Amp losing power ..

Steve Richter · Post by **Steve Richter** » 16 Jan 2000 11:20 pm

I have a fender "The Twin" amp .. it seems to be losing power as the night wears on .. any of you tube amp guru's have any suggestions?

thanks

Steve

Jack Stoner · Post by **Jack Stoner** » 17 Jan 2000 3:19 am

Are you sure it's the amp?? If you have any effects between the guitar and the amp, one of them may be causing it. If you do have effects, try to isolate what is causing the power loss - the effects or the amp.

If it's the amp, there are several general things to look at. Tubes are the main cause, whether it's the 6L6 output tubes or one of the 12AX7 preamps or the driver (either a 12AT7 or 12AU7 - I don't remember). If you have one with a rectifier tube (5U4) it could be the culprit too.

One other thing to consider is the AC line voltage. Many clubs really overload the AC line and a voltage drop could cause some power loss too.

There's really too many possibilites to do a "remote" troubleshoot.

Bobby Lee · Post by **Bobby Lee** » 17 Jan 2000 10:39 am

Turn it off between sets.

Steve Richter · Post by **Steve Richter** » 17 Jan 2000 11:01 am

LOL .. I thought about that this morning. But it's definitely the amp and nothing in the chain. My other amp maitains it's volume.

Donny Hinson · Post by **Donny Hinson** » 17 Jan 2000 5:07 pm

Take it to a technician, and tell him to check the coupling, or bypass capacitors, and also check the plate resistors. Either of these will cause that type of problem if they overheat.

Bobby Lee · Post by **Bobby Lee** » 17 Jan 2000 6:35 pm

I'm serious, Steve. The way I've found to get consistant performance from a tube amp is to turn it off between sets. Not just "Standby" - all the way off. Let it cool down.

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Bobby Lee

www.b0b.com/products
Sierra Session S-12 E9th, Speedy West D-10, Sierra S-8 Lap

Mike Fried · Post by **Mike Fried** » 17 Jan 2000 10:00 pm

While b0b's advice may temporarily fix the power loss symptom, there is a problem there that should be addressed. Donny's recommendation is right on the money.

Jerry Hedge · Post by **Jerry Hedge** » 17 Jan 2000 10:46 pm

Steve, it sounds to me like it could be new output tube (6L6) time. How old are they? If you change them be SURE you change the 12AT7 tube next to them. that's the phase inverter tube, and the only tube in the amp that works as hard as the 6L6s. Also have a tech set the bias if you change output tubes.
[This message was edited by Jerry Hedge on 17 January 2000 at 10:49 PM.]

David Mullis · Post by **David Mullis** » 18 Jan 2000 8:42 am

I thought the Fender "The Twin" was solid state? I know the Twin Reverb is Tube of course but a buddy of mine has one called "The Twin". It looks like a modern day Twin Reverb and his is solid state. Am I wrong?

Jay Ganz · Post by **Jay Ganz** » 18 Jan 2000 8:50 am

Best thing to do is, after the amp is good &
warm (with the loss of volume) have your tech
spray around with an aerosol "coolant" one
section at a time. That will quickly "chill
out" the culprit causing the power loss &
help to identify it quicker if it's a resistor or capacitor. The volume should jump back to normal when he hits it. But obviously this is only if tube substitutions don't do the trick right off the bat.

Steve Richter · Post by **Steve Richter** » 18 Jan 2000 1:36 pm

Bob .. I know you were serious, not sure where I saw the humor. I think taking it in for a checkup is the thing to do and investing in a tube job.

thanks for the tips!!

Steve

Craig Allen · Post by **Craig Allen** » 18 Jan 2000 2:14 pm

You may be experiencing "brown out."

It does happen more often than you might think.

This happens when the venue can't supply enough power/electricity to supply everything in the place.

By all means check your power tubes,(if you have any), but don't rule out brown out.

Rodney Shuffler · Post by **Rodney Shuffler** » 18 Jan 2000 3:53 pm

"The Twin" is a newer tube amp; or the 80's "red knob version". Both are tube and both are 100 watters; most any amp over 45-50 watts isn't going to have a tube recto and that's likely not the problem.

I'd guess caps....tubes never hurt either way. Rod

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Rod's Place www.geocities.com/vibrasonic9/index.html

Tom Ward · Post by **Tom Ward** » 19 Jan 2000 4:02 am

I'd look for a voltage-dropping resistor in the output tube section that slowly changes value after it heats up (sometimes in the screen grid section). If that don't work trade it for a Nashville 400. Tom

Bill cole · Post by **Bill cole** » 19 Jan 2000 7:15 am

When you take it to get it checked make sure they change the fuel filter and chek the catalitic converter if either is pluged you will lose power

Steve Richter · Post by **Steve Richter** » 19 Jan 2000 8:11 am

Are you sure?? I tried to get a pcv valve for it but they swore it didn't need a new one ... didn't even have one listed ..

David Mullis · Post by **David Mullis** » 19 Jan 2000 10:04 am

thanks for the correction, I could have sworn that my buddy that has one of those amps said it was solid state

Rodney Shuffler · Post by **Rodney Shuffler** » 19 Jan 2000 10:25 am

Lemme see if I can do this:

The rest of the info is here: http://www.ampwares.com/ffg/index.html

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Rod's Place www.geocities.com/vibrasonic9/index.html

[This message was edited by Rodney Shuffler on 19 January 2000 at 10:32 AM.]

Bill cole · Post by **Bill cole** » 19 Jan 2000 10:25 am

nope don't remember that year havin no Pcv but it could be the Alternator aint alternatinor the carborator aint carbernatinor may the hootinany slip the whatchacallitand check the roght back wheel and make sure it aint turnin frontward or as my wife alway says. It sound like popcorn poppin

Bill cole · Post by **Bill cole** » 19 Jan 2000 10:28 am

Yep by golly that looks lika amplifier or else it's a heater for my music room and I could sure use one o dem bout now. Hey are we havin fun yet

Bill cole · Post by **Bill cole** » 19 Jan 2000 10:30 am

Hey I think I see the problem you see on the left corner it say fender now don't they belong on cars and trucks

Bobby Lee · Post by **Bobby Lee** » 19 Jan 2000 6:07 pm

Awww shucks!

(drawing by Bob Kosak)

Bill cole · Post by **Bill cole** » 19 Jan 2000 6:49 pm

Darn that not sounds fermillar but it looks that way tooo