Tremoverb is kind of quiet

[ketiov]

I just bought a Tremoverb. The clean channel with maxed everything is quiet enough to hear my guitar strings clacking even when my ear is next to the speaker.

The red channel is a bit better, but at maxed active master (the black knob) and the channel master at about 2 O'clock, the amp is quieter than my Mark IV at 7 channel volume and 3 master.

New tubes needed? The guy I got it from took it to a good local shop in August so they checked everything over, and everything was fine. They replaced two gain pots and that was it. The tubes could be old, other than that I don't know what it could be.

Thanks for any help.

 

[94Tremoverb]

First, bypass the FX loop using the switch on the back. If that fixes it, replace V4. If it doesn't fix it, chances are that V4 is OK, so use it to test the other five positions.

Just to be sure, select Silicon Diode rectifier - it's unlikely both rectifier tubes are dead, but possible.

It won't be a power tube problem because it would need all four to be dead at the same time for there to be so little volume, and it would sound really bad too.

If it's not a tube problem, it's most likely a broken connection somewhere since a bad LDR (which are fairly common on Tremoverbs) would still leave at least one channel and mode working normally.

 

[ketiov]

I bypassed the loop and problem solved. I don't use it so I'll hold off on swapping the tube just yet.

Another issues I have (not really that bad) is that on the clean channel, with tremolo off, my speakers flub back and forth very slowly. I can see them pulsating. When I turn the tremolo on (even if the setting are turned down all the way) problem solved. Is this a regular problem to have?

 

[94Tremoverb]

That sounds weird! Mine definitely does not do that, I just checked.

I am now trying to think why it might...

 

[ketiov]

That sounds weird! Mine definitely does not do that, I just checked.

I am now trying to think why it might...

I'll get a video up tomorrow to show it. I'm only worried about it because if it happens at high volume it could blow the speakers, but it works fine as long as I keep the switch for tremolo on channel 1 on.

 

[ketiov]

http://www.youtube.com/watch?v=Cz8iK5PvIX4 Tremolo issue.

http://www.youtube.com/watch?v=wWrpGUZ8S6U Reverb issue.


Is there one tube that drives all this? The reverb feedback gets ridiculously loud, like, the floor shakes.

 

[94Tremoverb]

The tremolo issue is interesting - technically I would describe that as 'randomly oscillating DC voltage' rather than 'slow pulsing'... this is important. It's probably a tube issue, and most likely V5 which is the reverb drive tube and also the gain stage immediately before the tremolo LDR. (The tube has two halves.) When the tremolo is switched on, the LDR has a low enough resistance to suppress the oscillation. It may also explain the reverb feedback if the tube is leaking signal from this stage back to the other stage, so the reverb is part of the unintended circuit.

I'm not sure, but it seems to fit and is the first thing I would change. V5 is in the row of two tubes, not the row of four, nearest the input jack. Personally, I like a 12AT7 in this position because it cleans up the amp a bit and makes the reverb drive deeper and smoother - it also reduces gain, so it would help to cure any problem like this if it existed in my amp. (Make sure you don't try 12AT7s in V3 or V4 by the way, they don't have the right voltage rating.)

 

[ketiov]

The tremolo issue is interesting - technically I would describe that as 'randomly oscillating DC voltage' rather than 'slow pulsing'... this is important. It's probably a tube issue, and most likely V5 which is the reverb drive tube and also the gain stage immediately before the tremolo LDR. (The tube has two halves.) When the tremolo is switched on, the LDR has a low enough resistance to suppress the oscillation. It may also explain the reverb feedback if the tube is leaking signal from this stage back to the other stage, so the reverb is part of the unintended circuit.

I'm not sure, but it seems to fit and is the first thing I would change. V5 is in the row of two tubes, not the row of four, nearest the input jack. Personally, I like a 12AT7 in this position because it cleans up the amp a bit and makes the reverb drive deeper and smoother - it also reduces gain, so it would help to cure any problem like this if it existed in my amp. (Make sure you don't try 12AT7s in V3 or V4 by the way, they don't have the right voltage rating.)

Unfortunately neither issue seems to have been resolved with these tube swaps. The amp is still functional by my standards, but I'm worried about what could happen if I decide to crank the amp all the way one day.

I swapped out both V4 and V5, and the situation hasn't changed at all. I'll try swapping out more tubes when I get back home on Friday, I don't have time to crawl behind my speakers right now (I have a weird setup).

 

[94Tremoverb]

Try swapping out the other tubes (including the power tubes, these can sometimes do weird things in the preamp that don't immediately appear to be power-amp issues, via the negative feedback loop), but at this point I would expect it not to be a tube problem - the oscillation might be, but not the FX loop issue. You could possibly have a problem with the FX loop relay - it's in between V5 and the tremolo LDR, and if it's faulty would stop the FX loop circuit working at all, as well as possibly doing this thing with the oscillation - but that wouldn't explain the reverb feedback or why the oscillation only happens on the clean channel. I suspect there may be something more nasty going on with the switching matrix... tech time I think.

It's worth getting it sorted properly - these are great amps when they're working properly, even if they are also complex and have a few issues sometimes, mostly related to the switching.

 

[ketiov]

Resurrecting this old post because I got around to actually tinkering a bit. The amp recently started intermittently going wishy-washy at band practice, and when I turned it off it chirped. Like there was a bird stuck in the tube.

I figure this is not a tube issue as I hoped. I took all the tubes out of my Mark IV, including preamp tubes (12AX7, all of them), and popped them into the Tremoverb. One of the preamp tubes in the Tremoverb stayed as the original, whichever one is closest to the back and to the left, but I swapped it with one other with no effect.

So yeah, the amp goes intermittently wishy-washy (think of something like putting a seashell to your ear). The effects loop issue is still going on, and I noticed the tone changes dramatically when the loop is engaged (putting aside the volume thing). Loop engaged, the amp sounds like it has much more presence. There is a lot of high frequency buzz to it, whereas normally it is a very chunky sounding amp, more in the midrange.

Also the tubes got extremely hot very quickly. Maybe 5 minutes into playing (with the master at maybe 10%), I could feel the heat radiating from about 6 inches away. My Mark IV isn't like this, which is why I'm noting this.

Should I just send the thing in to Mesa? The only thing I haven't tried yet is swapping out rectifier tubes, but I've been running it on the silicon diode setting since I got it and switching to the tubes made no difference.

 

[94Tremoverb]

If the tubes are getting that hot, there may be a fault with the bias circuit - these amps do run a bit hotter than a Mark, but probably not enough that you would notice it as a substantial difference after only a few minutes. Likewise, running on the diodes is a bit hotter but not that much.

If you can send it to Mesa, I would at this point - they're complex amps and it sounds from what you're describing that there may be more than one issue, and it could need a general overhaul for things like filter caps - which could explain some (but not all) of these problems.

 

[fluff191]

If you can send it to Mesa, I would at this point - they're complex amps and it sounds from what you're describing that there may be more than one issue, and it could need a general overhaul for things like filter caps - which could explain some (but not all) of these problems.

+1

Time to see the doctor!

 

[ketiov]

So it's on it's way back. LDRs were replaced. Tubes were ridiculously hot because some genius installed a bias pot and had twice the correct current going through the tubes.

In other news I found out myself that Mike B is a total G. It's not exactly news but hey.

 

[boss4]

I was curious about this problem. So the LDR's were the only issue? Congrats for the reborn TOV!

 

[ketiov]

I was curious about this problem. So the LDR's were the only issue? Congrats for the reborn TOV!

Thanks! It was $160 of LDRs according to the packing list but they gave a $160 credit for them, pretty neat of them to do. As far as technical faults the amp had the LDRs and the bias pot (with the wrong bias set...) were the only ones present.

Mike B also said that the gain pots were replaced with ones that were really jumpy and sensitive at very low settings but I asked to leave them as is. There's also some reverb related item listed on the packing list but I'm not sure exactly what it is.