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FDP Forum / Amp Mods, Repairs, and Projects / Could house voltage problem cause my tube amp to lose volume and cut in and out?

Tinkerer
Contributing Member
****

San Diego, CA USA

Oct 16th, 2018 10:58 PM   Edit   Profile  

The band that I am in practices at one of our band mate's homes. Twice now in the last few weeks, my amp (a Monoprice 15/1 W tube clone of a Laney amp) will just drop volume, almost completely cut out, and make sound intermittently. This also has happened once with a Bugera tube amp that I was previously using. I always set up in the same spot in the room and plug into the same outlet.

The odd thing is that when this has happened, I switch and use a solid state Roland amp that my band mate has, and I have experienced the intermittent volume drop through that as well. I change cables, plug direct into the amp rather than through my board, etc, but the intermittent problem remains for that night. When this has happened, I bring my entire rig home to try and trouble shoot and the problem never occurs at my house. The total 3 times this has happened were separated by weeks where I did not have any problems.

This leads me to wonder if there is an intermittent issue with the voltage at my band mate's home. Could this account for these kinds of problems? I have ordered an inexpensive line voltage meter to plug into the outlets to see what is going on, but are the other things I should look into? If it is a voltage problem, am I doing damage to my amp?

Thanks!!

(This message was last edited by Tinkerer at 11:07 PM, Oct 30th, 2018)

Leftee
Contributing Member
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VA

Oct 17th, 2018 05:39 AM   Edit   Profile  

I think your initial steps are good. While annoying, if it is brown-outs, I doubt they would hurt a tube amp.

Peegoo
Contributing Member
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They warned you

about me in Bible school
Oct 17th, 2018 08:31 AM   Edit   Profile  

Low power (voltage and/or current) doesn't hurt things. It's the high stuff--voltage spikes--that can and sometimes do blow up amps.

Make sure the fuses in your gear are all the correct rating (amperes) and type (slow/fast) for the equipment they're in.

I've worked on a bunch of amps, and a small percentage of them had fuses in them that were over the spec'd rating. In one instance the owner admitted the spec'd fuse was popping too often.

Yeah, THAT'S a good fix.

Leftee
Contributing Member
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VA

Oct 17th, 2018 08:39 AM   Edit   Profile  

The other thing I was going to ask is, what else is on that particular circuit? Maybe an old, worn out fridge that, when it kicks on, drags down the voltage?

My long distance guess would be to hunt that situation down, whatever it is.

This from your description of the issue. Me on the other side of the country. (-:

SonicBlue

Sunbury-on-Thames

Oct 17th, 2018 10:22 AM   Edit   Profile  

The first thing I'd be checking is the wiring to the power socket, making sure the terminals are done up nice and tight and that the actual socket itself still has sufficient spring to make good contact with the plug.

It goes without saying you MUST make certain the house fuse to this particular socket has been removed and is in your pocket, if you or your friend are going to have a look at it.

Tinkerer
Contributing Member
****

San Diego, CA USA

Oct 17th, 2018 10:58 AM   Edit   Profile  

Thanks everyone!! I will inspect the amp fuses, and will be able to check the wiring situation further when I am at practice next week. My line voltage meter should arrive by then.

Tinkerer
Contributing Member
****

San Diego, CA USA

Oct 30th, 2018 09:16 PM   Edit   Profile  

Update

I took the amp back to practice last week and it worked fine. At practice tonight, however, the problem repeated- dramatic loss of volume and "blattiness" to the sound. I checked the house voltage- it was 117V, I plugged into a different outlet but the problem persisted. I checked my cables, turned the amp on and off, and switched between the 15 watt and 1 watt settings' and back to the 15 watt setting. When it is working, I use it on the 1 watt setting and at volume set at 3 and gain at 2 to 3, I can hear myself fine. When it was acting up tonight, I had to really turn the volume up to hear. This continued for maybe 20 minutes, then the amp was working fine again.

I would appreciate any ideas about what might be going on, and how to address. The amp has (2) El84 power tubes, and (3) 12 AX7s for preamp and reverb.

Thanks!

(This message was last edited by Tinkerer at 12:41 AM, Oct 31st, 2018)

Peegoo
Contributing Member
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Beside the

fly-pecked black doorway
Oct 31st, 2018 12:57 AM   Edit   Profile  

Is it possible the issue is a heat-related problem in the amp?

I ask because at band practice, you're playing for an hour or more at a loud volume. When you take the amp home and plug it in to attempt to replicate the problem, the amp is not running at the same volume level for the same amount of time as band practice.

Clean and tension the tube sockets to start, and see where that takes you.

(This message was last edited by Peegoo at 02:58 AM, Oct 31st, 2018)

Tinkerer
Contributing Member
****

San Diego, CA USA

Oct 31st, 2018 07:11 AM   Edit   Profile  

Hi Peegoo, the problem has always occurred earlier in the practice session, and I have wondered if a symptom that happens when things are "colder" suggests a particular component? When this happened with this amp 2 weeks ago, and I brought the amp home to troubleshoot, I left it on for hours, and checked it periodically to see if the problem was occurring and everything was fine.

Does this info help point to a particular component?

I have contacted Monoprice (the amp is less than 6 months old, and only gets used for 2 hours once per week at practice) to see how warranty applies to this. I want to get this sorted out- when the amp is working right, I am very happy with its performance.

I will pull the tubes to clean and retention- thank you!!

(This message was last edited by Tinkerer at 09:11 AM, Oct 31st, 2018)

Leftee
Contributing Member
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VA

Oct 31st, 2018 09:50 AM   Edit   Profile  

Can you play it exactly as you would during rehearsal at home?

The ringer in this whole situation is that his amp acted up, as well.

Peegoo
Contributing Member
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Beside the

fly-pecked black doorway
Oct 31st, 2018 12:48 PM   Edit   Profile  

Turning the amp on and leaving it at idle does not get it as hot as playing the thing at practice volume.

I mentioned this because loose tube sockets can cause intermittent issues like this--they are often temperature dependent.

Another possible temperature-related cause might be a poor or cracked solder joint somewhere in the circuit.

These intermittent problems can be maddening.

Tinkerer
Contributing Member
****

San Diego, CA USA

Oct 31st, 2018 05:41 PM   Edit   Profile  

Another update- I called Monoprice this afternoon, and they are sending me a replacement amp. They emailed me a return label for FedEx and will send the new amp when they get the old one back. I just dropped it off at FedEx.

I like this kind of customer service!!

Leftee
Contributing Member
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VA

Oct 31st, 2018 06:14 PM   Edit   Profile  

Excellent!

Peegoo
Contributing Member
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Beside the

fly-pecked black doorway
Oct 31st, 2018 08:08 PM   Edit   Profile  

Well that is outstanding.

I've never ordered from Monoprice.

stratcowboy
Contributing Member
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*****

USA/Taos, NM

Oct 31st, 2018 08:58 PM   Edit   Profile  

Once they get the defective amp back, it would be interesting to see if they give you a follow up report detailing what it was all about.

Tinkerer
Contributing Member
****

San Diego, CA USA

Nov 16th, 2018 09:28 AM   Edit   Profile  

Update- I received my warranty replacement amp- tried it out at home by plugging straight into it- everything good. I then took it to practice this week, and plugged my pedal board into the effect loop jacks and no sound!! I brought the amp home and did a bit of research online, and found references to the possibility of the effect loop jacks being dirty or not switching properly. I sprayed some contact cleaner into both jacks, plugged and unplugged into them a bunch of times, and everything is working properly again. I have been playing it since, both straight in, and through the effects loop with a jumper cable and there have been no other problems.

Anybody had this kind of thing happen before with a new amp, and if so, how "confident" should I be about the no sound issue being resolved?

Thanks!

FDP Forum / Amp Mods, Repairs, and Projects / Could house voltage problem cause my tube amp to lose volume and cut in and out?




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