Jordan Bosstone question

[p1_ind]

I built a Jordan Bosstone using the corrected schematic, but I have a question about its operation.

With the Attack control turned low I get an oscillation until I turn it up a little more.  And it has a hollow overtone like the sound of using a wah in front of a fuzz.

Is this normal?
I did a seach and found a discussion about it but no one really said if this is the way it is suppose to sound.

Adam

[al3151]

I built one and had a problem with oscillation,but at the maximum attack setting.I saw a Voodoo Labs Bosstone and it uses a 2K resistor between the 100K attack pot and the input of the circuit.The VL Bosstone uses an mpsA18 and a nte159 transistors.

[aron]

I have heard about the oscillation, but I didn't have it in mine.

It shouldn't have a hollow sound either.... weird.

[p1_ind]

The oscillation only occurs when the Attack setting is under about 10 o'clock and I play a lower frequency note then the oscillation starts and can't be stopped unless you turn the Attack knob past about 10 o'clock.

Also in the first 1/2 of the Attack knob adjustment I get the overtone that just clutters up the sound but as the Attack knob is turned up it sounds less cluttered.

With the Attack knob at max I can turn down the guitar volume down and the fuzz will clean up some without the clutter.

I will double check my wiring but I has me confused.

Has anyone else had any similar problems?

Adam

[al3151]

The oscillation only occurs when the Attack setting is under about 10 o'clock and I play a lower frequency note then the oscillation starts and can't be stopped unless you turn the Attack knob past about 10 o'clock.

Yup,that sounds like the same type of oscillation.I'll hit a lower note and that will trigger it,but it only happens at the maximu attack setting(a little past 3'0clock).I haven't tried to correct this because aside from this it sounds great IMHO.

[RGW]

try this just to see what happens:

On your attack control pot, lift the wire going from the #1 terminal to ground.

This will change the attack control so that you are now adding series resistance on the input versus grounding the input cap.

This will totally change the way the attack control sounds when turned up or down, but I am curious if it will stop the oscillation.

Another thing I would try is substituting transistors and see if if some lower gain ones solved the problem.

take care,
Robbie

[brett]

The VL Bosstone uses an mpsA18 and a nte159 transistors

IMO an MPSA18 is NOT the sort of resistor to use for Q1 in a BossTone.  Bosstones had, and are suited to, transistors with low hFE.  Try a 2N3904, or something else with low noise and hFE less than 400.  Or place a 100 to 220 ohm resistor between the emitter of Q1 and ground.  Or both.  I'm fairly sure that these things will fix your problem (which is one of turning your pickups into an antenna for a high-gain circuit).