I have a quad set of EI KT90 on the way and am psyched! While I know a few of you guys are not enthused with the EI KT90, my Aronov sounds lush enough with the Svetlana, and going to KT88 would probably be overkill.

I pulled ou the tubes last night in preparation for the KT90 (hoping they would arrive today) and it was a trifle unnerving, since they would not budge! I had to pull so hard I thought the damn tube would implode in my hand! The fact that they are so close together only compounds the problem. Is there any trick to removing tubes?

 Re: What advantage do ceramic tube sockets offer? - Bryan F. 13:59:00 3/31/99 (0)
 Re: What advantage do ceramic tube sockets offer? - Joe 10:31:36 3/31/99 (1)
 Oops! thats should be from Joe S (nt) - Joe S 10:54:09 3/31/99 (0)

...

Show full thread outline!

 Re: What advantage do ceramic tube sockets offer? - Bryan F. 13:59:00 3/31/99 (0)
 Re: What advantage do ceramic tube sockets offer? - Joe 10:31:36 3/31/99 (1)
 Oops! thats should be from Joe S (nt) - Joe S 10:54:09 3/31/99 (0)
 Rocking them slightly, even when they are close... - Dave VH 09:09:12 3/31/99 (1)
 Thanks guys! (nt) - Q-bert 13:32:27 3/31/99 (0)

Dave VH

Well, that depends. NOS tubes in the 9 pind miniature family often have blackish / blue colored pins rather than the shiny silver polished ones of some current production tubes. Typically no amount of polishing can make them all that silvery. Does it effect sound quality? Most of the time probably not - but I have found some tubes where it does. Maybe 10 to 20% of the NOS tubes I buy in this family have enough gunk / oxidization that the tube will make a subtle intermittent contact when inserted in the socket that can seriosuly degrade noise performance and even make the tube sound just a touch grainy. I can easily detect & even measure this in my George Kaye Small Signal Tube Checker which has a mode which allows you to measure a tube's noise level and let you hear its noise spectra through a built in speaker or through a pair of headphones. I've found that the noise level of some tubes will drop by as much as 5 - 10 dB after polishing their pins (for those tubes so afflicted). I polish with MAS metal polish on an electric toothbrush (one of those cheap Bosch units with a single rotating tuft of bristles) for 30 seconds or so, followed by a quick buff with a soft shoe shine brush that can reach down among the pins without bending them and remove the residual polish & gunk. The tube pins are still a bit blackish blue, but they will be shiny after this and the noise problem goes away. Another impact is that tubes that have been cleaned like this seem to exhibit slightly more extended & cleaner highs....

Regarding ceramic sockets - Ive noticed that the 9 pin miniature variety seem to retain their grip on tube pins better than some of the cheaper sockets after frequent tube swaps....

Joe