QUASI Amplifier for Beginners

sir can you re design your qusai with a op amp input?

BGW750A.gif


Q1, 2, 4, 5 2N3440/5415 or MJE 340/350
Bias transistor, just about anything.
Outputs (and drivers) 2N3773, MJ15022/24, etc.
Opamp LM318

Protection was a DC crowbar, a thermal cut-out on the heatsink, and a circuit-breaker on the transformer primary.


have this amp as quasi and complementary model 750 B
 
"Go to post #273. "

Yes, but the BGW is much simpler, and the parts are easier to find.

"have this amp as quasi and complementary model 750 B "

I have a few 250, 500D, 500R, and various 750 models. Old workhorses for sure.
 
God gracious Apex, this is a great success. I made it and it works fine. Thanks you very much for the schematics and the PCB layout. Even tough I modified it a bit but it still retain the same artwork as yours. Thanks again. Below are the images:


I am using ExpressPCB for the PCB layout and the schematic. You can download it for free from this website: ExpressPCB - Free PCB layout and schematic software

please post your pcb design in pdf format.
 
Later BGW designs have same schematic but add VI Limiter,

if you like quasi amp Design

I suggest you to use design quasicomplementary design from DIY Member

"Quasi"

you can find it under Thread "power amp under development"

and..... BGW 750A and 750B sounding much better compare to a lot of Professional Class D Amplifier.

Have test before some weeks Class D amp with IRS2092 IC V/s old BGW 750B

No way,...BGW kick Class D amp out of the job, Class D amps are very good in effeciency but no way in premium sound


Finally: If you want better sounding amp as BGW use quasicomplementary design from DIY Member "Quasi"
 
hi apex,i have made pcb for this amp.Now i am about to place components.At my place a1943/c5200 & mje15030/15031 pair is available for same price i.e.2 $,so is it not fair to use these as drivers.Kindly reply me because i have bought all components except drivers.
 
hi apex, i have completed this amp through self made pcb.it is working fine ,currently only with +/-12 volt.pcb track for ccs mje340 base resistor is wrong in your pcb layout.
with this supply there is offset voltage of 32millivolt on output, is it right.I will increase the supply voltage after confirming about offset voltage.which set of in4148 diodes are placed on heatsink for thermal bias control ?
 
hi apex, i have completed this amp through self made pcb.it is working fine ,currently only with +/-12 volt.pcb track for ccs mje340 base resistor is wrong in your pcb layout.
with this supply there is offset voltage of 32millivolt on output, is it right.I will increase the supply voltage after confirming about offset voltage.which set of in4148 diodes are placed on heatsink for thermal bias control ?

PCB with corrected track layout, offset is high but OK, no need to place 1N4148 to heatsink this is class B amplifier. Can you post pictures?
Regards
 

Attachments

  • APEX 550w class B PCB.jpg
    APEX 550w class B PCB.jpg
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hi apex, i have completed this amp through self made pcb.it is working fine ,currently only with +/-12 volt.pcb track for ccs mje340 base resistor is wrong in your pcb layout.
with this supply there is offset voltage of 32millivolt on output, is it right.I will increase the supply voltage after confirming about offset voltage.which set of in4148 diodes are placed on heatsink for thermal bias control ?

Test amplifier with +/-12V rail voltage is wrong. Use 10R instead fuses or serial bulb 100W/220V in transformer primary for test, and use proper rail voltage.
Regards