This is what it should sound like with an expression pedal.

It’s not defective. Without an expression pedal, there are two modes: chorus, and vibrato. The expression pedal mode is the same as the chorus mode without an expression pedal attached. With an expression pedal, the expression pedal mode allows you to sweep from slow chorus to fast vibrato, and everything in between.

In either chorus or vibrato mode, if you have an expression pedal attached, you can use it to change the delay time parameter. This is a little trickier that simply plugging in the expression pedal and going to town. You have to preset minimum and maximum delay times. Here’s how this is done:

1) with the expression pedal in the toe forward position and the Memory Boy engaged, set the delay time knob on the Memory Boy to about 9:00. This will give you about 500ms of delay with the expression pedal in the toe forward position. With the delay time knob on the Memory Boy set any higher than approx. 9:00, the expression pedal will push the delay time beyond the useable limits of the pedal in the toe forward position–it will yield ugly, unusable sounds.

2) rock the expression pedal back to the heel down position. Then adjust the knob on the expression pedal to preset the minimum delay time.

Now you’re good to go and can sweep between the preset minimum and maximum delay times with your expression pedal.

According to the manual. There are suppose to be 3 rates.

MODULATION RATE: With nothing plugged into the EXP. PEDAL jack, this switch selects three different modulation rates: CHORUS for a slow rate, EXP. PEDAL for a medium rate and VIBRATO for a fast rate. When an expression pedal is plugged into the EXP. PEDAL jack, the CHORUS and VIBRATO settings remain the same; flipping the switch to the middle position, EXP. PEDAL, allows the expression pedal to control the rate of modulation. The full range of the expression pedal extends past the two rates set by CHORUS and VIBRATO

I think that may be a mis-print in the manual. With my Memory Boy, without an expression pedal attached, there’s no difference between the exp. pedal and chorus modes. The Deluxe Memory Man, on which the Memory Boy is based, has 2 modes (chorus and vibrato), so it stands to reason that the Memory Boy would be engineered the same way.

This may be a question for the engineering/design dept.