MOSFET Amplifier IRFP240/IRFP9240 - Page 3

AP2 · 03:09 PM

Hi Apexaudio,
I'm testing an amplifier with complementary 240/9240 similar to yours (not equal)
what is the frequency response at (0dB) on you amplifier.
my post is My idea di MonoBlock esoteric

Regards

apexaudio · 27th February 2010, 03:19 PM

20Hz-30kHz, THD 0,5 at 240W on 8ohm load.

AP2 · 27th February 2010, 03:31 PM

Thanks for info,
before I had the same response (20Hz-30kHz),before any intervention.
I have 0.03% at 230W 8R, think is good.
Regards

sakis · 03:52 PM

an amplifier that its designed to work with V limmiters in a PA housing with controled ventilation might escape the smoke even if bias is unstable

it might looks thermally unstable as a circuit but it might be stable enough as a complete product ....

Let us not forget that even that even pro amps like QSC dont use a transistor to monitor temperature .... just a simple noisy inexpensive thermistor ...still the get away with it ....

And by the way i also agree on the bias issues and also to my understanding there is no chance that an amplifier like that will keep stable without a zobel, with inductor,and clamp diodes that is missing from your schmtics and pcb ....unless all the above is located else where

Bottom line is if you invest money in a PA or any other big amplifier construction ( since amplifiers like that tent to cost some money ) it would be wise to have all mistakes corrected and use state of the art circuit and semis any way....

apexaudio · 27th February 2010, 04:36 PM

Why anyone have no any coment on unusuall circuit Q8,Q9,R17,R21 and Q7,Q10,R18,R22 in voltage amp... Mosfets IRFP240 and IRFP9240 had integrited clamp diode, R50, C11 are zobel, and inductor is on speakers terminal. On the fotos you can see an amp without fan, make for home listening many years ago. Amp is simple to build and test, work with two output mosfets on +/-50V DC.

qusp · 27th February 2010, 05:05 PM

Apexaudio, thanks for sharing, but I think if you expected to come here, put your design on display (and perhaps sell some PCBs) and get universal praise for your design and think that because it has been in use for 10 years that it cant be improved on, you are mistaken. these guys are not criticizing, they are bouncing ideas to improve the circuit around. there are some serious pros here, in general the attitude here is a proactive one, no need to be defensive. if you dont want constructive criticism, I have to wonder why you posted...... take it on board; or not. up to you

apexaudio · 27th February 2010, 05:14 PM

In last tree years in my PA amplifiers I use new design with 2SA1943/2SC5200 bipolar output tranzistors and IRF2807 mosfets for step. Amplifier work in H class 0,+/-60V,+/-120V.

black · 27th February 2010, 05:20 PM

schematic complete atach ?

apexaudio · 05:45 PM

For qusp:
I sharing my expirience about building amplifiers, I do not sale anything. I dont expected anything, if someone is usufull my post , and give some ideas for design thats all.

apexaudio · 05:44 PM

For black:
Schematics for APEX MOSFET?

27th February 2010, 03:05 PM	#21
AP2 diyAudio Member Join Date: Dec 2009 Location: Italy	Hi Apexaudio, I'm testing an amplifier with complementary 240/9240 similar to yours (not equal) what is the frequency response at (0dB) on you amplifier. my post is My idea di MonoBlock esoteric Regards Last edited by AP2; 27th February 2010 at 03:09 PM.

27th February 2010, 03:44 PM	#24
sakis diyAudio Member Join Date: Jan 2006 Location: nea makri athens greece	an amplifier that its designed to work with V limmiters in a PA housing with controled ventilation might escape the smoke even if bias is unstable it might looks thermally unstable as a circuit but it might be stable enough as a complete product .... Let us not forget that even that even pro amps like QSC dont use a transistor to monitor temperature .... just a simple noisy inexpensive thermistor ...still the get away with it .... And by the way i also agree on the bias issues and also to my understanding there is no chance that an amplifier like that will keep stable without a zobel, with inductor,and clamp diodes that is missing from your schmtics and pcb ....unless all the above is located else where Bottom line is if you invest money in a PA or any other big amplifier construction ( since amplifiers like that tent to cost some money ) it would be wise to have all mistakes corrected and use state of the art circuit and semis any way.... __________________ SERVICE ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr Last edited by sakis; 27th February 2010 at 03:52 PM.

27th February 2010, 05:28 PM	#29
apexaudio diyAudio Member Join Date: Feb 2010 Location: Serbia	For qusp: I sharing my expirience about building amplifiers, I do not sale anything. I dont expected anything, if someone is usufull my post , and give some ideas for design thats all. Last edited by apexaudio; 27th February 2010 at 05:45 PM.

27th February 2010, 05:37 PM	#30
apexaudio diyAudio Member Join Date: Feb 2010 Location: Serbia	For black: Schematics for APEX MOSFET? Last edited by apexaudio; 27th February 2010 at 05:44 PM.

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27th February 2010, 03:19 PM	#22
apexaudio diyAudio Member Join Date: Feb 2010 Location: Serbia	20Hz-30kHz, THD 0,5 at 240W on 8ohm load.

27th February 2010, 03:31 PM	#23
AP2 diyAudio Member Join Date: Dec 2009 Location: Italy	Thanks for info, before I had the same response (20Hz-30kHz),before any intervention. I have 0.03% at 230W 8R, think is good. Regards

27th February 2010, 04:36 PM	#25
apexaudio diyAudio Member Join Date: Feb 2010 Location: Serbia	Why anyone have no any coment on unusuall circuit Q8,Q9,R17,R21 and Q7,Q10,R18,R22 in voltage amp... Mosfets IRFP240 and IRFP9240 had integrited clamp diode, R50, C11 are zobel, and inductor is on speakers terminal. On the fotos you can see an amp without fan, make for home listening many years ago. Amp is simple to build and test, work with two output mosfets on +/-50V DC.

27th February 2010, 05:05 PM	#26
qusp Sometimes a square peg fits a round hole just fine diyAudio Member Join Date: Oct 2009 Location: Brisbane, Australia	Apexaudio, thanks for sharing, but I think if you expected to come here, put your design on display (and perhaps sell some PCBs) and get universal praise for your design and think that because it has been in use for 10 years that it cant be improved on, you are mistaken. these guys are not criticizing, they are bouncing ideas to improve the circuit around. there are some serious pros here, in general the attitude here is a proactive one, no need to be defensive. if you dont want constructive criticism, I have to wonder why you posted...... take it on board; or not. up to you

27th February 2010, 05:20 PM	#28
black diyAudio Member Join Date: Dec 2006	schematic complete atach ?

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