Ampeg Help! Please!

[LouieStyx]

OK I am having such a horrible time lately I just need a fix, im at my wits end. I have and Ampeg SVT-4 in a rackmount now with 2 holes cut in the sides for vents. Here is what keeps happening...

I was playing a show a few months back and at the end of the set (about 45-50 min) it started acting up. What happens is the sound cuts off, the power on the unit stays on but the sound stops....then comes back on.....the stops....back on....stops. There is a clicking noise in the back when this happens. I took it to many people who couldnt even get it to shut off like this. Then I did get a guy who could, he said it was a thermal issue and he put the holes in the rack. I played tonight and about 25 min into the set it did it again...It seems to so it when I really push it, like during slapping, if I lay back a bit it stopped it for a little while, but then bam on, off, on, off. about a second in between the on and off. I touched the unit right after it did this and it wasnt hot...so thermal? IDK.

I have it mono bridged on an Ampeg 8x10 cab.

Does anyone have any suggestions, im so desperate.

Thanks

Louie

 

[M.Wrenn]

It certainly doesn't sound like a thermal issue to me, sounds more like some messed up circuitry, take it to a somebody who knows electronics or a music store, as long as it's a legit store

 

[Mr Jansreb]

I've heard of a lot of people having random problems with different Ampeg SVT Pro heads. Many of them are related to overheating. Most suggestions I have heard amount to "Don't mount it in a rack." I have an SVT 3 Pro myself, which I leave out of the rack. I haven't ever had any problems with it. Do you ever have these problems during practice? I would suggest just taking it out for your next gig. See what happens. These things generate a massive amount of heat, so another idea would be additional cooling, i.e. a fan of some sort. In all honesty, you might have already fried something inside, and despite additional cooling from the holes, the problem may continue. You could also open it up and see if anything inside looks amiss. Hope that helps.

 

[will33]

Sounds to me like thermal shutdown. Of course, being here on the internet, I can't hear it.

One of two thing may be happening...either the amp is getting hot and the thermal switches are shutting down to protect itself (that's how it's supposed to work)....OR.... the amps is effed up and the thermals are shutting it down because they think it's getting too hot when it may not be. Try putting a jumper wire around the thermal switch(es) and see what happens.


What's the worst you could do, make it worse than it is? It already doesn't do what it's supposed to....

 

[Jerrold Tiers]

It is very much like thermal issues.........but a 1 second delay is too short for the thermal most likely..... it is a lot more typical to have 10 to 15 seconds....

I am going to guess that you have some serious low end boost on that....... maybe even the "ultra-low" Do I get the prize?

IF so......................

what I think is going on is that you are triggering the DC protector on the slapping...... Slaps produce a big "pulse" of low frequency, and if you are not hearing what you want from teh 8-10, maybe you goose it up a bit, and some more, and more... about the time you say "that's good", it is too much...... the big low frequency pulse (down around 15 or 25 Hz) triggers the DC detector.

The cure is to first turn off the "suck button" (ultra-low) it's for jazz gigs, and not for rocking out..... and really doesn't belong on the 4 PRO.....

Then see if maybe you can deal with less low end boost

 

[mophead]

This is probably too simple but check amd make sure the fan is working properly. If the fan isn't working the amp will get hot and cut the sound output, cools a little and back on, then gets hot and shuts off again. Had this happen on an Ampeg head once. New fan and no more problems.

 

[Jerrold Tiers]

That definitely can happen, but with no fan, the time is usually more like 20 seconds.....

If teh OP's problem is not a lot of boost, it could be that the DC detector is just misbehaving...... Thermal is still a possible, it's just more typical for it to be a longer delay, even if the fan is working.