500W PA amplifier with Limiter

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Joined 2009
If you use a light bulb limiter, you don't need to step it down first or use any DC protect. The light bulb is actually better than a variac. A lot of amplifiers will work perfectly at lower voltage and get unstable at full voltage. With a variac turned down it may behave, and then go bang very suddenly as it is brought up. The light bulb will let the amp get to 90% of normal voltage when it's idling, and bring it down automatically if it goes unstable.
sorry i dont understand.why use bulb?
amplifier just use example -+70v.how the connection of bulb with this amp?
 

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@ apex

Sir if b500 will be bridged at 77+- vdc because. i have trafo 55 0 55 2000va and loaded with 4 ohms. i think i will end up burning my amp. i will have peak to peak voltage of 154 then try loses or voltage sag to 134vdc p-p. so the amp power would be 4489 watts at 4 ohms. if the power is continues the current 33.5A. if it is possible to do this way how many trannies needed? maybe need to used mjl4281 bec. have higher voltage rating than 2sc500.
pls. comment sir apex about this. thanks alot

You need add predrivers (post #967) and use 7 pairs of outputs for 4 ohms load in bridge mode.
Regards
 
apex.b500 need step driver or not?or step driver only for h900?i still collect enough information to build this amp.i want to drive car subwoofer speaker.

Step driver is separate circuit and can be use with any classAB amp to get classH amp.
B500 and H900 don't need step driver, B500 is classAB amp and H900 is classH amp with integrited step driver.
Regards
 
B500 - one channel

Hy everyone! I finally finished the metalwork with the B500 heatsinks, and could start one of the amps. As soon as I have time, I'll post pictures of it, but at the moment all I can say is: WOW! This sounds great. As far as I can only try it on my 50w kenwood hifi speakers, it is very powerful and has excellent sound (for my ears). So thank you Apex for sharing this with us, and as soon as I can I will post pictures.
Bye