Re: Tubes for Hammonds & Leslies (and more)

[Ted Weber <tweber@gatem02.netusa1.net>]

>>For what it's worth, I recently bought several sets of matched 6550s and
6L6s, 
>>made by Groove Tubes.  They're available almost everywhere guitars can be 
>>found.  You can specify "hardness" - resistance to distortion.

>     I have several tube testers that measure transconductance as well as
>inter electrode shorts etc. I've never seen "hardness" listed as a tube
>parameter as mentioned. ????

Aspen Pittman (Groove Tubes) had an engineer design him a whiz-bang computer
controlled
tube tester that does some dynamic sweep tests on tubes for the purpose of
matching
them closely in pairs or quartets. While studying the dynamics of their
individual curves, it can be found that some generate more distortion than
others for a given input with comparable operating voltages. So, he called
this a 'hardness' factor and suggested some would be better for 'clean' such
as jazz and surf, while others would be more suited for rock and blues. It's
part credible, part marketing. I'll keep my opinions to myself, though. ((-:
You are correct, though. 'Hardness' was unheard of until Aspen came along.
I've heard alot of good things about GT tubes, though, I must admit.

                                                                     Ted