500W PA amplifier with Limiter

[HighTec]

NMOS,

Keep up the good work. What I want to know are those over-current protections. Have you actually tested this amp under very low loads, short- circuit etc? How does it behave?

 

[NMOS]

I have modified Apex B500, now its B500 NMOS AMP

Attachment schematic

have build apex B500 with NMOS output stage but now big problem....

have 79V DC positive rail on speaker output but cant find fault....
Mosfets and driver stage and vas stage transisitors ok....no short circuits


have make some test and after disconnect R13 = 4K7 from from T1 MPSA42 ( 4k7= R14 and Q2 = 2n5551 in origiginal apex schematic) 79V DC positive rail on speaker output is gone

have replace Mosfets and T1 MPSA42 ,...after connect 4k7 with +15Vdc fault is not gone.... 79V DC positive rail again on speaker output

what could be the fault or big mistake in my B500 nmos output stage ?

I cant find solution

Thanks for help

attachment schematics

 

[TonyTecson]

hi,
positive 79 volts on the output indicates that T8 is not pulling current, or T5 is shorted....could be one of these things....or you could have the MPSA'a installed the wrong way.......check and double check....

 

[NMOS]

hi,
positive 79 volts on the output indicates that T8 is not pulling current, or T5 is shorted....could be one of these things....or you could have the MPSA'a installed the wrong way.......check and double check....

Hi have double check,...

have replace T8 with another new one 2SB649a

If Im removing T8 dont have positive rail on speaker output

after fit T8 in PCB have again positive rail on speaker output


I cant find shorted devices

MPSA installed in right way....have no idea

does somebody have solution ?

 

[TonyTecson]

^yes, you are lucky, no smoke is coming out, and that means that your biasing network is probably correct......

so now you can check that voltages are right in all places like output pins of the opamps, the rails of the op amp.....etc......

 

[khalsa]

hi nmos i think your MPSA42and MPSA92 is not orginal use 2n5401 and5551

 

[NMOS]

B500 Amp is working now but in my opinion Sound is not so good.....

with Mosfets in output stage sound is more clear and natural

with BJT 2 SC5200 in output stage highs not so clear compare to mosfets,...really

No way for B500....Quasi ACRTK and NMOS 300/500 Amps kick B500 out of the job in sound quality

 

[TonyTecson]

you can use that as a subwoofer amp then.....

 

[sandeep kayarkar]

can i use 2 24-0-24 5amp tranformer for b500?

 

[sandeep kayarkar]

can i use bd243 on for bd241?

 

[sandeep kayarkar]

gm sir, i m done with H900, bt i have a problem with ir2117, bav21 n sfa 1603, this parts is not available in nagpur's market, so i have desided to go with B500, can u pls tell me how to connect.wht changes i need to do?

 

[sandeep kayarkar]

An externally hosted image should be here but it was not working when we last tested it.

my H900, but i dont have ir2117, so i m going with B500

 

[sandeep kayarkar]

http://www.facebook.com/editphoto.php?fbid=100673086636042&aid=1402&id=100000800533883#!/photo.php?fbid=238526186184064&set=a.100673086636042.1402.100000800533883&type=1&theater

 

[sandeep kayarkar]

my H900, but i dont have IR7117, so i m going with B500. so pls suggest me abt wiring n jumpers just edit my pic n post me. pls help me out.

 

[sandeep kayarkar]

H900

 

[jlcastro77]

B500 as sub amp

hello apex, i just want to ask if i can use the b500 for my home theater sub or do you have any suggested amp to build...

Regards

Julius

 

[sandeep kayarkar]

i just tested my amp last night, and its like dream come true,
my amp B500 is ready,

 

[sandeep kayarkar]

ggggggggggggggggggggggggooooooooooooooooooooooooooooooooodddddddd mmmmmmmmmmmmmmmmooooooooooooooooooooooorrrrrrrrrrrrrrrnnnnnnnnnniiiiiiiiiiiiiiiigggggggggggggg
and thank u aman sir, my amp is ready. i think u rcv my sms last night, thank u so much,

 

[aman khalsa]

thank's to sir apex...ya i got ur sms last night.....good luck...

 

[sandeep kayarkar]

THANK U SIR,