900W H-class PA Amp with Limiter

Ft Value

Amplifier sound quality depend of circuit topology more than outputs.
Regards


After Some research.

I don`t think this is true, Because Higher FT transistors require less compensation and offer much high slewrate and bandwidth.

That proves MJL21196 + MJL21194 are not better than 2SC5200 +2SA1943 in terms of Full power bandwidth.

Either the best circuit topology, using transistors with low *FT* value will _NOT_ sound better than, basic circuit topology using transistors with high *FT* value. ;)

Thanks
 
hi apexaudio
greetings thanks a ton for your step driver schematic today i wired up the amp with step driver and it came on the very first time amp driver pcb
is a modified pa 600 by oliver d in diy thread.THANKS for teaching me h class 3
months ago i did not know a thing but know have made 2 h class amps
thanks once again for sharing your wonderful schematics
thanking you
andrew lebon
is your vertex 2500 a 3 step amplifier in post 608
 
hi apexaudio
greetings thanks a ton for your step driver schematic today i wired up the amp with step driver and it came on the very first time amp driver pcb
is a modified pa 600 by oliver d in diy thread.THANKS for teaching me h class 3
months ago i did not know a thing but know have made 2 h class amps
thanks once again for sharing your wonderful schematics
thanking you
andrew lebon
is your vertex 2500 a 3 step amplifier in post 608
Yes Vertex 2500 is 3 step class H amplifier use IR2117 like H900, but VAS current in H900 is to low for drive more outputs. H900 can be upgrade with 15mA VAS current for 3 step class H and add more outputs for more power. I will share upgrades when amp was tested.
Regards
 
R15,R16-1k replace with 680R to increase VAS current. MJE340/MJE350 must have heatsink.
 

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  • APEX H900 SCH ref.jpg
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BL-1 Balance Input & Bridge Module

HEY APEX AUDIO......
greetings is this schematic yours?

thanking you
andrew lebon...

This is balanced input with low-cut circuit and limiter switchs from CROWN XLS amps, can be used with B500, H900 and also with older B250, H750 without limiter. LDR in this schematic is integrated resistor in NSL32, and integrited LED can be connected instead CLIP LED.
Regards
 
Last edited:
hi apexaudio
greetings finished step driver tlo72 working in my amplifier thinking
if a 3 step can be applied can vertex step driver be applied if made will it work
with h 900 or do you have any 3 step schematic to share like tlo 72 step
driver so easy to intergrate into amplifer.Hoping you can guide me

thanking you
andrew lebon
 
hi apexaudio
greetings finished step driver tlo72 working in my amplifier thinking
if a 3 step can be applied can vertex step driver be applied if made will it work
with h 900 or do you have any 3 step schematic to share like tlo 72 step
driver so easy to intergrate into amplifer.Hoping you can guide me

thanking you
andrew lebon

Yes you can use vertex step driver for H900. For this power is best to use step driver with IR2117, and not alternative with TL072 or similar.
Regards
 
hi apexaudio
greetings thanks for reply looking forward to make this project
1 can diode rhrg 3040 be substitued with diode 30ETH06 FRO INTERNATIONAL
RECTIFER both diodes are hyper fast 30 amps 600 volts
2 will design pcb for step driver circuit
3 have 3 50 0 50 spare transformers so can i wire them up in series for
testing
4 supply condensers voltage rating should be 80 volts is it okay
5 can ac voltage be reduced to 40 0 40
6 with this supply can 2sc 5200 and 2sa1943 be used in output stage to keep cost down and they are easily available
thanking you
andrew lebon