A: The audio amplifier in every Sore-Throat Amp is based on the 1458 dual Operational amplifier, or op-amp. It has 8 pins, and fits in a handy socket that is mounted on a small circuit board. It can be replaced by many similar numbers made by different manufacturers. For example, designations can be
LM1458, KA1458, NTE 778a, MC 1458, and MM 4558. They all plug in the same socket, and sound very much the same. Many "guitar effects pedals" use the same chip, so it is very common in the industry.
Q: Whats different about the STGA circuits?
A: The circuit board mentioned above has the chip in a socket, the required resistors to make it function, and one diode. These are "solid state" components that rarely fail. There are no capacitors or electrolytic capacitors on the board. These components are made from chemicals and can cause failure and leakage.
There are no switches, transformers, or connection devices on the circuit board. These things are partially mechanical and will eventually fail. Mechanical devices also cause vibration and movement that can cause premature failure of a circuit board. A sore-throat amp has all chemical and mechanical devices mounted externally from the board, to improve life-span and reliability.
Q: Why do the amps use full -sized 1/4 inch jacks?
A: The 1/4 inch "tip-ring" jack is the standard size for guitars and guitar cables, to directly plug-in, without using an adapter. The 1/4 inch headphone jack is the industry standard for higher quality headphones, like the large over-ear 8 ohm stereo type, or the higher end 150 ohm hi-fidelity type. These work the best with STG amps. People can use the smaller mini headphones with an adapter, but the volume and sound quality will be compromised. The headphone jack is also a TRS or tip-ring stereo type, so it can be used to source two inputs-like a stereo amplifier or a mixer board.
Q: What is the purpose of the RCA Jacks?
A. All STG amps have at least one RCA female connector. It provides access to the output of the first amplifier stage ( the pre-amp). An RCA cable can be connected to it and the other end to a larger amp, or a home stereo, so a player doesn't need a large guitar amp to play at room volumes. The same jack is also an "input" to the second amplifier stage. This can be connected to foot pedal outputs so players can hear a pedal on the headphones. Its a great way to test pedal boards!
A SECOND RCA Jack is being added to some of the newer STG amps, connected to the output of the second amplifier stage( headphone out). This makes it easy to drive a SPRiNG REVERB CAN or a stage monitor amp/speaker. ............................thanx fer askin soo many questions......prof. Edward
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