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Re: Excuse my ignorance, but what is a "transconductance amp"?

A transconductance amp is one where the output current is proportional to the input voltage, no matter what the impedance of the load. The amp adjusts the output voltage so the current through the load remains constant (for a given input voltage).

This circuit is about 2 watts (calculated to be 2.4 watts). It will not work well for driving traditional multiway speakers. The standard crossovers are designed for traditional "voltage" amps. So these types of amps are usually used for single driver speakers such as Lowther or Fostex. You might also want to look at Nelson's article at firstwatt.com fro details of the RC network that many speakers need to work well with this type of amp.

It should also work well with headphones, but I have no idea what the network would be.


As far as the MOSFETs go, don't substitute for the Spertex LND150s these have some special properties that few other transistors have. The IRF820s are not as picky, there are many different MOSFETS that will work here.

John S.


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  • Re: Excuse my ignorance, but what is a "transconductance amp"? - John Swenson 16:22:53 05/27/05 (0)


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