MOSFET Amplifier IRFP240/IRFP9240

[apexaudio]

Originally Posted by db!

Would you happen to have a schematic that contains the component values? Also, what are your thoughts on using the IRFP250 instead of the 240?

Idea full complementary simetry for minimized distorzion and posible oscilation.Design use lokal feedback and minimum compezation for low TIM. This concept sound beter to me than unsimetry design with quasy complementary output stage useing only N-tip mosfet like IRFP250. IRFP250 have no P-tip complement (IRFP9250 for example) and that was reason not use them. I use IRFP250 in D class amplifier.

[apexaudio]

Originally Posted by andrewlebon

hi apexaudio
greetings what is the output power of the h class amplifier using 2sc5200 2sa1943 and irf 2807 any schematic please nice mosfet amplifier
thanking you
andrew lebon

H class amplifier
Pout 480W 8R, 750W 4R
H class amplifier is stil in comercial use. I post schematics when he was remain with new driver model. I will post schematic of older version H class amplifier with NE5532 in iput stage and IR2117 for driving step mosfets.

[andrewlebon]

hi apex audio
greetings thanks for the reply

thanking you
andrew lebon

[apexaudio]

Redrawing mistake. 2N5551 and 2N5401 wrong notification, corect on this schematics. 2SC2383 replaced with MJE340, 2SA1013 replaced with MJE350 in newer version both are OK. 2SB861 and 2SD1138 in VAS can be used too.

[homemodder]

Hi Apex, i dont think your vas is unusal, its a cfp, I use it in alot of my amps, what is unsual is the your temp compensatiom circuit, Im still guesing how it could work.
The thought has come to mind that the cfp transistor that gets mounted on the heatsink has something to do with it but Id have to build it to see the exact effect.

[sumaudioguy]

Originally Posted by apexaudio

Redrawing mistake. 2N5551 and 2N5401 wrong notification, corect on this schematics. 2SC2383 replaced with MJE340, 2SA1013 replaced with MJE350 in newer version both are OK. 2SB861 and 2SD1138 in VAS can be used too.

Dear Apex, Please take time to try this. Tie a 1000µF capacitor between the emitter of Q9 to the emitter of Q10. I truly believe this will really clean up the highs even though the amp sounds good now.

Now a question, why are the gate resistors of the output FET 470 ohms? It seems to me I have measured this device and its impedance is 50 ohms so a gate resistor of 50 ohms would make more sense to me. This may cause some other problem and if you do not feel like taking time to answer that is fine. No insult is intended!

[sumaudioguy]

Originally Posted by homemodder

Hi Apex, i dont think your vas is unusal, its a cfp, I use it in alot of my amps, what is unsual is the your temp compensatiom circuit, Im still guesing how it could work.
The thought has come to mind that the cfp transistor that gets mounted on the heatsink has something to do with it but Id have to build it to see the exact effect.

I suspect the temperature compensation is non-obvious. Maybe D1 D2 D3 and D4 slight increase in temperature decreases bias current through the differential pairs (x20 as that is the gain of that section) which tends to turn off Q7 Q8 Q9 and Q10 limiting bias. This seems plausible as 1N4148 are very sensitive to any temperature change having very low thermal mass and change temperature even from radiant energy. If this thing was all in a box I am willing to bet it has a negative temp of bias due to this effect.

This is very easy to test. Use freeze spray on the diodes and watch the bias for big changes. This "theory" will quickly prove right or wrong.

[qusp]

Originally Posted by apexaudio

Sory, I dont speak English, is hard to me to replied becouse I dont understend question or sugest sometimes, I hope my tone will be beter in future.

dont worry about it, likely its partially my interpretation too.

[apexaudio]

Originally Posted by homemodder

Hi Apex, i dont think your vas is unusal, its a cfp, I use it in alot of my amps, what is unsual is the your temp compensatiom circuit, Im still guesing how it could work.
The thought has come to mind that the cfp transistor that gets mounted on the heatsink has something to do with it but Id have to build it to see the exact effect.

I dont use this PCB in a last 2 year (repleced with H class in PA and A class for home aplication), but I must build couple PCBs again and try to see the effect on some sugestion.

[apexaudio]

PCB size: 200X50mm