by EWBrown » Fri Feb 22, 2008 7:46 am
Interesting little observation.... ANd totally nothing to do with GSG...
I'm ginning up a simple PP 6V6 based guitar amp on the old Grommes "Little Jewel" chassis.
The original rescifier tube is 6X5GT. I decided to do a little experiment, and since I have some Dumont brand 6X5GTs and 6AX5s, I'd try a little comparison. The power trannie is the "default standard" 350-0-350 @ 90 mA, etc, and I wanted to see if the 6AX5 would be a better fit. Nice and easy-breezy, since both have the same pinout Yellow_Light_Colorz_PDT_03
Well, it turns out that the 6X5 delivers a significantly higher B+ voltage than the 6AX5s (and I tried several of each, all NOS Dumonts,, in order to eliminate any "sick tube" factors).
The 6X5GT delivers 362VDC B+, and the 6AX5 delivers 331 V B+, measured at the OPT primary centertap. I'm running 33-34 mA through each tube (620 ohm cathode resistor for each) and the G1 voltage is around 21 vDC.
Still working out the driver section, I'll probably just copy the "18 watter" design, a couple of 12AX7s, or just to be contrarian, 6N2Ps...
I'da thunk it would have been the other way around , maybe I have to print out the data sheets and look at teh curves again... 6X5GT doesn't have enough current capability to feed a GSG, it will get the dreaded glowing red plate syndrome, I'm sure...
/ed B in NH
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