Help with small rack cabling.

[Chris Nixon]

I'm putting together a small outboard rack containing 2 in 2 out FX, 2 in 2 out EQ and 6 in 6 out of compressors. It will mainly be used in small venues up to maybe 300 seats with GL2400's and similar. It's not impossible that I'll run into a console with balanced inserts, but 90% of the time it won't be. I want to make up the cabling for this myself mainly to get more experience soldering (and possibly some experience troubleshooting cabling problems :roll: ) but also so that I can get a cable with the exact connectors I need.

I would like it to be about 5 metres long and it would be very nice if it fit in the back of the rack. The rack hasn't been purchased yet. The deepest unit is 9cm deeper than all the others, which leaves some extra room for cable to be stored inside.

It comes out to 20 lines which means using a 24 channel multicore if I put it all in one cable (can't find a 20), or a 12ch cable for compressors, and two 4 or one 8 channel cable for the FX and EQ, maybe 16ch for comp and FX, 4ch for EQ...

...but then I'm carrying around two or three outer sheathes rather than just one.

FX will be on balanced TRS connectors and I'll carry TRS - XLR adaptors for it.

EQ will be on XLR, I think.

The most versatile way of cabling the compressors seems to be to run them to "dual point" balanced TRS on the console end and use (2) TS F to (1) TRS M adaptors to get into unbalanced inserts, which has the advantage of letting me swap the send / return configuration by just flipping that adaptor. I could plug into XLR inserts too with some short adaptor cables. I like this, but I'm aware that I'll be mostly unnecessarily carrying quite a lot of metal.

The other way I could do it is unbalanced with dual TS on the rack end single point TRS on console end, and carry adaptors to get into balanced consoles. That still lets me swap tip / ring send at the rack, but means I can never use balanced insert lines. It does mean I'm not using adaptors most of the time, and it does seem logical to employ adaptors for the exceptions rather than the norm.

How much of a problem are unbalanced lines of about 5 metres, generally? Is the level difference from using unbalanced lines into a device expecting balanced just a matter of setting the compressor threshold 6 dB lower?

I know most of this is stuff I need to decide for myself, but any advice from experience would be appreciated.


Chris

 

[Eric Simna]

Re: Help with small rack cabling.

I'm putting together a small outboard rack containing 2 in 2 out FX, 2 in 2 out EQ and 6 in 6 out of compressors. It will mainly be used in small venues up to maybe 300 seats with GL2400's and similar. It's not impossible that I'll run into a console with balanced inserts, but 90% of the time it won't be. I want to make up the cabling for this myself mainly to get more experience soldering (and possibly some experience troubleshooting cabling problems :roll: ) but also so that I can get a cable with the exact connectors I need.

I would like it to be about 5 metres long and it would be very nice if it fit in the back of the rack. The rack hasn't been purchased yet. The deepest unit is 9cm deeper than all the others, which leaves some extra room for cable to be stored inside.

It comes out to 20 lines which means using a 24 channel multicore if I put it all in one cable (can't find a 20), or a 12ch cable for compressors, and two 4 or one 8 channel cable for the FX and EQ, maybe 16ch for comp and FX, 4ch for EQ...

...but then I'm carrying around two or three outer sheathes rather than just one.

FX will be on balanced TRS connectors and I'll carry TRS - XLR adaptors for it.

EQ will be on XLR, I think.

The most versatile way of cabling the compressors seems to be to run them to "dual point" balanced TRS on the console end and use (2) TS F to (1) TRS M adaptors to get into unbalanced inserts, which has the advantage of letting me swap the send / return configuration by just flipping that adaptor. I could plug into XLR inserts too with some short adaptor cables. I like this, but I'm aware that I'll be mostly unnecessarily carrying quite a lot of metal.

The other way I could do it is unbalanced with dual TS on the rack end single point TRS on console end, and carry adaptors to get into balanced consoles. That still lets me swap tip / ring send at the rack, but means I can never use balanced insert lines. It does mean I'm not using adaptors most of the time, and it does seem logical to employ adaptors for the exceptions rather than the norm.

How much of a problem are unbalanced lines of about 5 metres, generally? Is the level difference from using unbalanced lines into a device expecting balanced just a matter of setting the compressor threshold 6 dB lower?

I know most of this is stuff I need to decide for myself, but any advice from experience would be appreciated.


Chris

If you go the route of one large multicore, make sure your fanout can span your ENTIRE console and then some. I ran into the problem of my sub bundles not fanning out enough as well. There is nothing quite as frustrating as needing 4 channels of compression, and the last channel you need a compressor is about 3 channels too far for the fanout.

On the flip side, you could forgo the sub bundling, but then the fanout gets messy FAST.

 

[Chris Nixon]

Re: Help with small rack cabling.

Yep, I've run into that before trying to do a non 1-1 input patch on an analog console that took some careful work with a swiss army knife. It's one of those things that seems really obvious after you have the problem. My 5M estimate includes reaching the opposite end of the console from where the rack is, so I'll trim back about 32 channels worth then bundle it back up with velcro ties at 8 channel intervals. 8)~~

Chris

 

[Branson Sagear]

Re: Help with small rack cabling.

For all insert cables, I would suggest to run balanced sends and returns, and use adaptor sat the console end to get it down to trs send/return. That way you can change between fully balanced, send on the tip, and send on the ring. The cabling will work in every situation.

 

[Geoff Doane]

Re: Help with small rack cabling.

Back when I owned some analog consoles, I ran into similar problems: some were tip send, other ring send, although I didn't have to worry about anything with balanced inserts.

I wound up using individual pairs, one for each send and return, with TRS at the console end, and TS at the rack end. Sends and returns were grouped using nylon sleeving. I didn't have any devices that were XLR only, so if I used a console with the opposite send on the insert, I could just reverse everything at the rack end. That was a PITA, but better than carrying a whole lot of adapters. Unbalanced was never a problem with 5m or shorter cables. Individually jacketed cable was not as common back then as it is now, so using individual pairs meant I didn't have to use heatshrink or tubing on each pair. The cable bundles were a bit bulkier than snake cable, but more flexible, I think.

If you do the math, I suspect it's cheaper to build a whole new set of cables rather than build a bunch of adapters that you will rarely need anyway. Female inline TRS jacks are hideously expensive. Your original plan would require two for each adapter. Even adapting unbalanced cables to a balanced console will require a lot of hardware, that will leave a lot of weight hanging off the back. You might be able to find some female TRS to 2x TS molded adapters that would make this more practical than rolling your own.

For EQs, I preferred to insert them wherever possible, and use the XLR on the console as the ultimate send point to the snake and eventually stage. That gives me the console fader as the master output, and the console metering also still means something. There are differing opinions on this, but that's mine.

For FX sends and returns, I just did TS on both ends of each pair, wired unbalanced of course. At the lengths I was using, there were no problems.

I think the racks I had back then were 16" deep, not including the covers (another 2"). There was always enough room to coil up the cable bundles in the back. Putting the front cover on first, then tipping the rack onto its front, before coiling the cables, made this pretty easy.

GTD