Conveniently using stereo equipment in mono with a patch bay?

maxmax77

Member
Hi everyone,

I am setting up my first patch bay (TRS), and I’m plugging in some of my stereo equipment like the FMR really nice compressor. This piece of gear, in addition to some others I own, can operate in either mono or stereo/dual mono.

If I have cables plugged in to both the left and right channels, can I still send a signal to just the left channel and have it operate in mono?

Thanks! I hope this question makes sense.
Max
 

mjbphotos

What?!?
Yo're not thinking of it correctly. You have a 'stereo' compressor - it is 2 single channel (mono) compressors. If you send a signal to just one 'side', it is a single mono track, with a single mono track out the other side.
 

ecc83

Well-known member
I do note that the RNC 1773 is a 'true' stereo compressor, i.e. not two independent mono compressors in the same box.

That means you cannot send two different signals to it and have them treated differently.

Dave.
 

bouldersoundguy

Well-known member
Ok, I think I see what you mean. Does this apply to stereo equipment in general?
Compressors don't add anything to the signal, so you can use one side of the RNC without any issues. Most 2-channel compressors can be operated and two independent mono compressors or one stereo linked pair. They would also be perfectly happy running just one side. Equalizers would be similar.

An effect like a stereo reverb might be missing some of what it adds if you use just one side. That's not too much of a problem. A stereo delay, however, might be missing too much, depending on the setting. For example, a ping-pong delay would be missing half the echoes.
 

RRuskin

Rick Ruskin
Compressors don't add anything to the signal, so you can use one side of the RNC without any issues. Most 2-channel compressors can be operated and two independent mono compressors or one stereo linked pair. They would also be perfectly happy running just one side. Equalizers would be similar.

An effect like a stereo reverb might be missing some of what it adds if you use just one side. That's not too much of a problem. A stereo delay, however, might be missing too much, depending on the setting. For example, a ping-pong delay would be missing half the echoes.
The RNC can be operated in stereo or single mono but not dual mono. The left channel input controls the gain reduction of both channels.
 

rob aylestone

Well-known member
The thing to remember is that all equipment, mono and stereo goes to the patchbay to either one channel, or two - so a 'stereo' device with 1 3.5mm stereo output goes to two channels on the patchbay, unbalanced. you can of course always take one source (on the top row) and over patch it from the top row to the next channel, if you've done something clever on just one channel and want that mirrored on the left and right output.
 

mjbphotos

What?!?
I do note that the RNC 1773 is a 'true' stereo compressor, i.e. not two independent mono compressors in the same box.

That means you cannot send two different signals to it and have them treated differently.

Dave.
From what the OP said, he was just trying to use one side (one mono compressor).
 

maxmax77

Member
Aw goddamn, I wrote up a whole response to a lot of your comments and it got deleted. But this is all really helpful, and I appreciate the responses. I think I’m starting to understand a bit.


I have a related question that I think might help me understand a bit better. I’m thinking about how I can set up my patch bay so I don’t have to plug or in plug anything from any of my gear. So I’m wondering—with all other variables held constant, can the simple act of plugging in a cable to a piece of gear (namely fx processing gear) alter the internal circuit path?

I know that this can happen in some instances, for example when I plug in a 1/4” line input to the a channel strip on my mixer, it bypasses the mic input. So, plugging in the ts cable to the line in changes how the current is allowed to flow within the circuit. But what about in other situations, particularly as I said with fx gear?

To continue using the RNC as an example—if I’m running a guitar track through the left channel, just using the RNC in mono, and then I plug a ts cable with no current going through it into the side chain jack—will the RNC automatically stop listening to the guitar track as the source for making compression decisions, and listen to the dead signal coming from the side chain input? If that’s the case, then I’ll have to stick my head behind my little rack to unplug or plug in the RNC’s side chain every time i want to use it.

The thing to remember is that all equipment, mono and stereo goes to the patchbay to either one channel, or two - so a 'stereo' device with 1 3.5mm stereo output goes to two channels on the patchbay, unbalanced. you can of course always take one source (on the top row) and over patch it from the top row to the next channel, if you've done something clever on just one channel and want that mirrored on the left and right output.
Rob, I’ve read this like five times and I know it contains useful information but I can’t totally follow thanks to my little noob brain. I understand that a TRS cable can either carry an unbalanced stereo signal or a balanced mono signal, but I didn’t quite follow the rest. Could you shed a bit more light on this idea for me? It seems important.

Thanks again, all
 

ecc83

Well-known member
I think the most common setup for patchbays Max is 'Half Normalled'. The top row of jacks are outputs and the bottom row are inputs.

For example, say OUT#1 is a mic pre out and below it is IN #1 for the compressor. The signal runs through the switches on the lower jack and so you do not need a patch cable to link the two. Now you want to plug something else into COM IN #1? Just plugging it in breaks the contacts from the mic pre. N.B. you can still take a signal FROM the mic pre out without disturbing the 'thru' signal.

Setting all this up needs considerable planning as to the 'default' routing of your system. Lot of paper diagrams!

Dave.
 

bouldersoundguy

Well-known member
The RNC can be operated in stereo or single mono but not dual mono. The left channel input controls the gain reduction of both channels.
Right. I didn't mean to suggest the RNC could do dual mono. It's either single mono on one channel or stereo linked.
 

rob aylestone

Well-known member
Dave's post is what I was thinking - so it's always possible to do useful things - use Dave's example, the mic pre normally feeds a compressor - a two channel one that has it's inputs on the bottom row sockets 1 and 2. The output from the mic preamp comes out of top row sockets 1, and another comes out of socket 2. With them half normally, the connection between top and bottom - the way it will normally be connected, is made inside the bay. so top row 1 is connected to bottom row 1, but if you stick in a patch cable to top row 1, you could put that into bottom row 2 - the preamp output is now feeding bottom row 1 AND 2.

This half normalising thing is really important. If you get it right, all your everyday connections don't need any patch cables at all. You just use the cables to connect the one-off unusual connections.
 

ashcat_lt

Well-known member
In most cases the sidechain/key input will be a switched jack which disconnects the input from the detector path so yeah youd end up with no compression. If the input is coming from some other gear (preamp output or whatever) on the patchbay, you could maybe find a way to mult/split that to both the input of the comp and the sidechain, but you’d definitely have to make both of those connections.
 

maxmax77

Member
I’m going to try to respond to these comments individually, they are all so helpful. I think the half normaling stuff is really starting to click now. And the side chain thing makes sense, super good to know.

Once the work week is over I’ll have some time to draw up some wiring diagrams and respond to everyone here!

Cheers
 

bouldersoundguy

Well-known member
Depending on the compressor, a sidechain jack might be set up like the insert of a mixer, with switching to complete the circuit when there's no plug inserted. You should be able to use the normaling function of a patch bay the same way you use it on a mixer channel insert, to pass signal through when nothing is inserted.

Other compressors have a sidechain jack that's just an input (e.g. dbx 166, original blackface version). You would have to perform the signal splitting externally to make that work.
 

Slouching Raymond

Active member
My Behringer compressor is 2 separate mono channels, each with their own knobs, so are totally independent.
There is a 'stereo' button, which enables you to operate both channels the same from just one of the sets of knobs.
 

maxmax77

Member
Whew..after a lot of drawing and re-drawing diagrams, I finally got a wiring setup I am happy with. I set up the patch bay with enough space above it to adjust the normal/thru/half normal mode (thanks again Dave and Rob), and with enough space above the RNC shelf to reach back and plug in a side chain input as needed.

I also learned a lot this weekend about how to route power cables and audio cables to minimize interference. When I first plugged everything in earlier this week it was a noisy mess. I was so happy to turn it on today and crank up my mixer, without any significant background hum! Woohoo!

Thanks for your help, everyone.
 

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ecc83

Well-known member
Whew..after a lot of drawing and re-drawing diagrams, I finally got a wiring setup I am happy with. I set up the patch bay with enough space above it to adjust the normal/thru/half normal mode (thanks again Dave and Rob), and with enough space above the RNC shelf to reach back and plug in a side chain input as needed.

I also learned a lot this weekend about how to route power cables and audio cables to minimize interference. When I first plugged everything in earlier this week it was a noisy mess. I was so happy to turn it on today and crank up my mixer, without any significant background hum! Woohoo!

Thanks for your help, everyone.
Glad you are sorted! Ref "cables and hum", good idea to make a 'silent' recording, levels set as per normal but no signal and then run the .wav (must be 16 bits 44.1khz) through Right Mark Audio Analyser an excellent way to display residual noise on a system.

Good to do this once a month or so because gear gets added/moved and noise can creep up on ya!

Dave.
 

maxmax77

Member
Glad you are sorted! Ref "cables and hum", good idea to make a 'silent' recording, levels set as per normal but no signal and then run the .wav (must be 16 bits 44.1khz) through Right Mark Audio Analyser an excellent way to display residual noise on a system.

Good to do this once a month or so because gear gets added/moved and noise can creep up on ya!

Dave.

Oh that sounds like an excellent idea. What a useful bit of software. Cheers!
 
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