Using phantom power with a balanced TRS patch bay

flyingace

flyingace

Active member
What are your thoughts on this? I have a Tascam PB-32B balanced TRS 1/4” patch bay. My ART XLR 16 channel patch bay is connected to it, then TRS 1/4” to XLR going to my Tascam M-520. Although the preamps in the M-520 are nice, I’m trying to figure out a way to use my ART MPAII tube pre amp and using phantom power for a condenser microphone.

That said, using this set up of patch bays (XLR-TRS-XLR), if I chose to use the M-520’s built-in phantom power, is that possible as well? It’s just such a hassle with the M-520 having the +48V switches on the back (what were they thinking in a recording console placed in a desk in a tracking room?).

TIA
 
I do it. Lot of people consider it a bad idea. IMHO you just have to be thoughtful in setting up and using a bay that has phantom going thru. YMMV
 
There are two things to consider. With a patchbay it allows anything to be patched, so a line level patchbay rarely cause issues, even if you take an output and patch it to another output. Mix-in mic level and even worse, as I’ve seen a few times, headphone distribution, danger increases. Having some with phantom is ok maybe if it’s only ever you who does patching and it’s your common sense keeping the thing functional.

my only long term phantom powered mic patching bay was separate and further away from the main bay, too far for cables, and it was useful, but always needed cleaning far more often.
 
rob aylestone said:
There are two things to consider. With a patchbay it allows anything to be patched, so a line level patchbay rarely cause issues, even if you take an output and patch it to another output. Mix-in mic level and even worse, as I’ve seen a few times, headphone distribution, danger increases. Having some with phantom is ok maybe if it’s only ever you who does patching and it’s your common sense keeping the thing functional.

my only long term phantom powered mic patching bay was separate and further away from the main bay, too far for cables, and it was useful, but always needed cleaning far more often.
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Thanks Rob,
My plan is to have the ART 16 channel XLR patch bay on the front of my vertical rack to easily plug in mics as needed to channels 1-16 on my console. By using the PB-32B (balanced patch bay) in between it and the console, and nothing is patched, it should just route direct to the console as if it was a single mic cable (dynamic mics or other balanced non Phantom power needs), but my “want/need” is to utilize my ART MPAII tube pre amp from time to time and use it’s phantom power on condenser Mics. It wouldn’t be anything that would be on all the time and I will be the ONLY person using this set up. Oh, and the balanced patch bay is ONLY to be used for XLR mic inputs going to my console, no other inputs or outputs, and it will be labeled accordingly to keep me from plugging the wrong thing in by accident and thanks to your idea, I think I’ll mount them both in another location away from other patch bays.
In that situation, most likely safe?
 
What are you recording to? It would be easier to put the patchbay between the record outputs of the board and the recorder. Then you could just patch the ART to the recorder input you want.

If you are recording to a computer, and you have enough inputs on the interface, you can plug the preamp into the last two inputs on the interface and leave it plugged in. Just choose that input when you want to record through it.

What is the rest of your setup?
 
Farview said:
What are you recording to? It would be easier to put the patchbay between the record outputs of the board and the recorder. Then you could just patch the ART to the recorder input you want.

If you are recording to a computer, and you have enough inputs on the interface, you can plug the preamp into the last two inputs on the interface and leave it plugged in. Just choose that input when you want to record through it.

What is the rest of your setup?
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All analog set up:
Tascam M-520 20x8 console
Tascam MS-16 16 Channel 1" Multitrack recorder
I have multiple patch bays set up between the console, recorder in/out, out to daw, outboard gear, 2 track 1/4" mastering deck, 2 track cassette, CDRW and so on. as well as inputs for keys and guitars. The patchbay in question is how I'm dealing with the MIC IN to my console only and how to utilize phantom power on outboard gear instead of onboard my console since Tascam saw fit to put all the phantom power switches on the BACK of the dang console and making it hard to get to in my desk confirguration.

I would not want the preamp in the line between my console and the recorder, I want to bring it: MIC - PRE - Console - SND/RCV (for other outboard gear like compressor) - AUX 1234 (for effects and other outboard gear) - down channel strip - then to direct out to my recorder. That's why I'm thinking if it's safe to use a TRS based balanced patch bay in between the MIC/XLR patch bay and the console MIC INPUTs, that's what i'd like to do - that way at the point between MIC - PRE I can insert the tube preamp that I enjoy using with +48V phantom power for a condenser microphone, right?
Interface and DAW are after I record to tape when I dump direct from the recorder all tracks to Logic Pro X to further work them up. That's my plan, but things might happen that redirect that as I am still learning and discovering how best to work, but all in all, analog path is my goal here... you know, for fun (ha ha it's so much more work but I love it!):ROFLMAO::P
 
Maybe I'm not quite understanding.

I would plug the mic directly into the art, come out of the art to a patch bay. Patch the ART to the insert input on the channel strip. That way it bypasses the tascam preamp in the console. If you want to put outboard gear between the preamp and the console, you do it there.

It's not the greatest idea to run the output of one preamp into the input of another one. It won't hurt anything (unless the phantom power on the console is on and trying to power the output of the outboard preamp)

For the most pristine signal, you would connect the art to the recorders input and monitor the deck through the board.

The thing that's making this a little more complicated is the board not having line inputs. That's where the preamp would normally plug into this system. The next best thing would be the insert return.

If you only ever plug microphones into the mic inputs of the console, you can simply leave the phantom power on. Assuming you don't use any rare, 60+ year old ribbon mics, it will be fine. I ran a commercial studio for over 20 years and the only time the phantom power was turned off was when I was doing something different, like plugging the output of a guitar Sim or direct out of a bass Amp into the mic inputs.
 
Farview said:
Maybe I'm not quite understanding.

I would plug the mic directly into the art, come out of the art to a patch bay. Patch the ART to the insert input on the channel strip. That way it bypasses the tascam preamp in the console. If you want to put outboard gear between the preamp and the console, you do it there.

It's not the greatest idea to run the output of one preamp into the input of another one. It won't hurt anything (unless the phantom power on the console is on and trying to power the output of the outboard preamp)

For the most pristine signal, you would connect the art to the recorders input and monitor the deck through the board.

The thing that's making this a little more complicated is the board not having line inputs. That's where the preamp would normally plug into this system. The next best thing would be the insert return.

If you only ever plug microphones into the mic inputs of the console, you can simply leave the phantom power on. Assuming you don't use any rare, 60+ year old ribbon mics, it will be fine. I ran a commercial studio for over 20 years and the only time the phantom power was turned off was when I was doing something different, like plugging the output of a guitar Sim or direct out of a bass Amp into the mic inputs.
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Thanks Jay,
I'm seeing your point on that. The largest problem with the ART MPAII is that it doesn't have input on the front for XLR mic in. That was why I was going to connect it to a patch bay to insert where needed, which is what led me to thinking I'd have the MIC plugged into the XLR patch bay front - 1/4 TRS patch bay - then on to the tascam MIC IN - then I'd bypass the tascam MIC IN when I patched the front of the 1/4 TRS patch bay - into the ART MPAII - out of MPAII into (Originally MIC IN again but with your thoughts...) channel insert (SND/RCV)? right?

BUT that said, I guess if all I'm really doing is tracking to a Track on the recorder, why not just go from MIC - MPAII - Track (say) 7 for vocals on the MS-16 since the MPA is the preamp... the only reason I wanted to go through the console was so that I could further use compression, and post-only reverb/delay effects through AUX 1/2.

I like the idea of trying your first option patching it into the insert (RCV) on the channel so I can use other gear, then the D-OUT to my recorder to whatever channel I want to work on.

Thanks, I'm learning with each helpful comment and I really appreciate your attempts, I hope its starting to get through to me :)
 
All of this is personal preference and workflow. There was a point early on when I thought it was a great idea running everything in the world to a patchbay, so I could do anything at any time in any order. A while later I noticed that I never touched 3 patchbays worth if I/O, it was just worthless possibilities that were never used and potential failure points.

Eventually, when I went with computer recording, I got an interface setup that had enough I/O to just have all the mixer channels and outboard preamps plugged into the interface permanently. The outboard preamps went to the patchbay and were normally to the interface. The channel inserts on the console also went to the patchbay, and of course all the compressors were at the patchbay too.

The snake from the live room had the last 8 channels permanently connected to the inputs of the outboard preamps. (The rest went to the first 16 channels on the board) I chose the preamp by plugging into the corresponding channel on the snake.

You can always bring the input to the front of the art by just running a mic cable to the side of the rack. Running the mic through the patchbay isn't necessary.
 
I have not really got this old head around OP's setup but in general there are two situations when phantom power can be 'dangerous' to certain external devices.
First one is if it gets into the OUTPUT of a pre amp say or AI. These circuits are not protected against 48V and there is no reason why they should be and the result could be a blown output IC. Such outputs are almost invariably served by 1/4" jack and since spook juice should really only ever live on XLRs the chances of such a connection are low.

The second vulnerable area is those mic inputs WITHOUT phantom power. These will be found on synths (though nearly always jacks) and active PA speakers. Such inputs are again not designed to accept 48 V DC.

Lastly there is of course the pops and bangs you get if phantom power is plugged about recklessly but that is down to good operational practice.

Dave.
 
If you use submixers live, you can easily do this. Large frame Yamaha (analogue) being fed from a soundcraft. Phantom was on, and when connected, every LED on the Soundcraft output panel lit up! All the output meters, the groups and even the PFL bus - lit up like a christmas tree! No harm done but it did NOT like it!
 
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