Descriptions of Amplifier Features


Following are some brief, non-technical descriptions of the various features of some Sound City amplifiers. If you have suggestions for additions or corrections to this work-in-progress page, please contact me.





Slave Multiplexer


Many of the Plush amplifiers were made with the ability to connect that amplifier as the control for one or more other amplifiers with the rest acting solely as power amplifiers to increase your power.  The benefit of this is that you can control your volume and tone with one set of controls instead of having to go to each amp and tweak them independently.  The slave multiplexer on Plush amplifiers is one or two RCA jacks on the back.  These RCA outs would go to slave amplifiers or some how connect into other amplifiers (I haven’t seen any of the Slave Multiplexer jacks being inputs to the amplifiers).  So this is a bit of a mystery.   


Contour Control


On the larger amplifiers along with Bass, Middle, and Treble, there were contour controls.  These controls alter the frequency where the bass and treble (for the 4000G) and midrange (for the 8000) controls work.


Impedance Selector


No Plush amplifiers had a separate control for the impedance.  Instead the some amplifiers were hard wired for a specific impedance range (unknown at present) or the impedance would be switched as more cabinets were plugged in (true for the 4000G amplifiers at a minimum).  On these amplifiers with the switching of the impedance by plugging in cabinets, these switches can go bad causing the amplifier to not properly switch impedance (or making the output an open).  If you get no sound from your amplifier, these jacks would be a good first place to look.


Instrument Inputs


The instrument inputs on the various Plush amplifiers provide similar functionality and differ primarily in number. There are two essential types of inputs: Bassl and Guitar(vibrato). Each of these types provides one Attenuated input, through which the signal to the preamp is reduced.

     The Attenuated inputs would be suitable for instruments with an active (battery-powered) preamp, while the non-attenuated inputs would be suitable for passive instruments.     




To be continued...





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