Enjoy the benefits of a premium membership!
Upgrade Account
-
TalkBass has been independent since 1998. Add your voice.
Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
Join free Log in
Want zero display ads or expanded classifieds tools? Compare plans.
3000 watts not loud enough
- Thread starter demon666
- Start date
The "gain" knob on a power amp is not really that, it's an input attenuator. The amp is capable of producing full power at any setting of the input attenuator. It just takes more voltage at the input for lower settings. So yes, crank it all the way up. But be careful. Three kilowatts into a 750-watt cab will probably incinerate it.dannyboy15 said:
The 0x said:
NO, we've (as a forum) gone through this a million times; set your preamp gain to a few db below clipping on peaks and control your volume with the power amp attenuator. "Running wide open" does nothing except to raise the noise floor, it does not "make your power amp put out the full xyz watts", it does nothing good.
+1. I run my setup this way (Manley Voxbox to QSC PLX 1602), and set the QSC on the lowest setting that actually makes sound. Absolutely zero noise or hiss, but when played it's louder than the rest of the band put together.Tim__x said:
arock said:
works for me too. putting gain on preamp just below clipping and knobs on poweramp around halfway(just below clipping).
sounds the best for me!
no problems with hiss, or volume here.
You can run your power amp wide open, and may need to if your preamp has relatively low output, as it sounds like in this case. Yes, it is better to bring the preamp up to just below clipping, then bring the power amp up to just below clipping, which maximizes useable power out. But he may need to crank it if his preamp has low output.Mr. voodoobass said:
I still think he's not bridging the amp properly.
Yup, something is not right...Munjibunga said:
Taking the speaker output off the 2 red binding posts? Is there an input pad/sensitivity switch on the power amp (switchable from 0dbm, +4dbm, -20dbm?) something like that? Switchable output level on the preamp?
I noticed on my Mo'Bass, the input "clip" light lights up pretty early, so I was having trouble getting full output. Then I noticed that the "clip" light was really "input signal" light, which turns "red" for clipping. Oops. Then had no trouble getting full output after realizing that...
Randy
The PLXs have input filters (off, 30 Hz, 50 Hz) and Limiter (On and Off), but no input sensitivity switch on the back...
Thanks for all of the input I should of rephrased my original question of why isn't my power amp louder then my other amps. I 'm pretty sure everything is hooked up right. tommorrow I'm gonna go through all of it again . I do not need to be "that loud" i got a good deal on the power amp and figured it would just be more head room and the amp won't have to work that hard. I think it might be the pre amp does any one know if there is a way to boost the output. I have also run the amp stereo into my 2 wayne jones and same thing didn't help
How is the pre connected to the PLX ?
If he's using the XLR output to the XLR input on the PLX he will find it's lacking in volume as the output signal will be much less than using the 1/4" output.
I used to run my SWR bass 350 into a PLX 2402
When I first hooked it up with the XLR DI output from the SWR into the XLR input on the PLX I was disappointed with the volume I was getting.
When I changed to the 1/4" output into the 1/4" input of the PLX I got way more volume.
Nowdays I have a Demeter HBP-1 and the same PLX2402.
With the PLX at the point of clipping there is some SERIOUS volume coming out of the speakers
If he's using the XLR output to the XLR input on the PLX he will find it's lacking in volume as the output signal will be much less than using the 1/4" output.
I used to run my SWR bass 350 into a PLX 2402
When I first hooked it up with the XLR DI output from the SWR into the XLR input on the PLX I was disappointed with the volume I was getting.
When I changed to the 1/4" output into the 1/4" input of the PLX I got way more volume.
Nowdays I have a Demeter HBP-1 and the same PLX2402.
With the PLX at the point of clipping there is some SERIOUS volume coming out of the speakers
I've got it hooked up like this shure wireless into svp-cl then from pre amp out 1/4" jack into channel ones 1/4" input on plx all dip switches are set to run mono with low pass filter set to 30 hz and clip protection on (i've tried changing all of them around) from the power amp banana plug bridging output ( both red terminals top + ) with speakon at cab end into ampeg 6x10 (4ohm) or 2 wayne jones 2x10 (4ohm total) I played friday night and had no stage volume at all couldn't hear anything I always have way more then enough with my SVT and thats only on 4 or 5.
Demon666...is the "Bridge" light on the front panel on?
When you play, are the signal level lights on the PLS coming on?
Is the battery in your bass good? (if applicable)
Is the battery in your transmitter good?
Does the Shure have an output level control? Is it turned up?
Are you sure that the cables between the Shure and the Ampeg and the Ampeg and the QSC are all good?
Are you sure that your speaker cable is good?
Have you tried just plugging your bass directly into the power amp?...it will work, it might not be very loud...
Have you tried running the output of the SVP-CL into the power amp input of your other amps? Did that work better?
When you play, are the signal level lights on the PLS coming on?
Is the battery in your bass good? (if applicable)
Is the battery in your transmitter good?
Does the Shure have an output level control? Is it turned up?
Are you sure that the cables between the Shure and the Ampeg and the Ampeg and the QSC are all good?
Are you sure that your speaker cable is good?
Have you tried just plugging your bass directly into the power amp?...it will work, it might not be very loud...
Have you tried running the output of the SVP-CL into the power amp input of your other amps? Did that work better?
yeah i checked all that i was using the pre into the power section of my mesa m pulse 600 and it was about as loud as it is now through the plx. i'de say volume wise it would be comparable to the mesa on half. i think its the pre i don't think it has a hot enough signal. thanks again for everyones help in all of this
That sounds likely at this point, seem to have covered everything else.demon666 said:
If you can borrow another preamp and/or power amp you should be able to test that theory definitively. Besides the power amp in the mesa, its obviously expecting a signal of the same magnitude that the internal mesa preamp puts out.
You could try another preamp into the mesa, vs the plx, see if the same signal level cranks the mesa and barely tickles the plx.
Randy
The PLX' gain can be easily increased by changing out just a few resistors... This is a QSC blessed mod and since I have a weak preamp (Pearce BC-1) I ordered my PLX with increased gain...no extra charge at the time (a few years ago).
Lord Valve (in Denver) used to do it for $50... I would image any qualified local tech could do it...
Perhaps we should summon Bob Lee (QSC) for further help!
Lord Valve (in Denver) used to do it for $50... I would image any qualified local tech could do it...
Perhaps we should summon Bob Lee (QSC) for further help!
Is it possible that you're EQing too much bass boot in your signal and therefore you're not getting really audible volume but just wasting power on sub-low freqs your cab can't reproduce (you can over-excurse/blow your speakers easily this way while hearing a realatively low volume). Just a guess...
ANDRUCA
ANDRUCA
A couple things.....
First, what's the serial of the SVP-CL?
The first run had lower gain. After a considerable number of folks wanted to use it with bigger power amps that need a lot more signal, we upped the gain. That mod has been discussed here before, and a number of folks have had it done. You may or may not have it already in your preamp, depending on serial.
The PLX3002 needs half again more voltage input than the 1602, and not quite double what the 1202 needs, according to the specs I had handy.
It makes a difference. Double the level is 6dB higher input, meaning if you don't have it, it could sound only half as loud.
So, it sure sounds like a sensitivity mismatch issue...... assuming everything else is hooked up OK and working.....
OK, you are comiing out of the 1/4 inch "Preamp Outputs" on the SVP, I assume.
I am assuming that you are NOT using the tuner out, which is also 1/4". The tuner output won't have enough juice to get even close to usable volume...... its for a tuner..... that would be very weak for driving a power amp. Ditto for the XLR line out, which you are not using.
From what you said, you have the speaker end hooked up OK. BTW, the 3002 should be able to blow your speaker into the next county...... watch out after you get the level deal fixed..... the 610 is rated for 1/5 the amp power, getting solidly into the risky area, depending on your style.
If it is indeed a gain issue, you can deal with it either at the preamp (if yours is the pre-mod lower gain type) or at the power amp, since QSC does have an input mod for lower level inputs.
It is fairly usual for higher power amps to require more input level than lower powered amplifiers.
First, what's the serial of the SVP-CL?
The first run had lower gain. After a considerable number of folks wanted to use it with bigger power amps that need a lot more signal, we upped the gain. That mod has been discussed here before, and a number of folks have had it done. You may or may not have it already in your preamp, depending on serial.
The PLX3002 needs half again more voltage input than the 1602, and not quite double what the 1202 needs, according to the specs I had handy.
It makes a difference. Double the level is 6dB higher input, meaning if you don't have it, it could sound only half as loud.
So, it sure sounds like a sensitivity mismatch issue...... assuming everything else is hooked up OK and working.....
OK, you are comiing out of the 1/4 inch "Preamp Outputs" on the SVP, I assume.
I am assuming that you are NOT using the tuner out, which is also 1/4". The tuner output won't have enough juice to get even close to usable volume...... its for a tuner..... that would be very weak for driving a power amp. Ditto for the XLR line out, which you are not using.
From what you said, you have the speaker end hooked up OK. BTW, the 3002 should be able to blow your speaker into the next county...... watch out after you get the level deal fixed..... the 610 is rated for 1/5 the amp power, getting solidly into the risky area, depending on your style.
If it is indeed a gain issue, you can deal with it either at the preamp (if yours is the pre-mod lower gain type) or at the power amp, since QSC does have an input mod for lower level inputs.
It is fairly usual for higher power amps to require more input level than lower powered amplifiers.
I wouldn't risk wasting the money on a couple of resistors in an attempt to change the gain. I'd just start shopping for a 12,000 or 24,000 W amplifier and be sure. 
Randy
Randy
rockstarbassist
Inactive
Man, I thought a side in stereo on my PV1500 wasn't loud enough, but golly!! 3k? Amazing as my 1210 is, I don't think it could take that... I'm hoping it'll be ok when I get my new speaker cable in and run at 1500W!
My pre seems to have somewhat of the opposite problem, actually... Demeter VTBP-201s?? I seem to clip no matter what I do most of the time... Kinda crazy, but oh well. I think it's just the power amp. Like it's almost TOO sensitive at times. I borrowed a Mackie 1400i (400W/stereo @ 4 ohms) when I first got the Dem, and it never clipped at all. So, who knows... But my custom Pro Cables 'N Sound 11-gauger is comin' in this week, so we'll see what happens!!
I've been experimenting with the concept brought up here about running the pre as hot as possible, and then controlling volume with the amp- works TONS better, and so much less hiss and noise I could barely believe it!
I'm hoping it'll be ok when I get my new speaker cable in and run at 1500W!My pre seems to have somewhat of the opposite problem, actually... Demeter VTBP-201s?? I seem to clip no matter what I do most of the time... Kinda crazy, but oh well. I think it's just the power amp. Like it's almost TOO sensitive at times. I borrowed a Mackie 1400i (400W/stereo @ 4 ohms) when I first got the Dem, and it never clipped at all. So, who knows... But my custom Pro Cables 'N Sound 11-gauger is comin' in this week, so we'll see what happens!!
I've been experimenting with the concept brought up here about running the pre as hot as possible, and then controlling volume with the amp- works TONS better, and so much less hiss and noise I could barely believe it!
