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Discussion Starter #1
So, I bought a used one last week and got to give it a real go during rehearal today It started out alright, but after an hour to hour and a half I noticed that the sound had gone from the usual chimey/punchy to quite crunchy and substantially less bright sounding. I hadn't changed the volume at all, it stayed at about 3 or so the whole time.

I've never had a tube amp do this on me before and suspect it's because the power tubes need to be replaced and rebiased (and possibly a preamp or two).

Now, the only thing that I know isn't working at it's best is the rectifer tube. When I tried it out in the store I noticed that the rectifier tube was buzzing a little bit when bassy notes were hit and they have a replacement one on order for me. Is it possible that a failing rectifier tube could cause a problem similar to this?

I'd really appreciate some input on this. Thanks. :banana:
 

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Discussion Starter #3
mandocaster said:
A failing rectifier tube could get downright ugly! Maybe don't play it until the new one arrives.....
Yeah, I wasn't planning on it. The tube should arrive this week anyway.

Now, I'm not totally certain it's failing because I'm no expert on tubes, but like I said- it was buzzing like something was loose in it so I assumed it was on its way out.
 

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Discussion Starter #4
Other than this problem........... what a freakin' fantastic sounding amp. Just beautiful.
 

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Discussion Starter #6
The amp has worked wonders on my sound. It really allows my SG to shine. Tons of definition and none of the muddiness that can sometimes creep into the SG tone when run though a slightly darker sounding amp. My previous amp, the Peavey Classic 30, really did the SG no justice. It did, however, sound great with my Strat, which makes sense because it's a more piano-y sounding guitar to begin with.

Anyway, enough gushing. I'm just glad I bit the bullet and bought the Deluxe Reverb. It's lived up to its own legend and more.

Okay- just a little more gushing. 22 watts? Totally enough to compete with a drummer. We were rehearsing in a small room with three guitarists, a bassist and a fairly loud drummer and there were no problems at all. Volume at 3 the whole time. I have no idea what kind of rocket launch decibel levels some people play at that they think this amp isn't loud enough. And we were quite loud.

Okay, that's really the last of the gushing. Haha. Time for bed.
 

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Drool Drool Drool Drool

Wasn't it you with all the handi-wipes a while back?

That's OK, I have a vintage Super Reverb which is a gusher as well.

So what if I have to wear a raincoat when I play.
 

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Discussion Starter #8
I used to have a Super Reverb. It got stolen while on tour though. That really sucked.
 

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Yeah, suckage indeed. My Dean Markley 400B with cab is among the AWOL as well. Odd amp, but super clean at low volumes, great for acoustic instruments.

Sigh.
 

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nine said:
Other than this problem........... what a freakin' fantastic sounding amp. Just beautiful.
Agreed, great sounding amp to be sure. I just got one last week from a friend of mine who purchased it last year. It's basically new. The only problem I'm having with it right now is that during a couple of hours of playing time, the sound will cut out once or twice. When it does, flipping the standby switch on and off brings the sound back.

It's been in shop once already for this, but whatever is causing it the problem couldn't be found since it's intermittant and didn't cut out. I will get to the bottom of it though hopefully sooner than later.

Lawrie
 

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Sounds as though the standby switch itself might be at fault....it sends the high voltage to the power tubes when turned on, and the sound would cut out if that voltage is interrupted.
 

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mandocaster said:
Sounds as though the standby switch itself might be at fault....it sends the high voltage to the power tubes when turned on, and the sound would cut out if that voltage is interrupted.
I'm thinking the same thing. I didn't have a chance to play last night, but I'm going to give it a workout this afternoon for a couple of hours. If it cuts out, before I flip the standby switch, I'm going to plug into all the various channels to see if that has any effect. If the sound is still off, I'm going to check to make sure that all the tubes are lit (as suggested by someone else). Assuming they are, I'm going to flip the switch. If the sound kicks back in, which it has done in the past, then I would say the switch itself may be the culprit. If there's anything else that I should be looking at while the sound is off, please let me know. The more info I can give the tech when I take in for repair, the better.

Lawrie
 

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mandocaster said:
Sounds as though the standby switch itself might be at fault....it sends the high voltage to the power tubes when turned on, and the sound would cut out if that voltage is interrupted.
Yeah, it could be the standby but this amp is really new. It normally takes a few years for the switch to go wonky.

I just dakked over to SchematicHeaven to refresh my memory of the circuit. From the symptoms described I'm not strong on it being a tube, even the rectifier.

Of course, you should ALWAYS swap in a new tube as the first test! It's quick and easy. Many times I've wasted troubleshooting only to find it was a tube all along. Still, I got a hunch it's something else.

My money's on a bad coupling cap! If a cap goes leaky it lets unwanted high voltage from the previous stage pass through with the signal to the next one. This voltage slowly screws up the action of the next stage.

Caps often will start up fine and then start to leak over the next hour or two. If it happens in the preamp the volume is ok but the tone will go sour.

If you look at the tubes when the amp is screwing up see if the outside plate in the tube has any orange or red glowing spot on it. This is a sign of the bias on the tube being overridden by the leaking cap and the tube is jammed full on and starting to cook itself. If you remove the shields from the preamp tubes you can see the same thing. I'm not talking about the normal heater glow from the top and bottom but the actual outside plate surface that you see through the glass. Remember there are two separate sections in the preamp tubes.

The rectifier doesn't use bias of course but if there's a much bigger than normal current draw its plates can start to glow as well.

If it were on my bench I would put a meter on the bias voltage/output tube grid feed splitter point and let the amp cook for an hour or two. If the voltage won't stay steady that's a sure sign.

The coupling caps are cheap and it wouldn't hurt to "shotgun" change 'em just in case, either. Why charge the player for hours of time checking each individual cap when $10 will eliminate the couplers as suspects in 10 minutes of labour?

The fact that snapping the standby resets the problem is also telling. It resets the charge on a failing cap, letting it start off ok again.

Finally, the re-issue DRs I've seen are not hand wired but rather printed circuit board, as I recall. If so, I'd flip the board over and touch up every solder joint. Printed circuit boards are notorious in tube amps for getting intermittent problems after a few years (like the few years after the warranty is over!). The constant heating and cooling from the tubes causes the solder joints to "flex" as they expand and contract, causing them to go flaky. The board was almost certainly originally soldered by a wave-soldering machine process. You could have a weak solder spot right from the factory that shows up in just a short time.

Now that I've listed the scary stuff, by all means try the tubes first! If it is a tube it's 90% likely to be a 6V6. Preamp tubes only handle signal and don't wear like output tubes. I've seen 50 year old and more 12AX7s still going strong. Often when output tubes get near the end of their life they start up ok and then crap out as they get good and warmed up, just as you describe.

Despite this problem, you chose perhaps the best sounding of all Leo Fender's designs!:rockon:
 

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Discussion Starter #15 (Edited)
Wild Bill said:
Finally, the re-issue DRs I've seen are not hand wired but rather printed circuit board, as I recall. If so, I'd flip the board over and touch up every solder joint. Printed circuit boards are notorious in tube amps for getting intermittent problems after a few years (like the few years after the warranty is over!). The constant heating and cooling from the tubes causes the solder joints to "flex" as they expand and contract, causing them to go flaky. The board was almost certainly originally soldered by a wave-soldering machine process. You could have a weak solder spot right from the factory that shows up in just a short time.
This was my guess as well (for Lawrie's problem, not mine). When I was researching the amp, I found a few mentions of people having to get this issue fixed.
 

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Discussion Starter #17
Just to revive this thread, I replaced the rec tube on Saturday and the amp did the same thing on Sunday (less treble and gets more and more crunchy as practice goes on), so I've brought the amp to get retubed and biased. Hopefully that solves it. I'll update the thread after I get the amp back and have another band practice.
 

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The number one problem with tube amps is the tubes(go figure).They don't make them the way they used to in the 50's,but there are some current production tubes that are good.The quality control is the issue these days with tubes being made in Russia and China.
The Reissue Deluxe Reverb is a good sounding amp to be sure,but it has it's faults.One being a quite thin circuit board and the other being the quality of the components on that circuit board.They cut corners to keep costs down and do stuff like using 1/4 watt resistors where 1/2 watt resistors were originally.All to save a few bucks on each amp,and that adds up to bigger profits in volume sales.Numbers crunching at it's best.
But all in all,a far better amp than a Hot Rod Deluxe.
One thing that will bring out the real tones lurking in the Deluxe is the bias.Get your tech to bump up the bias to a reasonable level.The stock bias from the factory is set so it doesn't eat those cheap tubes they put in there.
They actually put some great speakers in those reissues too.I really like the Jensen P12Q in a DR.Nice!But a P12N kills it,if you can believe that!
Your problem sounds suspiciously like a power tube on it's way out.Hope it works out for you.

www.claramps.com
 

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nine said:
Just to revive this thread, I replaced the rec tube on Saturday and the amp did the same thing on Sunday (less treble and gets more and more crunchy as practice goes on), so I've brought the amp to get retubed and biased. Hopefully that solves it. I'll update the thread after I get the amp back and have another band practice.
I guess these amps are a work in progress. In the interest of continuing a DRRI thread, since I originally posted my "cutting out" problem, my amp has yet to cut out after a weeks worth of playing. Hopefully it's good thing. Here's some interesting reading on the DRRI that you (and maybe others) might be interested in;

http://waynereno.com/Introduction.htm

Lawrie
 

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Discussion Starter #20
Fajah said:
I guess these amps are a work in progress. In the interest of continuing a DRRI thread, since I originally posted my "cutting out" problem, my amp has yet to cut out after a weeks worth of playing. Hopefully it's good thing. Here's some interesting reading on the DRRI that you (and maybe others) might be interested in;

http://waynereno.com/Introduction.htm

Lawrie
I've seen that site. While the work and results are very admirable, it's not really much of a mod. They built a completely new amp and stuck it into the old shell. Probably cost a small fortune as well.

I'm sure it sounds great though.
 
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