Hello guys.
...at first I want to apologize for my bad english. I have no practice at all, and only remember a little of school education in this language. Please don´t think too bad of me, therefore! ^^ ...at second I have to say, i´m practiced in working with (simple constructed) high voltage projects, and know about the hazards, and what to do for security. But --- in audio the only project i did, was a LM 3886 amplifier (as Siegfried Linkwitz showed on his site).
Now I have a problem: I have nearly zero money, but want to build an amp with an output of about 800 - 1200 (best would eventually be 1000) W RMS. From a former project i have some probably usable parts in stock. This is the simplest usable scheme i could find. What do you think about it? Is it good for a subamp? I got (each 24 pcs) IRFPC50A(from IRF) and IRF450(but from Harris, less I.ds and also P.tot). The IRFPC50A seems to have nearly the same parameters like IRFP448, but, unfortunately, only nearly... :(
Could I use one of this FETs? And when, what do you think, how many pairs should i use for 1000 W RMS at 4 Ohms? And can I still use the showed gate driving BJTs (Q10 and Q11)? Or stronger ones, and when, then which? (Only thing I really know, is, that I´d have to use bigger fuses...) I got two transformers, rated at 2,5 kVA (permanent), 13,3 kVA (short time), with center tap, and by changing primary taps, i can get (+/-) 70.96, or 74.35, 78.05, 81.32 (8 steps of ~ 3.5 V) 102.72 VDC (without diode losses). These are a little too big, but I have no other. (Yes, I know, I only need one... ^^)
Is this schematic acceptable? (No real foults, I mean.) The sound must not be "audiophile", it only should work, without bigger complications. I know, normally in this modern time, if one wants to get so much power, he should do with class D, but this (now) is too complex for me as a more electric (and not electronic) experienced guy. And cannot make PCB, so I´d be glad if I must build the driver stage only once, cause I must use "breadboard" (I think this is the name of this in english), and combine with point-to-point (better silvered copperwire or is varnished enough?), where necessary.
I have one further schematic (which HAS already the possibility to ad enough FETs [the gate-driving BJTs, who drive 2 x 5 IRFP 460, surely would drive a bigger number of smaller FETs, e.g. 2 x 10 of my IRFP 450 [Harris, not to forget, otherwise, if they were "real" IRFP450s from IRF, 2 x 8 would be roughly enough, i think] , cause it is mentioned in the text, that the driving capability is not exhausted) but this needs one voltage 10 volts higher than rail, and i don´t have a transformer with those further tap. (Like I wrote, my voltage changes by changing PRIMARY...) I don´t know, if it would be a good idea, to ad some windings, but... I think, it would not. :D (Isolation etc.) But, the good thing with the second circuit is, it has a complete description of getting the amp started. And has a second pot, to do this... (Begins with: "Put some 100 Ohm resistors in place of the fuses..." --- really good described, a fine thing.)
I don´t even know what kinds of resistors (evtl. metal film ok?), capacitors (film types like MKS ok? --- except the unipolar electrolytic, of course), and what kind of inductor should be good? (From the inductor in scheme 1 there´s no information at all, and cause I´m not experienced at all, I have no idea. Should it be ferrite or plated iron? Have or have not an air gap, and when, how wide? Only thing I am sure, copper wire should be thick enough.)
Please, help me! Could I make it work?
(P.S.: In a thread I found, one guy said, it would be cheaper, to buy a used PA amp, than build an amp of this power. I hope, he meant the costs of the transformer (my ones I got in former times, when I had money, for 200 Euro each) and the Power-FETs, cause used PA-amps of this power never come under 100 or more Euros --- I simply don´t have, and wouldn´t get, such an amount of money, for now)
First possibility, which fits my transformer:
400 W MOSFET Audio Amplifier Using IRFP448 : Tasel
Second possibility, which needs 10 "extra" Volts:
600 Watt Quasi Amplifier With Mosfet IRFP460
...or do you have a better one? :smash:
Greets,
FQR
...at first I want to apologize for my bad english. I have no practice at all, and only remember a little of school education in this language. Please don´t think too bad of me, therefore! ^^ ...at second I have to say, i´m practiced in working with (simple constructed) high voltage projects, and know about the hazards, and what to do for security. But --- in audio the only project i did, was a LM 3886 amplifier (as Siegfried Linkwitz showed on his site).
Now I have a problem: I have nearly zero money, but want to build an amp with an output of about 800 - 1200 (best would eventually be 1000) W RMS. From a former project i have some probably usable parts in stock. This is the simplest usable scheme i could find. What do you think about it? Is it good for a subamp? I got (each 24 pcs) IRFPC50A(from IRF) and IRF450(but from Harris, less I.ds and also P.tot). The IRFPC50A seems to have nearly the same parameters like IRFP448, but, unfortunately, only nearly... :(
Could I use one of this FETs? And when, what do you think, how many pairs should i use for 1000 W RMS at 4 Ohms? And can I still use the showed gate driving BJTs (Q10 and Q11)? Or stronger ones, and when, then which? (Only thing I really know, is, that I´d have to use bigger fuses...) I got two transformers, rated at 2,5 kVA (permanent), 13,3 kVA (short time), with center tap, and by changing primary taps, i can get (+/-) 70.96, or 74.35, 78.05, 81.32 (8 steps of ~ 3.5 V) 102.72 VDC (without diode losses). These are a little too big, but I have no other. (Yes, I know, I only need one... ^^)
Is this schematic acceptable? (No real foults, I mean.) The sound must not be "audiophile", it only should work, without bigger complications. I know, normally in this modern time, if one wants to get so much power, he should do with class D, but this (now) is too complex for me as a more electric (and not electronic) experienced guy. And cannot make PCB, so I´d be glad if I must build the driver stage only once, cause I must use "breadboard" (I think this is the name of this in english), and combine with point-to-point (better silvered copperwire or is varnished enough?), where necessary.
I have one further schematic (which HAS already the possibility to ad enough FETs [the gate-driving BJTs, who drive 2 x 5 IRFP 460, surely would drive a bigger number of smaller FETs, e.g. 2 x 10 of my IRFP 450 [Harris, not to forget, otherwise, if they were "real" IRFP450s from IRF, 2 x 8 would be roughly enough, i think] , cause it is mentioned in the text, that the driving capability is not exhausted) but this needs one voltage 10 volts higher than rail, and i don´t have a transformer with those further tap. (Like I wrote, my voltage changes by changing PRIMARY...) I don´t know, if it would be a good idea, to ad some windings, but... I think, it would not. :D (Isolation etc.) But, the good thing with the second circuit is, it has a complete description of getting the amp started. And has a second pot, to do this... (Begins with: "Put some 100 Ohm resistors in place of the fuses..." --- really good described, a fine thing.)
I don´t even know what kinds of resistors (evtl. metal film ok?), capacitors (film types like MKS ok? --- except the unipolar electrolytic, of course), and what kind of inductor should be good? (From the inductor in scheme 1 there´s no information at all, and cause I´m not experienced at all, I have no idea. Should it be ferrite or plated iron? Have or have not an air gap, and when, how wide? Only thing I am sure, copper wire should be thick enough.)
Please, help me! Could I make it work?
(P.S.: In a thread I found, one guy said, it would be cheaper, to buy a used PA amp, than build an amp of this power. I hope, he meant the costs of the transformer (my ones I got in former times, when I had money, for 200 Euro each) and the Power-FETs, cause used PA-amps of this power never come under 100 or more Euros --- I simply don´t have, and wouldn´t get, such an amount of money, for now)
First possibility, which fits my transformer:
400 W MOSFET Audio Amplifier Using IRFP448 : Tasel
Second possibility, which needs 10 "extra" Volts:
600 Watt Quasi Amplifier With Mosfet IRFP460
...or do you have a better one? :smash:
Greets,
FQR