Pandora

[emrr]

LM-401 limiter.  Feel free to make a clean drawing!  EDIT:  see below for better drawing....

 

[Bill Wilson]

Here is the Gray Ghost phantom power supply manufactured & sold by Studio Supply Co., Nashville; they were the Nashville dealer for MCI recording equipment 1969-1972. They sold accessories under the name, Pandora Systems. Studio Supply was founded and owned by Dave Harrison of Harrison Console fame.

Dave got his start as chief engineer for King Records in Cincinatti, Ohio. While he was at King he originated the track select switching concept; which he licensed to Jeep Harned at MCI for the new console he was designing. The console was the MCI JH-416. It was the first commercially manufactured console using circuits designed around opamps, throughout.

The supply uses a power transformer having a secondary voltage of 56 vac rated for 2 amps. The output can be varied from 52 vdc down to approximately 42 vdc; using the 10k pot.

 

[Bill Wilson]

I have redrawn the Pandora Compressor circuit for clarity. The circuit was designed by Claude Hill when he was sales manager for Studio Supply, in Nashville. This was designed to be used for informal recording setups & pa systems; it was never intended to be used for professional recording
purposes. To improve the performance the 748 op amp could be changed to an NE 5534.

The design of the FET gain control element would need to have the circuitry around it to reduced the harmonic distortion content. Today we have much improved circuits & devices.

 

[ruffrecords]

The design of the FET gain control element would need to have the circuitry around it to reduced the harmonic distortion content. Today we have much improved circuits & devices.

Isn't that what the pair of 2.2Meg resistors do?

Cheers

Ian