Arfa Daily wrote:
"N Cook" wrote in message
...
Reported as fuzzy sound on the bass guitar E string even at relatively low
levels
but otherwise fine sound rendition or backing off the bass control .
Feeding a signal generator in then indeed a distinctly fluttery distortion
in the range 50 to 70 Hz on top of the wanted output, ok above or below
that
range.
No external speaker output on this cube and before getting inside to scope
it or run an external speaker I took the front grille of in case of
parasitic rattling but no change. But putting a sock in the front/back
vent
tube in the speaker surround cured it.
Where to go from here ? sci.acoustics.repair ? charge for an old sock ?

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/


Interestingly, I have had a similar problem on several Ashdown bass heads.
Just as you describe, fuzzy distortion at around 44Hz only, otherwise
sounded fine. On each occasion, it has been really bad joints on one of the
main smoothing caps - to the point where the cap is effectively not there.
With a 'scope on the supply rail, just about full level ripple, but
curiously, not a hint of hum on the undriven audio. Only when that string on
the bass guitar plucked, or a sig genny put in at that frequency. I
completely missed the first one that I had doing it, as it sounded perfectly
well on all other material, so sent it back to the shop. He came back a day
later armed with a bass guitar, and demonstrated the problem ...

Arfa



I have also had that fault, we call them Trashdowns around here. I agree
with Arfa that it`s probably a dry joint. Roland combos are generally
better constructed, or at least, they were!

I had a similar fault on a Peavey bass combo, and it turned out to be
air fluttering in the bass port, I presume the speaker had somehow
deteriorated, a wodge of dacron in the port stopped it temporarily.


Ron(UK)