Tube Amps / Music Electronics
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|5/28/2004 7:36 AM|
||Jim Kelly amp,anyone fimiliar with these?|
If anyone has some info on these amps they might share. I have one here with problems. Mostly all works fine,but no reverb. its a 4x 6V6 amp..losts of boosts[push pull]. the owner needs it to play this weekend. One tube was redplating. After checking the plate voltage,they are running at 500v screens about 497.. it has Philips STR 6V6s in it.
The amp has a 30-60 switch. And you can hear the reverb crash,but no reverb when played. And its got some funky parts. kinda reminds me of some of the insides of boogie amps,the way its made. Probably a little better.
It was late and had to quit for the night,so i'll do some more checking today. But any info on this amp might help.
|5/28/2004 8:40 AM|
Jim Kelley posts on alt.guitar.amps sometimes. His email is:
He might be able to help you.
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|5/28/2004 9:10 AM|
Thanks Steve; I'll try the e-mail and see if he has some info.
|5/28/2004 1:40 PM|
Is this the F.A.C.S. model? These amps love to lose bias and the plates subsequently runaway. Re-tension very carefully the power tube sockets and inspect all bias point solders carefully, updating when necessary.
Have you checked the reverb tank (#1 cause of Reverb failure)?
The reverb is pretty straightforward but there some relays in this amp, if I recall. I would check these out also. Replace the driver and recovery tubes. If that doesn't work, try to isolate the problem to determine if it's in the drive or recovery stage of the reverb.
You can find a schematic if you search the net. Even if you don't find the proper model, there is more than a passing resemblance between all the circuits/models.
|5/28/2004 8:20 PM|
Steve,Bob, Thanks for your help! I did get a reply from Jim,and some of his suggestions. The problems were pretty much the same as you'd find in a fender,as Bob was pointing out. This amp had 3 bad 12Ax7 tubes. It also needed the reverb tranny.
And dc on the volume controls,,which also was a bad tube causeing it. So its all going now.
the voltage did drop some on the 6v6s when i got the good tubes in the amp. But still these amps run very high voltage on those 6V6s..
Since all these tubes were the ones that were stock tubes that came with the amp. Jim suggested
""" I recommend
NOS Phillips or Sylvania from Lord Valve."""
I'll have to order those,its just the guy was needing the amp for this holiday weekened.
I matched up some NOS i had,and it should be ok till he can get the other tubes for the amp.
I've never been in one of these amps before,never even seen any in this area.
Jim said he'd send me a schematic for the amp. it may help if i ever need to work on it again.
its a combo,with a 12" celestion sidewinder
I didn't care much for the gain boost sound,but its not bad with just the straight amp,with a little gain.
Thanks again for your help.
|5/29/2004 2:03 AM|
I believe one of the channnels uses a 12AT7 (or, maybe, both) for the first preamp tube, as the stock design goes. These amps have a tremendous constituency, especially on both coasts.
|6/3/2004 12:42 PM|
Richie, in KOC's new book TUT5, he has a section on those particular amps. He said not to worry on the high voltage on the 6V6's as they were used in TV's with 1500v pulses on them. I've never seen ones of those amps myself, but I would think if you get some good NOS 6V6 they should be able to handle the high voltage fine.
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