how to make amp distortion meter

space2000 · 18th May 2008, 06:44 PM

hi,

is there any amp distortion meter? like led type or analog panel meter type? just want to know can mswr the amp output distortion easily without osiloscope.

thank you.

Mooly · 18th May 2008, 07:00 PM

Hi Space,
Please please, get a 'scope (does not have to be fancy) and learn how to make your own PCBs.
There used to be a few designs for distortion meters, John Linsley Hood did one years ago, and I think Ian Hickman published one as well.
A 'scopes much much more use to you

lumanauw · 18th May 2008, 07:13 PM

If you've already got a scope, look for citation.pdf from Nelson Pass.

Read the section "using the amplifier to analyze itself", I think it's the easiest way to see an amp's distortion.

unclejed613 · 18th May 2008, 08:00 PM

you could make a distortion indicator using an op amp to compare the input and output of the amp. a differential amplifier circuit would compare the two waveforms, and if one of them is different (such as when the amp clips) the LED lights up. the xircuit is simple and only requires sampling the input and output of the power amp. the amp output needs to go through a voltage divider with a division ratio equal to the power amp gain.

teemuk · 18th May 2008, 09:08 PM

Or if the amplifier has a differential input stage just compare the signal of the two inputs.

nigelwright7557 · 19th May 2008, 11:40 PM

Quote:

Originally posted by space2000
hi,

is there any amp distortion meter? like led type or analog panel meter type? just want to know can mswr the amp output distortion easily without osiloscope.

thank you.

I find a signal generator and a scope vital to amp design.

I use the scope to tune out cross over distortion without passing too much current through the output transistors.

You can also check the bandwidth of the amp too with sig genny and a scope.

18th May 2008, 06:44 PM	#1
space2000 diyAudio Member Join Date: Mar 2008	how to make amp distortion meter hi, is there any amp distortion meter? like led type or analog panel meter type? just want to know can mswr the amp output distortion easily without osiloscope. thank you.

18th May 2008, 08:00 PM	#4
unclejed613 diyAudio Member Join Date: Dec 2006	you could make a distortion indicator using an op amp to compare the input and output of the amp. a differential amplifier circuit would compare the two waveforms, and if one of them is different (such as when the amp clips) the LED lights up. the xircuit is simple and only requires sampling the input and output of the power amp. the amp output needs to go through a voltage divider with a division ratio equal to the power amp gain. __________________ Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net spammer trap: http://www1284177414881.v-dc.net/

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18th May 2008, 07:00 PM	#2
Mooly diyAudio Member Join Date: Sep 2007	Hi Space, Please please, get a 'scope (does not have to be fancy) and learn how to make your own PCBs. There used to be a few designs for distortion meters, John Linsley Hood did one years ago, and I think Ian Hickman published one as well. A 'scopes much much more use to you

18th May 2008, 07:13 PM	#3
lumanauw diyAudio Moderator Emeritus Join Date: Oct 2002 Location: Bandung	If you've already got a scope, look for citation.pdf from Nelson Pass. Read the section "using the amplifier to analyze itself", I think it's the easiest way to see an amp's distortion.

18th May 2008, 09:08 PM	#5
teemuk diyAudio Member Join Date: Nov 2004 Location: Suomi, Finland	Or if the amplifier has a differential input stage just compare the signal of the two inputs.

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