Kora Triode 100 SB Mono Block Power Amps


I have recently agreed a deal to buy a pair of the above from a pre-owned hi-fi dealer and who has sent the amps off for testing prior to sale and his engineer will be renewing the MOSFET capacitors and repairing a valve connection.  

Back in 1997 these amps were measured, reviewed and recommended by Bascom H. King, so I thought that was a good reference point to begin my first venture into valve amps. 

I would be very grateful to know if any members here have owned or heard these amps in the past and in a particular if they have any experience of biasing with this model?

Here’s some more info from the net:

“These mono blocks use the Russian 6C33CB output tube, 6922 for input, and the 6BQ5WA for driver stage to achieve 80 watts output power. An incredibly high 115db signal to noise ratio, superwide 10Hz to 60kHz bandwidth, and a low rated distortion of only .07% @ 1 watt might just make those 'tube measure bad' naysayers finally concede in defeat. This triode amplifier uses metal film resistors, polypropylene capacitors, silver solder, gold connectors, double-sided circuit board and more make this unit so good and reliable that Kora guarantees this unit for two years"

Thanks very much.    

soma70

Showing 2 responses by almarg

Roberjerman, the amp in question uses two 6C33C-B tubes per monoblock.  And although I could be wrong, I suspect the two tubes are used in push-pull, rather than being paralleled in a single-ended configuration.

Regards,
-- Al 

The engineer or technician should make a point of checking out the condition of the sockets for the power tubes. The 6C33C-B (and the 6C33C) run extremely hot, each tube consuming something like 75 watts or thereabouts, depending on the specific design. And my understanding is that replacement of the sockets may sometimes be necessitated by long-term exposure to the heat.

...his engineer will be renewing the MOSFET capacitors
Perhaps they meant the capacitors that are used in a MOSFET-based circuit. To be sure it’s clear, a MOSFET is a transistor, not a capacitor.

Good luck. Regards,
-- Al