DC Servo MOSFET Amplifier

[mathez]

ok,i will try to find Bf420/21 here.

 

[binhaudio]

Schematic in JPG

APEX ! I have a 650w transformer, 35v-0-35v . Can I use it for this circuit ?
If I have to change anything in this circuit ?
please guide helps !
THANKS !!!!!!

 

[apexaudio]

APEX ! I have a 650w transformer, 35v-0-35v . Can I use it for this circuit ?
If I have to change anything in this circuit ?
please guide helps !
THANKS !!!!!!

You can use this transformer without any change on amp circuit.
Regards

 

[binhaudio]

thank you! very much !

 

[apexaudio]

thank you! very much !

What version of this circuit you want to build?

 

[cabbageman]

Harrison x1000 mentioned in #19

Hi
Great thread, good to see such a flexible design.
Back in #19 you mentioned a design based on the harrison x1000 schematic. Can you please post this schematic on the thread as I can't find a copy anywhere and I have a problem with my Harrison.

Thanks

 

[apexaudio]

Hi
Great thread, good to see such a flexible design.
Back in #19 you mentioned a design based on the harrison x1000 schematic. Can you please post this schematic on the thread as I can't find a copy anywhere and I have a problem with my Harrison.

Thanks

Harrison schematic is same as HH in post #18 only without protect circuit, and use 2SK1529/2SJ200 in newer series.
Regards

 

[apexaudio]

FB400

Amplifier for 1R load

 

[apexaudio]

2SK135/2SJ50 and MJ15024/MJ15025 can be used instead 2SK1058/2SJ162 and 2SC5200/2SA1943 for FB400

 

[apexaudio]

Speakers used with this amplifier will be between 1-3 ohm ( full range ribbons)

 

[a.wayne]

I'm happy .....

 

[apexaudio]

This old pcb with 5 pairs of outputs and protect can be redesign for FB400

 

[AndrewT]

........... and 2SC5200/2SA1943 for FB400

what/where is FB400?

I like many of the topologies adopted in this schematic.
With 5pair and 1ohm loading, what would you set the PSU voltage to?

 

[apexaudio]

what/where is FB400?

I like many of the topologies adopted in this schematic.
With 5pair and 1ohm loading, what would you set the PSU voltage to?

FB400 use +/-45V DC rail voltage with 5pair and 1ohm loading.

 

[a.wayne]

what/where is FB400?

I like many of the topologies adopted in this schematic.
With 5pair and 1ohm loading, what would you set the PSU voltage to?

Hello apex,

What is the Idle bias current used on the FB400 ? Recommended heat sink area necessary for 1 ohm operation ..

Regards,

 

[apexaudio]

Hello apex,

What is the Idle bias current used on the FB400 ? Recommended heat sink area necessary for 1 ohm operation ..

Regards,

FB400 use 200mA bias, and heatsink like for 100W class A amplifier for 1 ohm operation
http://www.diyaudio.com/forums/pass-labs/166784-pictures-your-diy-pass-amplifier.html
Regards

 

[AndrewT]

FB400 use 200mA bias,

per device or total for all 5parallel pairs?
Would it be more helpful to builders to specify the Vre for best performance rather than Ire?

 

[apexaudio]

per device or total for all 5parallel pairs?
Would it be more helpful to builders to specify the Vre for best performance rather than Ire?

Total, but only MOSFETs are biased.

 

[apexaudio]

For 1R load use transformer 2x30VAC, 1000VA per channel.

 

[AndrewT]

200mA for Ib

per device or total for all 5parallel pairs?

Total,

40mA per output MosFET is quite low.