|
Despite all the pins on a tube, it is really cool at just how simple they really are - plate/screen/grid/cathode/filament is just about the whole shooting match!
When I'm designing a preamp, I like to sketch out some triode stages. Then with some math, I plug in the numbers I want for the 3 main spots that are tweaked on any gain stage...
...After you do this awhile, you can sort of 'sketch out' a preamp in the way that a composer writes sheet music. You can take into account how much the tube will conduct, how you will alter the bias, and when you get really comfortable with it, you can start tweaking the interstage impedance, compensate for 'insertion loss' created by tone stacks, and use the 'Miller effect' to your advantage (one of my favorites).
...You can also eventually glance at schematics and see what gives some amps some of their signature characteristics. Conversely, you can sometimes spot some Achilles' heel issues with some amps as well.
I'm a total amp geek, completely addicted by amp design. I'm currently working on a potential better solution (than the traditional ones) for reducing AC filament hum. Rather than switch to DC fils (which causes a mess of heat at the bridge rectifier), and rather than shield the surrounding components, I'm trying to figure out a way of shielding the filament leads themselves. Alternatively, I'm considering using a high amp 6 volt battery that will be recharged when the amp is not being used. While it's possible to make an amp very quiet with proper lead dress alone, the geek in me is not content with the idea of having an AC transmitter in the guts of my tube amps...
__________________
|