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Old 6th May 2013, 11:20 PM   #1
Zero D is offline Zero D  United Kingdom
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Lightbulb New type Zobel = <THD

Well new to me anyway

Been tinkering again

I've only shown the relevant parts, but the full simmed Amp shows lower THD with this configuration. Not much lower i admit, but lower = Lower

@ any level below clip it went from 0.004% - 0.003% @ 1kHz. @ 10kHz it went from 0.034% - 0.020%

I havn't extensively tested this, or changed the caps/res much, as i've just done it. The values of the Zobel components as shown are just examples of what was achieved so far. Other values/components may be substituted.

Further options "could" be as in screenie 2 & 3 for eg, and/or variations on the same theme.

If it's not new, why don't vendors etc do it ?
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File Type: png z2.png (4.9 KB, 239 views)
File Type: png z3.png (5.0 KB, 236 views)
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Old 7th May 2013, 01:23 AM   #2
djk is offline djk
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Mark Levinson ML3.
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Old 7th May 2013, 09:08 AM   #3
AndrewT is offline AndrewT  Scotland
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Why did you choose emitter resistor at 4r7 for a power amp?
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Old 7th May 2013, 09:25 AM   #4
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Real loudspeakers are not 8R2 resistors. Up to a few nF of cable capacitance is the problem
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Old 7th May 2013, 04:22 PM   #5
Zero D is offline Zero D  United Kingdom
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@ djk

Thanks, i'll try & find the circuit diagram ! Interesting that it does actually work Even if i wasn't the firstt o discover it.

@ AndrewT

It was a headphone amp sim i had on hand.

@ davidsrsb

Indeed
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Old 7th May 2013, 04:53 PM   #6
JMFahey is offline JMFahey  Argentina
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Quote:
It was a headphone amp sim i had on hand.
Fine, but then it might be useful to re-simulate with real Power Amp values.
Using, say, 0.47 to 0.1 ohms (which would be the actual value range) makes me think that the already minuscule distortion reduction will be even smaller.
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Old 7th May 2013, 07:27 PM   #7
Zero D is offline Zero D  United Kingdom
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@ JMFahey

I tried it with 0.25 Ohms & you're right it @ 1kHz anyway it was still 0.003% !

My motto is, if you don't experiment, you might never know what's Actually possible. Sometimes good things have been discovered just by tinkering
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Old 7th May 2013, 10:49 PM   #8
JMFahey is offline JMFahey  Argentina
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Fully agree

But I had a gut feling that a smaller ballast resistor would put both feedback points closer to each other.
Thanks for checking.
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