Speaker Buzz/Rattle
Hi Skip,
I just received a used Maxi-Mouse battery powered amp, which seems to be working fine except: Any low frequency note or vibration, regardless of amp volume or gain/volume settings, elicits a buzzing/rattling sound. This occurs even when just playing a muted Low E string. After doing my best to rule out all the potential non-speaker causes for such a sound, I removed the speaker from the cabinet. What I find is that when I tap the edge of the magnet housing, a hear a metallic buzz, rattle sound that lasts a full second or two. Shock damage from shipping? Blown Speaker?? Any thoughts/suggestions Skip? BTW, it's an 8" 2 ohm speaker, if that makes any difference.
Thanks,
Loren
Thanks Skip, good to have expert confirmation of my suspicions. Unfortunately the manufacturer confirmed they have no more replacement speakers, nor will they, since the amp has long since been discontinued. I asked if they could recommend someplace to get a suitable replacement but they had no suggestions. They did however provide me with fairly detailed technical specs, the basics of which are: 8" pin cushion, 2 ohm, 15 watt. Any suggestions on replacement speaker suppliers worth checking?
In the event I can't find an 8" 2 ohm speaker, do you have any thoughts on the likely effects of installing a 4 ohm speaker on this 5 watt amp? Loss of volume? excessive power drain on the amp's battery? Earlier break-up? I've got no experience running impedance mismatches between amps and speakers.....
Thanks,
Loren
Hello Loren- Sorry for the slow reply. Feel free to call me any time (days). I would say that any two-ohm, full-range speaker (not a "woofer") that fits in the cab will work. However, I'm not sure about the availability of 2-ohm speakers and I wouldn't suggest a 4-ohm for this particular amp. Try MCM Electronics. They have a ton of speakers.
No worries, thanks for the info Skip.
Hello Loren- Please let everyone here know about your speaker search. The Maxi-Mouse is very popular and I'm sure others will be interested to know what you have turned up.
Skip, good point, so here's the follow-up:
The best solution I could find for the moment was to look for vintage 8" Pincushion speakers. No matter where I looked I could not find 2 ohm, which didn't surprise me, but I did locate a couple of 4 ohm pincusions on eBay. One was sold to me as a Rola brand, the other allegedly a vintage Jensen C8R, but it's been repainted, so who knows......
Anyway, they cost me about $35-40 each, with the shipping, and they fit in the Maxi-Mouse cabinet correctly. I've soldered in the "Rola" and it sounds fine, but I can't say how it sounds relative to spec, since I never heard the amp with its properly working 2 ohm speaker. I do get the sense that distortion starts early with the 4 ohm speaker, but there is enough clean headroom for my current purposes. Still, I'd rather have the greater headroom if possible.
With that in mind, doing a Google search I found a speaker parts supplier (MWA Speaker Parts, Inc. in Arizona) that does repairs and custom voice coil winding, BUT they will only deal with speaker repair shops and "technicians", not the general public, according to their website. I'm going to write and see if I can at least get a quote and I'll follow-up later.
Hello Loren- Thanks for writing. Great job troubleshooting; you have already answered your own question! Something in the speaker has gotten loose. A good speaker will never have a physical rattle when tapped, either on the frame/magnet assembly or the cone itself. Reconing is not cost-effective except for valuable vintage speakers, so I would suggest getting another stock speaker from the amp manufacturer. Those are very good amps that have been around for a long time and it is certainly worth spending some money for a speaker.