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 Elliott Sound Products Ko'lok - The world's biggest single-ended tube hi-fi amplifier 

Ko'lok: Technical Specifications

Ko'lok consists of a number of separately cased modules, each performing a different function and coming together to form the amplifier as a whole. The modules are as follows:

5J/180E units
These are each 380mm x 355mm x 305mm (15in x 14in x 12in) and house the 5J/180E transmitter pentodes, each rated as having an anode dissipation of 3.5kW.  A 150mm (6in) circular hole is in the base, which permits air from the air-blast units to be directed up through the valve fins.  The pins of the valves are at the top, and are 12.7mm (1/2in) in diameter.  The air vents out of two rectangular slots at the top of the unit either side of the connector block which links it to the other modules.  Mass 23kg (40lbs) each.

The photo on the left gives some idea as to what these monster valves look like.  An idea of the scale can be had with the realisation that each of the pins on this valve are over 12mm diameter!

EHT PSU
This produces a maximum of 6kv at just over 1 amp. Internally it uses a 2100v AC transformer followed by a doubler consisting of 45 470uF 200v capacitors. Mass 41kg (90lbs).

LT PSU
This is a large toroidal transformer which supplies 9v at 60 amps for the pentodes. Mass 13.6kg (30lbs).

Autotransformer 1
This consists of 4 x2KVA toroids wired so that they can supply a series of different voltages to the EHT PSU for testing purposes. Mass 48kg (105lbs).

Autotransformer 2
This consists of a 3KVA transformer which supplies different voltages to the LT PSU, again for testing purposes.  Mass 25kg (55lbs).

Control unit
This is a very straightforward unit which connects the valves to the power supplies and I/O transformers.  It also biases the valves. Mass 4.5kg (10lbs).

Transformer unit
This is the output transformer for the amplifier. Details are in the book.

Fan unit's PSU
This consists of two large 12v accumulators intended for tractor use. Mass 41kg (90lbs) each.

Fan units
These are 12in car radiator fans, over run as necessary to 24v. They produce well in excess of the 16,240 l/m (580cfm) needed by the valves.

Driver amplifier
This is a massively parallel single-ended class A circuit using slightly overdriven PCL86 valves. Details in the book.

In summary
Ko'lok has a mass of 260kg (over ¼ of a ton) and produces 3kW at 42% efficiency. Not bad for a single-ended valve amplifier …

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