Just built ad-3208... The delayed signal is heavily distorted. NEED INSIGHT

[Bornhorst]

I just completed the ad-3208... I can hear its awesome potential, but I still have a few bugs to work out....
I'm able to get the dry signal plus the delayed signal. The problem is that the delayed signal is much louder and is abnormally distorted... when the delay level is turned all the way down, I get a completely unaffected dry signal.

I've double checked the usual suspects... solder work, component values/placement, bias pots...
Is there anything obvious that might be causing this?

Any insight would be greatly appreciated.

Thanks,
Daniel

[Mark Hammer]

Normally, I would say that the cure for a distorted delay sound is to verify that the bias controls/trimpots are set right.  The distortion produced by a mis-set bias trimpot, however, is not accompanied by a big volume boost.  If anything, you get less delay volume with a mis-set bias trimpot.  It is quite possible you have some sort of malfunction in the expandor half of the compandor that is resulting in a distorted and overly amplified signal.  Aother possibility is a short somewhere that results in the exândor getting too large a signal.

If you have a meter, set it for a range of 200mv or less, and stick the probe at the emitter of the transistor in the first filter stage and the second filter stage between the second 3208 and the expandor input.  You *should* get a reading of somewhere in the <150mv range when you strum your guitar, and no particular change in level from the first filter output to the second one.