KT 88 with Leben cs 600

Hello,

I know the thread is old, but as it contains information that's partially incorrect, I thought I'd chime in.

"The KT88 and the EL34 are not directly interchangeable. Although some amps can handle both types of tubes. Your Leben is not designed for the KT88".

The Leben manual contains a settings table showing how to use the amplifier with a wide range of output tubes, including the KT88 type.


[source]

 6L6GB, 350B, KT66, KT77, KT88 and 6550A tubes are all perfectly usable even though it's correctly stated that the KT88 and EL34 tubes are not directly interchangeable in other amplifiers.

For the driver stage, though, only (fource) 6CS7 tubes can be used in the CS-600 - and only 12AU7A and 12BH7A tubes in the CS-600X (two of each).

So the KT88 tube would be perfectly compatible in both the CS-600 and the CS-600X.

Thanks for the update.  I am aware of the above chart. Currently listening blissfully to some NOS EL 34.

Hope I get a good 5 years out of them.

Thanks again

But PS.

Should I ultimately try the KT 88, how does one decide the optimal plate voltage position?

@mdrone Plate voltage on the Kt88 is dealers choice. With the switch in the “up” position the KT88’s will be slightly more resolute. With the switch in the “down” position, the KT88’s will be slightly softer. You may or may not notice much difference. I believe the CS600x sounds better with EL34’s or 5881’s or KT66’s. One man’s opinion.

The KT88 is not a very good sounding tube relative to the other tubes your Leben can take looking at that chart the KT88 and 6550 are the worst of the bunch.