Wiring my first patch bay and confused as to how it normals.

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TheGuitarist

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Apr 5, 2009
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This is the first time I've wired a patch bay and I'll be following keiths wonderful guide to neat patch bay wiring.

I got a  lovely full normalised switchcraft patch bay and this wiring diagram here http://www.switchcraft.com/Drawings/ttp96k1series_cd.pdf

I'm just a little bit confused how to make the patch bays normal vertically.

Basically its mic line normalled to mic pre in then mic pre out to pro tools in.

I think i will keep all the grounds isolated though, bussing or lifting seems a bit daunting if there are problems.

If it's all just as simple as connecting tn to t and rn to r then awesome.

Just all a bit confused
 
Depends on whether you want full or half normal

For mic, I'd go full normall. Half normal for line level stuff

For full normall, you connect the lower row normals to upper row normals.
For half normall, you connect lower row normals to the upper cable contacts (split)
So Rn goes to R and Tn goes to T.

Personally I'd prefer to bus the grounds but it depends on the rest of your setup.
 
Well aside for these lines the rest is odd bits of patch points, comps, reverbs and pt outputs.

Actually does anyone know how these labelling strips are supposed to be stuck on?
 
in studios the common thing to do is half normals all around except on the mic lines into the mic pres on the console and also the outboard fx devices. The outboard fx devices will have no normal at all and the mic pannel to mic pre's will have a full normal.

As for grounding.
I'm against bussing grounds on patchbays, though some console manufacturers and installers have bussed line level grounds over the years. If the console design and the rest of the install is carefully tailored to the bussed ground on the bay, it can work ok. In many situations though, especially on the fly type installs that aren't carefully thought out, ground noise problems can result.

But mic lines should never have their ground connections bussed on a patchbay. No manufacturer that I am aware of has ever used this method. Grounds on mic lines should remain isolated from one another, all the way to the front end of the preamp. Otherwise, there's a big risk of ground noise. This is mainly because the large amount of gain in a preamp stage can magnify the slightest ground loop issue and make it annoyingly audible. I guess exceptions are possible, but in my experience I've never seen one.

In my opinion, which cannot be gotten around, is that bussing grounds on the patch bays undermines the concept of a star ground.

On nearly all gear the grounds of the inputs and outputs will be connected together at the gear. If they are also connected together at the patchbay this creates a type of ground loop. If there are just a few instances it may not produce audible ground noise, but on the other hand, it may. If there are many instances, there is a better chance it will produce ground noise.

In any case, there's no advantage in doing this. The ground buss is just another wiring step, isn't it? So why not skip that step, avoiding the time it would require and avoiding the chance of more ground noise.
 
Cool well that sorts out my wiring and grounding questions! Thanks heaps guys, aside from glueing them on has anyone used these patch bays and know how to get the strips to stick on?
 
TheGuitarist said:
Cool well that sorts out my wiring and grounding questions! Thanks heaps guys, aside from glueing them on has anyone used these patch bays and know how to get the strips to stick on?

label strips? usually there is a plastic cover the fits over the little row where the label is supposed to go. If the patchbay was used chances are it got lost
 
pucho812 said:
In my opinion, which cannot be gotten around, is that bussing grounds on the patch bays undermines the concept of a star ground.

On nearly all gear the grounds of the inputs and outputs will be connected together at the gear. If they are also connected together at the patchbay this creates a type of ground loop. If there are just a few instances it may not produce audible ground noise, but on the other hand, it may. If there are many instances, there is a better chance it will produce ground noise. just another wiring step, isn't it? So why not skip that step, avoiding the time it would require and avoiding the chance of more ground noise.

Reading this reminded me how much balanced interconnect has changed in the last 40 years and how much easier things were in the old days when everything was transformer balanced and floating.

What concerns me is all this talk about 'grounding' in balanced patch bays and I guess that is simply because with electronic balancing the screens are also signal grounds (0V). In the good old days of transformer balanced floating outputs and inputs there were no 'grounds' but there were 'screens'. Connecting up screens through a patch bay was simple. Screens in transformer balanced floating systems carry no signal current so you simply left one end unconnected (usually at the patch bay end) and connected the screen at the console end to chassis (not 0V) which was then usually starred to a technical earth or something similar. There was therefore zero possibility of a ground loop. The only exception was mics which were themselves floating so you had to continue their screen through the bay to the console so it could get connected to chassis.

Score one for transformers.

Cheers

Ian
 
Transformers are lovely.

Galvanic isolation.

Current making sound... not voltage.

Unbalanced cheapness and bean-counter transformerless outputs have moved the goalposts somewhat since then... (sigh!)

Keef
 
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