Here are some more sims like Hugh did, but at 20vp (40vpp)
Green is the current over N-channel
Blue the current over P-channel CCS
Original AN8R with 8R load
Original AN8R with 4R load, running out of current(clipping) on N and P-channel
New ANxR with 8R load
New ANxR with 4R load, only clipping of current on P-channel CCS
Green is the current over N-channel
Blue the current over P-channel CCS
Original AN8R with 8R load
Original AN8R with 4R load, running out of current(clipping) on N and P-channel
New ANxR with 8R load
New ANxR with 4R load, only clipping of current on P-channel CCS
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Can one use the FQA40N25 / FQA36P15 combination for this ?. I have 2 fans and 2 cpu coolers at the ready, and if I had to, I have 2 extra fans / coolers in the case I need to rig up some extra cooling concepts.
Thanks,
MM
Thanks,
MM
Anand,
From Danny's graph it does appear the SJEP looks very good.
I do see that the current range on the nmos is not so low as with the hexfet, but it works very well and you might expect results. You could force a greater differentation by using 0.27/0.10 however.
Myles,
Yes this change of source resistors will work just fine with FQA40N25 and FQA36P15. These devices are my first choice for this amp. Good luck with the completion of your Alpha Nirvana!
Hugh Dean
From Danny's graph it does appear the SJEP looks very good.
I do see that the current range on the nmos is not so low as with the hexfet, but it works very well and you might expect results. You could force a greater differentation by using 0.27/0.10 however.
Myles,
Yes this change of source resistors will work just fine with FQA40N25 and FQA36P15. These devices are my first choice for this amp. Good luck with the completion of your Alpha Nirvana!
Hugh Dean
I seem to talking with Anand about this some years back, Vunce, and I think we decided on 100R. He highlighted Nelson Pass' design using the same SJEP from memory....... His post was at #2218 at page 111 of this thread in fact.
In fact, Anand, did you swap out your hexfet for the SJEP? If so, did you use a 100R stopper and did you measure ANY voltage across it, showing a finite gate current?
Hugh
In fact, Anand, did you swap out your hexfet for the SJEP? If so, did you use a 100R stopper and did you measure ANY voltage across it, showing a finite gate current?
Hugh
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Not yet Hugh! Too many projects! I will be building up the Alpha Nirvana’s in their own monoblock enclosures though and all these goodies we are discussing will be added in!
Best,
Anand.
Danny
Thank you very much for all this information.From the first moment I play the amplifier at 2.6A with 0.15+1Ω=0.13Ω resistors for P and Ν mosfets.
I trusted my ears especially at high volumes on 4Ω speakers.
Hi Nikos,
Yes, at 2.6A it's even better, if you can handle the heat 😎
With 2.1A 2x25v 105w my 4U 400mm passive heatsinks are 25°c above room temperature.
I just listened to Daniel Pemberton - Escape From East Berlin
Never heard it this good, AN is really a very very good amplifier, excellent !
Yes, at 2.6A it's even better, if you can handle the heat 😎
With 2.1A 2x25v 105w my 4U 400mm passive heatsinks are 25°c above room temperature.
I just listened to Daniel Pemberton - Escape From East Berlin
Never heard it this good, AN is really a very very good amplifier, excellent !
2.6A 2x 21.5V =111.8W piece of cake for CPU Fan 12cm P12 Arctic .Very very quiet, temp on cpu heatsink 44-47C, body 54-57C, room temp 30C.
Attachments
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Nice sandwich of the mosfets ! Works great looking at your temperatures.
A quick question if I may:
Will a transformer change from 22V secondaries I have on the stock AN39 be required. If so, I was thinking that 18V secondaries would suffice assuming that the SLB will drop approximately 3V. This should give approximately 22VDC to work with if my calc's are correct. Thanks for the help.
MM
Will a transformer change from 22V secondaries I have on the stock AN39 be required. If so, I was thinking that 18V secondaries would suffice assuming that the SLB will drop approximately 3V. This should give approximately 22VDC to work with if my calc's are correct. Thanks for the help.
MM
Myles,
No. 18vac will give you an idling rectified voltage of just over 25Vdc. Loaded with this Class A amp would drop around 10% to just 22V then less the 3V of the SLB which is 8V shy of the required design AN39-8 voltage of 27V.
However if you are building a 4R amp 18Vac trafos would still be unacceptable as you still find up with a little less voltage of 19V.
I would always go for the 22Vac trafos. Better to have more than less as removing 5-10 turns off the toroidal secondaries is doable!
Hugh
No. 18vac will give you an idling rectified voltage of just over 25Vdc. Loaded with this Class A amp would drop around 10% to just 22V then less the 3V of the SLB which is 8V shy of the required design AN39-8 voltage of 27V.
However if you are building a 4R amp 18Vac trafos would still be unacceptable as you still find up with a little less voltage of 19V.
I would always go for the 22Vac trafos. Better to have more than less as removing 5-10 turns off the toroidal secondaries is doable!
Hugh
Thanks Hugh,
I was thinking of possibly building the amp with the different source resistors 0.22 and 0.15 ohms. Danny66 post #3751, indicates:
25v 0.22-0.15 8Rload
2.12A 107W
vpp: 47.5202
power_output: 35.3979
So using 22Vac with the SLB's should be around 27V, so maybe a bit less biasing applied and should be OK.
Does this make sense ?
Or, I just build the 8ohm version with the 0.22 ohm source resistors and not worry about getting fancy 😉
MM
I was thinking of possibly building the amp with the different source resistors 0.22 and 0.15 ohms. Danny66 post #3751, indicates:
25v 0.22-0.15 8Rload
2.12A 107W
vpp: 47.5202
power_output: 35.3979
So using 22Vac with the SLB's should be around 27V, so maybe a bit less biasing applied and should be OK.
Does this make sense ?
Or, I just build the 8ohm version with the 0.22 ohm source resistors and not worry about getting fancy 😉
MM
No Myles use the 22Vac trafos and you can set the 25Vdc rails with 5V dropped across the SLB.
In truth the 27Vdv rails will not add much dissipation so it should be a slight headroom advantage!
Hugh
In truth the 27Vdv rails will not add much dissipation so it should be a slight headroom advantage!
Hugh
Thanks for the info Hugh. I was trying to think and manipulate the V and the bias to keep the dissipation around the 100W number. I will keep my eye on this thread for future tips before I get back to working on the AN39. Right now enjoying a month in Mexico.
Cheers,
MM
Cheers,
MM