Measure with a bias at 1.5A
Test frequency: 500 Hz
Amplitude: 100mV AC Vgs signal
Either measure AC drain current direct with a good multimeter or use a drain resistor and measure AC voltage across and convert to current.
Transconductance Values
IRFP250 between 2.9 and 3.1 Siemens
IXTH64N10L2 between 3.8 and 4.0 Siemens
However out of the parts I purchased there was very little variation between parts so I am reasonably confident you won't need to perform measurements unless you really want to.
Test frequency: 500 Hz
Amplitude: 100mV AC Vgs signal
Either measure AC drain current direct with a good multimeter or use a drain resistor and measure AC voltage across and convert to current.
Transconductance Values
IRFP250 between 2.9 and 3.1 Siemens
IXTH64N10L2 between 3.8 and 4.0 Siemens
However out of the parts I purchased there was very little variation between parts so I am reasonably confident you won't need to perform measurements unless you really want to.
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Got some time to listen. Took about 12 hours listening to all kinds of music. Settled on Nora Jones as baseline to audition a couple different cabinets. I made a Pair of clone JBL L-100’s....where I had a complete set of original transducers. Crossovers were per Dennis Murphy. The Vintage JBL West Coast Sound becomes the… | Audioholics Home Theater Forums
The amp was Very smooth, refined highs, good clear midrange, bass was sharp having clean edges to the strings (stand up bass). I did not find it harsh or fatiguing over time. The F6 drove these 94db speaks pretty well.
I set bias for first 6 hours at .323ma..the entire amp got no more than 102 degrees. The last 5 plus hours set at .350ma. (.35/.22= 1.59a)
I’m very impressed with the sound. It was a great project!
Thanks!
The amp was Very smooth, refined highs, good clear midrange, bass was sharp having clean edges to the strings (stand up bass). I did not find it harsh or fatiguing over time. The F6 drove these 94db speaks pretty well.
I set bias for first 6 hours at .323ma..the entire amp got no more than 102 degrees. The last 5 plus hours set at .350ma. (.35/.22= 1.59a)
I’m very impressed with the sound. It was a great project!
Thanks!
OK, thanks. I guess I can get a batch and go for it, and if problematic, get set up to measure. Seems like a few others are trying this here, so I will watch a while. First, to get some parts
Russellc
Did you just buy the outputs and use as were, or did you perform any kind of sorting, matching, measuring? Sounds like Pico has found these to be very close, so I was going to buy some and go for it.
If something becomes obviously wrong, I will get more samples and do what needs to be done.
russellc
No matching. From what I understood testing/matching would not be required to achieve good sound.. I had purchased several outputs to try but went with Mr PicoD as he’s far smarter than me & he liked the results.....besides there are already changes in sound depending on speakers, pre’s, etc etc. I need to listen to this configuration (my baseline) for awhile using different pre’s. I’m curious to see what my DHT X201 pre sounds like...fun stuff
The parts are basically different enough to get the desired result.
Measurements are not really necessary.
It doesn't hurt to measure them to know for yourself exactly what you have though, if you wanted to be certain.
We're not matching for the purpose of current sharing. We are doing the exact opposite (so it behaves more like a J2 circuit) so the level of precision required is not as great as matching paralleled parts etc.
Measurements are not really necessary.
It doesn't hurt to measure them to know for yourself exactly what you have though, if you wanted to be certain.
We're not matching for the purpose of current sharing. We are doing the exact opposite (so it behaves more like a J2 circuit) so the level of precision required is not as great as matching paralleled parts etc.
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I was on of them, circa 70's. Mainly small block chevy and large block Mopar.
Bracket drag racing, etc. Those engines I could get the most go for the least money.
Located blocks and heads in salvage yard, rebuilt/blueprint, installed balanced assembly, cam etc and button her up.
Hot rodding is a different game today. I wish the engine heads that are available today were back then. Not to mention variable cam timing, computer mapping fuel systems etc. Most of our stuff was very seat of the pants, but much fun.
Mechanicals are expensive, but tires are as well! I only wore them out on the rear, track cars are way more expensive. never did those.
I often want another project, but between building amps and firearms, play money gets used up, and car projects are WAY more expensive these days! I keep looking at the FACTORY FIVE AC Cobra sets...
Back to amps...
russellc
Bracket drag racing, etc. Those engines I could get the most go for the least money.
Located blocks and heads in salvage yard, rebuilt/blueprint, installed balanced assembly, cam etc and button her up.
Hot rodding is a different game today. I wish the engine heads that are available today were back then. Not to mention variable cam timing, computer mapping fuel systems etc. Most of our stuff was very seat of the pants, but much fun.
Mechanicals are expensive, but tires are as well! I only wore them out on the rear, track cars are way more expensive. never did those.
I often want another project, but between building amps and firearms, play money gets used up, and car projects are WAY more expensive these days! I keep looking at the FACTORY FIVE AC Cobra sets...
Back to amps...
russellc
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