Some time back I inquired about running a 5V rectifier tube on 6.3v.
Here's why. This is my brother's Christmas present, a blacked out AR-15 themed amp for the office area of his wood shop. He has a SS Bluetooth amp now that he uses with his phone. I have a switched outlet on the back for an Esinkin Bluetooth adapter. It is built in an 8x10x2-1/2 aluminum chassis. That doesn't sound too bad until you decide to put all the iron underneath. A pair of 6J5s drive the 6V6s.
The ON/OFF is an "adapted" genuine AR-15 SAFE/FIRE switch. The volume knob is a genuine AR-15 flash hider "adapted" to a 1/4" pot. It is surrounded by a piece "adapted" from a genuine AR-15 quad rail hand guard. The side rails are "adapted" from AR-15 style carry handles but are actually made for AR-15 looking Air-soft guns. I couldn't afford $30+ EA for genuine AR carry handles. ("adapted" = don't ask)
It is largely based on the Lacewood 1&2 amps but I also stole some ideas from pbpix here on ARF. I liked his use of the CL-90 to ramp up the B+ while the tubes were heating.
Voltages were taken by a DMM and the current was across a 10A (close enough to) 1 Ohm resistor.
I did a single channel mock up and tried multiple typologies, screen resistors, bias resistors, B+ voltages, ETC. A tone generator showed my input - pre-amp - final sine waves on my scope (2 at a time).
It was quite the learning experience. So long as you don't exceed the tubes limits you can get quite acceptable if not great performance.
This thing rocks and can get a little loud for an office or bedroom amp. It really liked my Klipsh CF1s but he ain't getting them. He has some bookshelf speakers similar to the metal KLHs right now. It did OK with my set of KLHs but much better with my Bose 201 III. I may let him audition them.
This amp provides exactly what I wanted. I'm sure there are guys here that could "improve" it. But I don't see how.
BTW Here's an all new example of "Tube Matching!"
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