GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Audio Discussions
In the Thread: How to get a LOT of SET power.

Post Subject: Drum'n'bass party ampPosted by N-set on: 3/30/2011

I've made an itellectuall excercise and tried to see hoe to fullfil (some of) Romy's
points regarding the bass amp.

1) To get 100+ W from 833, HT between 2.5kV and 3kV will not work.
Spending some time over the curves, 1400V, 0V, 280mA loaded with
6.5k should give 130W with the swing approx. +60V to -60V, grid current 80-100mA.
According to the data the tube can handle this power 390W if force air cooled.
I'm wondering what is the GU-48 secret knowldge. How does people abuse it?
At this pont the Rp is approx. 3.3k, so 100+H should give 5Hz.

2) The driver is the hardest element: gain around 30, support 100mA grid current
and have lowish Rp. At this moment nothing comes to my mind as other 833.

3) I have a problem with DC: I do not know how stable that would be. The designs
I know (Axiom, Romy's MF, etc) have a cathode bias, which gives some self-balancing.
Here we don't want cathode bias. What is the advantage of DC? No cap/IT. But
their most nasty features reside in MF/HF, not in bass. Besides the driver has to be loaded
somehow and loading it with a resistor is a waste of power. Since we don't care about anything
above 200Hz, the difficulty between making an anode choke and an IT is not that big--we couple
only via the core. I'd even experiment with Dave Slagle's idea of canceling some of the DC flux
with the heater current. The resulting intellectual proposal is below:

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