can't get my new SD-1 to sound like my old one...

[MetalGod]

ok, I've got a new SD-1 as a spare that I'm modding to be exactly like my old (MIJ) one as a spare.

I've swapped out the caps in the signal path for the same green Mylar types - the only ones I didn't change was the tone cap and the caps in the switching circuit.

I've checked the voltages all through the signal path and it's very very close.

The opamps are both socketted so I swapped them round, not sure if there was any difference there.

Anyone got any ideas why my old MIJ one still sounds smoother and more harmonically rich? - the input and output buffers are different part numbers in my new one, but since they're setup as EF's that shouldn't make a difference right?

[Melanhead]

My guess is that some of the parts (capacitors/resistors) in the older one have drifted in value changing the the overall sound of the pedal.

[Papa_lazerous]

Smoother and richer....... Sound like the clipping diodes could be playing a part there

[MartyMart]

I do a lot of A/B testing when modifying pedals and even two brand new SD-1's sounded slightly
different !! ( one a little thinner sounding with controls at 12 o'clock )
Think about not only the age difference but perhaps 10% or more variations in the caps etc and you
didn't change the tone cap yet either.
To get two pedals the same, you would need to use expensive matched parts all thoughout the build
to get "exact" copies, cheap caps and electros etc just wont do it.

[Mark Hammer]

....Not to mention the pots, which are rarely as consistent in value and taper as many would believe.  NEVER confuse where the pointer on the knob is with what is taking place inside the chassis.

[jonathan perez]

send it to japan, and let it age.

[MetalGod]

I personally think it's the clipping diodes in the old one - I remember when I was first modding that pedal it wouldn't sound right unless the original diodes were in there. 

In the new pedal I've put in some 1N914s with the same threshold as the diodes in my old SD-1. 

Do 1N914s sound different to 1N4148s? - I personally can't hear the difference (I can with 1N4001s though)

Finally, anyone know where to get .018uF and .027uF Mylar caps?