How does the sound of a Fet Valve amp cahnge...

tonyptony · « **on:** 8 Jan 2006, 11:06 pm »

as the tubes age? I'm heartily convinced of the beatiful sound that the Fet Valves can produce, but my only experiences with tubes have shown me that tube aging sometimes changes the sonic abilities of a piece of gear. Is this true with the Fet Valves? On a related note, how does one actually know when to replace the tubes in these amps?

avahifi · « **Reply #1 on:** 9 Jan 2006, 02:00 am »

The first sign of tube ageing likely will be excess noise (hiss) or microphonics (tinging sound when you touch the unit). If the tube escape this, as they get very old their gain will go down and the sound will get "warmer" finally trending to muddy. (Some people like this best).

Our experience is that the tubes do not change much over a period of several years. We see products back for tune ups that are 10 -20 years old still running well on the original tubes.

Frank Van Alstine

tonyptony · « **Reply #2 on:** 9 Jan 2006, 02:03 am »

That's good to hear, Frank. I thought amplifier tubes typically began changing much more quickly than that.

skrivis · « **Reply #3 on:** 9 Jan 2006, 01:55 pm »

Quote from: tonyptony

That's good to hear, Frank. I thought amplifier tubes typically began changing much more quickly than that.

That's true for output tubes. The FV amps don't have these. The tubes in an FV amp exist in a much gentler environment than is typical for tube equipment. (I think that's part of the secret - the tubes are used in a nearly ideal manner, without the loads that make tubes misbehave in other tube equipment.)