Trem-O-Verb Issues/Possible Concerns-NOT SOLVED!!!!!

[Critter]

So I just recently bought a Trem-O-verb and all in all its great. It seems to be in fantastic shape and performs well with one exception that I am not sure if its actually something to be worried about or not.

When I bring the TOV from standby (which is obviously dead silent) there is a "hum". It seems to me this is normal tube amp hum and nothing major. However a few observations (these are all with NOTHING plugged into the amp. Its just On:

1. The "Bold" power option makes the hum more noticeable.
2. The hum is also more noticeable when using the "Diode" rectifier option over the Tube rectifier.
3. Different outlets in my house make no difference (which may mean nothing. I may have to test on a completely different source).
4. Turning the gain up makes the hum more pronounced
5. When I do plug a guitar in and start playing, the hum is not noticeable.
6. Also, the sound seems to be coming from the near the transformer, from what I can tell. But honestly, this could be an aural illusion and I am just hearing it amplified in the speaker.
7. One other weird anomaly, when I touch the Gain knob on the Orange setting, I can hear it in the speaker, similar to touching a microphone. Not loudly at all, just a faint little noise. But it does not happen on any other knobs switches or the Red channel at all. It sounds like when you guitar cable is plugged into the amp and not your guitar and you touch the end of it with your finger.
8. If I touch the Gain knob and leave my finger on it, the Standby switch does the same thing, but only if I am touching the Gain knob at the same time. No other knobs do this and the Stan-0By switch does not do it unless I am touching the Gain knob.

I do not know how old the tubes are or the amp since I bought it used. They could be stock for all I know. My goal is to have it re-tubed completely as soon as possible, but that may not be until after the holidays.

So is this normal? The only real thing that concerns me is the Gain knob acting as a mock microphone. I called Mesa and they seemed helpful with something in regards to that issue but mostly had no other advice other than have a tech look at it.

Thanks in advanced.

 

[Critter]

New discovery: If I touch the Standby switch first there is the sound but then I do not get it on the Gain knob at all. If I touch the gain knob first, both become heard through the amp when touched.

Maybe a ground issue? The ground switch does nothing wither, by the way...

 

[Critter]

OK one more update....

The possible "ground" issue is only occurring in the Orange channel. The strange thing is if I switch over to Red once or twice, then switch back to the Orange channel, I can no longer get it to do it for a few minutes. Its fine for awhile.

I am starting to think it is a bad pre-amp tube as it is only in this one channel that the Gain and Standby knobs have a "microphone" type thing going on. Plus I do get some minor microphonics.

I still haven't ruled out though a faulty ground somewhere and the "hum" is still present (though I am thinking new tubes and a Furman power conditioner would help these situations as well).

Any and all advice though is welcome, though I'm no stranger to tube amps and can do general maintenance and what not as all guitarist should, I am by know means and amp or electronics expert. far, far, from it (though I am learning).

 

[Critter]

Solved!!! So As I stated I bought this new. I feel like a real as right now, but am somewhat happy. I checked everything over, so I thought. After banging my head against the wall and expecting the worse I noticed one small detail;

The Speakers were plugged into the 16 OHM port and not the 8 OHM! I can't believe I missed that!,. Anyways, dead silent now, no hum, no weird microphonics and no weird ground type issues!

I just hope nothing was damaged long term because of this. It seems the manual said at most the power tubes would wear out faster. I was planning a re-tube anyways.

God I hope this solves everything now.

 

[Critter]

So the effin' hum is back. :evil: :? :x

I really hope a new set of tubes fixes this. I would really hate to have an amp tech have to service it after only owning it for a week. :x

Again, any advice or experience with this would be so very helpful....

 

[jared]

Any tremoverb I've owned, head or combo, was always a problem. It's a shame because in concept it's a great amp, and for when they actually worked, they were killer.

Even the "tech" that the last one "got sent out to" for "new tubes" and numerous knobs not responding properly, and some humming, basically gave it back to me with all JJ's but none of the actual problems fixed. I know how to change tubes, thanks.

Careful to anyone else thinking of getting one. You might be in for some surprises.

 

[Chrissmoth]

I had the exact same problem on my Subway Blues - only it was all of the pots - not just one

I went through the pots with a meter - you would assume that they are grounded by the chassis - but they weren't

I can only put this down to the paint on the chassis acting as an insulator and preventing a solid ground connection.

I soldered ground wires to the back of all of the pots and connected them all to a single point (ground)

Problem solved

You might also want to replace the input jack with an insulated one - this can help enormously reducing hum.

 

[Commander Coo1]

my t-verb also has a hum, its a 94 but the entire circuit board and all of its components were replaced by mesa about a year ago . where can i get an insulated input jack?

 

[1vic1]

mine hummed like a ***** bold diode makes it worse cos their for high power my red channel modern was insane for loud humming

 

[Critter]

So after a complete re-tubing (which was a pain in the *** as half the pre-amp tubes were either dead on the spot or severely microphonic. Thanks Guitarget (Guitar Center)! I should have known better but I needed the tubes quick like...I really was hoping thwe hum was due to bad tubes (they had NEVER been changed by the previous owner. Its a 2000 TOV, I believe...)

Anyways, the hum is still there. I have a few more things that have narrowed it down:

1. It seems to be in the power section. The the FX loop setting turned to anything other than Bypass, there is no hum (and again the hum is independent of the volume. It stays at a constant 60 cycle.). But if I put it on Bypass, there is a hum when off of Standby, the hum is there again regardless of the master volume.

2. The Channel Cloning option of "Orange to Modern" makes it worse. As do the Diode rectifier setting, the Bold power setting and the Modern channel. these all increase the hum by a few DB's.

3. The hum happens using the Slave Out, so again, it seems to be in the Power stage of the amp.

4. The Presence knob on the Orange channel increase either the hum itself or its noticabilioty as well as the Reverb on both channels. This again makes me think its in the power stage as the Presence on the Orange channel is tied directly to the power stage where the Red is not (Mesa'a manual).

5. The Tremolo effect, when on turns the hum o n and off. Example; set the Tremolo to a high rate and depth and you hear (hum, no hum, hum, no hum, hum, no hum, etc).

Anyways, time for a tech to take a look at it for me....

 

[Commander Coo1]

my tverb does the same thing that your last post described. similar hum on cleans and dirty, tremolo turns it off and on, increases with reverb... i dont like it but i just ignore it because as soon as i play a not i cant hear it

 

[nyeguy]

Same problem here! Just jumped on here to see if anyone else has this hum and a solution! Mine is a 93' or '94 ToV and ive played the **** outta it since i bought it new. Started gettin some "motor boating" a few years ago and now its a loud hum! Thinking about changing the filter caps since its 15yrs old now. It may be a grounding issue somewhere, when i get time(someday...) im gonna go thru it and see what happens. If anyone can point us in the right direction, please post! Just started a new band and need my MESA!!!

 

[jakehop]

Hi guys,

I own two ToV's that I love with all my heart. But as complicated as they are, there are a couple of problems that you need to know how to identify and address.

My newest also hummed bad from the transformer. I had it shipped from the US to Denmark where I live, and it turned out that one of the transformers windings had been kicked loose from the trip over here. I was replacing the mains transformer with a 230V model anyways, but I wanted to use the old one for something. My solution was to remove the transformer from the amplifier, get one of those metal bands you use to secure plastic tubing to metal studs, tie that around the transformer TIGHT and then pop the whole deal in a toaster oven at 70C (about 150F) for a couple of hours. It was the lowest setting the oven I had would turn on at, and I was careful not to let any of the wires touch the heating filaments in the oven. After aprox. 6 hours of "toasting", I carefully removed the transformer from the oven (remember, it's hot!) and let it cool till the next day. That removed the mechanical hum the transformer had.

However, yours doesn't sound like mechanical hum, as it gets louder as you turn up your amp. The fact that turning on the effects loop removes the hum tells us, that the hum is placed in the preamp. I had a problem like this on my older ToV which was a european model. I don't think the amp had a proper center-tap for the heaters. I solved that problem by tying two 100 ohms-1W resistors, one on each side of the heaters, to ground. That made that amp silent like the dead of night!

There are more problems that needs attention in these amps IMHO. I get by my economics studies by working on amps in my spare time, so I have some knowledge about how they work. This is my lowdown of things to be ware of:

Older ToV's are especially tricky, as they can get several types of problems, sometimes all at once:

-> The LDR's for channelswitching sometimes die out, sometimes all at once. They are a pain to replace, but most VACTROL-types can replace them without problems. Don't be too anal about getting the exact types Mesa used. The VACTROL's I used were about 5-8% off from the Mesa's, which themselves drifted ~10%. I actually believe that Mesa uses VACTROL's, so that's one less hassle to worry about.

-> Some older Rectifiers (incl. ToV's) share the same tap for the bias-circuitry as well as the switching- and tremolo circuitry. The latter two circuits are isolated by a large 10W resistor, that get's VERY hot. As it gets older, white dust starts falling out of it and into the amp. I always replace that resistor with a MOSFET using the chassis as a heatsink, but isolated from it by a mica spacer to prevent shorts.

-> All preamp sockets except V1 are all soldered to the PCB as their only means of mechanical support. Be very careful when changing preamp tubes. Slooooowly wiggle them, while rotating your hand, so it's not up or down or left or right, but all 360 degrees, in a careful, steady motion. To preserve your power tubes, do the same thing, and be sure to hold onto the base and not the glass - especially if you are using Mesa brand tubes. However, the power tube sockets are bolted onto the chassis and connected to the PCB by wires, unlike VHT's/Fryette's which are prone to problems in the long run due to thermal expansion.

-> Mesa's pots are of poor quality mechanical quality. Be sure to measure them!

-> As mentioned earlier, make sure to measure for continuity between the grounds around the amp. Mesa's diffent grounding scheme is prone to error, if a pot or jack gets loose.


I hope this helps! I would def. check out the heater-problem.

Kind regards, Jake

 

[Monsta-Tone]

The early ones had a 'Technical Bulletin' that addressed changing 6 LDR's and some resistors in their power supply circuit.
Also, these amps are getting older. I've seen quite a few with leaking or humming capacitors. Especially the bias caps for some reason. You might look into a cap job if the amp still hums after a tube change and changing the ground switch. I make sure that all of my amps of this age have new caps, regardless of hum.