ggg jordan boss tone

[weirdbeard]

hey guys,i'm new here and at building effects. i ordered the jbt pcb from ggg and all of the parts from small bear. put everything together and it fired up the first time,but i'm getting some oscillation. JD sugggested i post here to see if any of you could give me some advice on what could be causing this. thanks

[Mark Hammer]

And the oscillation disappears depending on the setting of the input level control?

[weirdbeard]

anything before 10 oclock on the attack knob starts to oscillate. anything past that it's not as bad but still there.

[Mark Hammer]

Common problem.

Use the search function and see how others dealt with it.

[bluesdevil]

Years ago when I built the ol' Bosstone I found that putting a 10k resistor in series with input did the trick for me.

[brett]

Hi
The original transistors had low hFE and low Ft.  Try using TIPs or BD139/140 instead (with a 10/22/33 pF cap from collector to base). 
The gain will be lower, the ultrasonics gone and the effect will be more like the original.
cheers