Harbinger distorting

[Jules]

Hi All, I am having trouble with the Harbinger 1 i built distorting at the test stage. The lamp and Led are working and flashing in time with the speed pot and all appears well but the signal is distorting. I have powered it with both 9 and 18 got regulated power supplies, Any help diagnosing would be greatly appreciated.
Jules

[brejna]

You should check part values. I had similar  problem, it was wrong cap value. Also try another j201..
Brane

[aballen]

This is a great pedal, I have one and I absolutely love it.

Are you using a charge pump?  That would be for running it at 9v(the charge pump doubles the voltage)  if you pumped 18V in to the charge pump, that would double the voltage to 36.

• make sure all your parts are rated that high. 
• reflow the solder joints
• check for solder bridges
• check all the part values
• if you are still stuck, start posting voltages, and pictures

[midwayfair]

if you pumped 18V in to the charge pump, that would double the voltage to 36.

GAAAAH. Do not do this! The maximum rated voltage for an LT1054 is a well-regulated 16V. If you're using any other charge pump, they can't even take that much.

The J201 has a very low input headroom, under a volt. If you have hot pickups, you'll distort it. It's a source follower, though -- just use a JFET with better headroom, like the MPF102 or even 2N5457/8/9 or 2N5952 (backwards pinout).

Best thing to do, though, is get out your audio probe and trace the audio signal and find out where it's distorting. That will narrow down the problem.

Also, the univibe will distort a little even when working properly. It's actually part of the sound. If you're just getting a little bit of distortion, that's probably it.

[luks999]

+1 to the parts values and the voltage supply

does the problem occur with the modern input only (J201) ? or is it also distorting in the vintage mode?
how much does it distort? a little bit can be normal. i did the gain mode to my neovibe and then it distorts more, but also has more volume. (it was set with the resistors at the input, so maybe you got parts wrong there)

@jon: good tip for the tranny, maybe ill try a different one too

[madbean]

The dry signal path will definitely distort with a misplaced resistor value (assuming it is a large enough error). Like Jon said and audio probe is the best way to track it down.