2nd Order Distortion Circuit

lineup · 18th December 2005, 01:50 PM

Hello

Second order distortion is good and third order distortion is unpleasant.
Now many power amplifiers show more 3rd order distortion, than 2nd.
I do not think this is optimal.

Say for example I have an amp output with
2nd order -80 dB
3rd order -75 dB
I am looking for an Op-amp based circuit for adding 2nd order distortion to correct this problem.
After distortion correction I would get a total output of
2nd order -70 dB
3rd order - 75 dB
And so achieve corresponding improvement in total output.

Such an Op-amp based distortion correction circuit
maybe could be between preamplifier output and power amplifier input.

Is this possible?
I have searched here and the web, but found nothing

pinkmouse · 18th December 2005, 01:59 PM

To clarify - you want to build an op amp circuit to add 10db of 2nd order distortion to your system???

lineup · 18th December 2005, 02:03 PM

yes
to get the proper relationship between 2nd and 3rd order distortion
and so improve the sound of output

pinkmouse · 18th December 2005, 02:09 PM

Hmmm.

Wouldn't it make more sense to just build a pre with less 3rd order distortion? The whole idea of adding distortion to what is supposed to be as distortion free reproduction as possible just seems wrong to me. Yes, if you want to use it as a musical effect, but for proper listening? I just don't get it.

MikeB · 18th December 2005, 02:15 PM

You could also build a circuit that creates 3rd harmonics with reversed sign (180°shift), so it cancels out when amplifier adds his own 3rd harmonics...

Or, (commercial !) you build a symasym, it has by design ~-85db 2nd harmonic and ~-100db 3rd harmonic...

Mike

pinkmouse · 18th December 2005, 02:20 PM

Hey Mike, if you don't shut up soon, I'm going to have to build one of your &*&^%^%$ amps, and I haven't got the time!

MikeB · 18th December 2005, 02:23 PM

Har har ! I couldn't resist...

Mike

anatech · 18th December 2005, 03:18 PM

Hey Al,
Mike's already bitten me! That's the next amp I'll build as soon as I can make the PCB's up.

Then I'm going to try a FET diff pair in it.

-Chris

darkfenriz · 18th December 2005, 03:20 PM

http://www.diyaudio.com/forums/attac...amp=1089450255

You may add a cap across first op-amp feedback R-D ladder for unconditional stability and use bigger caps in output filter (nF instead of pF, my mistake)

but this is probably not exactly what you search for, more like musical crunch for guitar or so.

sychen0301 · 18th December 2005, 03:38 PM

A single side clip will do. All you need is a R and a D.

18th December 2005, 01:50 PM	#1
lineup diyAudio Member Join Date: Dec 2005 Location: the north	2nd Order Distortion Circuit Hello Second order distortion is good and third order distortion is unpleasant. Now many power amplifiers show more 3rd order distortion, than 2nd. I do not think this is optimal. Say for example I have an amp output with 2nd order -80 dB 3rd order -75 dB I am looking for an Op-amp based circuit for adding 2nd order distortion to correct this problem. After distortion correction I would get a total output of 2nd order -70 dB 3rd order - 75 dB And so achieve corresponding improvement in total output. Such an Op-amp based distortion correction circuit maybe could be between preamplifier output and power amplifier input. Is this possible? I have searched here and the web, but found nothing

18th December 2005, 01:59 PM	#2
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	To clarify - you want to build an op amp circuit to add 10db of 2nd order distortion to your system??? __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

18th December 2005, 02:09 PM	#4
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Hmmm. Wouldn't it make more sense to just build a pre with less 3rd order distortion? The whole idea of adding distortion to what is supposed to be as distortion free reproduction as possible just seems wrong to me. Yes, if you want to use it as a musical effect, but for proper listening? I just don't get it. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

18th December 2005, 02:20 PM	#6
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Hey Mike, if you don't shut up soon, I'm going to have to build one of your &*&^%^%$ amps, and I haven't got the time! __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

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18th December 2005, 02:03 PM	#3
lineup diyAudio Member Join Date: Dec 2005 Location: the north	yes to get the proper relationship between 2nd and 3rd order distortion and so improve the sound of output

18th December 2005, 02:15 PM	#5
MikeB diyAudio Member Join Date: Apr 2004 Location: Gütersloh	You could also build a circuit that creates 3rd harmonics with reversed sign (180°shift), so it cancels out when amplifier adds his own 3rd harmonics... Or, (commercial !) you build a symasym, it has by design ~-85db 2nd harmonic and ~-100db 3rd harmonic... Mike

18th December 2005, 02:23 PM	#7
MikeB diyAudio Member Join Date: Apr 2004 Location: Gütersloh	Har har ! I couldn't resist... Mike

18th December 2005, 03:18 PM	#8
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hey Al, Mike's already bitten me! That's the next amp I'll build as soon as I can make the PCB's up. Then I'm going to try a FET diff pair in it. -Chris

18th December 2005, 03:20 PM	#9
darkfenriz diyAudio Member Join Date: Jun 2004 Location: Warsaw	http://www.diyaudio.com/forums/attac...amp=1089450255 You may add a cap across first op-amp feedback R-D ladder for unconditional stability and use bigger caps in output filter (nF instead of pF, my mistake) but this is probably not exactly what you search for, more like musical crunch for guitar or so.

18th December 2005, 03:38 PM	#10
sychen0301 diyAudio Member Join Date: May 2005 Location: Taipei, Taiwan	A single side clip will do. All you need is a R and a D.

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