In 1967 Ampeg was began using circuit boards in their amplifiers instead of the eyelet board construction they had used since the 50s. The advantage was simple; the circuit boards helped cut down the assembly cost. Ampeg amplifiers were generally more expensive than their fender counterparts and any savings in production costs could help them close that price gap.
When they changed over to circuit boards they also started using an integrated tone stack module. Ampeg was using the Baxandall tone circuit, which again was more expensive as it used used more components than the tone circuit fender championed. However,by using the PEC6470000 integrated tone stack module that combined 4 capacitors and 2 resistors into one 7 pin package Ampeg was able to reduce the parts count and make the construction of their amplifiers marginally less expensive.
The down side is that the internal components of the integrated circuit are not high quality. the capacitors are ceramic type, which have high distortion characteristics, and impart a sharp abrasive quality to the high frequencies and poor low frequency imaging. Even the ultra high (or bright) caps were ceramic type.
