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Author
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Topic: Alesis Microverb III hum
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Jack Anderson
Member From: Scarborough, ME
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posted 05 June 2003 05:32 AM
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I like my Alesis Microverb III, but it puts out a nasty 60 Hz hum (or "ripple," to you EEs). I guess they are well known for this. Since it uses an AC wall wart feeding an internal power supply, I don't see how this could be remedied externally, unless with a 60 Hz notch filter in the signal path. Has anyone tried adding better filtering to the internal PS, or otherwise modified (or completely bypassed) it, to quiet the hum? I haven't opened the enclosure -- if it consists internally of a single, fragile board with tiny surface mounted components and wispy traces, I suppose mods might not be too practical. |
Paul Osbty
Member From: Seattle, Washington, USA
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posted 05 June 2003 09:08 AM
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Try connecting a section 20 to 24 gauge wire to a chassis screw on your amplifier. Touch a chassis screw(s) on the Alesis with the other end of this wire. The Alesis doesn't have that 3rd prong earth ground. See if that helps. |
Donny Hinson
Member From: Balto., Md. U.S.A.
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posted 05 June 2003 06:22 PM
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Have you tried a different "wall wart"? Most all of these little power supplies have just "brute force" filtering (unregulated), meaning they are built rather cheaply. Often, the caps in them dry out, and they become noisy. |
Jack Anderson
Member From: Scarborough, ME
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posted 05 June 2003 08:05 PM
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Ah, thanks guys, but this turns out to be one of those "doh!" threads. The ground wire seemed like a good idea, but didn't help. The wall wart delivers AC, so it's just a transformer, I think. But, gee, as it happens, I have been using the Microverb with a Sho-Bud, and often with an single-ended tube amp. When I plugged my Fender through it into a clean solid state amp, the hum diminished substantially; and, yep, a 6-string with a humbucker straight in without a volume pedal seems very quiet indeed! So much for believing bad press on Alesis. Guess it's time to talk to Jerry Wallace about that Sho-Bud.... |
Jack Anderson
Member From: Scarborough, ME
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posted 06 June 2003 04:57 AM
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After experimenting further and more carefully, although I am relieved that the M'verb is not a huge hum generator (compared to an old Sho-Bud pickup, anyway), I found that it does add a little noise of its own, which it would be nice to get rid of entirely. Donny, I suspect you are right about the cheap filtering, although I think it's in the built-in power supply. However, the real cautionary tale here (other than "don't leap to conclusions") is that this unit (and probably many others) really amplifies any hum coming into it, and great care has to be taken with its pre- and post- gain controls to avoid making things much worse than need be. | |
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