Why the high price for tube amps?

I've seen this before. That's a lot of work, but he looks like he's having fun. :)

The 'professor' needed that equipment on Gilligan's Island to build a transmitter.

RIP Russell Johnson, 2014-01-16. His website hasn't been updated in years.

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Anyone wanting to run for any political office in the US should have to 
have a DD214, and a honorable discharge.

Nelson Pass had the zen series of mosfets - circuits still on line I'm sure.

Here's one

class A for clean sound, with light bulbs as current ballasts in the constant current side of the amp. Light bulbs are still cheap, nice porcelien/ceramic sockets still available, what's not to like?

The glow will be there, particularly if you parallel a few, and unlike the light show, when they change brilliance it will be because the current is modulated.

I cobbled together one of his "Zen" amps and the sound was exceptional; much better than any bipolar DC coupled class AB I've listened to. I used a three terminal regulator as a constant current source. Light bulbs make a lot of sense - dynamic current ballasting with no heat sink requirements.

You can always wind your own output transformers if you like a challenge. I worked for a PS manufacturer in San Diego and he wound his own 60 cycle (400 HZ and switch mode) transformers with some better quality grain-oriented silicon steel cores with a 1:1 stack.

One Tube amped guitarist had him wind a custom power transformer and it ran so cool compared to the OEM one (and was a little smaller too) that he wanted us to start making output transformers. We dissected one very expensive one to copy. I think it was called an "ultra-linear" design and had both plate and cathode windings.

Winding transformers is not that hard. Designing them is somewhat harder - particularly in the days of slide rules when spread sheets were unavailable. Wind the first one from calculations then wind another using results of the first. Two times would almost always nail it. We'd often build our own bobbins or modify stock ones to suit the core stack.

I wound a 1 KW induction coil with some 13 miles of wire (32 AWG) in the secondary. It took me a month to build, but I did the secondary winding in a week's worth of spare time. I adapted a DC tape reel drive motor to make a kluged together winding lathe (that took all of two hours or so) A primitive variac controlled power supply tensioned the wire and spun it on. The design was from an early wireless text with modifications since "double cotton covered wire," hard rubber sheets and gutta-percha is hard to find these days.

What do you do with a KW class induction coil? Excite Tesla coils and throw lightning, make ozone and X-rays, among other things.

< I have been thinking about making a tube amp for fun so I can compare < the sound to a good solid state amp and because I like making things.

That makes me sound warm and fuzzy...

< I remember with fondness the sound from my old tube amps years ago. < But it could be that my memory is flawed. Anyway, I looked at kits and < they are all very expensive. Tubes themselves are not that expensive < and many amps that get good reviews only have a couple tubes.

I would think the main cost would be the labor of point to point soldering - but the truth of the matter is that aluminum chassis do not exist. You are supposed to use adhesive and there is no such thing as bakelite (I don't know what that means.) No - the box can not be 5 inches deep. It's some kind of universal truth or something.

< Transformers are really expensive. Are the transformers used for tube < amps really that special?

I think that the selenium rectifiers might be a bit difficult to find. I only have one and am using it.

< What if I just buy an old amp from a thrift < store and replace the tubes and any other components that might be < bad. Do the transformers go bad? Does the insulation degrade?

The electrolytic capacitors usually dry up from what I understand.

The condenser (read: variable capacitor) is patented and aluminum is no longer available. If you accidentally mention the phrase ``xyz plating'' as in silver plating they will probably commit you to the psych unit. I tried building a tuning condenser and ran out of washers only to find out that I was committing a crime by asking for knurled copper split rings at the home depot.

Reduction assemblies for the tuner are diffucult to find. I dreamed of one day making a mold and pouring in some aluminum but again finding aluminum these days is difficult and who wants to tear apart a still working gear assembly to attempt a mold - I know there are people that can do this - I however am not one of them.

< I have < and use electric motors that are over 50m years old and their windings < don't suffer from bad insulation.

They used to use better wire and better insulation I think. I have a current transformer that looks like it has been soaking in sea water since the 1950s. the black tar ``transformer varnish'' seems to have worked well as the transformer and the meter still work. Unfortunately the battery is dead and the resistors are not replaceable (asking for carbon 1 watt resistors will only make people laugh at you when they try ``correcting'' you with ``you mean ... '' metal film) ... Damn magnets!

< I even have old magnetos on old < tractors that work perfectly and the insulation in them must be pretty < stressed because of the high voltage.

Yes high voltage at several milliamps still scares people. They will think you are making a taser or a plastic truck that plugs into the electical outlet.

< Thanks,

thank you - needed to vent.