 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
69.233.6.199
In Reply to: Re: Being one of those 'hard nosed' non belivers ... posted by rdf on March 10, 2007 at 08:58:33:
I get different results than you. With the 6.8uf in place there is a 25 volt drop increasing the current from 100ma to 150ma. With a 100uf in the C1 position there is an 8 volt drop.Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Follow Ups:
PSUD is a godsend but has its limits. Oddball circuits like this push past. With a small L followed by sub- 0.1uf C it's possible to simulate kilovolts from a 200 VAC transformer. It's still useful to put you in the ballpark though, try 14uf. The transformer's secondary is 23 ohms per winding, 209 VAC. I get just over 6 volts from 70 ma to 130 ma (30 ma per SE output tube doubled, 10 ma constant for the two drivers), about 8 1/4 for 100uF. Again, in the ballpark of the measurements. My old EE prof used to tell us calculate for within an order of magnitude of the target and tune the rest by hand. I never bought a product he designed though. ;)
Thermionically addicted.
The problem is that the supply in your sim is not well tuned (sorry, Henry.) My guess is that rdf's transformer and first choke have DCR different from the ones you used.For a given T1 and L1 (DCR included) you will find that there is a specific value of C1 that not only maximizes the output voltage, but also maximizes the supply stiffness (i.e. minimizes the step in voltage when the current is stepped.) Try playing around with the value of C1 in your sim. When you find that value I'll bet that the change in output voltage when the current is stepped will be smaller than 8V.
FWIW, according to the simulations, a second stage of low L low C filtering can improve stiffness further, though the optimum value of C2 is not the same as C1 even if L1 and L2 are identical. Around 3x in the cases that I've played with. I haven't seen much of an improvement with a third stage, but it could be I haven't found the sweet spot.
In any event, I'm talking about simulations. Finding the right tuning (sorry, Henry) in a real circuit might be a real challenge. rdf reported measured results. He wins. :)
-- Dave
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]
