HA-PRO Single-ended MOSFET

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istvan

Member
Joined 2004
mihalcz.ingyenweb.hu
xslavic said:
shouldnt R16 R31 be removed ? it will form RC filter with headphone impedance -and you cant compensate for cable capacitance this way.
i also used line filter as no filtering device after 7824 ,next time use a low noise transistor please +1 irf610 wont be much of an expense
Click to expand...
Dear Mr. Slavic,
R16 and R31 are used to remove parasitic charges which appears at powering on the circuit. Their values are enough high, to not disturb this circuit functionality. Please remark, this circuit runs with single supply, and before output capacitor the voltage are half of supply voltage. With delay circuit that cannot be eliminated.
Remark regarding IRF610 - is an often used transistor in audio electronics regarding its low gate capacitance. Same famous circuits: Mr. Pass preamplifier (Bride of Zen) or amplifiers, or Ernő Borbély All FETs circuits, or long time ago was publised by SDS Lab one class A headphone amplifier - but I am shure on the net you can find hundred of other famous circuits using this mosfet.
 
X

xslavic

Member
Joined 2011
hapro irf610 class A LJM

...done,working -had a blown irf610 nice mids into 150R headphones
just need some caps upgraded -in rest ok
 

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I

istvan

Member
Joined 2004
mihalcz.ingyenweb.hu
Dear XSlavic, was necessary to insert those 22pF? You have high frequency oscilations? Why is better now the sound?
Till now I made several headamps. The best sounding one is a Heed Canamp clone: /keret.cgi?/headamp/HeedCanamp.html :::::: Powered by: www.webtar.hu ::::::*
Sound is warm, detailed, very pleasant.

From instrumentation point of view, means not as listening, just as technical parameters, is this one:
/keret.cgi?/headamp/TPA6120A2.html :::::: Powered by: www.webtar.hu ::::::*
The sound is very clear, but cold.
 
X

xslavic

Member
Joined 2011
Yes,it did the job .Now the sound is perceived like a straight line more or less not an arc as without it with lows and highs at its ends.Did not try zobel for mosfets yet.
I have something similar to heed Canamp,a diamond buffer with bc560 and bd139 -some pcbs but not tested yet,thinking of a parallel tpa6120a2 -have the ics and just for fun
-this amp is very nice,better than the Alc1150 with opa1642 i was listening to before ,sounds well even with pcm5102 -good details and you can hear the circuitry of the DAC
 
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M

metalmaster75

Member
Joined 2014
Hello. This is my first post here.

I put one of those together. While the sound is not bad in original form (no upgrades yet), the gain is absolutely ridiculous. At about 2.5 on a scale from 1-10 it is very loud! Someone mentioned here something about changing R13 (?) in order to reduce gain. Is there any schematic available. Thanks in advance.
 
S

Saturn7

Member
Joined 2015
hta95 said:
65mA or 650mV across 10 ohm resistor. You can bias it deeper at 100-200mA and larger heatsinks are required
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HI !
resistance of 64 ohms my headphones
Designer I bought supplied 22-ohm resistor is written 600 mV / 22 Ohm = 27 mA.
but on medium began prisuvstvovat distortion, I raised the quiescent current to 50 mA distortions became smaller, but the output transistors become much bask in design offers the radiators are not provided.
And so I ask - is there a dependence of the resistance and quiescent current of headphones? How do I choose the optimal mode quiescent current ..... listening?
What is the quiescent current to typically IRF610 -?
 
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