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Re: Updating & Refining the " DCR " Topic

Hello !!

Jeff here. I got this nice email response ( to the Forum comments ) from Dennis today, to share with those interested in audio amplifiers.

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Subject: --'ya done it now 1--
Date: Thu, 8 Mar 2007 11:54:49 -0800


Hi Jeff!

It's all a matter of balance. I didn't say that the power transformer DCR doesn't matter-- it does. I just said it matters a bit LESS than the chokes & caps do.

I didn't say that the rectifier doesn't matter-- it does matter-- a lot. I said DCR of the rectifier, matters LESS than the DCR of chokes does, that's all.

There is NO change in my ideas here-- just some intelligent application discussions going on-- as to how this all can work together.

Remember also-- that transparency and speed matter most of all-- musically. You do whatever it takes to get that... but you don't quit there..... Let's get it all-- and that requires a total systems approach..

If the power transformer core gets too large, then THAT would make too large a choke out of it.-- but that will not hurt its performance as much as doing the same thing to a separate choke would.

We can agree that other improvements can be gained when the Power Source is "too large to pull-down".

In practice, we simply must get all of these things into perspective. Would you install a D-9 CAT Dozer flywheel into your Honda Civic? The engine would break before the "flywheel" got up to speed! If you did get the flywheel up to speed, could you stop the car if you applied the brakes?

Are power supplies flywheels? Not if I can help it! I don't want energy storage-- I want energy delivery-- instantaneously-- without it being impeded. That is correctly called impedance! Sure, it's a good filter. So is capacitance. Both must be used sparingly, carefully, and intelligently.

Are Batteries, then, the ideal power source? Well, they would be if they weren't also capacitors! Or diodes! Or have long leads!

There, you have it! We buy or custom wind those expensive copper-foil and tin-foil capacitors-- for Power Supplies! Why? They store very little, and they act very quickly.

They're low-capacitance, but highly energy-reactive.

That sounds a lot like music..... not so impeded, not so "canned" (stored somewhere), and not so resisted (high-DCR series transfer components), and not so loaded-down-- (low-DCR loads-to-ground). Those old terms for capacitance, impedance, and resistance really do tell you what they do.

Look again at that last-- loaded-down -- there are places where we do want HIGH DCR. On anything that is a load upon a signal.

----D----

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I hope others will understand Dennis' intent a bit better by posting the above email. Hope it helps you.

Jeff Medwin




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