Bridged-mode question

[bofe]

If I have a stereo output from a preamp that I am running into a power amp which is set in bridged-mono mode, do I need to use a Y-adaptor to bring both preamp channels into channel one of the power amp? Or if I run each preamp channel into it's own power amp channel, will the power amp combine them for me?

 

[Bob Lee (QSC)]

It's generally not a good idea to try to combine signals using a Y-cable (see [Invalid or Expired Link Removed]).

If the amp is not also a mixer, do not rely on it to combine signals, either.

Can you set the preamp to mono?

 

[Bassman62]

It's generally not a good idea to try to combine signals using a Y-cable (see [Invalid or Expired Link Removed]).
If the amp is not also a mixer, do not rely on it to combine signals, either.
Can you set the preamp to mono?

Bob could that be why our desk has to have the faders (master and chanel) up so high, I saw last week that our vocalist who sets up the desk has two splitters on the mixing desk left and right outputs they then feed into separate power amps.
Regards

 

[Bob Lee (QSC)]

They're splitting and not combining, right? That shouldn't be a problem.

 

[bofe]

Bob,

I am so glad you responded. In my current PA setup, I have the low-freq stereo outputs of my crossover (BB Max-3) into a XLR Y-cable which is inputting into channel one of the power amp I am running the subwoofer with. Since I am running the amp in bridged-mode I needed to merge the stereo-out from the x-over down to mono. I had no idea that I was being bad. This certainly explains the lower-than-expected power I was getting from the amp.

But I still have a problem that perhaps you can help me with. The x-over does have a mono mode, but using it would also put my high-freq outputs into mono, which I'd prefer not to do. So my choices seems to be either I:
1) Run only one channel of my x-over low-freq outputs to the power amp (and I’m too inorant to know if that would hurt either the x-over or the power amp, but smart enough to know I'd have less power).
2) Spend hundreds of dollars on what seems to be unaccountably expensive “summing boxes”.
3) Be assured (by someone who knows) that I can use a “microphone combiner” to solve my problem. These are boxes which have two XLR inputs (outputs?) on one side and one XLR output (input?) on the other side and is intended to allow two mics to be run into one channel of a mixing board. Perhaps you are aware of these items and already know the answer to my question. Or perhaps these specifications from the Samson S-Combine are sufficient for you to tell:

Frequency Response 10 Hz to 30kHz +/- 3dB
Noise Level -110 dBu
Maximum Ouput Level Bal: +18 dBu
Max Input Level Bal: +22 dBu
Input Impedance
XLR: 10k Ohm
Output Impedance
XLR: 100 Ohm balanced
THD .003% Max
Noise Floor <-90 dBu
Dimensions 5.65&#211; L x 4.13&#211; W x 2&#211; H (144mm L x 105mm
W x 51mm H)
Weight 16.5 oz., 419 gm.

Or perhaps I&#8217;m out of luck.

Thanks in advance.

 

[Bassman62]

They're splitting and not combining, right? That shouldn't be a problem.

Cheers