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In Reply to: RE: LSES doesn't belong on this thread....... posted by richardson.sean@gmail.com on March 06, 2012 at 08:11:13
150uf per channel is a lot of storage for say a 50w PP amp. It's a HUGE amount for a 2w SE amp. Look at the classic HiFi designs of the 1950s and 60s. You had sometimes only 20-30uf and a 2hy choke before the finals. And those amps performed quite well. The Citation 2 was the first amp to really pile on capacitance with around 200uf and it was a late comer in the tube glory days.We use large caps today simply because we can. A 500uf 450v capacitor was simply not available in those days. Today it's a common commodity part thanks to switch mode power supplies.
Remember folks it comes down to watt-seconds or joules of energy storage. A 200w SS amp needs around 40,000uf at 75 volts per rail. A transmitter tube based 200w amp at 1200 volts B+ needs far, far, less capacitance to achieve the same ripple factor.
Edits: 03/06/12Follow Ups:
that 150uf value does include the final RC stage feeding the driver, for what its worth.
I don't think Dennis uses 50uf caps (smaller I think) or that much C in his supply, but what I have seen of LSES is two LC stages, .3-.5 henry chokes and 40-50uf caps per stage.
" You had sometimes only 20-30uf and a 2hy choke before the finals. And those amps performed quite well. "
so it was ok in those amps, however presented today in a "gorilla marketing" fashion it no longer works?
I think you guys just like to argue.
Because "building amps" has become a hobby for me, and I realize I'm a "newbie"... I'll build the damn thing and listen.
I'll also build other types. Choke input (l critical), etc... not because I don't believe the doctor -because I want to learn.
as I build more I'd like to get a good understanding for how measure these things.
To me this is far more productive than arguing.
The adamant arguing against these concepts, "LSES and Modern supplies" , pretty much everything drlowmu pushes... is half of what inspired me to build the thing.
The 2a3 DC amp, with Jeff's guidance on the build .......sounds excellent to me.
However non scientific these conclusions were arrived at - they do work....at least from what I hear. Maybe measurements tell a different story. I doubt it.
Then why not listen to the people here with professional electronics backgrounds and education. Otherwise you are just hacking around. And that's fine if this is just a hobby. Some of us here however do electronic design for a living.
Like I said below, if Jeff would simply outline his circuits and tell us he likes the way that sound that would be great. But instead he has a long history here of belittling others designs and spewing out technical mumbo jumbo that is impossible under the laws of physics. I and others have explained several times what is going on with Jeff's "fast power supply" We have explained why it works on an SE amp but does not on a PP amp. We have acknowledged and accepted his description of how it sounds. I for one just don't want my power amp to play the role of a signal processor. Instead of having a technical discussion Jeff just tells us we are clueless and wrong. Yet he has no plausible technical offering himself.
This is why he gets jumped on here so much.
I did think the yahoo group was pretty funny.
Well, a bit of energy storage is dicatated by filter type and the rest of the PS...not to mention how the load's PSRR works with it. If you've got PSRR to burn, one can get away with less filtering.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
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