This version - called the Space Charger - because of the space charge it develops within the tube .... is similar to the previous Mk1 and Mk2 incarnations. The difference here is that it is specifically designed to operate at higher voltages and quisceint current and therefore only with the XLS type of 300b. These tubes both sounded super with the normal operating pont of a 300b, but I wanted to hear what they are really capable of, when fed with a higher voltage and about twice the normal current. This gets them operating in a different and more linear region of the transfer curve and lower distortion... plus a little bit more power output!
The power transformer is of the Plitron style and manufactured by Amplimo to custom specifications. Output transformers are also Plitron. The rheostat is in order to allow adjustment of the bias current in order to taste the tube at various operating points. In addition, there are NO electrolytics used - even the bypass caps are of the ASC BlueLine custom made type. These ASC Blue LIne caps are not available off the shelf and are only made to your design and specifications.
Three line level inputs with AudioNote RCAs and a Greyhill selector switch. Top view Hammond choke cover is made from nothing other than mdf and aluminium sides. ASC BlueLine audio grade oil type caps and the mounting plate. These oil caps are used throughout the power supply and as the cathode bypass - worth every inch of real estate that they take up! Rheostat for bias adjustment and hum pot mounted on sub-plate to ensure spindles are flush with top of the chassis. Tube sockeet wiring. The BlackGate bypass cap has since been replaced with the same caps as used in the PSU - namely the ASC BlueLine oil caps.
Yes, they are big, expensive and possibly overkill, but the end result is pure magic ! Until you hear oil type caps in place of the like of BG, you just dont know what you are missing
Greyhill selector switch and Alps Blue Velvet pot. Fine Silver 4N 0,5mm internal wiring with teflon insulation. Tagstrip used for termination of the PTX wires. Detail of countersunk holes and hum and bias pot holes.