Note that this does not mean a Muff with a 1978 pot was actually made in 1978, it just means it was not made much earlier than 1978.
The Muff could have been made months or even years after the pots were purchased as it is known that Electro-Harmonix bought the pots in bulk, as did Fender, and other companies at the time.
Always remember that pots, speakers and transformers may have been changed!!
- All vintage USA Big Muffs have source-date codes stamped on the underside of the potentiometer cans, or “pots”.
Custom 30% Taper7% tolerance Dished back Lowest torque possible!
On the inside wall of your amp cabinet, there may be a tube location sticker which shows the tube layout, model number, production location etc..
There may also be some letter date codes rubber stamped on this sticker.