what do think about this schematic?????

[sekhar]

i want to make a monster amp that is capable of driving loads upto 2E and produce some wat like 1500W RMS .... i know i sound crazy but i like to have a very powerfull monoblock to drive my subwoofers ....
Using 30 mosfets in o/p stage seems insane but I wanna keep it very well under SOA....
I had a few doubt as the drive current for 15+15 mosfets is gonna be huge and normal MJE series drive transistors do not seem to qualify .... So I went on using 2sc5200 & 2sa1943 as drivers... i have never done it so was a bit confused is this ok ...
kindly give ur comment on this I would like to give this amp a try .......

SCHEMATIC


regards
sekhar

[ostripper]

Originally Posted by sekhar

i want to make a monster amp that is capable of driving loads upto 2E and produce some wat like 1500W RMS .... i know i sound crazy but i like to have a very powerfull monoblock to drive my subwoofers ....
Using 30 mosfets in o/p stage seems insane but I wanna keep it very well under SOA....
I had a few doubt as the drive current for 15+15 mosfets is gonna be huge and normal MJE series drive transistors do not seem to qualify .... So I went on using 2sc5200 & 2sa1943 as drivers... i have never done it so was a bit confused is this ok ...
kindly give ur comment on this I would like to give this amp a try .......

SCHEMATIC


regards
sekhar

With the IRF's you are not driving current driven devices. For 15 BJT pairs like MJL21193/94 , sure.. use the 2sc5200/2sa1943's. (ESP project 115) With the IRF's , you are just trying to "overpower" the gate capacitances. The 2sa1837/2sc4793 or the MJE15032/33 would be more than enough to do the job as well as offer more gain and speed. The circuit would work as is , but be careful. Ps - you forgot the output inductor.
OS

[sekhar]

THERE is a lot of thread about very high power amps in our forum & many have been given a try..... i would like u experienced diyers to give this amp a thought cause I think this amp is stable and has good sound I made this very amp but with a lot lesser supply voltage and it is still rocking at my frnds house for over than 6months . .....


regards
sekhar

[AndrewT]

+-80Vdc will not get you an output of 77.5Vpk on a sinewave signal.
Expect no better than 1230W into 2r0.
15Pair will probably make for excellent reliability into 4ohm speaker. Expect just under 700W into 4ohm.

I see I misread the supply voltage. You show +-85Vdc

[tinitus]

Originally Posted by ostripper

(ESP project 115)

OS

project 115 is gain clone design

[sekhar]

how many fets r needed in the o/p stage so that this amp becomes virtually indestructible at any load ...????????????//


regards
sekhar

[AndrewT]

as a starter, change the Zener across the gate and source resistor.

[ostripper]

Originally Posted by tinitus

project 115 is gain clone design

Off by 2 .. project 117. Project 117

My point is that

how many fets r needed in the o/p stage so that this amp becomes virtually indestructible at any load ...????????????//

This is a DREAM , give me your 50 pairs and it will not be indestructable. The layout , circuit topology , and device choices are more important than how many parts you throw at it. Then there is safety , I just spent 3 hours making a power supply that will do 100000uF , uses a 50A bridge , and can run at 100V and my greatest problem was not how many parts I could stuff it with .. but the spacing between traces for both the AC and DC to keep my safety margins to spec. Even added red and blue LED's to the rails for alert to VERY DEADLY VOLTAGE !!

My biggest amp(the ones the power supply above will power) are 250w/8r with 400+ watt peaks .... they can nearly throw every and any 15" or 18" woofer cone right out of the basket.(bounces right across the floor) That is why I have not built a 500w unit.

WHAT are you powering , and for what a 1000w analog amp costs, I can buy 5-10 500w class D amps. Another factor with many pairs is sound quality. A 2-4 pair BJT will sound better and be more reliable than a 15 pair monster.
If I had 4 inefficient 15" subwoofers rated at 300w - each , it would be cheaper, safer, and more reliable to build 4 - 250w amps than 1 big 1KW "arc welder" to power those 4 speakers.
OS

[sekhar]

this is just a dream that I am following .............. It does nt matter how many parts go into it cause its a one time build .... its nt for professional PA build .... i just wanna make large and robust ..... may be some thing that I can contribute to this great community ....

Come on guys I know its INSANE but lets make this happen ..... cause there r a lot of power fanatics who like the idea of a monstrous amp .... And with buying stuff from the market I am strictly against it ... this is whole reason I came to diy ... So that I can make my own stuff .....

regards
sekhar

[sekhar]

to andrew T
What should be zener rating for this given amp??????????

regards
sekhar