MXR Dist + and DOD 250 question...

[Steben]

Hi guys,

Just wondering if the sound would be much influenced by IC clipping. If one should put a pair of let's say... LED's in the feedback loop of the opamp (and thus blocking the chip to "hard clip"), would the sound be much different?

[Mark Hammer]

Certainly, in principle, dual clipping stages will have a sonic impact.  Whether than impact is audible in any given context is another matter.

The LEDs will have a much higher clipping threshold than the diode pair that follows the op-amp.  What that means is that the signal will be severely clipped by the GE diodes long before the LEDs are pushed hard enough to have any impact.  You *could* replace the GE diodes with Si diodes to reduce the discrepancy in clipping threshold between the LEDs and diodes, or simply stick the diodes after a second gain stage that would let you adjust how much gain is applied to the signal for each set of diodes.

In the case of the Dist+ as well, the use of a 741 op-amp restricts the amount of usable headroom.  Many builders, myself included, who thought they would be clever and score themselves a clean booster for the price of a switch position (to lift the diodes out of circuit) soon found out that the Dist+ is rarely clean, even without diodes.  The 250 may be a different beast.

[Steben]

Yes, thanks for the reply and sharing knowledge ;-)

I was thinking maybe the IC already distorts in the stock pedal, but the GE's clip the signal more off (but softy, so the timbre of the IC clipping remains...). So I guessed without the IC clipping or with soft clipping on the IC, the sound would be less mushy...