BF Deluxe Reverb- reverb feedback?

[Ocelot]

When I turn the reverb up past 5, even at lower volumes, the amp starts to feedback. Not a screech, but a low sustained feedback. I changed the reverb tube and that didn't help. The amp has been recapped already. Any ideas before I bring it to a tech? Thanks.

 

[JDJ]

You try swapping both reverb tubes?

 

[Ocelot]

Yep, swapped both tubes.

 

[GearHeadFred]

Is everything else good about the amp? Is this a new behavior? Does it still happen with the volume all the way down and no instrument plugged in? 5 is a lot of reverb on a BFDR..

 

[slider313]

Were the cathode bypass caps done? I've seen some techs replace the power supply caps and bias cap and leave the cathode bypass caps in. If they were replaced check the cathode resistors on V3 and V4 and be sure they're in spec.

 

[Ocelot]

I just bought the amp around a month or so ago. It sounds beautiful, but the 'verb gets buzzy as you turn it up, and feeds-back somewhere above 5 (the feedback creeps up; doesn't suddenly leap out; I hope this description makes sense). I've not tried the 'zero volume/no instrument experiment. I'll give that a try, too, to see how it reacts. I'll probably just have to bring it in to a tech. I just don't want to get led on an amp-mod goosechase and end up spending a mint only to find that the problem isn't corrected. Thanks for all the info, guys.

 

[Blue Strat]

Is the tank in the proper bag? If not, that's your problem. If it is, try stuffing some more padding on top of it...a blanket, pillow, etc. If that cures it you know what to do.

 

[Ocelot]

Is the tank in the proper bag? If not, that's your problem. If it is, try stuffing some more padding on top of it...a blanket, pillow, etc. If that cures it you know what to do.

As far as I can tell, it's the original bag. It doesn't have the original reverb cables, though. I'm not sure if that could affect it somehow.

 

[Gnarlly]

I experienced the same exact reverb feedback at 5+ levels with my DRRI that you describe. I tried swapping tubes, but that wouldn't get rid of it. Not sure what caused it, but I moved the reverb tank a little in the bag, towards the rear of the cab, and the feedback went away. Hasn't come back since.

 

[Ocelot]

I experienced the same exact reverb feedback at 5+ levels with my DRRI that you describe. I tried swapping tubes, but that wouldn't get rid of it. Not sure what caused it, but I moved the reverb tank a little in the bag, towards the rear of the cab, and the feedback went away. Hasn't come back since.

Really? Wow, that would be the cheapest fix of all. I'll give that a shot. Thanks.

 

[Gretsch47]

I have a similar issue with my Vibrolux (CVR). Turn the reverb up past 5 or so and slowly it will begin to hum until it gets crazy loud. The hum is not dependent upon amp volume or having a guitar plugged in. I'll try fiddling with the reverb pan (bagged) and see what I can do to move it or shield it somehow. Thanks

 

[RussB]

Take the lower rear panel off, and remove the entire reverb bag & tank from the cabinet. Place it on the floor but leave it connected to the amp.

Play the amp, and see if the reverb still oscillates


Make sure you have a 12AT7 in V3, and a 12AX7 in V4 as well.