Mosfet Headphone Amp

apexaudio · 08:25 PM

Headphone Amplifier for 32 ohm or more with TO92 mosfets, 100uF can be shorted if there is no DC offset on output (drains).

apexaudio · 7th March 2011, 11:21 PM

DIP4 mosfets IRFD014 and IRFD9014 can be use intead BS170 and BS250

zeraphine · 21st March 2011, 03:19 PM

Good looking Apex, you have any PCB designs for this Maybe, thanks for sharing

I'm building a Preamp these days and this would work as the HP amp on it, I already built ur A Class PSU its Brilliant Ill post pictures on that thread

apexaudio · 22nd March 2011, 10:08 PM

Quote:

Originally Posted by zeraphine

Good looking Apex, you have any PCB designs for this Maybe, thanks for sharing

I'm building a Preamp these days and this would work as the HP amp on it, I already built ur A Class PSU its Brilliant Ill post pictures on that thread

I must design new pcb, old pcb is mono.
Regards

SomekPoland · 25th July 2011, 03:43 PM

Can i use another mosfets, like IRF510 and 9510? Or another power mosfet?

jcx · 25th July 2011, 03:53 PM

lots of devices can be used, including "power" mosfests, but you should try to keep the Q size somewhat porportional to the circuit requirements to avoid excess parasitic C

4 A rated Q for 100 mA is already a little overboard

apexaudio · 04:04 PM

Quote:

Originally Posted by jcx

lots of devices can be used, including "power" mosfests, but you should try to keep the Q size somewhat porportional to the circuit requirements to avoid excess parasitic C

4 A rated Q for 100 mA is already a little overboard

BJTs also can be use instead MOSFETs

sgrossklass · 31st January 2012, 08:54 PM

Looking at the schematic, it uses the old trick of driving the buffer stage via the opamp supplies. Isn't that considered somewhat problematic when it comes to stability?

routhun · 14th February 2012, 05:09 AM

Not only the stability, I have a question about the distortion. The basic principle of this topology is the current drawn by opAmp is proportional to the input signal, and the resistors in series of the opAmp power supply generate proportional bias for the output devices which drives the load.

By my question is, how accurate is the power drawn by the opAmp proportional to the input signal? If it is not accurate, then output drive is not proportional to input signal means heavy distortion?

Thanks,
Routhun

sgrossklass · 15th February 2012, 03:28 PM

It all is within the feedback loop, so that shouldn't be too dramatic.

The opamp must be able to tolerate 1k2 of series resistance on the supplies though, which I guess means stability will depend heavily on the type used (ye olde TL07x isn't terribly critical AFAIK). A little too many ifs and buts for my taste, but YMMV.

7th March 2011, 11:21 PM	#2
apexaudio diyAudio Member Join Date: Feb 2010 Location: Serbia	DIP4 mosfets IRFD014 and IRFD9014 can be use intead BS170 and BS250 __________________ http://www.facebook.com/APEXaudio.MileSlakovic

14th February 2012, 05:09 AM	#9
routhun diyAudio Member Join Date: Mar 2005 Location: Sunnyvale	Not only the stability, I have a question about the distortion. The basic principle of this topology is the current drawn by opAmp is proportional to the input signal, and the resistors in series of the opAmp power supply generate proportional bias for the output devices which drives the load. By my question is, how accurate is the power drawn by the opAmp proportional to the input signal? If it is not accurate, then output drive is not proportional to input signal means heavy distortion? Thanks, Routhun __________________ routhun

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21st March 2011, 03:19 PM	#3
zeraphine diyAudio Member Join Date: Jan 2010	Good looking Apex, you have any PCB designs for this Maybe, thanks for sharing I'm building a Preamp these days and this would work as the HP amp on it, I already built ur A Class PSU its Brilliant Ill post pictures on that thread

25th July 2011, 03:43 PM	#5
SomekPoland diyAudio Member Join Date: Mar 2011	Can i use another mosfets, like IRF510 and 9510? Or another power mosfet?

25th July 2011, 03:53 PM	#6
jcx diyAudio Member Join Date: Feb 2003 Location: ..	lots of devices can be used, including "power" mosfests, but you should try to keep the Q size somewhat porportional to the circuit requirements to avoid excess parasitic C 4 A rated Q for 100 mA is already a little overboard

31st January 2012, 08:54 PM	#8
sgrossklass diyAudio Member Join Date: Nov 2004 Location: Germany	Looking at the schematic, it uses the old trick of driving the buffer stage via the opamp supplies. Isn't that considered somewhat problematic when it comes to stability?

15th February 2012, 03:28 PM	#10
sgrossklass diyAudio Member Join Date: Nov 2004 Location: Germany	It all is within the feedback loop, so that shouldn't be too dramatic. The opamp must be able to tolerate 1k2 of series resistance on the supplies though, which I guess means stability will depend heavily on the type used (ye olde TL07x isn't terribly critical AFAIK). A little too many ifs and buts for my taste, but YMMV.