• 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.

Ampeg SVT problems

B

boxnife

Aug 5, 2008
44
0
#1
I have a late model (2004-ish I think) Ampeg SVT-CL that has been giving me some problems. Occasionally it would suddenly kick over to standby while playing. The standby switch would be in the off position, but the LED would be red, as if it were in standby.

I checked the bias and it all seemed kosher. I had a guy replace the fan because it was noisy and I thought it may be a short. He also replaced the preamp tubes. The power tubes were getting weak, but he said that shouldn't cause it to do what it was doing.

Anyways, I kept having problems with it, and usually giving the head a good thump would kick it back on. At a show recently it did the same old act and wouldn't come back on under any circumstance. It just stays in standby.

any idea what the problem is?
 
#5
Line voltage, as in a faulty outlet or my insturment cable? I play a passive jazz. I've had the same problem using many different outlets.

I'm sure it needs a trip to the shop, but if someone can set me in the right direction I'd like to try and get it going just to hold me over for a while.

It's really only an issue when we play larger venues. I normally play through, brace yourself...

a mesa mark I guitar head.

thats hooked up to my svt 6X10. the amp was bought at the dallas guitar show. it belonged to that guy that played in tin machine with david bowie. here's my band for good measure

Link Removed

anyways, any additional ideas on the SVT would be appreciated.
 
#8
Dude, don't nerd out on me. I'm sorry shaved monks at the top of Mt. Everest aren't hand wiring SVT's anymore. Anyone who knows more than I do about electronics and thinks they know what may be malfunctioning with my SVT please chime in.
 
#9
The CL has an elaborate and probably not THAT helpful "protection" circuit to detect bad output tubes and shut down power.

it also has a time delay that holds the unit in standby for a bit even if you turn it on with standby "on".

It SOUNDS as if the protection is, rightly or wrongly, claiming there is a bad tube. If it just was the timer stuff, I don't think the standby light would come on.

However, it should flash.

If it isn't flashing, there may be a problem in the voltage detecting circuit.... but that wouldn't actually put the unit in standby, it would just light the light.

I assume it is actually putting the unit in standby, not just the light?

bad tube might just be it, since you said they are getting weak...... Or not, I'm not there and can't check stuff, so I'm basically laying out some possibles.
 
#10
boxnife said:
Dude, don't nerd out on me. I'm sorry shaved monks at the top of Mt. Everest aren't hand wiring SVT's anymore.
Click to expand...
HAHAHAHAHAHA!!! That's funny as hell! Listen, you rock that CL. There's not a thing in the world wrong with them...well, except for this thing you're experiencing. I think they get a bad rap, but even though they're not the same as the SVT of old, they're still better than 99% of amps out there.
 
#11
Jerrold Tiers said:
The CL has an elaborate and probably not THAT helpful "protection" circuit to detect bad output tubes and shut down power.

it also has a time delay that holds the unit in standby for a bit even if you turn it on with standby "on".

It SOUNDS as if the protection is, rightly or wrongly, claiming there is a bad tube. If it just was the timer stuff, I don't think the standby light would come on.

However, it should flash.

If it isn't flashing, there may be a problem in the voltage detecting circuit.... but that wouldn't actually put the unit in standby, it would just light the light.

I assume it is actually putting the unit in standby, not just the light?

bad tube might just be it, since you said they are getting weak...... Or not, I'm not there and can't check stuff, so I'm basically laying out some possibles.
Click to expand...

I remember reading about the protection circuit a long time ago, and the 'flashing' standby light. It's never flashed on me before. The unit is going into standby. I'm thinking: remove tubes, have them tested. They were weak two years ago, I wouldn't be surprised if a dying tube is the culprit. Second, I'll replace the standby switch. I doubt physically bumping the unit would revive a dying tube. A fulty switch seems reasonable.

As an aside, this unit obviously needs new tubes anyway. Where do you buy decent tubes for the newer SVT's?
 
#12
any good music store can get you some tubes . it depends on what grade of tubes you want to pay for . like electro harmonix tubes would be around 100 or so bucks .. rubys would be about 250 or more maybe even 300 or so .... and if you wanted to get froggy and piss off old school svt lovers , buy some n.o.s. ge tubes from the 70's and put those in your not so svt , SVT CL ...lol lol lol ... man ive had 4 70s svts , 2 mti era svts , 4 svt3pros (i know) ,2 400t and now my first cl . i will say it sounds just as good as the mti's , and close as hell to the old school 70s . i like it a lot ....... and thats all i care about is what i like to hear my bass rig sound like ....
 
#15
boxnife said:
I remember reading about the protection circuit a long time ago, and the 'flashing' standby light. It's never flashed on me before. The unit is going into standby. I'm thinking: remove tubes, have them tested. They were weak two years ago, I wouldn't be surprised if a dying tube is the culprit. Second, I'll replace the standby switch. I doubt physically bumping the unit would revive a dying tube. A fulty switch seems reasonable.

As an aside, this unit obviously needs new tubes anyway. Where do you buy decent tubes for the newer SVT's?
Click to expand...
A bump may not revive a dying tube, but it can make it work for a short period. Don't ask me why, but I've seen it.

I'm not all up on 6550's but JJ makes decent tubes. So does Tung Sol.
 
#17
JimmyM said:
A bump may not revive a dying tube, but it can make it work for a short period. Don't ask me why, but I've seen it.

I'm not all up on 6550's but JJ makes decent tubes. So does Tung Sol.
Click to expand...

Will the amp accept anything other than the 6550's? I've never been that stoked on my SVT. I can't coax anything out of it I like at low volume. That's why I use the Mesa head.
 
#18
I don't know if you can or not, but I've never heard of anyone doing it. Seems kind of wrong to me ;) I'd say if you like the Mesa tone better, use Mesa and sell the CL.
 
#19
JimmyM said:
I don't know if you can or not, but I've never heard of anyone doing it. Seems kind of wrong to me ;) I'd say if you like the Mesa tone better, use Mesa and sell the CL.
Click to expand...

You're probably right. The SVT is a pretty expensive backup amp. The Mesa has trouble keeping up at larger clubs or venues with crummy sound/sound guys. But I wouldn't record with anything else.
 

Latest posts

Top Bottom
Back