#1
hey folks, I'm new here and was wondering if I could get some input.

I've been playing for around 11 years now, but haven't owned my own guitar amp in a few years, as I've been broke and just playing an acoustic guitar recently.

Well, I'm finally craving to play electric and with a group again, so I stumbled upon a used Ampeg SuperRocket 2x12 in my town, read some good things (heard their similar to a twin reverb) and went to check it out. The dude is charging $600 for it, but I think I might be able to talk him down.

I really enjoy the tone on the clean chan. particularly, but the drive channel isn't so shabby either.

The issue I noticed when I turn up the clean chan. fairly loudly. The amp starts to make a weird noise. Now, I'm really not sure if it's a mechanical noise from the vibrations of the amp, or if it's something else.

I had the owner of the amp play it for a while while I felt around the back of the amp trying to find anything rattling. I've been over there twice, the first time it certainly seemed to be coming from both speakers.

The noise seems to become more intense when I switch the tremelo and reverb on.
And when I am holding out a note that is causing the crackly/rattly sound, as I let it sustain it will seem to suddenly stop whenever it fades to a certain level.

I also attempted unplugging the guitar from the amp and listening to it by itself, and it was making a much quieter crackling/static noise.

I really like this amp, but I've waited too long, and am too broke to buy something that's going to be a major headache for me.

So, I'm planning on borrowing my brothers Orange 2x12 cab and taking it over there and seeing how that effects the situation.

Any ideas on what might be going on, or what a tech might cost to do a once over on it?
#3
Now that I think for a moment, I recall also noticing some volume fluctuations (volume dropping or compressing really hard) when I would hit a lower note (while using the clean channel turned up decently)

I'm fearing that it might be power tube related. He said he ran it with only 2 of the 4 6L6's for a good while.
#4
I thought about the reverb thing. Would that cause noise even when the reverb is turned off with the foot switch?

It does seem the reverb box thingie (tank?) is just sitting in the back of the cab underneath a button down tarp thing, but it doesn't seem to have an easy way to just disconnect the damn thing. Perhaps I'll try bringing some foam and sticking it under.
#6
Volume fluctuations makes me think bad tubes, that would be an easy fix.

I almost picked up an old ampeg rocket myself (two channels, guitar and accordion, trem, no reverb) didn't get it because it because it had no reverb and I didn't want to fuss with the odd tubes it came with. Sounded frickin amazing though.
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#7
Sounds like it could be a tube problem. Look in the back, check their color. If the power tubes are glowing bright orange then it may blow soon. If he was only using 2 of the 4 power tubes, then try swapping the ones that weren't being used for the ones that are in there now. If it isn't the power tubes then it could be the preamps. Tap on them with the eraser of a pencil with the amp on. That's the test to see if they are microphonic.

If it isn't either of those problems, it could be the tremolo or reverb circuits, especially if they are tube driven circuits.

As for the rattling, have either you or the seller unplug the amp and go all around the chassis tightening any screws you see. If that isn't the issue well......talk him down to like 450 and say that you'll need the extra expenses for repairs

**EDIT** Dammit Kevin, I walk away from my computer while in mid-post for 2 seconds and you swoop in and steal my reply. But yea....whatever
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Last edited by LaidBack at Jan 24, 2009,
#8
It's what I do.


You actually gave some advice though, so it was worth the wait.

I'd also note, running an amp with only two of it's four tube shouldn't damage it as long as the impedance is set properly.
I don't give a shit if you listen to me or not
#9
Thanks for the help guys. So if it's running on only 2 power tubes, it's impedance should be lowered? I think it normally runs at 16 ohms, so it should run at 8 ohms with 2 power tubes?
#10
Quote by Dogfish2
Thanks for the help guys. So if it's running on only 2 power tubes, it's impedance should be lowered? I think it normally runs at 16 ohms, so it should run at 8 ohms with 2 power tubes?


Opposite (I think, maybe I'm misunderstanding)

If you pull tubes, you need to increase the impedence in...so, plug a 16 ohm cab into an 8 ohm jack and the amp.

If he went the other way (or didn't change anything), there's a good chance the output tubes are toast, and possibly the output transformer as well...
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#11
Quote by DLrocket89
Opposite (I think, maybe I'm misunderstanding)

If you pull tubes, you need to increase the impedence in...so, plug a 16 ohm cab into an 8 ohm jack and the amp.

If he went the other way (or didn't change anything), there's a good chance the output tubes are toast, and possibly the output transformer as well...



Yes exactly, when you pull tubes the amps impedance is doubled, so if you set it to 8 ohms it needs a 16 ohm load.
I don't give a shit if you listen to me or not