MOSFET Amplifier IRFP240/IRFP9240

[apexaudio]

Hallo apex, My HV350 is almost done, I wonder with this amplifier adjust the BIAS. could you help me?

I will help you to adjust BIAS, can you post some pictures?
Regards

 

[Valenca]

Apex, of course! so I finished soldering the components.

 

[Valenca]

Hi Apex,
Question 1: I can change 2n5551 for BC546 ?
Question 2: I can test the amplifier with only 2 IRFP240 and 2 IRFP9240 ?
I think so...

Thank´s !

 

[apexaudio]

Hi Apex,
Question 1: I can change 2n5551 for BC546 ?
Question 2: I can test the amplifier with only 2 IRFP240 and 2 IRFP9240 ?
I think so...

Thank´s !

1: Yes, but reverse pin layout EBC>CBE
2: Yes, for test, but BIAS must be adjust again when add 2 pairs

 

[Valenca]

Apex, The CLIP LED resistor layout is different from the resistor layout is 6.8k or 10K?

Thank you !

 

[apexaudio]

Apex, The CLIP LED resistor layout is different from the resistor layout is 6.8k or 10K?

Thank you !

This resistor confirm LED current: Urail/R, use 10k any LED will work.

 

[Valenca]

OK.

 

[Valenca]

Apex Hi, I power on the HV350 and the sound is coming out distorted, I think it can be ceramic capacitors of transistors drivers 100PF ... What's happening? So I can send you the photos.

 

[apexaudio]

Apex Hi, I power on the HV350 and the sound is coming out distorted, I think it can be ceramic capacitors of transistors drivers 100PF ... What's happening? So I can send you the photos.

I think bias is to low, use 10R resistors series in rail and set bias to get abot 2V on 10R resistor. Post pictures here.
Regards

 

[Valenca]

Apex, and power on the HV350 with 45v + / - PSU, can you be?

 

[apexaudio]

Apex, and power on the HV350 with 45v + / - PSU, can you be?

This is low, but can work, power will be 70W on 8R load.

 

[Valenca]

Apex, this voltage is only test... Now I'm on my work (informatica) when I get home, I check this problem in HV350.

Thank you !

 

[apexaudio]

Apex, this voltage is only test... Now I'm on my work (informatica) when I get home, I check this problem in HV350.

Thank you !

Ok, I use fets from many factorys IR, Fairchild, Haris... and gate voltage for bias is very diferent 2,5-3,5V (5-7V gate to gate), but that can be easy set by change 470R in base to colector of 2N5551 (BC546).
Regards

 

[Valenca]

Apex,
Question 1: the Zeners is 15v right ?
Question 2: the input capacitor is 1mf non polarized, but i used polarized...

Thank you.

 

[apexaudio]

Apex,
Question 1: the Zeners is 15v right ?
Question 2: the input capacitor is 1mf non polarized, but i used polarized...

Thank you.

1: Zeners are 15V
2: Polarized capacitor on input can't cause any distorsion
Do you use BC337 and BC327 in VI limiter?

 

[Valenca]

Yes, is the same your schema #171 post.

 

[apexaudio]

Yes, is the same your schema #171 post.

Do you use separate wires for input GND and power GND from PSU?

 

[Valenca]

não, eu juntei os dois GND.

 

[Valenca]

Sorry,

no, I joined the two GND

 

[apexaudio]

Try to remove 100nF from VI limiter.