Patch panel/amps

[Blah067]

This system has 4 QSC amps (CX203 if I remember correctly). We have a great patch panel with the inputs of each amp as well as the outputs. We also have a speakon-patch panel with all the speaker jacks throughout the auditorium. The problem is I want to run one of them in mono bridge mode, and that requires different wiring on the back of the amp. I really don't want to have to rewire the amplifier every time I go in for rehearsal and shows, as it would have to be re-wired every time (to work for the "idiot" system).

This was my thinking...

Since Mono-bridge mode uses the middle two terminals on the strip, which are sent to "amp output 1 and 2" -two separate speakon jacks, I want to build a custom cable with speakon ends so that I can avoid rewiring the back of the amp, and just mesh together the conductors I want. So...one speakon going to "amp output 1 (the plus side of the bridge)" with one wire connecting into it, and a second speakon going from "amp output 2 (the minus side of the bridge)". Both of those leads go into ONE speakon, with the bridged connectors, which then goes to a speaker.

Can I do this without ^&%$ing something up? Will it matter to the amp that something is connected to the unused terminals of the amplifier when it is in bridge mode?

Thanks!

[Thefoxygranpa]

Do you mean the QSC CX302? Only one I could find on their website.

After reading the manual it looks like you need to use dip switches to switch it to bridge mono mode. Just tying together the outputs when the amp is set in stereo mode could quite possibly damage your amps/loudspeakers.

[Blah067]

Yep 302 Sorry.

Umm I know to use the dipswitches, what I'm trying to figure out is if it will "hurt" the amp to have the extra wires still connected, just not TO anything?

If the extra wire goes from the amp terminal not being used to the patch panel, and from the patch panel it goes nowhere, will that be BAD?

[Blah067]

Also, they recommend turning channel 2's gain all the way down. Is it the end of the world if it stays up, provided nothing is connected to channel 2?

I'm just trying to minimize the amount of things I'm changing so strike is easier...and we'll virtually be "striking" after every practice and show...

[Blah067]

In case of confusion...

[Chris15]

The reality is that all bridge mode is doing is inverting channel 1's signal to feed channel 2.

By inference from the setup of the QSC, it would probably be best to attenuate channel 2 if there is a line connected to that input but not being used.

If you are wanting an something that will be quick to restore, then perhaps you would be better off ignoring the internal bridge mode feature of the QSC and doing it the old fashioned way, that is a Y split with one of the outputs polarity reversed feeding the inputs...

To wire bridge mode you want the load connected with + to 1+ and - to 2+, FOR MOST AMPLIFIERS. This is NOT TRUE of lab.gruppen as an example.

If you make your adapter lead, do so with nothing connected to the -ve terminals on the amp end and your amp should be fine. The bit of copper to the patch panel won't affect the amp (it's just an extension of the internal wiring to the back panel if you think about it...)

[rwhealey]

Why do you want to bridge the amp in the first place?

What speaker are you trying to hook up?

[Blah067]

I want to bridge the amp to have more than 200 watts of power. The use for this beyond "I want to bridge the amp and do this with it" is really irrelevant, with all due respect.

[Blah067]

Originally Posted by Chris15

The reality is that all bridge mode is doing is inverting channel 1's signal to feed channel 2.

By inference from the setup of the QSC, it would probably be best to attenuate channel 2 if there is a line connected to that input but not being used.

If you are wanting an something that will be quick to restore, then perhaps you would be better off ignoring the internal bridge mode feature of the QSC and doing it the old fashioned way, that is a Y split with one of the outputs polarity reversed feeding the inputs...

To wire bridge mode you want the load connected with + to 1+ and - to 2+, FOR MOST AMPLIFIERS. This is NOT TRUE of lab.gruppen as an example.

If you make your adapter lead, do so with nothing connected to the -ve terminals on the amp end and your amp should be fine. The bit of copper to the patch panel won't affect the amp (it's just an extension of the internal wiring to the back panel if you think about it...)

So wait, clarify what get's connected to what by avoiding the internal bridge mode. The speakers get connected + is 1+, and - is 2+, I got that part. Then how would the amplifier inputs get connected? I got lost when you stated "inputs" without referring to a device.

[museav]

What you are doing is very relevant and maybe somebody could suggest an alternative approach to achieve your goals. Personally, I would not have a patch panel with both bridge and 'stereo' connections if using both required changing dip switches on the back of the amps, amp input connections and/or amp input levels to accommodate both scenarios, that is just asking for problems. If all you care about is having more power output than the existing amp configuration provides, then get new amps, if you proceed as planned where it would be very easy to have something set or connected improperly than that may be the outcome anyways.