[Boatanchors] Yet another tube question

[Bob Young]

I'm a musician, a bass player to be exact and I use 300 WRMS Ampeg SVT's 
with 6 6550's, 3 in parallel on each side. I didn't buy matched tubes the 
last time although I agree they are clearer sounding, I like a little grit 
in my sound. Also matched tubes for a guitar player not only gives him more 
power it also makes the distortion that most guitar players use a little 
more uniform and clean (is not a contradiction, really). Audiophool for me 
starts when an audiophile feels that he "hears" a difference between #14 
lamp cord speaker cable and some "magic" cable for 100 bucks with gold 
plated connectors. I've used matched tubes in my audio stereo amps though 
and have used matched sets in my SVT, just can't justify the added expense 
for them when I'm playing rock n roll loudly and can't hear the difference 
anyway. I do buy good tubes though and next time probably will buy matched 
sextets of them, Svetlana makes good tubes for Russian, last a long time and 
sound good,

Bob young
Millbury, Ma
KB1OKL
>
>Message: 2
>Date: Mon, 5 Feb 2007 19:20:23 +1100
>From: "Brian A Clarke" <brianclarke01 at optusnet.com.au>
>Subject: Re: [Boatanchors] Yet another tube question
>To: <boatanchors at mailman.qth.net>
>Message-ID: <012f01c748fe$7c19b0e0$0202a8c0 at Belkin>
>Content-Type: text/plain;	charset="iso-8859-1"
>
>Just a moment fellas,
>
>Selecting tubes for RF PAs doesn't need to be too accurate. What you need 
>to
>bear in mind is that if you have a set designed to deliver 400 W from two
>tubes in parallel, and one of those tubes is a bit low in performance, and
>the operator tries to get the full bottle, then the life of both tubes will
>be shortened because of the excessive temperature rise. Balance within 20%
>is probably close enough.
>
>In audio applications, there is a very good reason for balancing tubes'
>emissions much more accurately, and that is that if there is an imbalance,
>then the secondary of the output transformer will be passing some net DC
>that will go towards magnetising the core and thus reducing the inductance.
>This will change the shape of the hysteresis curve and have two effects -
>distortion on high powered peaks that wasn't there before, and loss of
>bass - the OPT needs inductance in order to have enough reactance at the
>lower frequencies. For stage musicians, balancing the output tubes allows
>more power output before distortion sets in - very handy. Most musically
>inclined folks can hear these effects quite easily - dubbing them
>'audiofools' is a sign of ignorance.
>
>73 de Brian, VK2GCE.
>
>
>