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The ΦCH83

Audiophile Stereo Valve Pre-amplifier

 

The phiCH83 came to be as a consequence of our purchasing of about a ton of NOS valves destined to be crushed and recycled. There also existed a need for pre-amplification for our PHIcD180 power amplifier. Today one finds a multitude of valve pre-amplifiers based on a few "cult" valves (Russian valves like the 6N6Pi and the 6N30P are very popular at the moment, not to mention the ubiquitous and thoroughly mediocre 12AX7 and 12AU7). Many of these valves are indeed very good, but that does not preclude the existence of other excellent valves, most of which were not intended for audio use.

With this in mind, we are continuously looking for "hidden gems" in our stash of valves and when we do find a promising candidate, we build an amplifier and start listening. At the moment, for instance, we are testing a very nice valve made in the 1930's, the NR15A. Not wanting to stray too far from the simplicity we have been embracing since our beginnings, we opt for single valve amplifiers (per stereo channel) with a two-component constant current source as load, which basically comes down to a pre-amplifier with only 5 or 6 components per channel. This additionally makes it possible to for one to use the best components around the valves one can afford. If our customer wants a Duelund capacitor, we'll order one and wire it into the circuit.

The phiCH83 is constructed around a radio heptode-triode designed for 12V operation. Only the triode portion of the valve is used. It is constructed in a similar style to the PHIcD power amplifier range, with an external power supply to keep circuit noise at a minimum. The basic pre-amplifier has provision for a single CD/line level input but more inputs can be fitted if required.

Here's two photos of the completed amplifier. (In actual fact this is an integrated amplifier - a combination of the phiCH83 and the PHIcD180 power amplifier custom made for a client.)

 

 

The basic phiCH83 is currently priced at ZAR7500.00

 

For any information, please contact us

 

 

This work is licensed under a Creative Commons Licence.

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