IRFP240:
turn-on delay: 14 ns
rise time: 51 ns
turn-off delay: 45 ns
fall time: 36 ns
turn-on + (rise time / 2) = ~40 ns --> 25 MHz, fairly thorough, or not enough?
turn-on delay: 14 ns
rise time: 51 ns
turn-off delay: 45 ns
fall time: 36 ns
turn-on + (rise time / 2) = ~40 ns --> 25 MHz, fairly thorough, or not enough?
thanks for reminding me to pay attention:
so if this circuit is in Parallel with speaker,
C blocks everything below 33 kHz or so,
whatever gets through under 300 some kHz goes via 1K,
and whatever's above that starts running through LEDs?
even if I'm wrong,
thanks for reminding me not to skip over "little details" like 4.7 nF.
still working to get out of pre-K daycare,
so if this circuit is in Parallel with speaker,
C blocks everything below 33 kHz or so,
whatever gets through under 300 some kHz goes via 1K,
and whatever's above that starts running through LEDs?
even if I'm wrong,
thanks for reminding me not to skip over "little details" like 4.7 nF.
still working to get out of pre-K daycare,
Last edited:
nah,
in parallel with speaker,
it's a sensor for 300kHz+ freqs,
1K is there to protect amp in case LEDs blow up.
don't die laughing, ZM,
the rest would never forgive me!
in parallel with speaker,
it's a sensor for 300kHz+ freqs,
1K is there to protect amp in case LEDs blow up.
don't die laughing, ZM,
the rest would never forgive me!
I am wondering if anyone has the Gerber files for the Permander F6 boards, would appreciate if I could get a copy to print my own.
Thanks very much for this nice Christmas gift 🙂
I was about to clone the Permander board with KiCAD myself, but I can now save much time to just order some with a board house.
And I use the SemiSouth R125 FETs so don't need the extra LED 😀
My F6 remains unfinished but was wondering and it might speed me up...how well does this amp deal with 2 ohm and slightly under loads at high frequencies, if a pair of speakers ramps down to that via "5 ohms at 8kHz, 2.5ohms at 12kHz" and down to "a touch under" 2 ohms at the top end. 14 ohms at 200hZ, 60 ohms at 750. It's a pair of electrostat panels which if doubled per side produce 94dB at 1W.
Last edited:
Similar to an F5. It really depends on how loud you like to play them.
But 94db efficiency makes up for an awful lot... 🙂 🙂 🙂
But 94db efficiency makes up for an awful lot... 🙂 🙂 🙂
I don't know much about the F5 aside from its exceeding popularity, I'll infer a positive. Yeah, the 94dB thing is causing me to reconsider my plans! I've got a couple of tube amps (Akai M-8 SE 4 watt and an Eico HF-81) I was hoping to use with them but I've heard tube amps especially vintage prefer 16 ohms, etc. so the F6 may be a blessing in more than one way! Thanks!
Silly question - what do the C1 and C2 1000uf caps do?
I read Nelson's PDF guide but I still don't understand what is their purpose...
I read Nelson's PDF guide but I still don't understand what is their purpose...
Last edited:
The caps filter the bias voltage for lower noise, and also provide an AC path to the source.
There must be a controlled DC bias voltage on the gate (which is applied through the secondary winding),
and at the same time the lower end of the secondary must be referenced AC wise to the source to provide
the drive voltage, without affecting the DC gate bias. Note that the upper bias is referred to ground,
and the lower bias is referred to the source. This allows control of both bias and offset.
Last edited:
AC path to source - got it! thanks! I was confusing drain with source thinking it's referenced from the top to gate.
Last edited:
Believe me, I love it when people answer the questions for me. Allows me
more time for sleep...
😎
more time for sleep...
😎
Thank you sir - it's so obvious now.
I was thinking of building it with the IRFP240's mosfets, of course with 2 leds instead of 1 to get them to bias up correctly. I've got leftovers from a batch of salas shunt regs i did for my dac so would be good to use them.
Would it work? I don't see any reason why it wouldn't ?
I was thinking of building it with the IRFP240's mosfets, of course with 2 leds instead of 1 to get them to bias up correctly. I've got leftovers from a batch of salas shunt regs i did for my dac so would be good to use them.
Would it work? I don't see any reason why it wouldn't ?
Last edited:
I've got another silly question... does the 100R feedback resistor really need to be 5W rated? is it really going to pass that much current?
A couple of LED will work fine, as would an approximately 5.1V zener.
Yes, the feedback passes a bunch of current.
Yes, the feedback passes a bunch of current.