ampage
Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum. New: view Recent Searches.
New: visit Schematic Hell!
The sunn still shines online!

 
Listen to great tunes streaming live right now!

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  

Oscilation in a tube pedal...m


 
4/1/2000 11:49 AM
Lars
email
Oscilation in a tube pedal...m
Hi there I have built a Hotbox after this schem.  
http://www.techaccessinc.com/blueguitar/hotbox.gif  
 
when I go over 50% on the gain on ch 2 it starts to oscilate. I have tried to lower the plate voltage from 280V to as low as 180V it's the same it oscilate. I have short cabels for the plate voltage.  
help me with idees.  
 
Lars
 
4/4/2000 5:27 PM
Doc
email

The grid wires are probably picking up unwanted signal, due to their location in the layout. Can you shield the grid wires or sepatate them from plate wire proximity to decrease parasitic coupling?
 
4/4/2000 9:20 PM
Jim S.
email

You haven't taken any shortcuts in power supply filtering have you? I would guess that, with two preamp tubes (3 or 4 gain stages) this circuit requires at least two filter stages.
 
4/5/2000 5:58 AM
Lars
email

I have two filter stages.  
Lars  
 
   Page 1 of 1