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Bad noise on tube amp


BadLife

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I have a Fender Vibrolux Reverb from about 1970 or so. It had been unused for quite some time and I decided to fire it up today. It made a terrible noise for about ten minutes after I hit the standby switch. The power switch had been on for about 10 minutes before I hit the standby. After a while and several on off with the reverb and vibrato it cleared up. Any ideas ? Maybe a tube going out? One of the tubes is original as the new one from the last rebuild blew out. It is probably micro-phonic to some extent.

 

I don't really want to open it up without some idea of what to look for :blush:

 

I posted this in the Ask Myles thread but he seems to have not replied to the last several posts so I thought I would toss it out here in case anyone had any thoughts :ohmy:

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Take it to an amp tech, it might be the capacitors, they do go bad, especially when an amp is left unused for a long time. Good luck amigo. In any case that is a decent amp, so see if you can take it to an amp repair shop.
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Ha Ha yeah that might be a good idea, but I have built amps from scratch so I'll probably do it myself :crazy:

 

I think it's a tube and I know just the one I suspect as the problem was somewhere in the 2nd channel the one with reverb and virbrato and that is where the 40 year old tube is. I may have a new one laying around somewhere so I will try that first. Then yank the chassis and do a visual inspection for any leaking, swollen, burst or otherwise unusual looking parts. Could be a literal bug crawled in there. I am pretty sure what part of the circuit to start looking in and have the schematic on hand. So it's just a matter of discharging the capacitors and not getting zapped :thu:

 

I doubt it's anything except the very old tube as it has been rebuilt and only lightly used since then, but you never know :)

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I would give the caps a chance to charge up if the amp has been sitting for many years...leave the amp on for a few hours. Then I would pull the tubes and check them on a tube checker. Or, you can just replace them with new tubes. Make sure the power tubes are matched and if they are changed, set the bias. I have a couple of tubers out in the garage and this thread is reminding me to go out there and plug them in for an hour. Good luck and I hope you find the problem! Those old Fender Vibrolux amps are worth a pretty penny and would be worth a new set of tubes... :cool:
Take care, Larryz
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Could be as simple as corrosion. Jacks are notorious, check for scratchy pots and get some Caig De-Oxit if you don't have any and do all the tube sockets and tube pins.

 

Fender amps use the chassis as ground so check that ALL the jacks are tightend to clean metal on the chassis. Also check any ground connections from circuts to chassis for the same thing.

 

Little things but they mean a lot. If the amp has been sitting it is time for a bit of house-cleaning. Cheers, Kuru

It took a chunk of my life to get here and I am still not sure where "here" is.
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Could just be dust build up. That will cause hiss and some zaps when the current hits them little bunnies. When I hadn't used my Bassman for a long period of time, I made sure to turn all the knobs several full sweeps, and drop the head from the chasis and take a vacuum/dustbuster to it.

"Am I enough of a freak to be worth paying to see?"- Separated Out (Marillion)

NEW band Old band

 

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Yeah could be dust, but I suspect the old tube its one of the preamp tubes in the second channel. I think it's in the vibrato circuit if I remember correctly. I will pull it and replace. May need to order tubes. It has not been unused all the long a couple of months at most. I fire up all the tube amps every so often to make sure they are working correctly. :cool:
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Probably a tube then. Easy to test and never wrong to have a spare.

 

I've got a stash of vintage tubes pulled from Hi-Fi gear and organs I found at thrift stores.

After selling the amp chassis and speakers the tubes are free or less.

 

I'm down to two tube amps, I never gig with them anymore. SS has gotten good enough and the reliabilty and weight are complelling.

 

That said, I LOVE my 5d3 clone made from a converted Hammond organ with original transformers and my Vox AC-15 top boost channel clone that used to be a hi-fi amp.

Good stuff for a home studio!

It took a chunk of my life to get here and I am still not sure where "here" is.
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Yeah I have a pile of tubes from old tube stuff. Not sure how much I trust them though. I don't play out so all but two of my amps are tube. Those are just tiny practice amps :crazy: Almost got around to replacing the tube. I have more new and NOS power tubes than preamp for some reason :cry: I do have several of the correct preamp tubes that are pulls ;)
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Dang it was a 7025. That's $200 for NOS and I believe anything new labeled that way is just a 12ax7(ecc83) so I popped in a new ECC83 S I had laying around. That fixed the noise at startup but the real problem now it the volume pots. Both channels are extremely noisy is you even touch the knobs :cry: Going to have to pull the chassis and either replace them or clean the crap out of them. Not sure why but it is almost always the volume pots that do this. The rest of the controls are reasonable quite. It may be because I usually set the volume and don't mess with it much :ohmy: Not really sure really. Wonder whats up with Miles? Guess I should check his web site.
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Dang it was a 7025. That's $200 for NOS and I believe anything new labeled that way is just a 12ax7(ecc83) so I popped in a new ECC83 S I had laying around. That fixed the noise at startup but the real problem now it the volume pots. Both channels are extremely noisy is you even touch the knobs :cry: Going to have to pull the chassis and either replace them or clean the crap out of them. Not sure why but it is almost always the volume pots that do this. The rest of the controls are reasonable quite. It may be because I usually set the volume and don't mess with it much :ohmy: Not really sure really. Wonder whats up with Miles? Guess I should check his web site.

 

Remember what I mentioned above about Fender using the chassis as ground. I have a good friend who makes a living as an amp tech and he explained the maintenance regarding that.

You really have to clean all contact points every so often.

 

Organs and Hi-Fis run at lower voltages and put far less stress on tubes than guitar amps do. It won't hurt anythng to try one out of your stash. It may hace a lot of life left in it.

I used to have a few RCA 7025, that was V1 in a ton of Fenders for a long time. Great tube, I may still have one or two but I probably better hang on to them

 

It took a chunk of my life to get here and I am still not sure where "here" is.
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Hum I fired up another old amp and something similar happened. Dang I guess you need to turn them on more often than I have been. It was noisy at startup and the volume pots are again the culprit. This is an old Ampeg VT-22 I have had for a long time. It's also about a 1973 vintage and has been rebuilt fairly recently. After a while most of the noise went away but the channel one volume pot is still a little noisy :mad: I may have to replace those pots but I will have to pull the chassis to see what I need that is a fair amount of work :( Oh well I feel sorry for anyone who collects amps. I read an article In GP about a guy who is know for that sort of thing, but in this case is a popular contemporary guitarist. He had about 15 old amps in his parents basement (that had been there for around 15 years) and wanted something for a new record ( is that what we call it now?) anyway he was only able to find two that actually worked correctly. (GP April 2009) ;)
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Hum I fired up another old amp and something similar happened. Dang I guess you need to turn them on more often than I have been. It was noisy at startup and the volume pots are again the culprit. This is an old Ampeg VT-22 I have had for a long time. It's also about a 1973 vintage and has been rebuilt fairly recently. After a while most of the noise went away but the channel one volume pot is still a little noisy :mad: I may have to replace those pots but I will have to pull the chassis to see what I need that is a fair amount of work :( Oh well I feel sorry for anyone who collects amps. I read an article In GP about a guy who is know for that sort of thing, but in this case is a popular contemporary guitarist. He had about 15 old amps in his parents basement (that had been there for around 15 years) and wanted something for a new record ( is that what we call it now?) anyway he was only able to find two that actually worked correctly. (GP April 2009) ;)

 

Even playing them often does not ensure reliability.

 

Over the decades I've owned 9 Mesa, 4 vintage Fender Tweeds, a pair of Champs with consecutive serial numbers, a Bassman 70, a Rivera era Fender Concert, an Allen Accomplice, a Red Plate Blues Machine and who knows how many random vintage tube amps from Valco, Danelectro, Kay, Gibson, Orpheus etc.

 

The Red Plate was the last tube amp I gigged with, played a bunch of gigs and it sounded great. Brought it to a New Years Eve show and all of a sudden it sounded really weak and just not good. I had no options so I used it mic'ed into the PA. When I got it home one or both of the output tubes had "changed" and it needed to be re-biased which took about 10 minutes since you have to do it at operating temperature.

 

So I sold it and switched to solid state for gigs. I hardly use amps at home but my Roland Cube 40 or Peavey Vypyr VIP 3 both have great tones if you dial them in correctly. They can also sound terrible but I got some terrrible sounds out of tube amps too, especially Mesa because they are very versatile and the tone and gain knobs are very interactive so one tweak can change everything. I've developed a good ear for tweaking stuff, eventually I'll find something good from just about any amp. Most of the time the component that makes the biggest difference is the speaker. Lots of great amps have less than great speakers and we may dismiss something really nice because the speaker is crap. My latest version Peavey Envoy had a 10" Blue Marvel speaker in it that failed to inspire. I shoehorned a 12" Scorpion in there and it is a different amp, very useful.

 

I am keeping my last 2 tube amps at least until I have a chance to test all of my vintage tubes. Then maybe I'll sell everything and just go with reliable. The best amp is one that works!!!!!

Cheers, Kuru

It took a chunk of my life to get here and I am still not sure where "here" is.
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Even playing them often does not ensure reliability.

 

So I sold it and switched to solid state for gigs.

 

I am keeping my last 2 tube amps at least until I have a chance to test all of my vintage tubes. Then maybe I'll sell everything and just go with reliable. The best amp is one that works!!!!!

 

+1 :yeahthat: I'm selling my last 2 tube amps too!

 

Take care, Larryz
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I'm selling my last 2 tube amps too!

 

I have been trying to sell my Hot Rod Deluxe for several years, no bites. I put it up on Craigslist every Friday and take it down on Monday, so far no bites. (Other than low ball offers) If I do sell it I am going to buy another Egnater Tweaker 15 watt head, or some little road amp that will play my backing tracks. So far A Roland Street Cube or Street Cube EX.

 

I liked the Blackstar Super Fly a little more, but no pedal for changing from clean to overdrive, just a app for the i-phone to change channels via Bluetooth. I ain't taking my hands off of the guitar to do channel switching so that one is out of the running.

 

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DBM, I think you'll like the Roland EX Street Cube 50. Grab your mic and a guitar and the Cube and you're out the door. If you need OD on and off, just run your Blues Driver with the guitar instead of channel switching (I run my Boss Compressor)...I think going SS is a good idea and the Roland is clean, dependable and with no buzz...if you get around a GC give one a try. For small venues I would just take the Roland. For something bigger, I will pack my Fender SS amp with me as well. :cool:
Take care, Larryz
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I am liking the Street Cube. it is tiny it has channel switching, it is only 5 watts and has smaller speakers but for road trips up north, and for driving trips to vacation spots, all I need is an amp with foot-switchable channel switching and a headphone out put so there is no loud playing in confined spaces. Otherwise I will pull the trigger on another Super Champ X2 which has all the effects, foot-switchable channel switching, plus it is gig-able for small rooms, no mike/line but it kis all I need for road trips to practice guitar., I also have blue-tooth speakers and my MP3 player will play via blue-tooth. (I have a pair of Jam 2 blue-tooth speakers that my brother in law gave me a few years back and they work well). https://www.amazon.com/Portable-Speaker-Incredible-Rechargeable-HX-P240GY/dp/B00BYRPPHQ
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@ DBM, Those are cute little speakers. They would work well in a motel/hotel room at TV set volumes.

 

@ Kuru, +1 on swapping out speakers and giving a tube amp new life. Also, if getting bad noises, checking the speakers and connections is another consideration when trouble shooting. The only failure I have had on a tube amp was the input jack took a crap. On one of my Fender tube amps I bought used, I could see that one of the input jacks had been replaced as the hardware didn't match. The jacks can cause noise issues and failures and are an easy fix.

 

:cool:

Take care, Larryz
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@ DBM, Those are cute little speakers. They would work well in a motel/hotel room at TV set volumes.

 

The JAM2 speakers are remarkably loud, And the fidelity is excellent. They could easily drown out my unmiked vocals, and I sing fairly loud.

 

Plus the speakers are small and easy to transport. No wires needed, my MP3 player finds them in seconds.

 

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I think they would be great little traveler speakers. I was thinking that in Hotel/motel rooms you would probably keep the volume levels down to TV set volumes to keep security from knocking on the door. In other locations you could crank them up. My un-mic'ed voice is pretty soft and I prefer singing through a mic even at low volumes. I can sing over an acoustic guitar but I don't like having to strain my vocal cords. One of the few rules I have when playing with others ( or in bands), is everyone has to stay under the vocals unless they are taking a lead. :cool:
Take care, Larryz
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