Attention vintage guitar amp fiends

[Jarvicious]

I found a pretty little fixer-upper on the side of the road on trash day a couple of weeks ago.  At first I just thought it was just a radio so i grabbed it, threw it in the van, and went to work.  Once I got to screwing with it later i realized it was an amp, but just as I suspected is disfunctional.  As soon as the tubes get warmed up, it makes a crazy loud fluttering sound.  Doesn't matter if it's got a guitar plugged in or not, this thing just screams.  Anyone have any ideas to get her up and running?  I know this is a long shot since electronics are most easily diagnosed in person, but I was hoping someone has had enough experience to let me know if I should fix her up or just part it out on fleabay.  I'm not scared of tearing it apart and tinkering, but replacing tubes at random without knowing which ones are faulty seems like a pretty expensive endeavor, especially since I don't know anything about tube biasing, reverb repair, etc.   It's an old Sears Signature series (can't find a model) so I have no idea if it was supposed to be a decent amp in its time.  As I'm sure I'd get yelled at if I didn't post up, here are some pics.







Like I said, I'm not really worried about getting it running if it's not worth it, but it would still be cool nonetheless to try.  Oh, and you may need to shield your eyes from the blaring 3megapixel clarity.  I'll understand..

[Buckethead]

Should be totally doable.

Found you a too.

[il d00d]

It looks like you have a Sears/Silvertone 1482 -  (I'm no expert, I was just able to make out the model number on the back from the pictures )

Here's a mintier version

Tubes are not too expensive, especially if you buy Russian or Chinese, and they are not NOS/Vintage.  As with all things guitar, vintage = 1000% markup.
I would head down to your local guitar shop, ask for two cheap 12AX7s and two 6V6s, and try swapping them out.  Maybe clean up the sockets a bit with some compressed air  and clean the pots a bit.  What are the knobs marked?  Are any of them vibrato?

[Timmy Tucker]

In a former life, I used to be an amp/guitar repair tech and also built custom tube guitar amps.

Before I went out and bought tubes for it, I'd take the ones in it to your local shop and have 'em checked out. No need to replace ones that still work.

On something that old, the filter caps (tall silver thing between tubes and tranny + probably a few smaller ones inside) would definitely be suspect as they have a limited lifetime.

If you decide it's not worth the trouble to fix, I'd love to get my hands on that speaker. it's a '72 Jensen Alnico that would be perfect for a project I'm working on.

[superjohn]

Weren't the original 6V6's a lot better than the current crop from China/Russia? I was thinking that was one of the tubes that were like holy grail if you found an original RCA. Or maybe not. It's been a long time since I've kept up on guitar amp stuff.

[Jarvicious]

Ok, so I MAY have rushed into posting this without giving it too good an exam  .  I grew some balls and decided to try and fiddle with the knobs to get as much of a tone out of her as I could.  One of the instrument inputs doesn't work at all (I don't think) and the other has to be turned all the way up to be heard.  I don't think the speaker is stock either unless they designed it as an open back with the magnet sticking out half an inch.  

I found some tubes online, but what's the dif between just a single tube and a matched pair.  Do I have to buy them set to the proper bias, or will the amp adjust wattage as necessary?  What little tone I did manage to get out of it sounded growly and downright mean as hell so if I could change the tubes to give it a little more punch, I probably would.  The knobs on the front are volume and tone for the mic, volume and tone for instrument, and reverb strength and reverb speed.  

Wow, just got done reading over a tube amp troubleshooting guide and I don't know if I have the patience for this, especially since the more I pick at the amp the more I find that he's changed things like the speaker and apparently multiple tubes (when I pulled them out, none matched).

[Timmy Tucker]

Speaker is definitely not original, since it's about 8-10 years newer than the amp itself. Plus the one that came stock had a much smaller magnet. This is not a bad thing, as the stock speaker was flimsy shite. Jensen alnico's sound make the beast with two backsing great... had a pair in a '66 Pro Reverb and they were the shit.

As far as tubes, you don't technically have to buy a matched set to bias it properly. It's up to you though, it can be a bit easier if you're gonna do it yourself. Some salespeople will try to sell you on the importance of matched sets, but generally speaking it's not necessary. Even w/ a matched set, the tubes drift off from each other w/ use anyway, so what's the point? I suggest Ruby's. They're hands down the toughest and imo the best sounding 6V6's currently made.

And don't sweat the fact that the tubes that are in there don't match. Tubes have to be changed on a regular basis anyway (with use).

Bottom line... it's a POS. Just box it up and send it to me. 

[Timmy Tucker]

Weren't the original 6V6's a lot better than the current crop from China/Russia? I was thinking that was one of the tubes that were like holy grail if you found an original RCA. Or maybe not. It's been a long time since I've kept up on guitar amp stuff.

Yes, quality was much better. You can still find the RCA's from time to time, but they run anywhere from $75 to $160 a pair depending on previous usage and if they are a "GT" or not.

Ruby's actually hold up better, will take waaaaay more voltage (500+vdc  vs. 350-400vdc) and still sound 99% as good. I've got a set of the old RCA blackplate GT's stashed away and I used Ruby's in my last 6V6 amp.


You want holy grail... I had a set of assorted NOS tubes that I spent 4 years hunting down and hauled around for years using in all my different amps. Forgot and left them in my Matchless Clubman when I sold it. Last time I checked, they were gonna cost me almost $800 to replace. 

[redxblack]

I used to get my tubes from bob at eurotubes.com. I haven't needed tubes in a long time, but his service is excellent and has taken back bad tubes without question (none of the tubes I've ever gotten from him have been bad, but a friend got a bad one once).

I've been partial to svetlanas. I've had issues with Ruby preamp tubes going microphonic kind of fast, but never had an issue with their power tubes.

[Jarvicious]

Resolved (well, as far as I can tell anyway)!.  I had a friend of a friend come over and take a look and we did some troubleshooting and found that it was just one bad tube that was causing the whole shebang.  Both the power tube lit and ran fine, but both of the 12ax7's were run in a series, not just one tube per input.  Soooo, when the one tube shot craps, it took the entire circuit out with it which was causing all of the noise (or lack of noise) issues.  Went to a local repair guy, got a J & J for $10 bucks, and the thing fired right up.  I haven't been able to put it much past 1 yet (damn neighbors) but so far it sounds brilliant.  Timmy, I think you're right about that aftermarket speaker.  Even at somewhat of an earsplitting volume the clarity is rediculous.  It picks up everything (not that the stock Epi pickups are the greatest) but there is absolutely ZERO residual noise.  Quiet as a mouse unless you want it to be.  Thanks for the help folks and sorry Timmy, but I'm keeping this one.  My little Roland practice cube does well enough for the crunch, but the clean on this beast is mind blowing.  Now if it can just get rid of the overwhelming mildew smell.........

[Popeye the Sailor]

Does it go up to 11?

[Jarvicious]