150W MOSFET Amplifier with IRFP250x2

[apexaudio]

Dear Mr. Miles,

With NX-400, can I change BC547, BC557 by MPSA92, MPS42 and 2SC4793, 2SA1837 by MJE15030, MJE15031?

Thank and Best regards,
ThaiKy

BC547/557 can be replace with BC546/556 or BC550/560, 2SA1837/2SC4793 can be replace with MJE15030/15031.
Regards

 

[ThaiKy]

Dear Mr. Miles,

Please teach me. My NX-400 can't not adjust bias. When I checked, it show 0 mV on DVOM. And at SPK Out is <20 mV. But it worked, I play it about 2 hours and It is still OK.

Best regards,
ThaiKy

 

[apexaudio]

Dear Mr. Miles,

Please teach me. My NX-400 can't not adjust bias. When I checked, it show 0 mV on DVOM. And at SPK Out is <20 mV. But it worked, I play it about 2 hours and It is still OK.

Best regards,
ThaiKy

What is EC voltage on BD139?
Regards

 

[ThaiKy]

What is EC voltage on BD139?
Regards

Dear Mr Mile,

I checked, EC voltage on BD139 = - 4.29V
And How is this voltage?
By the way, my power supply is +/- 55VDC

Thanks and Best regards,
ThaiKy

 

[apexaudio]

Dear Mr Mile,

I checked, EC voltage on BD139 = - 4.29V
And How is this voltage?
By the way, my power supply is +/- 55VDC

Thanks and Best regards,
ThaiKy

Can you set EC voltage to about 6V? If not replace 1k resistor (in series with 1k bias trim pot) with 820R.
Regards

 

[ThaiKy]

Can you set EC voltage to about 6V? If not replace 1k resistor (in series with 1k bias trim pot) with 820R.
Regards

Dear Mr Miles,

Thank for your instruction so much.
Now I can adjust bias. And I am setting ab. 25.0mV (75mA).
EC voltage on BD139 = 6.5V.
I see that the sound is good with mid and high (treble) but low (bass) is not so deep. I haven't use this amp with pre-amp yet. I will try and report later.

Thank you very much once, Mr Miles.
By the way, can you recommend me the other?

Best regards,
ThaiKy

 

[Karmenko 46]

Apex NX200

Apex NX200

 

[ThaiKy]

NX-400

Dear Mr Miles,

This is my NX-400.




Thank you Mr Miles so much.
ThaiKy

 

[Karmenko 46]

What it is not the same NX200 is when my

 

[apexaudio]

Dear Mr Miles,

This is my NX-400.
View attachment 582503

View attachment 582504

Thank you Mr Miles so much.
ThaiKy

Nice work.
Regards

 

[Karmenko 46]

This amplifier Apex NX16

Dear Mr Miles,

This is my NX-400.
View attachment 582503

View attachment 582504

Thank you Mr Miles so much.
ThaiKy

 

[Karmenko 46]

NX 400 + Protect

NX 400 + Protect

 

[apexaudio]

NX 400 + Protect

Nice work/
Regards

 

[Karmenko 46]

Thank Mile that no you would not be not that

Nice work/
Regards

 

[Karmenko 46]

Nice work/
Regards

The following amendments practicing NX 14 and put NX 400 with clip protection, and then comes the A40

 

[Karmenko 46]

NX 200 + NE555 Protect + PSu10 56v

 

[kem69]

This circuit is upgrade on BUZAMP from Elektor. Use only N-mosfets, with +/-50V DC give 150W on 4R load.

Hi. No N10 layout?
Thanks.

 

[Yuriy64]

Hi, Mr. Mile! Tell me please nominal and maximum voltage PSU for amp APEX NX400, and what is the power per load of 8 and 4 ohms. BIAS - ??? mA. Thank you.

 

[apexaudio]

NX500

 

[Mark Tillotson]

Two inverting input stages means having to have at least 10k of Johnson noise added to the input. One non-inverting input stages would avoid that and save a stage.


No RF filtering on the input is a bit risky these days.