one of my fav post-
does not matter, what you know, or if you can really Hear-
http://www.audioasylum.com/forums/tubediy/messages/93457.html
i know this guy is a borderline genius, and has an ear,
yet as a doctor, his 'bedside manor' well...
lol
this parts not a joke-
http://www.audioasylum.com/forums/tubediy/messages/93307.html
does not matter, what you know, or if you can really Hear-
http://www.audioasylum.com/forums/tubediy/messages/93457.html
i know this guy is a borderline genius, and has an ear,
yet as a doctor, his 'bedside manor' well...
lol
this parts not a joke-
http://www.audioasylum.com/forums/tubediy/messages/93307.html
rdf said:
low dcr, separate supply for each stage, separate supply
for G2, use a variac to start and maintain voltage.
The Truly Hardcore know this stuff,
not often seen here, sadly-
http://www.audioasylum.com/forums/tubediy/messages/93307.html
parts-
smaller caps charge / discharge much
quicker than the large values.
http://www.audioasylum.com/forums/tubediy/messages/93318.html
power xformer-
http://www.skycraftsurplus.com/index.asp?PageAction=VIEWPROD&ProdID=367
i've known him about 10 years.
tomtt said:
True, however according to the sims at the expense of power supply ringing and increased ripple. Where the trade-off lies depends on circuit topology and building one, which I haven't done the latter yet so can't confirm. Seems promising though.
BTW, Hammond makes a little open frame choke - the 159Y, 0.6H @ 0.75 amp, 11 ohms - which goes for about $23. Double the inductance for just one extra ohm.
Edit: Have you tried low DCR?
I read a few of his posts and he certainly has a few problems understanding basic power supply design nomenclature. He calls his power supplies LC because the first component is a choke. But it has too small an inductance to act as a proper choke-input and is really nothing more than a low-value resistor with some inductance. His power supplies would have even less series resistance if he simply left the the first choke out. I personally like power supplies with optimum inductance values AND very low DCR.
I would think that G2 loads are quite small and a choke with an inductance of ca. 100 Hy is necessary to achieve a genuine choke input power supply and all of the benefits it entails.
John
I would think that G2 loads are quite small and a choke with an inductance of ca. 100 Hy is necessary to achieve a genuine choke input power supply and all of the benefits it entails.
John
Jeff gets carried away sometimes. He believes he's found the only true path to power supply design and cannot bear to think that there could possibly be another way to success. He feels that those who don't follow his path are lost sheep and it is his mission to save them.
Jeff admits that he doesn't have the knowledge to support his design with engineering/mathematical explanations but holds that, since it works, there is no need to do so. He tends to get angry with people who demand theoretical proof. He counters such demands by saying that "The proof of the pudding is in the eating." The fact that very few AA inmates actually disagree with the fundamental principle of low DCR is masked by the furore and the ensuing arguments that Jeff stirs up.
Low DCR has always been at the heart of Jeff's approach but this business of low inductance and low value capacitors is quite recent. It seems to have originated from his friend and mentor Dennis Fraker, who posted often on AA, under Jeff's name, a few months ago. However, Dennis seemed to have been focusing only on his 2A3 SE amplifier and what worked best for that, rather than the broader picture.
Good layout was a key point in Dennis's approach and few would probably argue with that, if it had been put in a reasonable way; however, Dennis's patronising attitude caused many inmates to rail against him.
Both Jeff and Dennis managed to make themselves unpopular in AA. Jeff is still there but his posts are fewer and lower key. Dennis is gone from AA.
Jeff admits that he doesn't have the knowledge to support his design with engineering/mathematical explanations but holds that, since it works, there is no need to do so. He tends to get angry with people who demand theoretical proof. He counters such demands by saying that "The proof of the pudding is in the eating." The fact that very few AA inmates actually disagree with the fundamental principle of low DCR is masked by the furore and the ensuing arguments that Jeff stirs up.
Low DCR has always been at the heart of Jeff's approach but this business of low inductance and low value capacitors is quite recent. It seems to have originated from his friend and mentor Dennis Fraker, who posted often on AA, under Jeff's name, a few months ago. However, Dennis seemed to have been focusing only on his 2A3 SE amplifier and what worked best for that, rather than the broader picture.
Good layout was a key point in Dennis's approach and few would probably argue with that, if it had been put in a reasonable way; however, Dennis's patronising attitude caused many inmates to rail against him.
Both Jeff and Dennis managed to make themselves unpopular in AA. Jeff is still there but his posts are fewer and lower key. Dennis is gone from AA.
I would think 5 Hy would be enough for most puposes. BTW, Jeff always despised voltage regulation for screen supplies, claiming that he had a lot of experience with it and had never found one that was free from noise. He stated that the screen is very sensitive to a noisy supply.
For screen voltage of 300vdc @ 5-10ma, critical inductance is on the order of 25-50hy. Twice that is optimal for a true choke-input filter.
So how would a brute-force regulated screen supply with proper first choke inductance values be noisier than what he's got? I'd like to listen to these amps to see if they are really that good.
You are correct, sir. A 15 ohm, 600 watt resistor would draw enough current (2 amps) to make a 12mH choke work.
I've heard plenty of DIY wonder projects, jumped up by the builder, that were actually pretty poor.
Nothing personal against Mr. Medwin, as he treated a friend of mine kindly during correspondence some years ago.
John
If we choose in this case a bleed resistor of 15K ohms, the resistor would pull 20ma, for a total load of ~25-30ma. Regulation would be much improved as a lower resistance choke could be used, and the bleeder would swamp out the effects of changes in the screen current.
No longer would the going from 5ma to 10ma current double the load, it would instead only raise the overall load to 20%. It would also maintain critical inductance regardless of the load.
sorenj07 said:
that thing is a 3 phase mercury rectifier used to feed arc lamps and the rest.
my dad managed a cinema which had two peerless carbon arc projectors, each burned 100A at about 100V when on full warp, one of those suckers would drive both of them. they looked like something out of frankensteins attic when going. purple, with lots of sparks bouncing around.
the amps were are all RCA rack things with pairs of 6l6s in them. behind he screen there were altec lansing bass horns about 5 foot tall and about 12 foot wide, sitting on top of that were pairs of multicell HF horns.
helluva set up, and with the efficiency of the drivers, bloody loud.
thought that you may be interested.
kind regards
bill
You're right. It was late at night and I thought 600 watts was was plenty enough unreasonable and neglected to double check.
No typo. He is insists the value be 12 millihenries. If he would just say that he uses a capacitor-input filter on his screens and a very large "RF filter" in front of it, then that's fine. But like I said in my second post, he has a problem with nomenclature, and stubbornly defends himself, in that regard.
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