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Patch bay woes.

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Patch bay woes.

Postby Arpangel » Fri Oct 09, 2020 3:53 pm

Just some words of warning for noobies, or people like me that want an lazy life, but very rarely seem to achieve it.
I added a couple of new things to my patch bay yesterday, which involved a bit of rewiring.
I switched on this morning to be greeted by a barrage of hum hiss radio interference etc etc, it’s taken me the whole morning to sort it out.
It was a mixture of things, fiendishly designed to mystify and catch me out.
I have some unbalanced synths connected to the back of my balanced patch bays, normalised to the inputs of my interface with balanced cables, I thought that this would be fine, but the cables from the bay to the interface were causing hum and noise, after swapping them with unbalanced ones all of the noise disappeared.
I’ve never had an issue with plugging unbalanced cables into balanced mixer inputs, but I guess the earthing arrangements are different on a patch bay.
Another annoying problem was a moulded jack cable, the shaft of the actual plug had worked its way up into the body of the plug, making it shorter, so the tip wasn’t making proper contact :(
I find it necessary to use unbalanced cables through a patch bay with unbalanced sources, problems don’t happen all the time, but when they do they are difficult to track down
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Re: Patch bay woes.

Postby Hugh Robjohns » Fri Oct 09, 2020 7:18 pm

Arpangel wrote:I have some unbalanced synths connected to the back of my balanced patch bays, normalised to the inputs of my interface with balanced cables, I thought that this would be fine, but the cables from the bay to the interface were causing hum and noise, after swapping them with unbalanced ones all of the noise disappeared.

That's a weird one that I'm struggling to figure out... There's definitely something more complicated going on in that one than you think!
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Re: Patch bay woes.

Postby James Perrett » Fri Oct 09, 2020 8:41 pm

What sort of cables are you using between the synths and the patchbay?
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Re: Patch bay woes.

Postby Arpangel » Sat Oct 10, 2020 6:49 am

James Perrett wrote:What sort of cables are you using between the synths and the patchbay?

I’m using unbalanced cables from the synths, as Hugh says, there may be something more going on, I think it might be some of the boards in the bays shorting out on the case, which I’ll have to check.
I must admit, that since having the patch bays problems seem to be popping up, all too frequently, I’m still in doubt as to whether I’ll continue to use them, but it’s difficult, as I’ve got to a point where I really don’t have any choice.
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Re: Patch bay woes.

Postby ef37a » Sat Oct 10, 2020 7:00 am

How many synths? The investment in a patch bay plus all the additional cables and plugs is quite a wedge. I think I would go the next few mtrs and fit transformers to unbalanced sources so that ALL sources are balanced?

Gets over grounding issues as well.

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Re: Patch bay woes.

Postby Arpangel » Sat Oct 10, 2020 7:47 am

ef37a wrote:How many synths? The investment in a patch bay plus all the additional cables and plugs is quite a wedge. I think I would go the next few mtrs and fit transformers to unbalanced sources so that ALL sources are balanced?

Gets over grounding issues as well.

Dave.

I don’t know Dave, this is all too much, I’m not going to, but it’s tempting to get my mixer out again, no problems with that, and routing was more flexible.
The thought of transformers, more PSU's, more cabling, it’s all a bit of a joke now, I have 5 synths, ten pedals, a couple of tape decks, and some effects units, plus bits and pieces like my a Monotrons, and Pocket Operators, my 20 channel mixer took all this, I had six aux sends, plus groups, and no need for patch bays.
I got the bays in an attempt to improve routing, and cut down on hardware, but I’m having the opposite experience now.
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Re: Patch bay woes.

Postby ef37a » Sat Oct 10, 2020 8:34 am

Yeah, see if it were I, I would buy a rake of OEP '600' Ohm transformers and stick 'em in a tin.

To be honest I see most synths operating at around -10dBV? Therefore you don't need expensive transformers that can handle +22dBu at 50 Hz but maybe Hugh will correct me.
You can get transformers made for the ICE industry at around ten quid a pair.

Pedals of course are neg ten'ish by definition.

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Re: Patch bay woes.

Postby James Perrett » Sat Oct 10, 2020 12:55 pm

I haven't bothered with transformers in my synth patch bay (which is pretty small compared to some people's) and I'd say that they aren't necessary in most circumstances. The biggest problems that I've found are leads that aren't pushed fully home and dirty contacts (as my patch bays were in a smoky studio for some of their life).
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Re: Patch bay woes.

Postby The Elf » Sat Oct 10, 2020 1:00 pm

Four 48-hole bays here and oodles of synths, some balanced, some not. Not a transformer in sight. No problems here.
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Re: Patch bay woes.

Postby Arpangel » Sat Oct 10, 2020 1:57 pm

James Perrett wrote:I haven't bothered with transformers in my synth patch bay (which is pretty small compared to some people's) and I'd say that they aren't necessary in most circumstances. The biggest problems that I've found are leads that aren't pushed fully home and dirty contacts (as my patch bays were in a smoky studio for some of their life).

James, I’m finding the size of the tips on certain brands of plugs varies quite a bit, I have some moulded Studio Spares ones, that are noticeably smaller than say Neutrik tips.
Also, I’m staying away from moulded leads now, especially after my short barrel incident.
I think what I’m going to do is just buy a drum of foil screened cable and a load of decent plugs and make up my own loom, the way the leads are run at the moment isn’t ideal, some are just off-the-shelf cables I found in my bin, and are way too long, hence a rats nest near PSU's on the floor.
Normally I haven’t had any issues previously with my mixer, but I guess as things have become more complex I need to be extra careful with my wiring.
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Re: Patch bay woes.

Postby Hugh Robjohns » Sat Oct 10, 2020 2:01 pm

Having had a think, the only probable cause I can come up with for the weird things described earlier is balanced plugs not inserted fully or duff contacts/normalling... As James suggested.

Unless there were specific ground loop issues I wouldn't use transformers for unbalanced synth connections, either. Unless you go for expensive transformers they often tend to affect the powerful low end in a deleterious way. Instead, I'd use simpler bespoke cabling for pseudo-balanced connections... But even straight unbalanced connections between synth and bay work fine in most cases -- especially with class-2 synths.

And finally... ive explained it before, but just to avoid confusion from anyone reading Tony's comments, a patchbay is not a replacement for a mixer. It is a simple passive signal router... It serves a very different role and is often employed with a mixer to extend the available sources or destinations etc.
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Re: Patch bay woes.

Postby Arpangel » Sat Oct 10, 2020 2:14 pm

Hugh Robjohns wrote:And finally... ive explained it before, but just to avoid confusion from anyone reading Tony's comments, a patchbay is not a replacement for a mixer. It is a simple passive signal router... It serves a very different role and is often employed with a mixer to extend the available sources or destinations etc.

And that’s exactly what I’m using the PB's for, with my little Mackie, but it seems the extra wiring, and contacts, are causing some issues, dodgy leads too, but that’s just bad luck.
My main reason for going with PB's was to save space, and do away with just a large mixer, I thought I would have more flexibility with PB's and a small mixer, but it hasn’t really worked out, initially it was going to be PB's and an interface with no mixer at all.
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Re: Patch bay woes.

Postby James Perrett » Sat Oct 10, 2020 6:42 pm

Arpangel wrote:James, I’m finding the size of the tips on certain brands of plugs varies quite a bit, I have some moulded Studio Spares ones, that are noticeably smaller than say Neutrik tips.
Also, I’m staying away from moulded leads now, especially after my short barrel incident.
I think what I’m going to do is just buy a drum of foil screened cable and a load of decent plugs and make up my own loom,

Sounds very sensible. Many of my studio cables are home made and have proved far less troublesome than some of the impressive looking factory made cables I've encountered. Factory made unbalanced jack cables seem to be the worst - some of the chunky looking cables actually use very little copper and are worse than cheap skinny screened cable.

Most of my patch leads came from a sample of multicore cable that I was given at a trade show many years ago which is handy as each cable has a number printed on its jacket at regular intervals.
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Re: Patch bay woes.

Postby Arpangel » Sat Oct 10, 2020 7:47 pm

James Perrett wrote:Most of my patch leads came from a sample of multicore cable that I was given at a trade show many years ago which is handy as each cable has a number printed on its jacket at regular intervals.

That’s a fantastic idea James! I’ve got a couple of long multicores that I could use for that.

Had to laugh, sounds like a 50’s pulp fiction title..."short barrel incident"

:D
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Re: Patch bay woes.

Postby James Perrett » Sat Oct 10, 2020 8:41 pm

It might be worth checking how flexible the cores are first though. Some of my other multicores have cores that are too stiff for patch cables.
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