The AV325B "ref" which I am currently using as powertube, is lacking just that "airy, mystical" what the TJ300B had. I must say, that's about all what is lacking because on all other points the AV 325B is a better powertube... When I read about the AD20M, a thought passed my mind: Could this tube add the lacking "airy-ness and mystics" to the AV 325B?? Primarily because the AD20M has a meshplate and, in my opninion, thàt is what mesh adds to the sound... I quickly contacted the distributor and a few days later he personally delivered the tubes to me (!) - How nice life can be!
The AD20M is a new product from Alesa Vaic, and is especially designed as a driver for his AV325B and AV 525B "ref's". Unlike its typenumber suggests, it has an amplification factor of 15 and is "equipped" with a meshplate. This meshplate is stiffened by the use of extra add-ons, which are made from his new patented NiXX-metal and also help dissipate the plate power. The AD20M has a plate resistance of about 2K5 and can operate up to 400Volts at 30mA. The filament consumes 4Volts at 2.2Amps, which indicates that this driver has lots of power! This makes it an ideal driver, in my opinion, since the required power to effectively drive the powertube can be delivered with ease....
The filament supply is equal to the supply used for the AV 325B. Very good sound quality, using a minimum of components: Schottky rectified followed by one 10.000mF capacitor. This means a relative big ripple which is cancelled using a hum-pot. Even at an amplification of 15 at the drivers' spot, this really works well: no hum is audible! Glowing this tube is a marvellous sight at night: you can see the filament/cathode shining through the meshplate (wow). I choose for a 1K5 cathode resistor and a 100mF/100V Elna Cerafine built in wood!!. The B+ is about 325V and this results in a 28mA platecurrent, which won't saturate my (current) interstage.
And? Do thoughts come true? Yes! very nice to say so (this time...) But these are not the only things that the AD20M do better: It is almost like the AD20M gives the music a "pre-wash". It is the perfect match of driver and powertube! The AD20M supplies plenty of "airyness and mystics" to the music, which is "powered" through the AV 325B resulting in the most astonishing driver/powertube combo I've ever heard..... Authority ánd subtility presented with ease.... wow! at last
Specs? Look at: Vaic-audio.info