Going to have to eat my words on this one. Earlier I stated I thought the 6C18C to be warmer than the 6C33C. After pulling out two new pair of tubes and doing a serious A-B, I found the 6C33C to be slightly warmer and the 6C18C tubes to have a splash more treble. Both sound beautiful. The best is where you wish to move the sound of your system. For more treble and a little more upper midrange presence, the 6C18C would be the best, and for a slightly warmer midrange, the 6C33C is better. Both sound similar.
6C33C-B tubes
I have 35w p/p Class A monoblocks which use two 6C33C-B tubes per unit. The manufacturer recommends a bias setting of 150mv. Before biasing (once a month), the tubes' measurements rarely deviate more than 10mv over/under the 150mv. Over the last year, I’m guessing that they’ve been in use for about 1000 hours. I have no idea what their expected lifespan might be. So far, biasing is still relatively easy. The manufacturer is no longer around to answer any questions. So, here’s a few for the Audiogon community.
1) For those of you using 6C33C-B tubes, are you able to guesstimate their lifespan in your amp – in Class A operation?
2) Generally speaking, how necessary is it to bias exactly to the manufacturer’s recommendation – in this case 150mv? Is there an acceptable tolerance +/- %?
Thanks! P.S. I’ve been replacing the sockets once a year.
1) For those of you using 6C33C-B tubes, are you able to guesstimate their lifespan in your amp – in Class A operation?
2) Generally speaking, how necessary is it to bias exactly to the manufacturer’s recommendation – in this case 150mv? Is there an acceptable tolerance +/- %?
Thanks! P.S. I’ve been replacing the sockets once a year.
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- 27 posts total
- 27 posts total