these people are insane!

[DummyLoad]

http://www.goodsoundclub.com/Forums/ShowPost.aspx?postID=2136

...no, really, insane... check out page 3 & 4 of the thread.

http://www.goodsoundclub.com/Forums/ShowPost.aspx?postID=5850#5850

--DL

[Willabe]

Are they putting tubes in liquid (water, oil?) to cool them while running 2,500VDC on the plates?????

You have got to be kidding me. How do you get a seal on the tube pins that is safe?


       Thanks,     Brad        

[Jack1962]

these people either need some meds or to stop taking the one's they are taking 

[G._Hoffman]

Are they putting tubes in liquid (water, oil?) to cool them while running 2,500VDC on the plates?????

You have got to be kidding me. How do you get a seal on the tube pins that is safe?


       Thanks,     Brad        

Well, it depends on the liquid.  If the liquid is an insulator, no problem.  People have made computers that are immersed in mineral oil so they can be overclocked to quite astonishing levels.  The only problem with it is you have to change the oil from time to time, because if it gets contaminated it can become a conductor.  Hell, as I understand it, pure deionized water is an insulator, and and it is only when becomes contaminated with other stuff that it becomes a conductor (though I'd confirm that before I put it to the test!)


Gabriel

[JayB]

Better question is, what would you do if someone brought that into your shop? It's not working, can you fix it? LOL

[HotBluePlates]

I couldn't keep my eyes on the screen long enough to read much of that. My eyes kept rolling...

But it is feasible to immerse a tube in oil to get better dissipation; it's just that it doesn't get you very far with a glass envelope tube (which is hamstrung by the empty space in the tube envelope). The plan would work a whole lot better on a ceramic-bodied tube, as used in a transmitter.

Besides, they pour mineral oil inside high voltage pole transformer cases, to insulate/pot the windings (yeah, there's still heavy paper insulation between turns).

[DummyLoad]

Besides, they pour mineral oil inside high voltage pole transformer cases, to insulate/pot the windings (yeah, there's still heavy paper insulation between turns).

true. some xmitter tubes are also designed to be liquid cooled. i don't think the ones mentioned are.

PRR posted something a while back something like 1.2KV into a 3K load for 200W using one of the GU81 in class A1. searching, i found that site. other insane folk that are actually using them for audio. not that i'm against experimenting...

[PRR]

Oh, bosh. These guys are small-thinkers.

Before the advent of push-pull, it was fairly common to use one power tube audio amps to modulate 5,000 Watt AM radio transmitters. True, perhaps not even 1,000W of audio and 30% maximum modulation; later they realized that this scheme wants more audio-tubes than radio-tubes (and with more than one, push-pull has other advantages).

Much of the krapola about flux and gap is straightforward engineering. There is some limit how low you can go before DC losses get "excessive" but 20Hz is easy.

The idea that there is musical content near 20Hz is dubious; if there is, surely the performer did not hear it and it should not be counted as music (anything can make random 20Hz signal).

The idea that bass-arrays "must" be 0.5 ohm or must need damping.... fooey.

The idea of staying below 500V is very attractive.... to humans. But large SE tubes require super-human scale. So what if a few guys may die... isn't it worth it?

[G._Hoffman]

The idea that there is musical content near 20Hz is dubious; if there is, surely the performer did not hear it and it should not be counted as music (anything can make random 20Hz signal).

You'd be surprised.  I've set up some big FOH rigs where we could really experiment with the SMAART software, and turning subs on and off, all of that stuff.  IF you get everything aligned properly in the low end, you can really hear the difference.  Mind you, if you don't have the timing of everything just so, it can be a nightmare of mush.  The first time I ever used SMAART was in a theater that had a lot of jazz acts, and so we wanted a very acoustic feel to things.  The biggest part of that was delaying the mains enough that the sound from the stage would get to the audience first, so things almost sounded like they were coming from the stage.  But the other thing that was very interesting was that, once we delayed the subs against the mains, we could get rid of most of the low end roll off that was on the mains, and SMAART was giving us a pretty flat response all the way down to 20hz.  And you could really hear the difference.  I'm sure part of it was the timing stuff, but the added low end was - not audible, per say - but perceptible.  More so on loud rock n' roll and dance stuff, where the kick was felt more than heard, of course.


Gabriel