Need help figuring out how to wire my patchbay(s)

WhinyLittleRunt

WhinyLittleRunt

Member
I got a couple of patchbays that have been sitting around collecting dust with the intent of using them but never got the wherewithal to even start. But I did some "live room" rearranging last week and now I'm finding it might be easier, and not to mention cleaner, to use a patchbay to connect all my keyboards and rack equipment together.

Until now, I have had my analog keyboards connected into a 12-ch Mackie mixer. which isn't true 12 channel, since it doubles up on 5-6. 7-8, etc. I have 8 keyboards that need connections to the patchbay, 3 of which have stereo outs, etc. Then I need to run my inputs from the mixer to the patchbay and probably any aux sends/returns, then my rack gear, which really I only have a reverb, delay, compressor, and sonic maximizer. My goal is to have all this stuff in the patchbay so that A) I can just patch what I need for the moment into the mixer, B) take the output of any keyboard at any time and patch it into my 388 (which is behind a wall in my control room and the 8 channels accessible through a custom mic/line panel I made), and C) take the outputs of any rack effects and also run those into the 388 if needed for post processing, although it's likely I'll be using effected signals when working analog and then just post-process digitally so I'm not as concerned about that last one.

My issue is understanding the whole normalled vs half-normalled vs thru argument. For instance, I would assume my keyboards should be half-normalled since I don't need the connection to flow through... is that right? Or do I have it backwards? I notice this seems to be where the hangup tends to be with understanding patchbays and why I'm sure others have stashed theirs in the corner to collect dust just as I did...

The other thing is that I have two completely different patchbays... one is an RCA Tascam PB32 which I've heard isn't like most patchbays but I don't have the data to support what I'm saying, and the other is a 1/4" 22 input AP Audio with some cable tester at the end which takes away the option of having another 2 jacks...got it for free. At this point I'd just like to see if anyone can offer any tips on how I can get the most out of this setup.
 
I find half-normalling the most useful connections. All my feeder equipment is wired through this connection to their normal inputs on the mixer. The half normalling is handy to send bits to other places at the same time as the original path. Works great for me.
 
Can I offer some "operational" ideas here?

One thing that can be a problem is the mix of balanced and unbalanced gear. The mixer line inputs will all be balanced I am sure but not everything will have balanced outputs? Very few synths I would think are balanced out?

This can be fixed very easily by making such outputs "impedance" balanced. For this you wire a resistor from the "cold" ring connection to the sleeve or ground/common. The value of said resistor should be equal to the output impedance of the particular piece of gear and that SHOULD be given in the specification. If it cannot be found 120 Ohms is a fair bet. Balanced systems are of course far better at rejecting ambient hum and to some extent they can guard against hum/ground loops but if the problem is stubborn do consider some "600" Ohm isolating transformers such as the OEP A262A6E. About ten quid a pop here and of excellent quality. You should only need them on one or two bits of gear.

Cables: You will need good quality* 2core screened for patch leads but there is no point in paying a lot for the essentially "static" cables between bay and gear. Also, quality cable is 5 or 6 mm in diameter and just a dozen or so starts to get unwieldy! Look around for some 3 or 4mm twin screened with a foil screen and a solid drain wire. This stuff is far easier to strip and there is no braid to fuss with or cause "whiskery" problems.

Jack plugs: Quality jobs on patch chords again of course but "round the back" look for real cheapos. These can be made up to snuff by the clever use of heat shrink sleeving to give clamping and strain relief.

Last thing. Draw out EVERYTHING! Then try to envisage on paper how it will all come about.
Very last thing! Make or find some way to test for out of phase circuits. With balanced (not Z bal) outs and balanced ins you can easily get a polarity reversal.

*But do not pay sill Russ Andrews monies!

Dave.
 
Interesting - I've never had any issue with simply unbalancing a balanced input, when the sleeve and ring connection is shorted by the unbalanced sleeve. There's a change in level, but well within a prod of a fader or turn of a knob - certainly hasn't caused me any grief. I've also been buying the 3 circuit moulded cables from CPC, which have proven pretty tough, and cheap enough to have plenty around.
 
rob aylestone said:
Interesting - I've never had any issue with simply unbalancing a balanced input, when the sleeve and ring connection is shorted by the unbalanced sleeve. There's a change in level, but well within a prod of a fader or turn of a knob - certainly hasn't caused me any grief. I've also been buying the 3 circuit moulded cables from CPC, which have proven pretty tough, and cheap enough to have plenty around.
Click to expand...

Yup, ubal to balanced is rarely a problem for the home bod, depends on the length of run I guess.
The vast majority of kit these days is Z balanced out so there won't even be a level shift.

I have some moulded 2 circuit patch lead from Maplin. Some people have had problems, call them ***t but mine have lasted as good 4 years no trouble at all. (some folks are just Golly-handed, clumsy b'std!)

CPC? Good people, they do the 4mm cable and cheap plugs.

Dave.
 
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