Rectoverb sounds like a motor boat when Output knob cranked

[gitman59]

Hello all,
I am getting a motor boat type of sound when I crank my Rectoverb. It only happens when the Output knob is very high and I hit some low notes. It will keep making the sound if I just let it go. Some time back I did (of course by accident) run the amp without a load. I turned it on and went into another room. When I came back the amp was making a high pitched sound. I saw that the cab was disconected. Shut it down and attached the cab and high pitch sound was gone.

Any help would be great. Transformer? I know it is not the cab as I put other heads throught the cab to test it. Only happens with the ROV.

 

[MusicManJP6]

Page 6 of the manual:

The OUTPUT control is also wired as the Effects Loop Return
Level control. Should you ever use your RECT-O 50 as a power amp alone by inserting a signal into the
RETURN jack, the OUTPUT control will serve as the master level control.

I'm wondering if this is the parallel loop causing this noise? Do you run any effects in the loop? I've heard a similar noise but only when running effects and pushing the effects' level too hard to the the return of the loop. I modded my loop to serial and problem solved.

Why do you have the Output cranked?

 

[gitman59]

Page 6 of the manual:

The OUTPUT control is also wired as the Effects Loop Return
Level control. Should you ever use your RECT-O 50 as a power amp alone by inserting a signal into the
RETURN jack, the OUTPUT control will serve as the master level control.

I'm wondering if this is the parallel loop causing this noise? Do you run any effects in the loop? I've heard a similar noise but only when running effects and pushing the effects' level too hard to the the return of the loop. I modded my loop to serial and problem solved.

Why do you have the Output cranked?

Good call. I just tested it with and without effects and cranked. It stopped the motorboating without effects. Unless I have the Output all the way up. Plug back in effects and motorboating from about 3 o'clock on. So it seems that I am driving the effects loop with too much signal?

I am cranking it just to see if the tone changes with a cranked Output. But I will never play it that loud with the band. Also I am thinking of selling the amp and want to make sure it all works well. I have a Studio Caliber (guess early because no DC on it and no eq) which I will keep as I like the tone better running through a 2x12 with 25 watt Greenbacks. The El84 seem to get a bit more creamer than the El34's in the ROV (I have the series II).

Thanks I was going to start replacing a buch of pre amp tubes as they seem original. Maybe I should change them anyways to see if I get a different sound.

 

[MusicManJP6]

Yea, it's just the FX loop getting bombarded with signal. If you were keeping the amp I'd recommend modding it to serial because it will solve this problem instantly. But, since you are selling then I would leave it be. I prefer all Mesas in the preamp of my RoV, but YMMV.

 

[JSutter]

Could it be a bad tube? Last time I tried the loop it did what you describe. All I had was an EQ in it. Any increase in out put level made that awful sound.

 

[Cleekster]

Yeah i've dealt with this issue from day one and i don't run any Fx in the loop....i've found that changing power tubes can make it worse or better....and using a pedal for a clean boost for solo's makes it worse as well......my amp pretty much lives in the 2:00-MAX range(output)so i would love to find a way to rid myself of this little demon.