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Patch bay wiring?

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Patch bay wiring?

Postby Arpangel » Wed Aug 26, 2020 9:32 am

I’ve been having noise issues with my patch bays, I’m running unbalanced synths and pedals through them. I’m using unbalanced cables into my balanced patch bays, and balanced cable from my patch bays to my interface, is this correct? or should I use unbalanced cables all the way through?
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Re: Patch bay wiring?

Postby Hugh Robjohns » Wed Aug 26, 2020 9:48 am

It's an inevitable side-effect of combining unbalanced and balanced cabling, and especially if there are common earths. All to do with ground loops, innit.

The way around the problem is carefully thought out and methodical customised wiring between the unbalanced sources and the patchbay -- generally involving some form pseudo-balanced connection.

Typically, you'd need to make up TS to TRS cables, where the sleeve of the unbalanced end connects only to the ring of the balanced end. That will avoid ground loop problems for unbalanced outputs feeding balanced or unbalanced inputs.

The same wiring arrangement will often work for balanced outputs to unbalanced inputs too, but here a little more care is needed because some balanced outputs don't like (or won't even work) with that kind of wiring... so you'll need a careful evaluation of all the equipment involved.

Obviously isolating/balancing transformers can be used in the trickiest situations, or active balancing boxes like the ART CleanBox Pro which also shifts the signal levels between pro and instrument standards.

But to make a patchbay work trouble-free in this kind of scenario requires some careful planning and thought... which I might have said once or twice before. ;)
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Re: Patch bay wiring?

Postby The Elf » Wed Aug 26, 2020 11:03 am

Using balanced cables throughout seems to give me the best degree of success. I only use an unbalanced cable when there's absolutely no choice - and that is a very rare occurrance. I've cabled many home studios this way and no failures to date.
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Re: Patch bay wiring?

Postby Hugh Robjohns » Wed Aug 26, 2020 1:47 pm

Using balanced cabling with unbalanced devices and FX pedals opens a large can of worms, because not all unbalanced devices will have anything connected to the ring terminal, and some of those that do use it to pass the battery DC supply.

But for those that do the logical thing of shorting the ring to the sleeve... there is then absolutely no difference in the wiring arrangement whether you use unbalance TS or balanced TRS cables...
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Re: Patch bay wiring?

Postby The Elf » Wed Aug 26, 2020 1:56 pm

Hugh Robjohns wrote:Using balanced cabling with unbalanced devices and FX pedals opens a large can of worms, because not all unbalanced devices will have anything connected to the ring terminal, and some of those that do use it to pass the battery DC supply.

But for those that do the logical thing of shorting the ring to the sleeve... there is then absolutely no difference in the wiring arrangement whether you use unbalance TS or balanced TRS cables...
I'm not saying it can't cause a problem, but I am saying that I can count on one hand the number of times it's actually *been* a problem.

If there's a 'rule of thumb' it's certainly not to always use unbalanced cables!
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Re: Patch bay wiring?

Postby Arpangel » Wed Aug 26, 2020 4:31 pm

Thanks folks, looks like I’ll have to buy some of those SOS cables :)
I’ve tried using balanced cables throughout, and for my A-Station synth, well, it just doesn’t work, no sound. And my Shallow Water pedal gives me level problems, that’s why I tend to stick with unbalanced, just in case.
I’ve dismantled everything, and I’m adding stuff back one by one, it’s a pain, but it’s got to be done.
My patch bay is one of those £60 Neutrik ones, it comes with little earthing clips for different scenarios, but I’m not sure how to use them, despite the description.
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Re: Patch bay wiring?

Postby Hugh Robjohns » Wed Aug 26, 2020 6:19 pm

Arpangel wrote:Thanks folks, looks like I’ll have to buy some of those SOS cables :)

Sorry... no longer being manufactured. Not enough sustained interest to make it profitable.

I’ve dismantled everything, and I’m adding stuff back one by one, it’s a pain, but it’s got to be done.

Quite so. Tedious, but necessary.

My patch bay is one of those £60 Neutrik ones, it comes with little earthing clips for different scenarios, but I’m not sure how to use them, despite the description.

In general, for your situation, it's probably best not to link the earths across different channels.
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Re: Patch bay wiring?

Postby Arpangel » Thu Aug 27, 2020 7:52 am

Hugh Robjohns wrote:In general, for your situation, it's probably best not to link the earths across different channels.

Yes, and the situation isn’t helped any by the fact the patch bays are mainly for routing a lot of dodgy pedals with their own peculiar idiosyncrasies.
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Re: Patch bay wiring?

Postby ef37a » Thu Aug 27, 2020 8:22 am

Buy a rake of theses,
https://www.amazon.co.uk/AV-Link-Ground ... ooghydr-21
and then balance and earth isolate the output of EVERYTHING not already balanced.

Yes, they are cheap and steam is probably coming out of Hugh's ears but I put one on a scope and oscillator a few years ago and loaded it down with about 1k and the performance was surprisingly good. Ok, you will not get a clean 30Hz wavvy at +20dBu (maybe not even at +6?) but for most sources and pedals at neg ten I am sure they will be fine.

Note, these should be used on OUTPUTS. 10K-10K line INPUT transformers are another and much more expensive breed! Mind you, a couple of boxes, one with a pair of line driver traffs and the other with two good quality 10k jobbies with an inter-winding screen can be a great solution to stubborn RFI problems.

Dave.
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Re: Patch bay wiring?

Postby Arpangel » Thu Aug 27, 2020 9:20 am

ef37a wrote:Buy a rake of theses,
https://www.amazon.co.uk/AV-Link-Ground ... ooghydr-21
and then balance and earth isolate the output of EVERYTHING not already balanced.

Yes, they are cheap and steam is probably coming out of Hugh's ears but I put one on a scope and oscillator a few years ago and loaded it down with about 1k and the performance was surprisingly good. Ok, you will not get a clean 30Hz wavvy at +20dBu (maybe not even at +6?) but for most sources and pedals at neg ten I am sure they will be fine.

Note, these should be used on OUTPUTS. 10K-10K line INPUT transformers are another and much more expensive breed! Mind you, a couple of boxes, one with a pair of line driver traffs and the other with two good quality 10k jobbies with an inter-winding screen can be a great solution to stubborn RFI problems.

Dave.

Thanks for that Dave, I’ll se how it goes today, I just want to make sure I do this logically, and build it back up one thing at a time.
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Re: Patch bay wiring?

Postby Sam Spoons » Thu Aug 27, 2020 1:12 pm

Orchid electronics will make you custom cables for a very reasonable price.
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Re: Patch bay wiring?

Postby Arpangel » Fri Aug 28, 2020 8:49 am

Sam Spoons wrote:Orchid electronics will make you custom cables for a very reasonable price.

I’m embarrassed to admit it, but I’m quite capable of making these myself, trouble is, I just can’t be bothered.

:blush: :blush: :blush:
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Re: Patch bay wiring?

Postby Zukan » Fri Aug 28, 2020 9:16 am

Hugh Robjohns wrote:It's an inevitable side-effect of combining unbalanced and balanced cabling, and especially if there are common earths. All to do with ground loops, innit.

The way around the problem is carefully thought out and methodical customised wiring between the unbalanced sources and the patchbay -- generally involving some form pseudo-balanced connection.

Typically, you'd need to make up TS to TRS cables, where the sleeve of the unbalanced end connects only to the ring of the balanced end. That will avoid ground loop problems for unbalanced outputs feeding balanced or unbalanced inputs.

The same wiring arrangement will often work for balanced outputs to unbalanced inputs too, but here a little more care is needed because some balanced outputs don't like (or won't even work) with that kind of wiring... so you'll need a careful evaluation of all the equipment involved.

Obviously isolating/balancing transformers can be used in the trickiest situations, or active balancing boxes like the ART CleanBox Pro which also shifts the signal levels between pro and instrument standards.

But to make a patchbay work trouble-free in this kind of scenario requires some careful planning and thought... which I might have said once or twice before. ;)

In days gone by I needed a quality Bantam patchbay and opted for a Mosses and Mitchel. I sat down and drew a flow diagram of everything I needed patched in. I carefully planned and accomodated for colour coded patch leads. I pondered on the best layout for a day and then thought 'sod it'.

I got Max to do the soldering.

Get someone like Max (Idris) to sort your patchbay out. He knows things others don't.
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Re: Patch bay wiring?

Postby Arpangel » Fri Aug 28, 2020 9:25 am

Zukan wrote:
Hugh Robjohns wrote:It's an inevitable side-effect of combining unbalanced and balanced cabling, and especially if there are common earths. All to do with ground loops, innit.

The way around the problem is carefully thought out and methodical customised wiring between the unbalanced sources and the patchbay -- generally involving some form pseudo-balanced connection.

Typically, you'd need to make up TS to TRS cables, where the sleeve of the unbalanced end connects only to the ring of the balanced end. That will avoid ground loop problems for unbalanced outputs feeding balanced or unbalanced inputs.

The same wiring arrangement will often work for balanced outputs to unbalanced inputs too, but here a little more care is needed because some balanced outputs don't like (or won't even work) with that kind of wiring... so you'll need a careful evaluation of all the equipment involved.

Obviously isolating/balancing transformers can be used in the trickiest situations, or active balancing boxes like the ART CleanBox Pro which also shifts the signal levels between pro and instrument standards.

But to make a patchbay work trouble-free in this kind of scenario requires some careful planning and thought... which I might have said once or twice before. ;)

In days gone by I needed a quality Bantam patchbay and opted for a Mosses and Mitchel. I sat down and drew a flow diagram of everything I needed patched in. I carefully planned and accomodated for colour coded patch leads. I pondered on the best layout for a day and then thought 'sod it'.

I got Max to do the soldering.

Get someone like Max (Idris) to sort your patchbay out. He knows things others don't.

It’s a small set-up Zukan, and I’m going to go down there after I’ve had a shave in a minute, to try and sort it out, if the same problems come back I’d quite happily pay Max to sort it out, even maybe remotely.
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Re: Patch bay wiring?

Postby Sam Spoons » Fri Aug 28, 2020 9:36 am

Arpangel wrote:
Sam Spoons wrote:Orchid electronics will make you custom cables for a very reasonable price.

I’m embarrassed to admit it, but I’m quite capable of making these myself, trouble is, I just can’t be bothered.

:blush: :blush: :blush:

Me too... but sometimes, if you haven't got all the right bits to hand, getting a professional to do the job.
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