Tubes Asylum

Posted by Joe Rosen (i) on June 06, 2001 at 11:30:54

In Reply to: Re: What's in Your tube box? posted by tomcat on June 04, 2001 at 16:03:53:

Actually I DIDN'T say that the 6AS7/6080 sounds better than a 300B, since this is about the only triode power valve that I've NOT auditioned extensively...
The 300B may well hold it's own, but I think it's got plenty of problems, and I don't like the way I see it used. It's not an easy drive, like the 6AS7. Maybe run at an Ep of 250VDC it may work much better than it does in most applications. No doubt the Western Electric reissue of this valve is something to be contended with, but at the price, which is some 40 times higher than that of the lovely 6080/6AS7 (and this for NOS, too!), you kind of lose interest fast, don't you?
The ECL86 is another underrated valve, very lovely sounding it is!
Problem I found with the things is that even if run gently (less than 300VDC and no more than 30mA), they just don't hold up, the cathodes get pooped out within a thousand hours or so, approximately one year and they're over the hill...I'm not just whinging about the Serbian jobs here, this is true of ALL NOS I've tried! Another problem is unequal levels of heater-to-cathode leakage. Getting the last vestiges of hum out of amps that use this bottle can be a minor pain in the arse...Try a set, swap one out, rotate the hum-balance control for the umpeenth time, swap out another, blah blah...bingo! OK! Next channel!
And do it again a few months later if you're REALLY fussy like that...
Congrats on getting the X-101 going (I assume the X-110 is a typo).
X-101's are all different, does yours have a suffix in the number?
Anyways, what's the output valve? Can you tell me the HT on the output valve anodes? Then I can tell you if it can be triode-connected...oh, and I'll need the stock G2/screen-grid voltages, since this will tell me how much the idle bias is likely to change if you were to try this. You can't just leave the G2 connection open, the valve will simply stop working! And that's no good, is it? As far as the power supply tap to the screens, yes, you can just leave THAT electrically open afterwards...
Fisher's can have that really soft, syrupy thick sound. You may have to modify the circuit, quite frankly! Fisher's aren't much good to get too fancy with modifications, they were designed to sound exactly as they do, in fact, most of their separates are far, far worse!
Don't get too enamored with your Sony! It may have V-FET's in the outputs, but I'll bet dollars to doughnuts that it doesn't exactly have a matching all J-FET front end, in fact those V-FET's may well be the ONLY FET's in the bloody thing! Sony is the king of Japanese marketing cynicism, they KNOW that the dumb narrow-noses will buy ANYTHING. VMOS-FET's had their day, and that day is over. New York Audio Labs and Counterpoint made their share of hybrids, with valve front-end circuitry and mostly Hitachi MOS-FET outputs. The sound was pretty good, but not exactly knocking on the door of either the best all-valve amplifiers or all transistor ones, either. MOS-FET's have their own sound, they're not thermionic valves and they don't sound it, hey what a surprise...
That said, if you like your Sony, it's probably a bit rare, don't blow the outputs or it's a museum piece...just enjoy it whilst you still can, perhaps one day GENTLY & CAREFULLY replace all the electrolytic condensers in it to extend its lifespan another 20 years or so...
Cheers!