Full Normal Microphone Patchbay - Shields?

Archived from groups: rec.audio.pro (More info?)

"nmm" <voxman@arvotek.net> wrote in message
news:1108135154.884485.158430@g14g2000cwa.googlegroups.com...
> I'm bringing 24 microphone lines to a Bantam patchbay, then out to 24
> preamps. The studio getting this built wanted the system Full
> Normalled.
>
>
>
> I'm just wondering what to do with the shields at the patchbay. Should
> they be carried through?
>
Yes, to maintain both shield and safety path
First, you must connect screen nearest to each preamp or mixer chnl i/p.
Good practice. Each screened cable takes its earth (ground) ref, assuming
the preamp hardware is itself permanently earthed to a good earth system,
from there...
for lowest noise, hum, cross-talk, and maximum human safety.

If contemplating using some pro capacitor mics, the common -ve or 0V from a
48V phantom power supply must merge at each preamp i/p jacksocket sleeve,
ie, normalled or eventually overpatched to any XLRs' pin1. Overpatching will
however double the screen source and 0V routes, unless you use patchcords of
the type where screen-is-terminated-only-one-end.
Make sure PSU is off when patching as damage to mics is alleged to occur,
besides generating 'orrible loud noises on speakers if faders are still open
So, note, if a mic route from stage box or studio wall box to its normalled
preamp is dissed by "overpatching", its screen will
still be earthed for safety.
Ensure 4th pole, the outer metal tab, on wandering mic female XLRs is also
linked to screen - as well as terminating pin1.
Make sure Bantam jacksockets are modern, ie having leaves plated with
palladium, not silver.
And of dire importance, what normalling pattern are you likely to use?
Inners to inners is best for mic default routes to avoid double- loading of
mics.

Jim

Archived from groups: rec.audio.pro (More info?)

Mike Rivers wrote:

> In article <1108135154.884485.158430@g14g2000cwa.googlegroups.com> voxman@arvotek.net writes:
>
> > I'm bringing 24 microphone lines to a Bantam patchbay, then out to 24
> > preamps. The studio getting this built wanted the system Full
> > Normalled.
>
> That's sensible, to avoid paralleling two preamp inputs on to a mic
> when patching it to an alternate preamp. I'd caution them to turn
> phantom power off when moving patch cables, however. Some mic preamp
> inputs don't like to be "hot patched" and you can blow an input stage
> that isn't properly protected.
>
> > I'm just wondering what to do with the shields at the patchbay. Should
> > they be carried through?
>
> Yes, of course. You need shield continuity in order to carry phantom
> power.

I thought it was generally considered bad practice to have a mic
level patchbay. Shorting phantom power supplies, problems with
high resistance patch jacks and sockets as they age and so on.

--Dale

Archived from groups: rec.audio.pro (More info?)

In article <420D8935.C201A03D@cybercom.net> dale@cybercom.net writes:

> I thought it was generally considered bad practice to have a mic
> level patchbay. Shorting phantom power supplies, problems with
> high resistance patch jacks and sockets as they age and so on.

Their mind is obviously made up - they're going to have a mic
patchbay. They might as well do it the best way they can. They have a
good start with the decision to use a patchbay with bantam (long
frame) jacks which are better for long term reliability. But it's one
more point of failure and one more thing that needs to be maintained.

It's not all that uncommon for large, multi-room facilities to have
tie lines between rooms that terminate in patchbays, and sometimes
they patch mics through those to record in a different studio than the
one normally attached to the control room. All it takes is doing the
job right and keeping the patchbay in good shape and it'll be OK.

But I wouldn't recommend using a $29 prewired 1/4" patchbay for mics
in a hobbyist studio. Better to build a panel of XLRs.



--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

Archived from groups: rec.audio.pro (More info?)

"nmm" <voxman@arvotek.net> wrote in message
news:1108242740.042314.139960@f14g2000cwb.googlegroups.com...
>
> Mike Rivers wrote:
>> In article <420D8935.C201A03D@cybercom.net> dale@cybercom.net writes:
>>
>> > I thought it was generally considered bad practice to have a
> mic
>> > level patchbay. Shorting phantom power supplies, problems with
>> > high resistance patch jacks and sockets as they age and so on.
>>
>> Their mind is obviously made up - they're going to have a mic
>> patchbay. They might as well do it the best way they can. They have a
>> good start with the decision to use a patchbay with bantam (long
>> frame) jacks which are better for long term reliability. But it's one
>> more point of failure and one more thing that needs to be maintained.
>>
>> It's not all that uncommon for large, multi-room facilities to have
>> tie lines between rooms that terminate in patchbays, and sometimes
>> they patch mics through those to record in a different studio than
> the
>> one normally attached to the control room. All it takes is doing the
>> job right and keeping the patchbay in good shape and it'll be OK.
>>
>> But I wouldn't recommend using a $29 prewired 1/4" patchbay for mics
>> in a hobbyist studio. Better to build a panel of XLRs.
>>
>>
>
>
> Thanks for all the help, everyone.
>
> I realised that the phantom power had to be carried through, but was
> thinking with "Listen Point" patching as in the line level set up I'm
> bringing both shields to the "A side" of the jackfields, I had no idea
> what to do with the "Full Normal set up. They didn't want to run a Buss
> wire and ground across everything, neither did I.
>
> What i ended up doing was bringing each shield to it's respective jack,
> and then running a short wire from the A to the B jack.
>
> The set up is wiring straight to the back of the jacks; I'm used to
> either having X-Mass Trees, or Punch Down/ Solder on Blocks. We are
> using high quality bantam jackfields from Switchcraft.

Agreed, never buss the screens towards the mic source paths. As you are
familiar with IDC racks, use this super mode of distribution for permanent
wiring at line/domestic levels with your jack rows, both inners and outers
to blocks. Then you can drape default routes wherever u want.
But at mic level (can be around -60dBU), you must stick to local simple
normalling a-a and b-b links within the jackfield.

Hope u read my contrib two msgs back!
If you hard-wire sleeves A to sleeves B in a row, when u patch, say, i/p 3
from mic path 7, the latter will get the screen and Phantom PSU 0V from i/p3
as well as the screen and PSU 0V from i/p7. Could cause hum /noise in one of
those chnls if using different mic cable types and lengths to remainder.
Do u follow?
To avoid this, u should use the type of patchcord which has its screen
terminated at only one sleeve (3-pole wired to 2-pole at far end) and notice
and identify which end is earthed (grounded). If this type is not available,
modify a few standard 3-p to 3-p by lifting screen to sleeve connection at
one end.
Do not hesitate to ask me 4 more info.
Jim
>

Archived from groups: rec.audio.pro (More info?)

In article <1108249497.598031.67180@f14g2000cwb.googlegroups.com> thecatspjamas@aol.com writes:

>> Better to build a panel of XLRs.

> On a metal panel? Would plastic work better?

It shouldn't make any differnce. Most panel mount XLR connectors don't
have pin 1 connected to the shell unless you put a jumber in the place
provided (if it's provided).

I suppose if you wanted to be fussy, a steel box (with steel panel)
would provide the best shielding.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

Archived from groups: rec.audio.pro (More info?)

Mike Rivers <mrivers@d-and-d.com> wrote:

> In article <1108249497.598031.67180@f14g2000cwb.googlegroups.com> thecatspjamas@aol.com writes:

>>> Better to build a panel of XLRs.

>> On a metal panel? Would plastic work better?

> It shouldn't make any differnce. Most panel mount XLR connectors don't
> have pin 1 connected to the shell unless you put a jumber in the place
> provided (if it's provided).

> I suppose if you wanted to be fussy, a steel box (with steel panel)
> would provide the best shielding.

This is the best way. But, don't forget, you won't be able to normal it.
This means you will have to have 24 XLR patch cables in place.

Rob R.

Archived from groups: rec.audio.pro (More info?)

>>>I suppose if you wanted to be fussy, a steel box (with steel panel)
>>>would provide the best shielding.
>>
>>
>> This is the best way. But, don't forget, you won't be able to normal it.
>> This means you will have to have 24 XLR patch cables in place.
>
>
> Or include DPST normalling switches.

Those switches would only cater for normalling each complementary pair of
male and female XLRs.
What if you need to divert chnl to another Source or mic to another Destin?
Just use coloured XLR jumpercords whose cord is 10% longer than distance of
the two XLRs furthest from one another, giving complete juggling flexibility
and obvious visual of your mic-to-chnl routeing, just like an old phone
switchboard. As I've said before, connect Shell to pin 1 screen only at the
roving, female mic end.
Jim