The 12SX7 tube is a 6SN7 with a 12 volt heater , as opposed to the 6SN7's 6.3 volt.
Its been tested to have the lowest distortion of any 6SN7 , and sounds very good, with attributes beyond current production 6SN7 tubes, and amongst the very best NOS tubes.
I have a stash of unopened General Electric 12SX7 tubes, enough to build 4 Grange preamps with spares.
The first one will be a Dual Grange. This configuration has two line level outputs, both with the famous Supratek quality.
This enables the use of a subwoofer, or for use in a bi-amp system.
As an example, one of my systems is a three way, with a 15 inch bass , a midrange horn and a tweeter horn.
The bass driver is driven by a solid state amp, which is connected to one of the Granges outputs, with level control to adjust gain.
The mid and tweeter horns are connected to the other Grange output, also with a level control.
The crucial mid range is driven by a wonderful 2A3 single ended amp, the tweeter with a small Class A solid state amp.
With a powerful amp on the bass , and a tube amp that is very synergistic with the mid horn i get the best of all sounds, and the abilty to do very fine adjustments to the overall balance , this is critical to getting optimal sound in each individual room, and to suit taste.
A master voume control sets the overall sound level.
Crossovers are passive on each driver, I personally prefer this to active crossovers, many speakers are bi-amp capable, which means the internal passive crossovers can be connected to seperate amps.
Ive been using this bi-amp method for many years , as I find it is quite superior to one amp driving multiple drivers. Impulse or transient recovery speed is much improved.
In such a system 2 or 3 reasonably priced amps will easily outperform an uber expensive high end amplifier.
The Grange preamp is built in a 1.2mm copper chassis with Australian Jarrah hardwood cabinets.
It has a state of the art tube phono stage designed for moving coil cartridges, which uses very high quality frame grid tubes designed at the end of the tube era - these are ideal for phono stages which need low noise and linearity.
The line stage of this particular Grange uses 4 x 12SX7 tubes as noted above.
They are run conservatively, and will last many years. A spare set of boxed tubes is included.
There are 10 expensive Lundahl transformers in the preamp, along with high quality components.
The power supply is separate from the preamp and is the key to the superlative performance.
It has a power transformer that is strong enough to power a big tube amplifier, with seperate constant current source and tube regulation for each of the phono and line stages, so 4 in total.
40 years of tube design and build experience results in a tube preamp that is as fine as can be built , a custom built unit that will provide a lifetime of musical bliss.
This individual preamp will be available sometime in January 2024.
Expression of interest to supra@supratek.com.au
