• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Just saw this and thought I'd pass it along. . .

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Hey Poinz,

Saw some thread where you posted a newer schematic for the Musical Machine and the Big Machine (which are a BIG inspiration for my amp aspirations). Have any thoughts of posting your latest on your website ?

I see you are now using a CCS and the 6gk5 for a driver tube. I've read that it is a single triode version of the 6SL7 , although I find it hard to believe considering the drastically lower Rp.

I am currently running cathode biased 6V6's or 6P6S (6n6c for us Cyrillic challenged) in Triode, with a wire for Triode strapping(not a resistor). I had a 100 ohm Rat Shack resistor in there initially , but it sounds clearer with the wire. Perhaps the RS resistor was just not up to the task ?

How big of an improvement is fixed bias, how much harder is it, and what can I expect from it ?

I know I've asked alot . Any help would be appreciated. Your amps are an inspiration , and your workmanship is quite beautiful. Thanks for giving me something to aim for !

Ok, enough brown nosing ;) , but seriously, thanks !


..........................Blake
 
For the "banned guy" ;) :

"If you have seen the AMZ article on alternate enclosures for audio use, then you may know that some of the interesting sizes and shapes are made of non-conductive wood or plastic and offer no shielding to external noise. Here is a quick tip on how to provide shielding for that special enclosure that you have found. Krylon makes a special spray paint that is intended to be used to coat a surface and thereby allow magnets to stick to the painted surface. The paint is loaded with iron particles, which is what allows magenets to stick, and a can is quite heavy.

Spray the inside of your non-metallic enclosure with the Krylon paint and it will add a coating that provides a shield to extraneous interference. It is quick, easy and fairly inexpensive. It certainly is easier than trying to line the inside of a box with glue and aluminum foil! I bought the can pictured here at a Hobby Lobby store, but it is likely available at Michael's and many other craft stores. Give it a try and use your imagination to put those unusual enclosures to work. "

Possibilities of what?

The author compares a paint with ferrite particles to an aluminium foil.

Don't be "that guy" . The possibilities of the paint's use for shielding , DUH ! :scratch2:



......................Blake
 
It depends on what you are trying to shield against, audio frequencies or EMI.
This sort of spray, and special particle impregnated plastics etc can be used to block EMI, ie in the megahertz, but it has no effect on audio frequencies, ie block power transformer radiation etc.

I suppose the only way to know for sure is to get some, spray a box, and measure fields inside and outside the box,
But
The particles in the spray paint are likely suspended in the paint and end up in isolated groups, like a ferrite material
and
I believe that unless the iron particles are contiguous, ie all touching and forming a continuous unbroken loop, then there will be no magnetic shielding. Eddy currents dont form since particles are disconnected, so no IsquaredR losses, so external magnetic field passes through undissipated.

Ferrrite can be used for shielding, but not in the sense of coating a box. Ferrite shielding only works at high frequencies, and it works on cables by effectively increasing the inductance at high frequencies.
 
'Pulsating Iron'.  Sounds like a skin site.

Nihilist, I've tried to provide the latest schems and development when guys on the fora ask for them.  You will perceive that updating all my DIY pages is now this monumental job, which I find intimidating.  Should I suddenly not have to chase after all the dimes and nickels necessary for survival, I shall definitely do so; but meanwhile, if you (or all y'all) have a question, don't hesitate to ask.

Aloha Nui Loa,

Poinz
AudioTropic
 
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