F4 power amplifier

[GRollins]

Originally posted by MikeW
Ok, I added a 25,000 uf cap from the plus to minus supplies. A little better.

Originally posted by MikeW


http://www.passlabs.com/np/MPA_PS_D0.pdf
They look like they go plus to minus rails to me.

Yep, it works.
Like everything, it's a question of tradeoffs. If you've got 100V caps and 40V rails, you can stretch clear from the positive rail to the negative one. The caps don't know or care...all they see is voltage and ground is not the absolute that many people think it is, anyway. It enables you to use higher voltage caps in ways and places you might not expect.
The downside is that the capacitance is "halved" between the two rails because there's a virtual ground point between the two rails. If you use a 10000uF cap, each rail will only see 5000uF between it and what you would normally think of as ground.
About every six months or so, someone starts a thread about this, thinking they've got something new and that it's equivalent to "free" capacitance. Well...no. Unfortunately, there's no such thing as a free lunch.
As to sonics, I've seen people argue that it sounds better to float the ground that way, but I've never been persuaded by their reasoning. I have not tried it personally, so I have no opinion. I'll get to it on the second Tuesday of next week.
Maybe.
Right now I'm beginning Chassis Wars, in which young Grey Skywalker does battle with the forces of the evil Empire, cleverly disguised as local metalworking shops. Wish me luck, as my light saber is on the fritz and my brown belt in Ken Po is dusty from disuse. The odds heavily favor the Empire for those of you who wish to place bets.

Grey

[carpenter]

Originally posted by GRollins


...Unfortunately, there's no such thing as a free lunch...

Grey

What'd ya mean, no free lunch?

[marginwalker]

Solved problems with inrush current, sb254 rectifiers and 8*15000uF caps were too much for the poor 2A fuse.
I added a CL60 in series with the live wire.

here it is:



still need a nice power up switch but after all who cares?!

hmmm i listened for about half an hour and it got VERY hot so i switched off (ehm.. well i unplugged the main plug). today i'll measure how hot it runs.
Sounds was very good even when i played for the first time.
THANK YOU MR PASS and DIYAUDIO FORUM!

Originally posted by GRollins
... cleverly disguised as local metalworking shops. Wish me luck, as my light saber is on the fritz and my brown belt in Ken Po is dusty from disuse. Grey [/B]

Grey, wish you good luck with da metalman

[jackinnj]

Originally posted by GRollins
Unfortunately, there's no such thing as a free lunch.

Quoth Milton Friedman -- we had TANSTAAFL T-Shirts printed at the University of Chicago.

[jacco vermeulen]

Cool. so that's what the guy at the salvation army center was shouting.
(tasted like a big mac)

[hayenc]

Friedman or Heinlein??

The Moon is a Harsh Mistress.

[Andrzej Sochon]

Originally posted by hayenc
Friedman or Heinlein??

The Moon is a Harsh Mistress.

Robert A. Heinlein,
From Wikipedia, the free encyclopedia

The Moon Is a Harsh Mistress is a 1966 science fiction novel by American writer Robert A. Heinlein, about a lunar colony's revolt against rule from Earth. The novel expresses and discusses libertarian ideals in a speculative context.

Originally serialized in Worlds of If (December 1965, January, February, March, April 1966), the book received the Hugo Award for best science fiction novel.

[GRollins]

Heinlein did indeed use the phrase and was the first (as far as I know) to even attempt to pronounce TANSTAAFL (rendered in the book by someone who doesn't understand as "tone staple" if I recall correctly). TANSTAAFL is derived from There Ain't No Such Thing As A Free Lunch.
Although I frequently use vernacular in my stories and here at DIY, I usually say there's no such thing as a free lunch, saving the word 'ain't' for other uses.
The phrase (and the sentiment it expresses) is old, however.

Grey

[chrismercurio]

"The Moon is a Harsh Mistress" makes me think of the song of the same name by Jimmy Webb. Particularly the version by Pat Metheny and Charlie Haden on Beyond the Missouri Sky.


or

As Leo Brouwer once said, "The guitar is a jealous mistress, she will not love you if you don't spend the time with her."

[zettelsm]

Pardon the dumb question, but I wanted to ask while I was thinking of it. . .

I've been reading through the posts on the F4 thread (currently at page 16) prior to starting the project, copying posts and downloading attached pdf and jpegs as they look helpful. However, I've noted that some of the links to attached files no longer work. Most recent example as I work through the posts is Mr. Pass' #397. . .

Does there exist a collection of files and notes pertinent to the project in some other location?

I have been to the First Watt site and read/saved the information there.

Thanks for your patience with a new member.

Steve Zettel
Libby, Montana