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In Reply to: Re: Why Tre', you are so emotional !! Unbalanced Whiner, UGH! . posted by Tre' on March 9, 2007 at 07:41:13:
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
Follow Ups:
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.
-- Dave
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 !!
Jeff Medwin
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.
-- Dave
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 ??!!
Jeff Medwin
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.Jeff Medwin
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
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.
Jeff
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