Should I look to get a new amp?

[XsSpeed]

For the last year and a half I have been using a Sunn Coliseum 300 amp with an Ampeg 8x10 both for practice and for gigging. It's been great but the other night during our 2nd song of practice, the "power Amp Limit" light came on and stayed on while no sound would come out.

After not being able to figure out (replaced fuse etc) how to get it to start working again, I plugged in a Kustom 200B amp to finish practice.

After a while, I plugged back into the Sunn and it works fine. I love the Sunn but I want to be confident that it won't do that to me during a live gig.

Should I save for a new amp that I can depend on or was this just an anomoly that I can prevent?

Incidently, I play pretty fast and often thumb and pluck but the volume was only 1/2 way up.

thanks
Sean

[Ironderby]

i don't know much about amps, but perhaps the head was overpowered? 300w head with an 8x10. I doubt its a fault with the speakers, because it has to take a lot to blow 810's especially a good brand like ampeg

[XsSpeed]

Yea like I said, I plugged a different head right into the cab and it worked fine. It's def the Sunn head.

[RickenBoogie]

A bench test done by a qualified amp technician is the only way to know what's going on.

[Ric5]

Those old Sunn coliseum heads are not that good by modern standards. Try an Ampeg B2r or something similar. Your tone will be better as a result.

[IvanMike]

Originally Posted by RickenBoogie

A bench test done by a qualified amp technician is the only way to know what's going on.

+1000

[tminus10]

If you love the Sunn then take it to a tech before making a decision

[XsSpeed]

good advice

[JimmyM]

Originally Posted by Ric5

Those old Sunn coliseum heads are not that good by modern standards. Try an Ampeg B2r or something similar. Your tone will be better as a result.

Nobody loves Ampeg more than me, but seriously? Entwistle used Coliseums and never sounded quite the same after he moved on.

[runmikeyrun]

The amp might have a thermal protection device. They shut down the amp when it reaches a certain temperature before something has a chance to blow. When the amp cools down enough it will come back on and work as normal. Make sure you had good air flow to the rear panel. If you don't normally jam with the volume 1/2 way up then maybe you just ran it too hard. If you do (and you weren't jamming longer than normal) then I'd get it looked at. Hopefully she's ok.

[XsSpeed]

Yea, I normally run it at about 11 oclock and kicked it up to 12. I dunno, I need to get it checked out. I do dig the sound out of the 8x10

[nashvillebill]

Originally Posted by JimmyM

Nobody loves Ampeg more than me, but seriously? Entwistle used Coliseums and never sounded quite the same after he moved on.

According to this site Entwistle used the Coliseum power amp, but Alembic and Stramp preamps.

John Entwistle Gear: 1974-1985 | John Entwistle Bass Gear | Whotabs


I had a Sunn Concert Bass rig with the 2x15 cab. In its day, it was OK, but I agree with Ric5 earlier...by today's standards it's not that great.

[JimmyM]

I have a soft spot for the old stuff...I love to hear about 40 and 50 year old amps still running.

[nashvillebill]

I understand about the old stuff, I gave my Concert Bass rig a thorough refurbishment (caps, cleaning, reflowed all solder joints, checked output on scope, etc) so it was pretty much playing as well as it would've played new. Nevertheles, I thought the preamp was noisy (way too much background hiss) and realistically it was underpowered. The Coliseum of course wouldn't be as underpowered, but still...my Concert really wasn't made very well IMHO, compared to my Kustom 250 and Ampeg V4, both from 1971.

[XsSpeed]

I just had it bench tested and was told there's a bad capacitor and I should replace both of them. He said about 140.00. I told him I'd bring it back when I have the cash. Can't I get them at Radio Shack and do them myself a lot cheaper?

[MK1]

The mere fact that you suggested radio shack tells me you probably shouldn't be poking around in an amp. There are very lethal voltages under that cover. Capacitors will store a charge and if you don't know how to drain them you will potentially kill yourself. Please don't poke around in an amp if you don't know what you're doing. Leave it to the professionals.

[XsSpeed]

ok thanks.

[XsSpeed]

Well the amp worked fine up until august. Then I noticed a loss in power and highs. I swapped it out with my Kustom 200B until I got a chance to bring it to Central Electronic to have it checked out. Well, he couldn't find anything wrong with it and cleaned the pots and jacks and charged my 40 bucks. I just brought it home and plugged in and the volume isn't half of what it used to be. Stumped!

[two fingers]

Take it to a tech for a good once over.

But the answer is always YES when it comes to looking for new gear. Just..... yes. Get a new amp. Keep the old one. Once you get the new one, look for another one, and another, and another.

Seriously though, I take a backup head (GB Shuttle 6.0) in my gear box to every gig. It sounds fine although my Walkabout and tube amps get all the paying time. But it only weighs about 4 lbs and is about the size of a textbook. So why not bring it along just in case? But, I may be the wrong person to chime in on this because I have at least one spare EVERYTHING (2 or 3 of most) at every gig. Heck I can string up guitars and switch out batteries and I don't play guitar and nothing I own uses batteries.

[B-string]

Use the poweramp in on the Sunn fed from the 200B's effects send or Pre out. That will localize the trouble to either the preamp or poweramp. You might want to try looping the effects send and effects return with an instrument cable to eliminate possible effects return jack trouble. Power supply caps go weak and have less reserve, transistor junctions can also get weak. First thing is to find out if it is in the poweramp section or preamp section.