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Please solve my amp problem...

G

GillesUnchained

Nov 3, 2005
124
0
46
Portland, OR
www.myspace.com
#1
Okay, this is my rig.

Ampeg SVP-BSP preamp through a
QSC RMX1450 Power Amp into an
Ampeg SVT 8x10

Here's my problem...
I used to play a GK RB400 through the Ampeg 8x10 but I decided a I needed more power to keep up with the band without getting distorted. So I got my current rig.

Now, whenever I turn up to a level that is barely level with the band, the red "clip" lights on my power amp start flashing. If I turn up to a level where I really feel I can hear myself well, the red lights start flashing like crazy.

I am running the power amp bridged, which as I understand is supposed to supply 1400 watts to the Ampeg 8x10. I checked the settings on the back of my power amp. They are all correct.

Am I overpowering the 8x10? I get a louder sound out the of the GK. Is it okay to run my red "clip" lights solid without damaging my power amp, or any other part of my rig?

I used to play through an Ampeg SVT-4 (which I not longer have access to). I could run that thing loud enough to drown out the whole band without the lights going crazy. How is it that turning the QSC up not even 3/4 of the way will make it clip?

Can someone give me an idea of something else I'm missing?
 
#3
Try the 50 Hz highpass filter setting. As I recall you need to set it for both channels when running in bridge mono. Your cab won't reproduce anything below that too well, so it's just a waste of headroom trying to push a ton of lows.
 
#4
Hhow do you have your pre amp set = possibly too much signal into the amp. - also and this is what i learned with my set up which is a stewart power amp - the clip indicator is an indicator or power from the wall - meaning, if you are turned up a lot and the power amp is not gettting 120 volts [whcih you will never get on a gig] but the amp is demanding it, the clip light comes on - bottom line it is not hurting the amp at all. This is from the guys at Stewart - I have never heard distortion and the amp is singing along.
 
#5
GillesUnchained said:
Is it okay to run my red "clip" lights solid without damaging my power amp, or any other part of my rig?
Click to expand...

Absolutely not! Solid clip lights at that wattage will melt your voice coils in no time....
Incidentally, if youve already done this and a couple of drivers are dead, this can cause your amp to clip even earlier which maybe part of the problem.

GillesUnchained said:
How is it that turning the QSC up not even 3/4 of the way will make it clip?
Click to expand...

Provided the input signal is hot enough, the amp should be able to output its full power before the control is maxed out.
-
I would say you should have enough power with that setup if everything is working well.
Although as stated above it will depend how much 'low stuff' you're trying to get out of the 8x10.
I sold a couple of 8x10's because they just couldnt do really low frequencies.
Assuming everything is still working correctly your best bet is EQ. As above, cut the lows, boost the mids.
But if youve run it into clipping for any length of time, I would suggest testing those drivers out....
 
#6
I know exactly what the problem is:

Ampeg SVP-BSP preamp through a
QSC RMX1450 Power Amp into an
Ampeg SVT 8x10

a few months ago I had the exact same rig (except for a QSC PLX Amp) and the exact same problem.

The Ampeg SVP-BSP preamp has a very low output voltage. It's not giving the amplifier very much power to work with, thus diminishing you amplifiers output wattage. I didn't believe it at first until the people here at TB let me in on that little secret.

I don't know why Ampeg would do such a thing, perhaps so their preamps were only to be used with Ampeg power amps? (which I hear are matched up to utilize the low output voltage correctly)

Anyways, I tried out my buddies Sansamp on the same rig and it was fine...better than fine...loud and proud! So, I ended up getting a Sansamp RBI.

My suggestion is: look for a new preamp or a new, very high wattage amplifer.


Hope this helps! :D
 
#7
Masher88 said:
I know exactly what the problem is:

Ampeg SVP-BSP preamp through a
QSC RMX1450 Power Amp into an
Ampeg SVT 8x10

a few months ago I had the exact same rig (except for a QSC PLX Amp) and the exact same problem.

The Ampeg SVP-BSP preamp has a very low output voltage. It's not giving the amplifier very much power to work with, thus diminishing you amplifiers output wattage. I didn't believe it at first until the people here at TB let me in on that little secret.

I don't know why Ampeg would do such a thing, perhaps so their preamps were only to be used with Ampeg power amps? (which I hear are matched up to utilize the low output voltage correctly)

Anyways, I tried out my buddies Sansamp on the same rig and it was fine...better than fine...loud and proud! So, I ended up getting a Sansamp RBI.

My suggestion is: look for a new preamp or a new, very high wattage amplifer.


Hope this helps! :D
Click to expand...
Ugh...I've heard the same thing.

But you might want to see if Ampeg has a kit available for it to increase the gain. Recently a guy on TB with a CL put one in and it did make the pre louder but still not as loud as his other pre's.

IIRC he also found a dodgy tube.

:D

Joe.
 
#8
Ampeg doesn't state on their site what the output voltage of an SVP-BSP is (how thoughtful), but the input sensitivity on a SVP-1600 power amp is 0.5v so I think it's safe to assume the output voltage on an SVP-BSP is somewhere in that neighborhood. Problem is, the RMX1450 has an input sensitivity of 1.15v so the BSP isn't a very good match for it. You'd get better results from a power amp rated @ 0.775v input sensitivity (crown macro or crest ca series) or hopefully the input sensitivity on the 1450 can be modded to handle a lower voltage.
 
#9
Alright, good, this is giving me a lot of stuff to check on. The first thing I'll try is playing with the EQ, because I do like a lot of low end.

Also, does it make a difference if the peak light on the preamp is jumping a lot? It doesn't take the turned gain up very much to make it come on, even with it set for an active bass. I notice turning the lows up on my Stingray really makes the peak light come on. So I try to keep things down when I can, but I really like the fat sound I get turning that low end knob up.
 
#10
If the power amp's clip lights are coming on then you don't have inadequate output from the pre. They'll only come on with excessive input signal. Assuming you have the amp set up properly for bridged operation the likely culprit is excess low end EQ. 10dB of boost will try to get 10 times the wattage from the amp. If it doesn't have it to give you'll get clipping. With an SVT you should not have any EQ boost below 62Hz if you're running at high volume.
 
#11
Turn your deep bass down, ampegs are mud anyway, forget the low bass and concentrate on your low mids, that's where ampegs shine. They are not capable of producing clean low bass. Kind of sorry for a $1400 dollar amp.
 

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