inserts to/from balanced gear

whoopgnash · Post by **whoopgnash** » Sun Jun 03, 2007 11:49 am

Hi All-

I am wondering how I can hook my compressor (JoeMeek SC2.2) to the inserts on my Mackie 24.8 board. The inserts on the board are unbalanced 1/4", but the compressor has balanced XLR ins and outs only. The XLR inputs are high impedance and the outputs are low impedance. I am new to using a mixing board, and a bit confused.
I hope this doesn't make me look too dumb. Any help and advice is greatly appreciated. Thanks-

-John Erickson

I'm Painting Again · Post by **I'm Painting Again** » Sun Jun 03, 2007 1:40 pm

John no, wiring is really confusing and veteran engineers get it wrong all the time..

you have a couple of options..

one is to use a transformer between the devices and is the only real way to make it technically 100% compatable..

you can make your own or buy a product like this:

http://www.ebtechaudio.com/lls-2des.html

I'm not sure how to make one though..I think it is a 1:1 transformer..but I am unsure of the wiring there and how to do it correctly..

the other way is a trade off and may or may not matter in your application..the symptoms are hum and noise and les than ideal gain staging..

you just wire them directly together..

like so:

http://websrvr25ca.audiovideoweb.com/ca ... _cable.pdf

see how it says to jump pins 1 and 3 on the XLR jacks in step 2..you can try it like that and also without anywires touching pin 1 on the XLR jacks and see which works better..sometimes one way works better than the other..

GarryJ · Post by **GarryJ** » Sun Jun 03, 2007 2:37 pm

A few notes to consult:

http://www.sdds.com/PDFS/technotes/TN99060401.pdf

http://www.meyersound.com/pdf/products/ ... evices.pdf

http://www.rane.com/note110.html

The rane link is pretty comprehensive for interconnections in general, some good info there.

Fletcher · Post by **Fletcher** » Mon Jun 04, 2007 5:14 am

Beauty&Wonder wrote:John no, wiring is really confusing and veteran engineers get it wrong all the time.

Then I dare say they aren't "veterans".

It ain't rocket surgery... from the XLR make an adapter cable. Pin 2 of the male XLR will be wired to the "send" of the 1/4" TRS that plugs into the Mackie. Pin 2 of the Female XLR will be wired to the "return" of the 1/4" TRS that plugs into the Mackie.

Tie Pins 1 & 3 on both connectors and run those combined wires to the "sleeve" of the 1/4" TRS connector that plugs into the Mackie and you'll be cookin' with gas.

You won't have any impedance mis-matches... and unless you're in a severely high RFI [Radio Frequency Interference] environment [like across NY in Jersey on the banks for the Hudson River] you shouldn't have a problem... especailly if you keep your cable runs to like 5-6 feet or less.

Best of luck with it.

dwelle · Post by **dwelle** » Mon Jun 04, 2007 9:38 am

interesting timing on this post...

i've been wiring patchbays to a ghost i bought and have been debating on how to handle the inserts for my busses. i have an 8 channel ebtech, but need it elsewhere. if i want to wire these into my patchbay, what would be the best way to accomplish this. i was thinking of using an 8 channel snake with trs ends into the insert points, connecting the appropriate leads to the top and bottom of some normalled points on the patchbay, but i don't fully understand how i should tie everything in from there. i'll obviously be patching in the front with a balanced signal, so how do i configure the back of the bay to accomplish the same thing as the custom insert cables?

any wisdom very much appreciated...

dwelle · Post by **dwelle** » Wed Jun 06, 2007 7:43 pm

anyone?

Mane1234 · Post by **Mane1234** » Wed Jun 06, 2007 11:50 pm

Dwelle,
I'm not sure I understand your question. What exactly is an 8 channel ebtech? Are these pres or is this signal processing? What are you going to be routing through it?

thesimulacre · Post by **thesimulacre** » Thu Jun 07, 2007 9:56 am

dwelle wrote:anyone?

The way I do it (I think my patchbay is half-normalled) is to plug the send left and right into the top row (back) of the patchbay and the return into the bottom. That way you "normally" just send/return nothing, but if you want to patch in something else everything is right there. As far as balanced and unbalanced, I just throw it all together until I hear something I don't like, which hasn't happened so far. As far as the Ebtech, I guess you would need another 8 or 16 really short patch cables to put that in line. But I have never used one so basically I just made that up. ?

dwelle · Post by **dwelle** » Thu Jun 07, 2007 6:54 pm

the ebtech is a conversion box that takes an ubalanced -10 signal and converts it into a balanced +4 signal. ts 1/4" unbalanced -10 in, trs 1/4" balanced +4 out, or visa versa. really handy device, especially if you have transformer balanced gear.

in thinking about this:

i have punchblock longframe patchbays. i'll just jumper the sleeve slot of the top patch point to the sleeve slot of the point right below it. from my trs insert cable, punch the sleeve to either sleeve slot, the send to the top tip slot, and the recieve to the bottom tip slot. all points normalled, all runs short. no problem.

i'm overthinking this as usual...

make sense?

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inserts to/from balanced gear

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