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Old 20th December 2010, 12:26 AM   #1001
spind is offline spind  Canada
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[QUOTE=MJL21193;2404630


Seriously!
OS, carry on with your efforts. I'll keep my distance and my comments to myself.[/QUOTE]

John,

If you could, it would be great if you could try OS's experiment. I find you both to be very credible and valuable members of this forum, and both able to express strong opinions. You are also similar in that you both can knock out completed projects faster than most people here can get past the planning stages. I don't think either of you post comments lightly, so I think Pete's experiment is worth a try---he seems to have figured the TMC stuff out quite well!

Steve.
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Old 20th December 2010, 12:43 AM   #1002
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Quote:
Originally Posted by spind View Post

If you could, it would be great if you could try OS's experiment.
I think I'll take a pass on that.
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Old 20th December 2010, 12:46 AM   #1003
AKSA is offline AKSA  Australia
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Hey John,

No one is criticising, least of all me..... give it a go, mate!

Hugh
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Old 20th December 2010, 01:37 AM   #1004
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Quote:
Originally Posted by MJL21193 View Post
You were doing well until this part:



Seriously!
OS, carry on with your efforts. I'll keep my distance and my comments to myself.
Well , I'm sorry you were SO offended. I did not state WHO's ears were untrained (or even if ears can be "trained") .. like dogs can. Can't please um' all ..

If what you say is true , there should be no DIYA ... just buy OEM "crap" , since there is no difference anyways ???


On with my "pandering"

First 4 attachments show what LT says about the diode mod ( I don't 100% agree with LT - BTW). To be "action oriented" the last few attachments show a magic current mirror in the making...

last attachments are the real "magic diode" ...

I will give it a go.. enough small, subtle improvements add up.

OS
Attached Images
File Type: gif nodiode1kfft.gif (29.0 KB, 546 views)
File Type: gif diode1kfft.gif (28.8 KB, 528 views)
File Type: gif nodiode10kfft.gif (30.8 KB, 530 views)
File Type: gif diode10kfft.gif (29.4 KB, 519 views)
File Type: jpg magicdiode1.jpg (126.8 KB, 535 views)
File Type: jpg magicdiode.jpg (77.8 KB, 179 views)
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Old 20th December 2010, 01:42 AM   #1005
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I might try this diode thing out on my amps. Do you notice any audible difference with and without the diode ?
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Old 20th December 2010, 01:46 AM   #1006
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Originally Posted by Tekko View Post
I might try this diode thing out on my amps. Do you notice any audible difference with and without the diode ?
I'll know in 5 minutes..
OS
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Old 20th December 2010, 02:12 AM   #1007
AKSA is offline AKSA  Australia
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Hmmm, Pete, those LT differences are truly insignificant!!

When I did this a couple years back on one of my power amps, I noticed improved refinement and better image focus. Not things you can measure, unfortunately, but worth having.

Awaiting results from your 'mountain ears'!

Hugh
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Old 20th December 2010, 05:32 AM   #1008
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I have listened ... for hours (below - ugly CM's) .... can not note any audible changes with the diode/ CM. I did not let any non-objective statements or opinions sway my decision. Same music , 2 pairs voltage stages (w/diode - no diode BX1.3's) , same power supply/output stage and bias. NO change.

The only real changes were in the static tests , the diode forced current balance down to 1 microamp vs. no-diode 20-30uA. As seen in the LT FFT's , the distortion components were within db's and at the -100db level ... even "mountain ears" could not discern these subtle soundstage changes. Tried the headphones hooked to 220R resistors tied to the OPS ... NO change.

Tolerances of the current mirror degeneration resistors would offset the "micro" improvement of the CM current balance. And , I forgot to mention that the diode made the LTP LESS balanced in LT (slightly level shifted it). So ... thumbs down.

Edit: where this "diode trick" DOES seem to have major effects, is in a non-beta enhanced VAS where the CM/LTP sees more load (also according to LT).

OS
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Last edited by ostripper; 20th December 2010 at 05:40 AM.
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Old 20th December 2010, 06:40 AM   #1009
AKSA is offline AKSA  Australia
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Thanks Pete,

Much appreciated. It seems that for most purposes the diode is a waste of time. That's good; it eliminates one more component, and one less part is less time and expense to make and more reliability as well.

Cheers,

Hugh
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Old 20th December 2010, 07:10 AM   #1010
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Thanks Pete,

Much appreciated. It seems that for most purposes the diode is a waste of time. That's good; it eliminates one more component, and one less part is less time and expense to make and more reliability as well.

Cheers,

Hugh
Except for a single device VAS , is that what you did your experiment on ?
Perhaps that is the reason for different results.
The beta enhancement makes the load on the CM miniscule (see below). A 40uA/20mV - current /voltage change will swing the VAS to 110V p-p. This is with a standard KSA992/KSA1381 BE-VAS (AX/BX).
OS
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