KR AUDIO ELECTRONICS
AUDIO POWER TRIODES

All KR audio triodes are guaranteed for two years from the date they were installed in an amplifier.   All tubes are  serial numbered and shipped with warranty documentation inside the box.  Prices given at enquiry. Please note that there is no VAT to pay on these prices as Valve & Tube Supplies is not VAT registered.

PX4 - £220 per pair
Beautiful balloon shaped PX4 fitted with original British made B4 bases.    Envelope is an exact copy of a balloon PX4 supplied to KR by Valve & Tube Supplies.     Electrically they are identical to the originals in terms of bias required and gm but will handle a bit of extra power due to the modern materials used in their construction.   We have had these evaluated by a PX4 guru in the USA who says they 'sound better than the originals'.  They are supplied with data and guaranteed for 2 years. 

The PX4 balloon can also be supplied with a UX4 base.

 

845.jpg (61883 bytes)KR845  -  £295 per pair

Probably the best 845 in the world in current production.   The KR replica of this popular tube offers outstanding performance by virtue of its oxide coated filament as opposed to the thoriated tungsten filament used in the original. 

One of the benefits of this change is that instead of the filament power being more than 30 Watts as in the original tube in the KR tube it is only about 10 Watts.    This means that when used near its maximum ratings the tube will run approximately 15% cooler than the original.   In addition the oxide coated filament has a very high peak emission capability which contributes to the KR 845’s excellent linearity. 

 Although nominally rated at 900Volts maximum on the plate the KR 845 has been tested at and will run at 1000 Volts due to its high degree of vacuum, similarly it can sustain a plate dissipation of 100 Watts.

 The only disadvantage of the oxide coated filament is that the KR 845 does not light up like a light bulb because the filament runs at a dull red heat.   Aesthetically some potential users may consider this to be undesirable but it’s a small sacrifice when the tube’s outstanding performance from the sound point of view is taken into account.

 rgb300bxls.JPG (14216 bytes)KR300BXLS  -  £260 per pair

The new version of KR’s popular high performance 300B.   Already very much used by HiFi enthusiasts around the world the new production version has been improved in a number of ways compared with the earlier designs.   Chiefly the plate is now made of thicker material and instead of being a flat plate with extra radiator fins it is of cruciform section.   This heavier plate needs firmer fixing and instead of relying on mica plates to hold the plate there are four sturdy support wires taken down to a clamp which is fixed around the glass stem at the base of the tube.   

This new design results in a much more rigid assembly thereby reducing the risk of microphony and guaranteeing constant performance throughout the life of the tube.  This tube is available with the traditional “coke bottle” shaped envelope.

 

KR 300B (BALLOON)    -   £245 per pair

A “drop – in” replacement for the expensive Western Electric tubes and far outperforming those from Russia or China, the new KR 300B has been rendered even more attractive to those for whom appearance is also an important consideration.     KR are now offering their standard 300B in a balloon shaped envelope similar to the early PX25, with the result that a standard 300B amplifier can be given that authentic historic appearance.

 

SPHERICAL 'R' VALVES   -  £65 each

We have managed to persuade KR to make some more of their excellent reproduction 'R' type valves.  Very similar to the original French-made 'TM', these have spherical 'tennis-ball' size clear glass envelopes with a top pip and a B4 base with a copper base shell. 
Bright emitter filament 4volts at 0.7 amps.  Gm is 0.4 mA/V at Va=60volts.

 

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