Marshall JCM 2000 is making strange noises

[Securb]

Wow. I envy you both. For having one and for knowing how to use one properly. Best I can do is throw one in my Picovalve and play it. And if it starts acting weird, I know that it's on it's way out. Oddly enough, tubes sing a swan song. Right before they die, they tend to sound the best that they ever have. Then within a week or so, bloop.

As I said it takes a minute to figure out how to use it. There is a book that lists all of the tubes. It reminded me of the wiper blade books in the auto parts store. You look up the tube and there is a series of numbers next to it. You dial in the numbers on the corresponding knobs, the model I used the last number was the tube socket to use. You pop in the tube and wait for the heat light to indicate you are good to go then you hit the test button. Then it reads good, bad, and medium on the meter.

The interesting thing for me was my bad tubes heated up and lit up but both of the GT tubes failed. The 12XTs that passed were a Solvtek and an EHX. I ordered a quad of Mullard 12XTs that should be delivered this week to replace them all. Next time you need to check a tube do what I did and hit your local old-school TV repair shop. The one I went to also sells new and NOS tubes.

[Demanic]

If I put an unknown tube into my Picovalve, I can tell if it sounds musical or like it's going to take a crap. Had a JJKT77 that started farting out and distorting at clean levels. Retired it.

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So this chapter seems over. I put in 4 40-year-old Sovtek 12AX7s, and the amp sounded great at practice. All of my low-register chords sounded crisp and chugged. My bass player's amp would sound like a theremin when he moved the cable. We ran an extension cord to another gang box across the room, and his issues are gone. The voltage meter is on the PA and was bouncing between 115v - 117v during practice without the heat or AC on. It is something I guess we will have to keep an eye on. For now, everything is sounding great.

[Demanic]

I wish that I could have heard a full practice. It's a good room.

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I picked up one of these voltage meters so I can monitor the juice as different gear is being used and the heating is kicking in. It was $9 on Amazon

I want to bump this and suggest you guys spend $9 and pick up one of these meters. We lost heat in the studio so my bass player brought up some space heaters. When I turned on my Marshall it was at a whisper fully cranked. I looked at the meter and it was reading 111v. We turned off the space heaters, the voltage returned to 118v, and all of the amps started operating normally. The voltage meter solved a bit of head-scratching. it is going in my gig bag for all gigs.

Side note the heat is getting fixed tomorrow.

[JMP/HBE]

Forget $9 amazon volt meters you want a "voltage regulator" i got one for $100 bucks.

https://www.ebay.com/itm/385208727704?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=385208727704&targetid=1263094004346&device=c&mktype=&googleloc=9022894&poi=&campaignid=14859008593&mkgroupid=130497710760&rlsatarget=pla-1263094004346&abcId=9300678&merchantid=6296724&gclid=Cj0KCQiA99ybBhD9ARIsALvZavXK6fIjHwl9EthPoOAmyPzXdNkK0TDoAljRj92ApORUteCDXxf3OZwaAqXmEALw_wcB

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We have a few of them. Samson, Furman, and others. The one on my bass player's amp was reading 119v, it was only the $9 amazon plug that gave us a true reading of 111v. If someone is a gigging musician, these plugs are invaluable. The power draw at soundcheck could be much less than when the club is in full operation, and everything is drawing power. It is also easier to move one of these $9 units around the stage or venue and monitor different outlets.

[JMP/HBE]

Line voltage can easily fluctuate +/- 9VAC or more and thats very common and should not effect normal operations.
Im not sure what you are trying to achieve.
a VOLTAGE REGULATOR ensures a steady 120VAC.
A VOLTAGE REGULATOR is not the same as a regular POWER CONDITIONER.
It just sounds like your obsessing over voltage readings in order to prove to yourself that you are right each time you gain or drop a volt.
Isn't this thread 2 months old already ?
FWIW USA Standard wall voltage is 120VAC. If your wall voltage is only 111 your house wiring is jacked.
But if your bass player has 119 and you have 111 that don't jive.
And amplifiers AMPLIFY or step UP voltage amps themselves are not a huge current draw unless you got bad power tubes.

[Securb]

Oh, man. I am not looking for any help or advice. I found a tool "that works for me". I thought others could get use from the same tool. It is $9, not a heavy financial lift. I am just suggesting something other musicians might want to throw in their gig bags. I returned to the tread to say I am happy with my purchase and I am finding the tool to be useful.