Switching multiple lines

[phil dekked]

Why shouldn't it work...? It's just a bunch of switches...

 

The audio should be fine as it's all low impedence stuff, but there are two problems I forsee:

 

a) Crosstalk - likely to be low level, but the possibility for crosstalk is there, as the balancing of the signals is lost in the switch, and just outside it, and

 

b) phantom power - only one of the venuettes you mention has split trannies. If both have splitter trannies then the problem goes away. I suspect you want to switch before one set of trannies, but that is more troublesome on every front than switching after two sets of trannies, as then the sources is always known (it's s winding on a tranny!), theres no grounding issues, as the recording system is totally isolated from both rooms equipment, and no phantom issues as you dont need phantom to run the trannies.

 

c) Better idea - go all digital with two sets of A/D converters...?

 

Ok ...a) I can live with cross talk, they`re just doing live mixing down to 2 -track

 

b) I`d presume with the vdm plug option the room being recorded will be plugged in so "seeing" the transformers

while the other room would be a "blank" end that wouldn`t affect the signal to the desk?

c) that was my first answer to them but they have a VERY low budget! any suggestions of cheap 32ch a/d switching! I thought about a cheap digital desk with switchable mic / line a/b inputs?

 

ta

.p.

[dbuckley]

Ok ...a) I can live with cross talk, they`re just doing live mixing down to 2 -track

What I didn't mention was that the crosstalk will also manifest itself on the house and monitor desks as well, it's system level crosstalk. But I still don't think it'll be an issue.

 

b) I`d presume with the vdm plug option the room being recorded will be plugged in so "seeing" the transformers while the other room would be a "blank" end that wouldn`t affect the signal to the desk?

In practice, true. If the cables were ridiculously long (ie big fractions of the electrical wavelength of the signal) you can ge bad stuff happening due to stub effects resulting in frequency cancellation, but we're talking 10+ KM of cable here before you get those sorts of problems

 

c) that was my first answer to them but they have a VERY low budget! any suggestions of cheap 32ch a/d switching! I thought about a cheap digital desk with switchable mic / line a/b inputs?

I was musing massed ranks of Behringer ADAs, but if money is tight it'll be too expensive.

 

Although plug swapping will be cheaper than other options, I remain concerned about connecting audio equipment in an ad-hoc manner over three floors, mostly from the possible problems of potential differences across grounds. It may work, it may not, or some fault one day may cause some toastage. An extra set of splitter transformers will allow both stages plus the recording room to run without audio ground continuity between any of them, which makes it quiet and safe.