> JA>         3. Do the "tube covers" (look like little tube sweaters)
 > JA>            actually increase tube life?
 > The consensus is that they do not. But they do provide some damping of the 
 > tube body. Helps lower the noise floor. Tubes are terribly sensitive to 
 > vibration.
 > JA>         4. What things are tube amps/pre-amps sensitive to/about
 > JA>            that might cause them NOT to play at their optimum?
 > They are sensitive to impedance mismatching, bad physical placement 
 > (noise), AC power noise and AC polarity. The reason they are sensitive to 
 > AC noise is because they STEP UP the AC instead of stepping it down. For 
 > instance, at 120VAC, all you get is a 370 volt sine wave. The jolida needs 
 > about a 600 volt sine wave to rectify down to about 550 VDC. Thus the 
noise 
 > sensitivity.
 > JA>         5. Are tube units more or less sensitive to vibration and
 > JA>            should extraordinary effort be put into their isolation?
 > YES!!  Turn up a tube amp (listening via the headphone socket for maximum 
 > protection and effect) and listen to the noise as you gently tap the tubes 
 > with a fingernail.
   It would seem that tube preamps, amps and integrated amps are the ideal 
front end for tweeks. I can see now where it would be very tempting to try 
the 
different methods of isolation of the units and the addition of premium 
quality AC cable, hospital grade AC wall outlets with ground run all the way 
back to the box, vibration damped shelving, well insulated "patch" cables, 
and 
on and on. It sounds like fun to me. With all electronic front ends those 
things help, but not to the degree I would suppose they do tube units.
   I can see now where very sensitive speakers don't actually translate to 
ideal speakers for tubes. I have some ancient ARs that will probably sound 
quite good with the tubes rather than full range towers.
   My idea for tubes was for something to play my more relaxing music on and 
not raise the roof with. Once you have your electronic equipment set up and 
dialed in just the way you want it, there isn't much to do with it but 
listen. 
The tinkering with the different tube units is very appealing for those among 
us that like to experiment and try new things.
   I now have such a horrible listening area that we are actively looking for 
another house that has "THE" ideal room for my gear. SOmething about 15 x 20 
with a cathedral ceiling, walls where they should be, and not part of a major 
route through the house. If I had to design a room least suited to good sound 
it would be my present livingroom. I have been looking for ways to keep the 
level/quality of music where it is, while improving the imaging for home 
theater applications. It just has not worked out. Everything I do to improve 
imaging for home theater degrades my music set up. Longer cables, moving 
speakers, chnaging primary reflections...on and on. So I thought about 
running 
two seperate units if it wouldn't cost too much more. Prices for entry level 
seem very reasonable, DIY and other instructive books and tapes seem 
plentiful,
 and it seems to be extremely popular. 
   I am putting off deciding or I should say buying, until we move over the 
next couple months. My wife cannot believe we are moving to find a better 
room 
for my stereo gear.
   Thanks for your information. Tubes sound like a real hoot and great past 
time for someone who like myself who tinkers and is accustomed to the small 
explosions and fires that sometimes result. 8-)
Cheers, John
grump@netzone.com
--- AdeptXBBS v1.07g (Registered)
---------------