old Ampeg - Hummmmmmmm

heatmiser

heatmiser

mr. green christmas
Hey,

So, I have a 1960's Ampeg Reverberocket amp that emits a constant loud hum whenever it is turned on whether or not anything is plugged into it.

I bought it used around 1990. Had it serviced once back in 2003. All new tubes: 6k11, 6u10, 12ax7 (2) and 2 7868's (which were $50 a pop). I saved the guy's notes and he wrote that there was also a low-grade hum present at all times. He felt this was due to the age and condition of the filter caps. He wrote that they should be changed every 20 yrs. or so. I didn't have enough dough then, so we changed the tubes and left it at that.

Now, 10 years later, I guess that same hum is now high grade? I'm hoping I don't need new tubes again.
Do you think his 10 yr. old explanation of the hum explains what is happening now? Does it sound like he knows what he's talking about?

People have had varied success with repairs at this place and I'd like to have some idea what's going on when I bring it in. It's my only amp and I'm kind of attached to it. Getting 10 yrs. of use between repairs seems pretty damn good though, right?
 
Yes its commonly recommended the caps get changed at around 20 yrs because they dry out. Yours are double overdue. You could probably do it yourself with the Google.
 
Hmm. What is this Google of which you speak? I'll have to search for it online.

I will check though. If it's extremely simple I may give it a go. My last electrical repair work didn't hold up so well though and I think I might also like to convert the 2-prong plug to 3-prong (do people do this themselves too?), so maybe a professional is in order.

Thanks Greg.
 
If you don't have the hands for it, or the patience and experience, it may be less stress just to pay someone to do it. If memory serves me correctly, the chassis is a wee bit cramped, and the main filter is an FP 'can' that is tricky to solder to the chassis. It can be done, if you have the tools and good fine motor skills.
You can be sure if if the caps are bad if you have even modest test equipment. Heck, with no test equipment you can do it. If you have a 22uF/+450VDC capacitor laying around (and who doesn't?), bridge the Plate supply or the 'first' capacitor if you are following a schematic. Hum-B-Gone? Change the FP can. Make sure to get it right; there's usually a pattern marked; typically 'symbols' such as half-circle,square, triangle, 'blank'. Follow them. It's the order the capacitor sections were rolled, and usually the blank one is the outer foil. That should be the preamp, and the inner foil should be the Plate supply.
Chances are more then one section is dried out, so the hum may just be greatly reduced by bridging one section. If you do bridge any filter, discharge that cap you use to bridge carefully.
 
Thanks. That actually sounds pretty intimidating! I've done a little soldering and while it looked okay, it didn't hold up well. If it's something people can do for themselves, I'm guessing it isn't too expensive to have done professionally - other than the labor of course.

So, it sounds like the caps would be expected to be bad at this point, and I guess that could cause the constant hum.

This amp probably isn't worth sinking too much $ into (last time they tried to talk me out of fixing it over a $280.00 bill), but it has sentimental value, so I'll pay to bring it back to life unless it is outrageously expensive.
 
heatmiser said:
Thanks. That actually sounds pretty intimidating! I've done a little soldering and while it looked okay, it didn't hold up well. If it's something people can do for themselves, I'm guessing it isn't too expensive to have done professionally - other than the labor of course.

So, it sounds like the caps would be expected to be bad at this point, and I guess that could cause the constant hum.

This amp probably isn't worth sinking too much $ into (last time they tried to talk me out of fixing it over a $280.00 bill), but it has sentimental value, so I'll pay to bring it back to life unless it is outrageously expensive.
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Dude you have a rare amp that you've put virtually no money into. Splurge a little and freshen it up. You'll have something cool and unique that works. You don't even wanna know what I've spent on guitars and amps this past year and a half. Lol.
 
Greg_L said:
Dude you have a rare amp that you've put virtually no money into. Splurge a little and freshen it up. You'll have something cool and unique that works. You don't even wanna know what I've spent on guitars and amps this past year and a half. Lol.
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ditto .... that amp is prolly worth some bucks when working right.

One thing you definitely won't need is pereamp tubes.
And unless you've been playing it a LOT it also doesn't need power tubes.
I've got old Ampegs with their original 40 year old tubes in them that work fine.
 
Greg_L said:
Dude you have a rare amp that you've put virtually no money into. Splurge a little and freshen it up. You'll have something cool and unique that works. You don't even wanna know what I've spent on guitars and amps this past year and a half. Lol.
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Yeah, I can't imagine. You used to be the drummer who also played guitar. Now you've got more, nicer gear than most "guitarists".

Lt. Bob said:
ditto .... that amp is prolly worth some bucks when working right.

One thing you definitely won't need is pereamp tubes.
And unless you've been playing it a LOT it also doesn't need power tubes.
I've got old Ampegs with their original 40 year old tubes in them that work fine.
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Cool. I love the amp when working properly. It has a nice, full, mellow tone to it that I like.

I don't use it a lot. At this point I only turn it on when I'm recording something.

I'm going to try to bring it in to the shop this week and see what they can do. Thanks.
 
heatmiser said:
Yeah, I can't imagine. You used to be the drummer who also played guitar. Now you've got more, nicer gear than most "guitarists".
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Lol. I suppose. I'm long overdue. I've never had good guitar equipment of my very own before. It was always junk plugged into junk or I used someone else's good shit. I kind of caught myself up all in one big expensive swoop.

Keep us updated on your amp. I'd like to know what the diagnosis is.
 
Greg_L said:
Keep us updated on your amp. I'd like to know what the diagnosis is.
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Will do. Thanks!

moresound said:
Heat - I'll be up your way in 2 months. If you can wait that long. I could do that cap change for ya in about an hour or less.
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Thank you very much for kindly offering assistance!

I hope to have this taken care of before then, but I will certaily let you know if that is not the case. :)
 
Right O

It shouldn't be to awfully expensive to have a tech up your way to have it done.

Do try to be sure that he can use NOS caps or you may find that *nice, full, mellow tone* to have disappeared!
 
moresound said:
.......It shouldn't be too awfully expensive to have a tech up your way to have it done.
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It depends on the tech, and how they deal with the amp. I know some who will go through all the capacitors, including the coupling caps, and check for leakage. Then they may check resistors for value and drift. Then they may test all the tubes. If you just want a quick slash-and-dash job of changing the FP can, then it should be cheap. But a thorough overhaul will cost a few bucks more.

moresound said:
.......Do try to be sure that he can use NOS caps or you may find that *nice, full, mellow tone* to have disappeared!
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Nooooooooooo! Take leaky caps with a high ESR over new caps that test fine? Not me. You can find NOS caps that aren't leaky, but that's an exception, rather than a rule. Try it, I guess. But you can ask your tech if he has much for test equipment. If he just says he has a Fluke, you're in trouble. If he thoroughly tests capacitors, and matches the output coupling caps, then he's worth paying a few dollars more to.
 
Just dropped off the amp today on a long lunch break.

The dude behind the counter was the same guy that worked on the amp 10 yrs. ago! He recognized his writing on the notes I showed him. He thinks it's probably the filter caps and didn't seem to think it was a big deal. They're also going to convert the 2-prong to 3-prong plug.

He agreed that it was worth fixing as I couldn't get much of a new tube amp for the cost of fixing this one.

They had a bunch of mexi-strats for $399.00 plus a bunch of modified vintage squires for around $300.00 and I was tempted as I need a strat-like guitar.

Then, I walked down the block to the drum store, and holy crap they had some nice kits. DW, Gretsch, etc. All way too pricey...$$$$$$ Damn, those were some fine looking drums! (I don't get out much :o :D).
 
Yes, I've seen that too. Not sure what they're getting, but I know what they're asking.

I forgot to ask them how long it will take, but I'll update this with the results - hopefully some new sounds shortly after that.
 
I've got an old V4 I bought new in the early 70's....original tubes, everything still and it's loud. Don't use it much however because of that and the head weighs about 75lbs on its' own.
 
mixmkr said:
I've got an old V4 I bought new in the early 70's....original tubes, everything still and it's loud. Don't use it much however because of that and the head weighs about 75lbs on its' own.
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yeah ..... I have a V2 ..... I do use it but it is loud and clean .... I also have a VT-40 and a VT-22 ...... I love them but one weighs 95lbs and the other clocks in at 105lbs! :eek:
 
heatmiser said:
Just dropped off the amp today on a long lunch break.

The dude behind the counter was the same guy that worked on the amp 10 yrs. ago! He recognized his writing on the notes I showed him. He thinks it's probably the filter caps and didn't seem to think it was a big deal. They're also going to convert the 2-prong to 3-prong plug.

He agreed that it was worth fixing as I couldn't get much of a new tube amp for the cost of fixing this one.

They had a bunch of mexi-strats for $399.00 plus a bunch of modified vintage squires for around $300.00 and I was tempted as I need a strat-like guitar.

Then, I walked down the block to the drum store, and holy crap they had some nice kits. DW, Gretsch, etc. All way too pricey...$$$$$$ Damn, those were some fine looking drums! (I don't get out much :o :D).
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Awesome, let us know what the tech finds. I need to find a good tech myself....or an amp repair for dummies book. My city has 5-6 million people and not one good reputable amp tech that I've heard of. Lots of hacks.

I'm gonna blaspheme for a moment here about those drums - DW, Gretsch, Tama, Pearl, etc......they're all about the same. If you're comparing apples to apples, a high end Pearl or Tama kit is no better or worse than a high end kit from another manufacturer. Obviously a DW is leaps and bounds better than a Sound Percussion kit, but I did say apples to apples. DW puts together some fantastic kits.....but they can sound just as shitty as cheap stuff. I know a guy with a....sit down for this.....$15,000 DW kit. It's your basic 6pc - one kick, two rack toms, two floor toms, piccolo snare. It looks stunning. Silver sparkle boat-flake finish. It sounds pretty mediocre. Well tuned, good heads, the guy can play, it just sounds like a good drum kit. Not spectacular. Just okay. If you sat in a room with three decent quality kits and someone played them all, you couldn't tell which is which. The area where those high end kits really shine is consistency with bearing edges, quality shells, lug locations, tuning range, and hardware. I think a gigging drummer will be better served with a quality kit. Not so much for the sound, but just for the better fit and finish. For someone that just wants a kit to record, any old decent name brand, good quality kit that's tuned properly with the right heads for the job will be perfect.
 
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