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In Reply to: Updating & Refining the " DCR " Topic posted by drlowmu on March 7, 2007 at 12:10:47:
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
Follow Ups:
"MUCH LESS" and "it doesn't count for much" has turned into "a bit LESS". Bull Shit!
"ACTIVE stuff-- (That is-- the SOURCE for the power in the Power Supply (transformer & rectifier) NEED NOT be low-DCR-- as it is electrically DRIVING the circuit-- and can instantly change to accommodate current demand-- its own internal resistance is MUCH LESS a factor-- it is still there-- but it doesn't count for much."
Come on Jeff, who do you think you are fooling? Do you think we are all morons?Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Tre',Hate is a a terrible thing to harbor inside you, and it certainly shows up here loud and clear in your EVERY word and action! How sad and how rude.
Why don't you try to grasp the goodness of the information, and / or my good intent, rather than how well it may, or may not be presented.
What is being suggested works like gang-busters. Maybe you could learn how to build a much better, more satisfying audio amp if you opened your mind and lost the hate.!!
Instead of fully-digesting what we present, you knee-jerk react, and just look to discredit me.
However Tre', know this, I am correct in what I HEAR - what this type of simple supply does sonically, so in the end, you will be the discredited one, not I. Actually, you already are discredited, only the early adaptors of this technology are all polite, and do not get in your face up here publically.
You could be a big boy, and fork out 50 dollars for two Triad C-40X inductors from Allied Electronics and two Percy ASC 40 uF @ 440 VAC caps, and implement the supply, but instead, you wanna play hateful verbal games up here.
Jeff Medwin
" with the solution to your problem "
When you think you are losing an argument or humiliated in some way, you suddnely turn vicious. Then we get to see what you are really like.
"What is being suggested works like gang-busters"Which of the many different suggestions are you talking about?
"what this type of simple supply does sonically"
What supply are you talking about now?
The one you proposed 8 months ago?
The one you proposed 4 months ago?
The one Dennis proposed at this post http://www.audioasylum.com/forums/tubediy/messages/118189.html on 3-7-07 12:10?
Or the one Dennis proposed at the next post on 3-7-07 17:55?They are all different. Can't you see how that shows that you don't know what you are talking about?
Jeff, I'm not full of hate but I don't like uneducated designers telling everyone they, and only they, have all the answers. I post so other, less knowledgeable persons don't buy into your unsubstantiated claims.
Jeff, it's wild, unsubstantiated claims like your's that give high end audio a bad name. Snake oil and magic dust.
I'm just standing up for what's right and not letting you get away with telling half-truths. If you want to call that hate, go ahead.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Tre',As time goes by, things get refined some. L1/C1/L2/C2 is as follows :
Ls are both Traid C-40Xs, available from Allied at only $10.79 each.
Cs are both ASC oils, the ones Mike Percy sells, 40 uF at 440 VAC, about $12.95 each as I recall.Anyone can just build and LISTEN to that, with THOSE precise parts.
Its what we have listened to now in my latest report, on Greg's 245 SE amp, both for his input and output stages. Heavy gauge wire from the rectifiers forward is a MUST. We eliminated his damper diodes and went with 5U4GBs.
As an fair estimate, assume PT secondary VAC times 1.35 = B+ VDC, minus rectifier drop.
I'll look at Greg's amp notes later, on both supplies, and post actual measured AC and DC voltages and current load, for each supply, when I can. We have that information recorded in our notes taken.
Jeff Medwin
With all due respect, Jeff, those Triad C-40X chokes have a DCR of 10 ohms. Wouldn't we be better using the Signal Transformer units that you mentioned earlier? The CH-1, while less than 1/3 the inductance (100mH vs. 320mH)it has only 1.5 ohm DCR.Both of these inductors were intended for low voltage supplies. Using them at the AC voltages we're talking about worries me a little. Not for safety reasons necessarily, I'm just worried that the chokes will easily saturate even when run well under their maximum DC current rating. They are subject to MUCH higher AC flux in this application. VERY generously over rating them in terms of DC current might prevent saturation. OTOH, maybe you like the sound of the supply with saturating chokes ... :)
Also, if anyone is interested in 'tuning' the supply to achieve the 'flywheel' effect (as described by Henry,) it seems to be easier with lower inductance, depending on the PT.
Hi Dave,Whoa.... written on the .32 HY L .... " 1500 VDC RMS insulation test " ... thats OK for tube amps of the 2A3 variety I'd think, thats surely not low voltage !!
It's not the DC voltage to ground that concerns me, it's the AC voltage *across* and SC currents through the choke. That's what might lead to saturation of the core.I did a bit of reverse engineering on the Triad unit (not too hard given the dimensions of the core, the inductance and the DCR) and it seems that you might be OK in your application. I wouldn't try to push the DC current up to 600mA though. Keeping the DC current down leaves more headroom for the extra AC flux that the core is subject to in this application.
Hi Dave,The Triad I'd prefer over the Signal, as the Triad posseses about three times the inductance, not too big and heavy a core, is well made, and rated for 600 mA current. I use under 60 mA through them, and have no worries with that part. The Triads and /or its similar "cousins" operate in amps known to me, in the L1 spot, at +490 VDC and never have failed, ever.
Two weeks ago, Greg and I listend to his vintage UTC L that was 1/2 HY, ONLY 2 ohms, rated at 1.2 A, and it sounded TERRIBLE. Too big, too heavy, too much core and too much wire inside it !! I mean, the $10.79 Triad smoked this 2 ohm UTC, the UTC lost everything we had gained, the music's presentation was ALL out of time and dynamically ruined. What else can I say ??!!
a few turns of heavy duty Litz wire wrapped around an engine block (steel, of course) nwould be perfect ...
Actually a dinky $10.79 Triad C-40X from Allied Electronics 1-800-433- 5700 will be way better bro'. C.Y. loved it in Korea last year...showed him the way.
Thanks, Jeff, for your honest report. It's a good data point.It appears that there might be more to all of this than we have figured out yet, so I hope you won't be offended if I'm not too quick to draw any conclusions about what differences between the Triad and UTC were actually responsible for the differences in perceived sound.
Dave,No problem, it was a good question I thought. I'd go back and reread Dennis'posts of mid 2006, as its really HIS baby, I'm just the messenger who finally got around to implementing and hearing it last month on Greg's RCA field coil horn system.
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