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First time setting up a rack

I

iamlowsound

Nov 30, 2005
8,152
259
Southern Ontario
#1
I have a rather stupid question regarding setting up my first rack set up. I am running a Yamaha PB-1 and a QSC CX302 into a SRW 2x10 cab @ 4 ohms and 800w. The QSC is either 375w @ 4 ohms stereo with both channels driven (do I have to use both channels?) or 1200w @ 4 ohms in bridged mono. How should I run it? I don't need a lot of power for my current gig, as I am doing fine running 100w at the moment.

Link to QSC cx302
[Invalid or Expired Link Removed]

lowsound
 
#4
I have that same amp. I would go bridge mono since it will require no wiring modifications later on if you need another cab on a gig. Just reduce the master vol on the QSC to less than a half and you should be ok.

I installed speakon connectors into my 302, and it has been the easiest thing ever to connect during a gig situation. All you need is two nl4 connectors and a soldering iron and some time. The holes are already cut (behind the sticker) and the circuit board already has the slots for the jacks. Just solder them in.
 
#5
It depends, I used to run a Trace Elliot pre into a Crest CA-4 and found that at small gigs running bridged I had to have my pre volume so low it was kinda wimpy sounding so I would use 1 channel at small gigs and bridge for bigger gigs. Flexibility brother!!!!!
 
#8
What you guys who recommend bridging and then "turning the amp down some" are missing is that the amp is capable of generating its full wattage potential at nearly any setting of the volume knob. The volume knob controls the amount of gain by which the amp increases the input signal, but it does not limit the amount of watts generated. If you send a very hot spike (like a strong slap/pluck on a low B with an active bass) into it, even a lower gain setting on the amp can mean a huge wattage spike out into the speakers.

To be clear, turning down the volume does not reduce the power of the amp.

That said, if your playing style is under control, and your signal peaks are under control, from good technique, a mellow style, a compressor, or any combination of those, then you can use the gain knob on the amp with a clear understanding of your signal levels and the relative risk/safety of those levels for your speakers.

I vote use the lower wattage setting, unless you are absolutely confident about your control over signal peaks.
 
#9
My concern is that you are using a single 2x10 cabinet. That will only take you so far. You say you need power but what you really need is more speakers. I use 2x10s too (Acme) and I own four. I usually use two at a time. I would never dream of gigging with just one cabinet. If you bridge that amp into your cabinet, I believe you will end up blowing your speakers. Headroom is great but it is very easy to go too far just looking for that little bit more.

Paul
 
#10
I went and set it up tonight at church (where it will be most of the time) and I have it running off of one channel at 375w. Way more than enough power, I have the gain settings on the amp at 1/4 and the volume controls on the pre at 1/4 and I was shaking windows. I don't need a lot of power, but it is there if I need it. Thanks for all your help and I'll be sure to let you know how it sounds in after tomorrow morning.

BassmanPaul
I have been playing the same space for the last four or more years with a 100w 1x15 combo and it has been fine. When I play anything bigger, I have PA support. A 2x10 will do me fine. Also, if I wanted to add another cab it would be difficult because mine is rated at 4ohms and my power amp isn't 2ohm stable.

lowsound
 
#12
bassmodder said:
Yes please do! I can barley get the the first signal lights to light up when I play at church. Any more and I would probably wake up on the front steps!:eek:
Click to expand...

Well the guy leading worship tomorrow is the bass player that I took over for a few years ago. So I have the approval of him to play to my hearts content and loud. I have no PA support, so I push all the bass from the stage.

lowsound
 
#14
bassmodder said:
Yeah, I di mine into the board. I installed the board, so I made sure to have a slot with my name on it. I feel special now.

The nice thing about the QSC is that the fan is quiet enough not to be picked up by choir mics during the quiet times.
Click to expand...

Our building in really small, so me DIing would be over kill. Sounded killer this morning, low note definition like crazy. We did a song this morning where I root most of it and the highest note that I play is an open E. Amazing, never heard my B string sound like that before. I was really surprised at how quite the fan is, although there are no choir mics to pick it up. We only have the band.

lowsound
 

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