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-   -   Growling, howling, shrieking guitar amp (https://www.vintage-radio.net/forum/showthread.php?t=80343)

stevekendal 23rd Feb 2012 1:04 am

Growling, howling, shrieking guitar amp
 
This Aria Loco bass combo 6126B is making plenty of output, but also unwanted noises as follows. With the volume at zero, moving the bass eq produces a growliing noise at full volume. Moving the mid controls makes an equally loud squawking sound and the treble makes a horrendous shriek. 8-o Tapping the boards has no effect. Not sure I will be able to find the circuit for this one, so any pointers please before I let my "phantom" fingers loose on it? :dunce: Steve.

maninashed 23rd Feb 2012 1:36 am

Re: Growling, howling, shrieking guitar amp
 
Hi Steve, not familiar with this amp, some pics would be nice. Its obviously oscillating, and I would say probably something in the pre-amp/tone control area. Im presuming its a valve amp so check coupling capacitors and cathode bypass capacitors.
Bill

GrimJosef 23rd Feb 2012 8:55 am

Re: Growling, howling, shrieking guitar amp
 
There's a picture about half way down this page http://www.locobox.com/amps.html showing a Micro Bass amp model 6162B (not 6126B). If this is the amp you mean then it looks from the outside as though it's a transistor unit.

Cheers,

GJ

peter_sol 23rd Feb 2012 10:12 am

Re: Growling, howling, shrieking guitar amp
 
It sounds as if the controls just need a squirt of switch cleaner.
High gain amplifiers often squeal instead of just crackle.

stevekendal 23rd Feb 2012 10:41 pm

Re: Growling, howling, shrieking guitar amp
 
Yes its a tranny amp and I will try the switch cleaner next time I have a look.


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