker) Apr 19, 2018:

Hi Tony and Terry -- I have heard back from the client and "diffuseur" indeed means simply "broadcaster ('s truck)" in this case. I was sure it was something more technical than that! Thank you very much again for all your ideas and fast responses. -- Steven

STEVEN DEWITT (asker) Apr 19, 2018:

Hi Terry and Tony -- I am going to ask the client for clarification. I will keep you posted. Thank you both for your help so far. -- Steven

Terry Richards Apr 19, 2018:

Part 2 Anyway, all of this doesn't really matter. The only real issue is where this third snake is going and there's really only two candidates. Either, as you say, it's the mixed signal returning to the amp. racks or it's the individual mic. signals going to some third-party.

FYI, I used to own a sound company in the US and have built many such snakes. Been there, got many t-shirts and have the bad back to prove it :)

Terry Richards Apr 19, 2018:

1) No, it says the *console* is digital. The snakes may be analogue or digital but nowhere in the source text does it say that. If they are digital, they don't need isolating transformers but it may be that the rider means "if analogue, must have transformers".
2) 3-way as in 3 destinations. The on-stage mic. signals are sent to 3 places. One is FOH, one is the monitor console and the third is this diffuseur, whatever it is. I'm still holding out for a broadcast truck.
3) The stage box contains the transformers, one per channel. They are used to split the mic signals to the various destinations. The FOH feed may well be direct with transformers (or one multi-winding transformer) on the other feed(s). The transformers are there to isolate the console inputs from each other. With a hard-wired (no transformers) snake, the two (or more, 3 in this case) inputs are effectively wired in parallel and adjusting the trim pot. on one console can reduce/increase the signal to the other leading to the monitor and FOH engineers messing up each other's mixes. In practice, with modern consoles, this is not as big an issue as you might think, the trim pots get set during sound check.

Terry Richards Apr 19, 2018:

Return snake There is sometimes a separate snake returning the mixed signal from FOH to the amp racks. I always used a separate snake for this because I don't believe in having signals travelling along snakes in different directions because there is a possibility of capacitive coupling between the inputs and outputs and a gain stage with a capacitor between the input and output is an oscillator! However, many (most?) people feel that the effect is too small to worry about and send the return signals down the main snake.

However, I don't think this is a return snake because it is shorter than the main FOH snake. It can't be 300' to the FOH in one direction and 50' in the return direction!

Terry Richards Apr 19, 2018:

@Tony OK, 300' makes a lot more sense.

OTOH, I don't get where you get the digital from. The snakes are referred to as "multipaire" and they are transformer isolated from each other. I see that they could be using multi-pair in a generic way but you don't have isolation transformers on digital snakes, that's purely an analogue thing (to prevent the console inputs from interfering with each other, which can't happen across a digital snake).

Tony M Apr 19, 2018:

@ Terry I'm guessing this is either destined for the States, or is from Canada, and they've helpfully given the dimensions in 'feet' — i.e. 'pieds' often abbreviated to 'pi', just as 'pouce' gets abbreviated to 'po'.

Terry Richards Apr 19, 2018:

Is the event televised? It could be the TV truck/room.

I have some other questions about this rider. What are you using for "pi"? Whatever it is, I can't imagine why they need 300 of them going to FOH. Even if it's pairs, that's still 150 channels to a console with 96 inputs. If it is pairs, that's only 25 channels going to the monitors and TV which doesn't seem like enough.