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In Reply to: Excuse my ignorance, but what is a "transconductance amp"? posted by soulcargo on May 27, 2005 at 05:13:14:
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.
Topic - CCS Transconductance Amp, schematic, Measurements - John Swenson 01:21:20 05/26/05 ( 13)
- Re: CCS Transconductance Amp, schematic, Measurements - kenev 11:12:24 07/15/05 ( 0)
New parafeed caps - John Swenson 14:23:55 05/31/05 ( 2)
- John, for a good cheap cap try... - Russ57 12:00:01 06/1/05 ( 1)
- Re: John, for a good cheap cap try... - John Swenson 16:36:46 06/7/05 ( 0)
Excuse my ignorance, but what is a "transconductance amp"? - soulcargo 05:13:14 05/27/05 ( 1)
- Re: Excuse my ignorance, but what is a "transconductance amp"? - John Swenson 05/27/05 16:22:53 05/27/05 ( 0)
bravo - keto 13:09:38 05/26/05 ( 0)
Be brave....my preamp is a P-fet... - Russ57 11:29:26 05/26/05 ( 0)
for larger plate chokes - mqracing 06:59:39 05/26/05 ( 3)
- SJPCs - soulcargo 05:10:12 05/27/05 ( 0)
Re: for larger plate chokes - John Swenson 13:28:30 05/26/05 ( 1)
- Re: for larger plate chokes - mqracing 08:05:16 05/31/05 ( 0)
you've been granted special dispensation - mqracing 06:55:30 05/26/05 ( 0)