In Reply to: DC couple a 5687 to 2A3 ? posted by Aria Seven on September 30, 2002 at 22:56:33:
This does not answer your question but I'd try the $5 6N1P. I've got running on a breadboard right now (paralleled) driving 300Bs and I like what I'm hearing mo' better than the 5687 and 5842.
I'm using the b) schematic from the url below except I'm using a 220 ohm cathode resistor and IT coupling to 300B. Next I'll try one side of the triode and also an ECC99. BTW, I use a 26 linestage ahead of my amp.
Got it going, sounds great, but not loud enough ...
I like the 6n1p in SRPP. It will give a little more gain than the 5687, but I don't think it will drive the 2a3 to full power without an active preamp ahead of it. Also it still may not swing enough voltage at your 146V or therebouts.
If you wanted to get more complicated with a constant current loaded mu-follower type setup to maximize the gain from your driver that may work. I wouldn't intentially setup your amp to not deliver its full output or run the driver to clipping before full output. But thats just me.
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