Hey guys,
I was playing guitar tonight and had a strange issue. The volume of my amp (Peavey Prowler) was swelling up and down on its own. Did the usual cable check and whatnot. Also determined that it was only after playing for 10 min or so. From what I've read it seems to be power tube related. Which makes sense.
My amp takes 2 x 6L6GC and 3 x ECC83S. What do you guys recommend. I've never changed tubes in this amp and am kind of looking for advice...thanks for reading / advising.
-Mike-
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Quote from: flanagan0718 on December 09, 2018, 01:49:06 AM
Hey guys,
I was playing guitar tonight and had a strange issue. The volume of my amp (Peavey Prowler) was swelling up and down on its own. Did the usual cable check and whatnot. Also determined that it was only after playing for 10 min or so. From what I've read it seems to be power tube related. Which makes sense.
My amp takes 2 x 6L6GC and 3 x ECC83S. What do you guys recommend. I've never changed tubes in this amp and am kind of looking for advice...thanks for reading / advising.
-Mike-
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I just get whatever I can afford at https://www.tubesandmore.com
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Power tubes are perishable goods, so it could well be that they're starting to fail and need to be replaced (I'd want to be careful to rule out other causes first, though). Your other tubes, on the other hand, can and probably will last for decades. My deluxe reverb still has its original 12ax7s and 12at7s and it's more than 45 years old. The idea that you should replace all your tubes is an old wives' tale made up by sellers to part you with your money.
Replacing power tubes in most amps requires that you bias them. I don't know if that amp is cathode biased or not, or how it's set up. So keep that in mind when you are going to do a power tube replacement.
Personally I like JJs for everything power tube. And for 6L6 I also have used 6L6wxt+ and have liked them. I think... and mind you this is hard to tell... but the JJs I think have more umph.
I wouldn't expect to hear drastic differences between tubes or brands. Most tubes come from the same two or three factories. More "reputable" brands are usually better tested, so you should be less likely to get something out of spec. JJs and Electro Harmonix have both worked fine for me. Definitely determine whether the amp needs to be rebiased. If you take it to a tech to bias it, then you I'd buy my tubes from them.
Big JJ fan here but like ahiddentableau mentioned I wouldn't overlook an iffy solder joint somewhere, or even an oxidized jack. Input jacks and, especially if you don't use them, the fx loop jacks are worth looking at. If you can duplicate it and tap/push the circuit board with a chopstick it might point you in the right direction.
Or like you say it might be tubes... The Prowler doesn't have adjustable bias so buying a matched pair of anything should just be plug and play. It can be modded to include a bias adjustment but having done a bunch of Fender Blues Jr to "open up the tone" (customer's words) I don't know that I'd spend the time or money. Prowler and the later ValveKing's are nice sounding amps.
Thanks for all the advice guys! I've done a bit of research and find that the amp does not have an adjustable bias. I'll definitely open it up and check the solder joints and see if there are any iffy ones in there. Going on the fact that I have owned this amp for 6 years now and never replaced the power tubes, I'm thinking it may be a good idea to just plop a new set in there anyways. There are quite a few options for the 6l6 out there. I've always heard good things about JJ and Ruby. I also found a set of Peavey tubes too. Assuming they are all pretty similar I may go with the Peavey tubes or the JJ like other have recommended. Still looking for input, feel free to post it.
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That's funny, because I'm having the exact same issue with my Vox Night Train 15. I have checked the guitar jack, switched guitars, swapped cables, everything within reason and there is just this odd, seemingly random fluctuation in the volume.
I definitely try replacing the power tubes.
-Mike
Nothing like an easy fix.
Apparently I was even the line with the universe because I pick the right tube on the first try. Awesome.
-Mike
Quote from: Ekimneets on December 10, 2018, 09:21:15 PM
Nothing like an easy fix.
Apparently I was even the line with the universe because I pick the right tube on the first try. Awesome.
-Mike
Nice good to hear!!
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Thx Flanagan, I was pretty happy myself.
-Mike
no adjustable bias?
try contacting the tube vendor about the specific brand of amp you've got for a matched set. this is what the mesa guys have to do if they don't want to buy Mesa tubes and generally tube vendors know this and accomodate. that said, vintage amps rarely had bias adjustment (or even matched tubes) so even if you just end up getting a matched set of tubes you're doing just fine.
Quote from: thesmokingman on December 10, 2018, 10:31:41 PM
no adjustable bias?
try contacting the tube vendor about the specific brand of amp you've got for a matched set. this is what the mesa guys have to do if they don't want to buy Mesa tubes and generally tube vendors know this and accomodate.
Huh this kind of makes me second guess the JJs I ordered. There were those and a Peavey set for 5 bucks more. Maybe I should have just ordered the Peavey ones
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Nope, you'll love the JJ's.
Quote from: gordo on December 11, 2018, 12:00:25 AM
Nope, you'll love the JJ's.
I just pulled the tubes out to have a look at them and it already has JJs in there. Haha
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So replacing the tubes didn't do the trick. After playing for a solid 15-20 min the amp started to to the exact same thing. Any thoughts? Is it possible that there is a cold solder joint?
Quote from: thesmokingman on December 10, 2018, 10:31:41 PMthat said, vintage amps rarely had bias adjustment (or even matched tubes) so even if you just end up getting a matched set of tubes you're doing just fine.
Those were different times, when tubes were more consistent (and more tubes were thrown away). You may get lucky though. In general, it won't blow up, but may not sound its best, which is a pity.
.
Quote from: flanagan0718 on December 18, 2018, 03:19:09 PM
So replacing the tubes didn't do the trick. After playing for a solid 15-20 min the amp started to to the exact same thing. Any thoughts? Is it possible that there is a cold solder joint?
Take it to a reputable tech and get it sorted out. Tube amps can kill, so I would not mess too much with it unless you know what you're doing.
Just a thought... I had this issue with a Laney LC 30 a few years back. Cleaned all valve and jack sockets, especially the effects loop which had been underused, with contact cleaner and it solved the issue. Not sure it will help, but might be worth a pop?
I always take the easy route first if I can. :D
Good luck!
I was emailing with Peavey support and they said the same thing. It may be "connected" Jack. They also said it may be a phase inverter tube 12ax7. I'll try both of these tonight.
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I was going to mention tube sockets as well. How are those set up on our amp...are the sockets soldered to any kind of daughter board? Sometimes if a solder joint on one of those gets iffy, it will start to get intermittent on you when your amp heats up.
Quote from: Bret608 on December 18, 2018, 10:02:24 PM
I was going to mention tube sockets as well. How are those set up on our amp...are the sockets soldered to any kind of daughter board? Sometimes if a solder joint on one of those gets iffy, it will start to get intermittent on you when your amp heats up.
I'll take a couple pictures of the amp while I have it apart tonight. I vaguely remember them being soldered to the main PCB.
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Did you try replacing the phase inverted tube? You mentioned it earlier.
Got it going!!! Here is what I did.
-Cleaned all of the input and output jacks with some Acetone on a Q tip then sprayed compressed air to dry faster.
-Replaced phase inverter tube. I actually had a new 12ax7 hanging around.
-Reflowed solder on the power amp tubes and phase inverter tubes.
Side note I got a "new" set of power tubes from a local guitar shop. He said he had the for 15-20 years or so. He wasn't sure if they were matched or not but they look vintage and sound good in my amp. There is no brand on them, all they say is 6L6GC and that worked for me. Plus he sold them to me for $10 for the pair. That was nice too! Anyway here are a couple pictures.
(https://uploads.tapatalk-cdn.com/20181219/67beff8d8db4de1d802ed8afb9ef55ee.jpg)
(https://uploads.tapatalk-cdn.com/20181219/d0771e5dc355d8df7d64252d63a449fd.jpg)
(https://uploads.tapatalk-cdn.com/20181219/54646d40f39a61b5854bafdbc3ee462b.jpg)
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The internet says those tubes are made by Shuguang Electron Group Corp.Ltd.
Glad you got it working! Nice one.
Quote from: Aentons on December 19, 2018, 03:40:43 PM
The internet says those tubes are made by Shuguang Electron Group Corp.Ltd.
Cool thanks. I may order a new set of JJs and A / B them.
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Cool! Could have been the phase inverter for sure, but I bet reflowing the joints on those sockets made the biggest impact.
It does feel good to be able to maintain your own gear, doesn't it?