May 25, 2012
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Sylvania 6CG7
In keeping with the recent green ink theme, I switched out the white label GE 6CG7’s in the Premier 11A for Sylvania 6CG7’s. These are 1958 vintage tubes, with triple mica grey plates and D-shaped top getters. The tubes were purchased approximately eight years ago from Jim McShane and have seen considerable use in the past. At the moment I have not seen them for sale, anywhere.
The 11A amplifier runs its output tubes in a push-pull configuration and its output stage is described as ultralinear. The amp uses the 6CG7’s as phase inverter/output drivers. These are the original, 6CG7 version of the tube with a central electrostatic shield that is said to reduce noise between the plates. The 11A does not ground pin 9, however, so the tube operates essentially as a 6FQ7, which lacks the electrostatic shield. The 11A, in fact, has “6FQ7” as the tube identifier for these two tube positions.
Sylvania 6CG7's on the batting in which they were wrapped With original box
Central electrostatic shield Close-up showing D-getter
Box with tube wrapped in batting
Listening Impressions:
- Deep bass response. Drums are taut and resonant.
- Percussive sounds such as wooden blocks are less realistic than the GE 6CG7’s, but not a day and night difference.
- Very good timbre and decay.
- Nicely extended treble with sharp leading edges.
- Larger image size with a more diffuse sound stage than the GE’s.
All in all, these are very nice sounding tubes that I could easily live with. However, I do prefer the GE 6CG7’s in the system’s current tube and equipment configuration.
Comments (2)
Anaheim, CA? That's the first I've ever seen a California city listed on an original tube box. What does the bottom line ("if signed after April 19") say?
@rpghero27 -
I've included a 5th photo showing the tubed wrapped as it came and the other box where it reads more clearly:
If stored after April 1961
Re-inspect before issue.
The Hallamore Electronics Co. was involved with, among other things, strategic launch systems for the Minuteman missile. I guess they felt that if the tube had been in storage for more than three years, then it should be checked out before being used.
You wouldn't want to hit the wrong target.