Re: JJ 6L6GC vs. Philips 6L6WGB comparision

["Bob Maglinte" <bbqbob917@xxxxxxxxxxx>]

- ----- Original Message ----- 
From: "The Bernadettes" <mdestefano@xxxxxxxx>
To: "Harp-l" <harp-l@xxxxxxxxxx>
Sent: Thursday, November 06, 2003 7:43 PM
Subject: JJ 6L6GC vs. Philips 6L6WGB comparision


>
> Having experimented with swapping out both JJ 6L6GC and Philips 6L6WGB's,
let me
> share my experiences.  First the Philips is a less powerful tube, it's
> dissipation rating is 23 watts, the JJ 6L6GC is 30 watts.  The Philips
will
> break up a little quicker and have a slightlier midrangier tone.  The JJ's
tend
> to be cleaner sounding and have a wider frequency response, more punchier
bottom
> end.  As far as durability, the JJ's are every bit as durable if not more
so
> than the Philips.  6L6WGB tubes are less tolerant of high plate voltages
than
> the 6L6GC's.  I had a pair of Philips 6L6WGB's in my SF Super Reverb which
has
> very high plate voltages and they lasted only about 6 months before they
started
> to sound real crappy and losing power.  The JJ's have been in there for a
year
> and a half and they still work great.  I wouldn't use 6L6WGB tubes in an
amp
> that runs over 450 volts on the plates, 6L6GC's can handle well over 500
volts.
> If you have lower plate voltages on your amp the 6L6WGB's are fine and
will
> last.  I have a pair in my BF Vibrolux Reverb (which puts around 415 volts
on
> the plates) they sound and work great.  I've heard people recommending
that
> people use the WGB's in amps such as the RI Bassman and Super Reverbs,
they'll
> work but not last, especially if you're also running high effiency
rectifier
> such as a solid state or 5AR4-GZ34 tube rectifier which will cause your
amp to
> run at higher voltages.  If you want to use Philips 6L6WGBs in a RI
Bassman or
> Super, you should also use a less efficient rectifier such as a 5R4 or 5U4
to
> lower the plate voltages...and make sure you get the power tubes biased
> correctly.  I should note that the famous Tung Sol 5881's are pretty
similar to
> the Philips 6L6WGB's in that they're not tolerant of high plate voltages,
I know
> people use them in RI Bassmans hoping to get the sound of the vintage
Bassmans,
> but I wouldn't risk it, not with NOS Tung Sols going for $150 a
pair...gotta
> remember the reissue Bassmans run at much higher voltages than the
originals.
>
> Don D.

Hi Don,
This is a really good, helpful, informative post here. It is kind of a
primer on why rebiasing an amp for tubes OTHER than the preamp tubes is so
IMPORTANT!!!! For the reissue Bassmans right on your post is the exact
reason why rebiasing is important, and when I read a copy of an earlier
edition of the owner's manual for the reissue, it only says you can change
the tubes, but NEVER mentions that the amp will need to be properly
rebiased, thus leaving people with the mistaken impression that just
changing power and rectifier tubes doesn't require the amp to be properly
rebiased for these tubes. On any tube amp, rebiasing is important, and
again, the only tubes not needing rebiasing are preamp tubes.

Sincerely,
Barbeque Bob Maglinte
Boston, MA
http://www.barbequebob.com