Double Bass Acoustic AB50 vibration noise?

[Jack Clark]

I've only had my AB50 practice combo for a couple of weeks, and I've never owned an amp before.

I'm getting a rattle when I play any A or Ab or G. Sounds like a vibration from the cab to me. When I play through the AB50's head into headphones only, it's clear as a bell--another reason it seems to me that the rattle would be in the cab. But I've felt all round in there trying to find something loose or flexible and everything seems rock solid. I've tried it in various locations in three different rooms in my home--always the same thing.

I'm using a K&K Pure Bass pickup with three transducers playing through a K&K Pure XLR preamp. My instrument doesn't buzz when not amplified--and, again, not through headphones.

Any ideas, anyone?

 

[Gearhead43]

I have one of those, that I ended up just using as our home practice room mini-PA for vocals.

The problem is that the amp unit is not sealed from the speaker cab area and air "chuffs" or "flutters" through the holes in the inside and control knob area. I have heard from a few guys that have the same issue.

 

[Jack Clark]

I read about that "chuffing" problem in a bad review that one guy gave this Acoustic AB50 combo at GC or MF, but is that really the problem I'm having, do you think? Would chuffing occur only on playing certain notes? In my case, I get a rattle only when playing any A or Ab or G. That sounds more like a sympathetic vibration problem, doesn't it?

 

[Gearhead43]

It could be, or that the most resonant notes could be causing the most air to move thru the holes. Not sure. Mine does the fluttering sound mostly with lower / bassier notes.

It actually works well as a vocal PA for our practices though. Two mic inputs / channels.

When I used it for bass during band practice, the noise couldn't be heard over the band, it was just annoying when playing solo.

 

[Jack Clark]

See, it doesn't sound like an air noise to me--not a "chuffing" or a "fluttering" sound. Rather, it sounds to me like a buzz or a rattle from solid objects vibrating against each other--like a loose screw or a loosely attached piece of wood. But I'll be darned if I can find anything inside that feels other than solid as a rock. But maybe I'd better check the screws holding the two speakers in in place again. I could have missed something the first time.

 

[Jack Clark]

I recently moved all of my music equipment to a separate "music room" in my house (my wife calls it the knitting room, but she's got that wrong), and all of the buzzing problems I mentioned went away . . . entirely.

The buzzing must have been because I had the AB50 closely surrounded by a wall and some furniture in its other locations. (It was close to hard furniture in these prior situations.) It wasn't touching anything, but it just must have been too close to something. Absolutely no buzzing at all now.