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Power amp woes

emohair

emohair

Jul 12, 2006
409
1
39
Gainesville, FL
www.myspace.com
#1
So, Im starting to get frustrated here - and I need some TB advise.

Rig in question is the following
1.SWR Grand Prix Pre
2.QSC PLX 1602 - 1600watts @4ohms 1100watts@8ohms
3.Schroeder 410L - 8ohm (using this stand alone)

Basically, it just aint loud enough lol...and I know my 410 can get LOUD, because I use my 400+ for some of my gigs and its the perfect pair for me in those few instances. I was hoping to get a backup rig that would offer that same amount of headroom but with cleaner overall vibe for slap or anything that doesn't need to be so pushed. I just don't understand, I cant push any part of my rack rig anymore, everything is on the verge of clipping but my Mesa is on like...2 or 3 and its loud as hell. I debated switching out my 8ohm cab for a 4ohm but I don't really know if that's going to make the difference. I love the sound of the QSC, and with the SWR I think its a good clean pair...but how much more wattage do I need to get me heardroom without damaging my cab? I am sure the amp is in Bridged mode...anyone have advice?
 
#3
Wattage is only a small part of the equation. People think that if you double the wattage you double the volume, which isn't the case. To achieve twice the volume you have to increase the wattage by a factor of ten - so if you had a 100 watt amp and went to a 1000 watt amp you'd double the volume. Adding more speakers is the easiest way to increase your volume.

Sorry, I know this isn't the answer you want to hear.
 
#5
I believe all cables are fine, the option to set the amp to Bridge is done on the amp, so maybe I dont understand quite what your sayin?

And yea, I dont want to hear I need to buy another cab LOL - but its really odd to me that running an amp that is rated at 500watts (all tube) would be so much freaking louder than an amp putting out 1100 watts @ 8ohms. I know the cab can handle it, should I just move onto something different?
 
#6
silky smoove said:
I have driven a Schroeder 410R with a QSC PLX1602 and assuming that you have your speakon cable wired specifically for bridge mode operation and you have your dip switches on the QSC set properly, you should have no problem generating deafening sound levels.
Click to expand...

See, this is the kinda thing I guess I don't get. Maybe I am setting the dip switches wrong? Or possibly the EQ is wrong somewhere? How did you have the dip switches set? Right now the amp is turned almost all the way up and on the verge of clipping - maybe I have something configured incorrectly? Using a speakon cable for the cab and have tried using both XLR and 1/4 connections for the signal from preamp to power amp

Also, was your cab 8 or 4ohms? thanks yall..dis stuff stressin me out!
 
#7
I think you may have missed a step with your bridged setup.

To bridge with the QSC, you must do TWO things:

1) Have the DIP switches properly set for bridge mode, AND

2) Have your speakon cable wired +1 and +2 on the end that goes in the amp, and +1 and -1 on the end that goes in the cabinet.

Have you done both????
 
#9
Take one speakon off, get a heavy duty dual banana connector for the wires and hook up to the red terminals for Bridge mode.

Ya ain't wired right as is.

I carry a dual banana to speakon because I have had to use other cabinets with those.

Jim
 
#10
Your speakon cable needs to be wired for pins +1 to pos and +2 to neg on the amp end and +1 to pos and -1 to neg on the cab end or you are only getting 300 watts to your cab instead of 1100. Double check that. Just open up the connectors and look.
 
#17
WOW! Enlightenment to the max, I had no clue I could fool around with my speakon cable. I will need to do some more research on the whole changing pins and all because I am not very familiar with all that. I did try and read the manual for real, this is just the first time I'm using Speakon's cables in my rig. I might opt to get that banana clip instead of messing with the speakon, but I will do some more reading on the amp. Guys, you rock...this thing is going to be so freaking loud when I get it truly hooked up in Bridge lol, seeing that im only running it at 300 watts.

Anyone have a site that explains the whole Speakon pin thing? I would be curious to read up on that (love to soak up as much knowledge as possible).

Oh and Sam, its a Mesa 400+....not exactly boutique but it sounds so nice!
 
#18
Speakons aren't rocket science. This is all you need to read:

Just unscrew one connector on your cable. You will see FOUR holes, each labelled with either +1, -1, +2 and -2 if you look closely right next to each hole. Take the wire that is presently going into the hole labelled -1 and move it to the hole that says +2. Use a standard screwdriver to loosen/tighten the connections. No soldering required. Once you've moved the one wire from -1 to +2 and tightened it back down, just screw the connector back together.

Be sure to wrap a piece of tape around that end so that you know it is the "amp" end for bridged mode.

This entire exercise will take about 3 minutes . . .
 
#20
there's really not much to 'read up' on it. a speakon only has 2 or 4 pins, depending on which one you have. normal wiring uses +1 & -1 on both ends of the cable. "bridged" uses +1 & +2 on the amp end, and +1 & -1 on the speaker end.

when i make a bridged cable, i put a 2 inch piece of red shrink tubing near the cable's speakon plug on the end that goes into the amp, so i not only know which cable is my bridge cable, but also, which end goes into the back of the power amp.
 

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