My Mark Bass Mini CMD 121 P is making funny sounds

[Timothy DeHan]

My Mark Bass Mini CMD 121 P is starting to make a slight distorted/rattle type sound on certain frequencies. I've only recently started to notice this. At first I thought it was my bass making a slight rattling sound so I checked on all 8 of my basses and it happens on all.

Any ideas as to what could be causing this?

 

[MarkA]

If it's an actual rattle, it could be something loose, either in the combo (loose wire, loose screw holding in the woofer/grill/whatever) or in the room (you'd be surprised how frequently this can turn out to be the case).

If the distortion is more of a paper-y, buzzy sound, you've got a few possibilities as well. One is a blown/damaged piezo tweeter. Could also be a damaged woofer. Could be an air leak. Could be something intermittent in the amp -- a dirty jack or effects loop or a cold/cracked solder joint.

My CMD 121P started making a papery/buzzy sound, intermittently, some time back. Took it to a tech, no joy. Replaced the piezo tweeter with a Monacor HF driver (there's a thread on this mod somewhere) which improved the tone (worthwhile mod, IMO), but didn't get rid of the intermittent buzzy sound. I tried several things, including different cables, instruments, cleaning/jumping the effects loop, etc. Eventually, I tried running the combo cab with other heads (the speaker cable is a short pigtail, so I had to set the other amp right by it on the floor) and the buzz was gone. Tried running other cabs off the combo head and the buzz/cutting out was there.

That didn't tell me, definitively, what the problem was, but it eliminated the cab as the cause -- it's something electrical, in the head.

I also tried recording from the DI -- don't think that there was any issue with the signal there, which, again, doesn't tell definitively what it is, but helps narrow down what it's not.

Good luck!

 

[Aquilador]

My Markbass 802 does this too when it is just over half volume. It’s a new combo too, so I checked the speakers and tweeter with no joy finding the reason.
It was worse when I used the VLE filter full on too. But only on certain frequencies/notes as Timothy DeHan has experienced too.
But it doesn’t happen using the headphones, however, I’m with MarkA on this as I think it could be to do with the input signal to the amp section as I used the headphone signal from another combo as the bass input to the Markbass and the buzzing disappeared completely and the sound was really big too.

 

[JimmyM]

My Mark Bass Mini CMD 121 P is starting to make a slight distorted/rattle type sound on certain frequencies. I've only recently started to notice this. At first I thought it was my bass making a slight rattling sound so I checked on all 8 of my basses and it happens on all.

Any ideas as to what could be causing this?

If it's only on certain frequencies, then there is likely something loose rattling. Go around and tighten but don't overtighten all the screws, including those on the speaker and tweet. If that doesn't work, take out the speaker and check the inside padding to see if it's loose. Loose padding can sometimes cause this. If it is, re-attach it with double stick carpet tape or wood glue or whatever they use to fasten it. Beyond that and you should contact Markbass and see what they think.