From bruce@ashbysolutions.com Wed Nov 07 16:39:52 2001
Subject:Re: Tubes

Ed,

>Bruce, or anybody else who knows about this stuff, can you tell me
>about the testing scales involved in rating a tube? A lot of NOS
>that's advertised on the internet will say it tests at '45/42 on a
>B&K 700' or '98/98 on a Sencore TC-162' or '80/95 on a TV-7'.

I believe that those are tube testers. I don't know what the scales
actually represent, however. If the tubes are dual-sided, that might
account for the two readings.

I should go on record as saying that I am clearly not a "tube hound". I
make it a habit to never pay more than about $15 for a preamp tube, or
about $40 for a power tube, no matter what its pedigree or references might
look like. My tube preferences are based more around the overall
characteristics of the tube design -- gain, frequency response, power
output -- than the more esoteric descriptions -- "warm", "open",
"glassy". This is not to say that there is no validity to the esoteric
ratings, but I'm not sure what they really mean. I also question whether
the use of all "warm" tubes in an amp, for example, will guarantee a warm
result; the various stages interact, plus a lot of the sound we equate with
tube amps comes from other parts -- transformers, rectifiers, and capacitors.

Regards,

-BW

--
Bruce Wahler
Design Consultant
Ashby Solutions™ www.ashbysolutions.com
CloneWheel Support Group and HiNote moderator
978.386.7389 voice 978.964.0547 fax
bruce@ashbysolutions.com