Check the middle switch at the rear: it enables switching between a Russian K-40 .22uF PIO, a 2.2uF Obbligato or both in parallel for the output. A cap shoot-out with the turn of a dial!

I just had to sneek a peek at all those 6SN7s. I don't know if I'll use the 5R4 rectifier but it looks cooler than the little 5AR4 spec'd...

Stay tuned.

I haven't looked at the Akido design lately. I was wondering if the second 6SN7 is a cathode follower? If it is, it might be fun to somehow install a switch where you can switch out the first 6SN7 gain stage.

I owned a VAC preamp several years ago that had switchable gain stages that used 12AX7's for the gain, and a 12AU7 for cathode follower. Switching out the gain stages all together was my preference, but had a slight negative gain. As with all components in the signal path, they introduce their own signature.

Keep us informed of your progress?

I am very curious of how well your 2 watts will go towards driving the Four Pi's?
I will be building a 2.5-way version of the Four Pi using 2226J's with Beyma CP-385ND 1" CD and TD-250 horn.

I am hoping two watts will be enough to get them a rocking at 100db efficiency.

Have fun!

NW

The Aikido is described by Broskie as "a 2 tube cathode follower with the first tube a vlotage divider of 50%, so that 50% of the PS noise is presented to the CFs grid; at the same time the 100k resistors also define a voltage divider of 505 so the bottom triodes grid also sees 50 % of the PS noise. Since both of these signals are equal in amplitude and phase, they cancel each other out, as each triode sees an identical increase in plate current."

I have no idea what any of that means...

.

G.