[sdiy] Beam modulators

[Ken Stone]

>> I've done another update of my synth site. Of interest are the photos of
>> my 6BN6 type beam modulator tube distortion effect, and some simple
>> demos I recorded using it. 
>
>I just listened to the samples and the only thing I can say is
>*Holy Shit*! 

It is rather impressive isn't it. I don't think I've heard a better
distortion. It certainly beats any of the semiconductor ones I've had (and
no longer have, for that matter).

>How does the beam modulator sound processing other inputs? Have you tried
>bass or guitar through it?

I haven't, but that's because I don't play those instruments. You would need
a pre-amp such as the one I used in the second version of the module, as
guitar signal levels are a bit low. 


>> Has anybody else on the list build any of these beam modulators yet?
>> 
>Where can I can a quick intro on building things with tubes (with emphasis
>on not killing myself)? I'm ready to try...

I can't think of any specifically, but there are a lot of tube resources
concentrating on guitar amps, hi fi amps and such. Some of those have
beginners' faqs

Here's a couple of tube sites. Follow their links.

http://www.werple.net.au/~kiewavly/audio1.html
http://duncanamps.com/

Things to remember when working on tube stuff is that capacitors hold their
charge for a while, so unless you provide a safe way of discharging them,
you run the risk of shocking yourself, even if the unit is turned off.

So to that effect, I do the following:
1) Before working on a module, I first switch off the power!
2) I then discharge the capacitors in the system using a switch I have
provided to do that. It is a momentary contact switch that connects a 1k5 5W
resistor across each of the power rails. This discharges both the supply and
decoupling capacitors. The switch needs to be held on for around 15 seconds.
3) I then use a meter to check the power rails really are down near 0 volts.
4) I disconnect the module from the power supply while working on it.
5) If I have to adjust something with power connected, I make sure I am not
forming a conductive path to ground. I keep one hand in my pocket, and make
sure I am not standing or sitting on anything conductive. (common tech
practice.)
6) Where practical, I insulate any high voltage connections that I may come
in contact with.
7) I make sure completed projects are propperly housed so stray fingers
can't find a way in.
8) I stick on a warning label to warn others, and remind myself when I'm not
thinking!

I hope that helps. If anyone else cares to comment or add to this, feel free.

Ken
_______________________________________________________________________
Ken Stone   sasami at blaze.net.au  
Catgirl Paradise <http://www.anime.net/~kens/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>