Ok, I said a mistake, I like direct radiator (sealed speakers) too, but I often noticed more dynamic with horn speakers (I like every speakers (if properly tunned) except speakers that radiate with both sight of the drivers (bass-reflex, tapped horn, horn-reflex, rear loaded horn...)) but it's not the subject.
About my project, I will probably chose GM-100 for final stage (I sent an email to http://www.ogonowski.eu/ in purpose to know if they would be able to build GM-100 power and output tranformer).
So someone know if we can get strong bass with a 10Y (VT-25) S.E. driving 4* 18 inch bass speaker for example, if yes what does it need, only good output transformer ? Or does too small S.E. amplifier not able to drive too big bass speaker ?
How should I run the GM-100, 3000 volt on the plate and -70 volt on the grid (that should give 300ma (900W plate dissipation)) ?
So 10 000 ohms output transformer (turn ration 35:1 for 8ohms)
so if the grid swing 140 Peak to peak it mean 48 volts RMS/35 (turn ratio)*18 (GM-100 approximative gain) ~= 24 volt in the 8 ohms speakers = 72 watts in A1. So I will need to run the GM-100 in A2 or to run her with higher plate, right ?
What is the recommanded plate voltage and negative grid voltage for to run a GM-100 at full power in A1 ?
I never played with 3000 volt power supply, and I all time used amplificateur case made by 18mm wood, is there any risk to don't use metal grounded case with such voltage ?