capability unknown-

[sekhar]

I am planning on making powerfull sub woofer amp nearly (600-1000W RMS)
I am including a circuit which i know works very well cause i designed it and has very good sonics .......

I need to know the following :-
1.How much voltage can be used in this amp safety ?
2.need help in reconfiguring the bias control scheme
3.Wat modification r needed.........
4.R the output & drivers good enough?

circuit



regards
sekhar

[nigelwright7557]

I dont like the bias due to an open wiper might wipe out all your output transistors.

Put the pot in the bottom leg wired as VR and put a set resistor in the top leg.

Teh 2sa1837 might need a 100pf from base to collector to stop oscilation.

[sekhar]

nigelwright7557
I dont like the bias due to an open wiper might wipe out all your output transistors.

Put the pot in the bottom leg wired as VR and put a set resistor in the top leg.

can show how is it supposed to be done .......AND how much voltage can this amp handle

regards
sekhar

[nigelwright7557]

Originally Posted by sekhar

can show how is it supposed to be done .......AND how much voltage can this amp handle

regards
sekhar

You wont need the zener, thats just me being overprotective.

[sekhar]

component values r nt readable .............

[nigelwright7557]

Originally Posted by sekhar

component values r nt readable .............

1k resistor
MPSA42 transistor.
1k pot.

[sekhar]

by nigelwright7557

HI, is this the way it should be and does the bias tranistor needs to sit on main heatsink ?????and wat is the maximum voltage applicable......??????

circuit


regards
sekhar

[BobEllis]

Is it me or would the 1n4007's across the Vbe multiplier limit the bias to barely on? Good safety for open wiper as originally drawn, like Nigel's zener. It just strikes me as too safe.

How much rail voltage the amp can handle depends on a number of factors, including the load, your heat sinks, your isolator choice and a few other things. Pull out the data sheet for your outputs and take a look at the safe operating area curves. Just a guess, but with 4 pairs of outputs, you should probably limit your rails to +/-60V or so. With 4 pairs of plastic outputs you should think 200W/ 8R max.

Output device Safe Operating Area (SOA) will be your main factor determining the maximum rail voltage your chosen design can handle - especially for Subwoofer duty which tends to be high power and low impedance. There are plenty of threads here discussing SOA calculations. Time to read.

For 600-1000 W out into 4 ohms (or is it 2?) you should have at least 8 pairs of outputs, if not 12. The more heat sink you have the fewer you can live with but reliability will be better with more. You may need to update the driver section to handle the increased drive current needed by the additional outputs.

I probably should have mentioned this first, but if this is your first amplifier build, for safety you should probably do something smaller first or buy something like HPA-NXV1200 1200 watt MOSFET Audio Amplifier Module The rail voltages needed for 1,000W are potentially lethal. In the US there are plenty of PA amp choices that work well for subwoofer duty that can be purchased for well below the cost of building something reliable yourself. Maybe you can find something used.

[sregor]

2 minor nitpicks. 1) you have the collectors and emiters reversed on the positive output transistors and 2) The outputs are mislabeled (2sa1943 x 4 should be on the positive side and 2sc5200 should be on the negatives side. Also a questtion going back to the 1n4007 diodes across the bias circuit. It looks like the current limiting circuit won't be able to current limit very well with this bias circuit. Good luck with it.

[sekhar]

Sregor
2 minor nitpicks

thanks for pointing out my mistake actually i was out of town for a few days i am uploading the corrected image and with bias arrangement kingly give out ur drawings an suggestion and wat do u think about multi slope vi limiter

corrected circuit



regards
Sekhar