Well done again Vunce, you always seem to have a drama free power up, now have a day off and enjoy a Merry Christmas.
I assume your R7/R8 at 28VDC rails is 3K6?
I assume your R7/R8 at 28VDC rails is 3K6?
🎄Yes, It will be a very busy two days 🎄
Correct, 3K6 installed at R7 and R8.
Quick update:
Heatsink settled at 45°C,
Bias current 1.78A
Elapsed time is 1hr from cold turn on
Buon Natale to All!!
Correct, 3K6 installed at R7 and R8.
Quick update:
Heatsink settled at 45°C,
Bias current 1.78A
Elapsed time is 1hr from cold turn on
Buon Natale to All!!
That sounds good Vunce, with your 28VDC rails at 1.78A - that is near enough to 100Watts dissipation per heatsink at only 45 deg C. What was your ambient temp do you remember? Guessing around 5 to 10 deg C. A nice garage warmer.
Thanks Vunce, so only a 24 deg C rise with your sinks. By the way, 21 deg C is no where near toasty. I will send you over some 44 deg C heat - that is toasty and way past warm.
Have a great Christmas.
Have a great Christmas.
Yeh, hopefully we only get a few days like that, we had 2 about a week ago - now only 27 degC on Christmas day.
Merry Christmas!
Happy building and much listening
Happy building and much listening
Interesting thread… is the F6 diamond the same, or higher gain, than the 14dB (5x) as specified for the original?
Thanks
Thanks
The F6 Diamond has the same gain as the original, given the same output Mosfets. The diamond buffer is unity gain.
High transconductance Mosfets affect the dynamics of the amp. I have not measured the overall gain of the amp, but I have built a separate F6 amp to try different outputs. The high transconductance parts I have used include the FQH44N10 and the IXTQ75N10P.
High transconductance Mosfets affect the dynamics of the amp. I have not measured the overall gain of the amp, but I have built a separate F6 amp to try different outputs. The high transconductance parts I have used include the FQH44N10 and the IXTQ75N10P.
TA,
When you say that higher transconductance MOSFETs affect the dynamics of the amp, is this measurable?
What MOSFETs do you have in the current iteration of you F6 clone build?
When you say that higher transconductance MOSFETs affect the dynamics of the amp, is this measurable?
What MOSFETs do you have in the current iteration of you F6 clone build?
I’m pretty sure it is measurable, I prefer using my ears. If someone has a signal generator and an oscilloscope, it would be possible to see the gain.
I am still using the IXTQ75N10P devices in my F6. The amp sounds wonderful this way.
I am still using the IXTQ75N10P devices in my F6. The amp sounds wonderful this way.
I have a new set of PCBs on the way; they should arrive sometime next Tuesday. Assembly, bias setting and break-in will be done over the remainder of that week.
Hopefully another very smooth build TA, what outputs will you use this time - do you have some Cinemag's to try?
Looking forward to your thoughts and the gerbers once all test are done.
Looking forward to your thoughts and the gerbers once all test are done.
Those were some N-P JFet pairs that I have had for a couple years (at least). About 6mA as I recall.