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Vacuum Tubes for Amps
6L6 Taste Tests
INTRODUCTION:
Well, here are the 6L6 Taste Test results. I tested 9 different sets of 6L6s
in a 1968 Fender Pro Reverb. Apart from some 6L6 tests that Gerald Weber did
in Vintage Guitar Magazine, I know of know other sound/taste tests for the
6L6-type tube. Although I have not read Weber's write-up, I have heard from a
number of sources that it was "rather sparse". Before we carry on any further,
let me confess that I am not a 6L6 type of guy. Rather, I favor smaller tubes
such as the EL84 and 6V6. In general, I did not get that excited about the
listening tests, perhaps because I admit to having an "untrained" ear with
respect to the 6L6.
The following list of gear is for "comparative" purposes only. This is NOT
meant to plug or praise certain manufacturers. The guitar was plugged straight
into the amp with a 20-foot Spectraflex cord. Volume and Tone knobs on the
guitar were set to full (10).
· 1968 Fender Pro Reverb loaded with EV-12L speakers. Although this Fender has
Silverface cosmetics, as far as I can tell, it came "Blackfaced" from the
factory. In addition to the "back-breaking" speakers, this Fender has had the
Negative Feedback and Vibrato circuits disconnected and there is a 12AX7A in
the Phase Inverter slot. The plate voltage in this amp is 460. I kept the
tone knobs as follows throughout the entire test: Bright=ON, Treble=8, Bass=5.
I used the #1 input and did not bridge the channels. Reverb was turned OFF.
· Heritage Les Paul copy with Seth Lover pickups strung with D'Aquisto nickel
round wound size .012-.052.
· Fender Stratocaster (American) with Fender Texas Special pickups strung with
D'Aquisto nickel round wound size .012-.052.
One thing to note about the pickups in these guitars: It seems to me that the
Texas specials are just as "hot" if not a bit hotter than the Seth Lovers. The
Seth Lovers are actually fairly low output and have lots of high end. Another
thing to note is that when the 6L6s were played distorted, a lot of the tube
seemed to exhibit a "Marshall" type sound. I attribute this to both the lack
of Negative Feedback and increased gain in the Phase Inverter section of the
amplifier.
Tubes tested were Groove Tubes 6V6HD (really, it's a 6L6), Sovtek 5881R,
AudioGlassic 6L6* (appear to be of Chinese origin), Ruby 6L6GC STR007,
PhilipsEGC 6L6, 6L6GC STR415, 6L6GCRC, Svetlana 6L6, and GE 6L6. Each duet was
evaluated with the volume knob at 2.5 (clean) and 10 (distorted. I played for
about 10 minutes on each 6L6 duet. Hot tubes were removed with leather gloves.
I kept my BiasProbe attached to one of the tube sockets and every time I
inserted a new pair of tubes, I adjusted the bias to 40mA.
To the best of my ability, I tried to do a "blind" Taste Test. The night
before the test (which occurred on 7/3/1999), I took all the duets out of their
cartons/boxes. I placed a rubber band around each set and placed the duet in a
box. I also assigned a random number (numbers "1" through "9" were written on
a Post-It "sticky", shuffled to randomize, and placed in the rubber band) to
each set of tubes. When all duets were banded and labeled, I put on a pair of
leather gloves and "shuffled" (careful and slow movement) the tubes within the
box so as to further randomize their test order. I sealed the box and went to
bed. The following day, I used the leather gloves each time drew from the box
when replacing tubes. Since I did not look into the box when selecting tubes,
the test order was random. After testing, the tubes were removed from the amp,
rubber banded, relabled (with the same random number), and placed in a separate
location. All-in-all, I did not know the manufacturer of the tube.
RAW DATA:
Groove Tubes 6V6HD:
Les Paul - When played clean the bass notes lacked definition, especially on
neck pickup (position #3), however chords in the upper register were
interesting and pleasing. Positions #1 (bridge) and #2 (bridge+neck) were
piercing and unmusical. Although fairly lifeless when played clean, they were
nice and "Marshally" in positions #1 and #2. The neck pickup, when distorted,
was muddy and useless.
Strat - When played clean, these tubes sounded fairly decent in positions #1
(bridge) and #2 (bridge+middle). Positions #3 (middle), #4 (middle+neck), and
#5 (neck) seemed lifeless. Overall, these tubes seemed to lack bass. When
fully distorted, position #1 was piercing and shrill. All other positions
seemed respectable, but still "Marshally", just like the humbuckers.
Sovtek 5881R:
Les Paul - Handled bass fairly well in all positions, but rather
two-dimensional. Not piercing, but nothing special; fairly even, but no
sweetness. When distorted, these tubes were not as loud as some others were.
Position #1 was decent and slightly "Marshally", but other positions were
splotchy where the bass was too "farty".
Strat - Very high-ended when clean, but not totally piercing. Seems to handle
bass well. The distorted sounds were actually not bad. Even though a tad
bright, it sounded fairly thick. Position #4 was the best.
AudioGlassic 6L6:
Les Paul - When played clean, these tubes exhibited nice highs, chime, and
stringy detail. Chords were nice and full. Chords on the neck pickup were
lacking in bass. When distorted, these tubes were very Marshall-like. All
pickup positions help up well in eveness and detail.
Strat - Toppy, but not piercing when played clean. These tubes seemed a bit
"wimpy" due to their lack of bass. All pickup combinations, while lacking
bass, seemed good. When overdriven, these tubes exhibited the "Marshall"
sound, and were very full, tight, and thick! Even though they were a bit
piercing, they reminded me of Richie Blackmore. Selection #3 was the best.
Ruby 6L6 STR007:
Les Paul - When played clean, these tubes were rather "generic" sounding.
However, they were very balanced - good highs, mids, and lows. Not piercing in
any way. When overdriven, they were very balanced and full. They did not fart
out at all. Position #1 just rocked.
Strat - Very nice all around when played clean. Seem very harmonically rich
with Strat - richer than other tubes in the competition. Did not fart out and
handled bass very well. When distorted, these tubes were muddy and splotchy.
Although excellent for cleaner Strat playing, these tubes did not like to be
distorted.
PhilipsEGC 6L6:
Les Paul - A bit "honky" and piercing on position #1 when played clean. Fairly
balance, but a bit to high-ended. Sounded best on positions #2 and #3.
Distortion was very full on #1, but totally splotchy on #2 and #3 - perhaps a
bit ratty.
Strat - When played clean in all positions these tubes were……WOW! Even though
they were a bit "toppy", they had incredible harmonic richness - very juicy!
When distorted, they were piercing on positions #1 and #2, but heavenly and
full on positions #3 through #5. These are Strat tubes - period!
6L6GC STR415:
Les Paul - When played clean, these tubes were very harmonically rich with very
even balance. All positions were good. Although they were very nice clean,
they were absolutely splotchy when distorted. All positions were terrible with
distortion.
Strat - Fairly balanced when clean. Very good in positions #2 and #4. Not
piercing and fairly rich. The distorted sounds were nothing to write home
about. Positions #2 and #4 were fairly nice and balanced. The other positions
were lacking.
6L6GCRC:
Les Paul - Fairly decent when played clean, but plain - not as 3-D as other
tubes. Very good in the #2 position. When distorted, these tubes were very
Marshall-like. Positions #1 and #2 were very full and tight. Not as
harmonically rich as other tubes when overdriven.
Strat - Position #2 was very chimey. These tubes had a nice full bass
response. Not piercing at all. When distorted, these tubes were great.
Position #2 was best, very full and fairly rich.
Svetlana 6L6:
Les Paul - Much richer than others when played clean. Seem to hold up well to
bass. Very full. The distortion setting was fairly nice, but not enticing.
Splotchy on the neck pickup.
Strat - Also very harmonically rich when played clean. Special note is that
they are very musical on position #1. Heck, they were also excellent in
positions #3 and #5, as well. Very full on bass and even. When distorted,
they were very harmonically rich. However, they did get a little splotchy on
the neck pickup.
GE 6L6:
Les Paul - Very nice and chimey in positions #1 and #2 when clean. These tubes
were very full and harmonically rich. When distorted, they were exceptionally
"Heavenly" and "throaty" on position #1, but got a tad splotchy on #2 and #3.
Strat - Very nice, chimey, and harmonically rich when clean. Although fairly
balanced, they were a bit shrill on position #1. Fuller than most tubes. Of
special note was position #2. These tubes were not that good when distorted.
Position #2 was not too bad, but other positions were piercing and also
"flabby".
CONCLUSIONS:
If rewards were given out on a scale from 1-100, I'd say the best tube(s) in
this Taste Test would start at about 85. That is, while some of the tubes
performed very well in most categories, they had a few "low" spots and flaws
that prevented them from getting a full score of 100. I'd like to split up the
final comments into four categories: "All-Around", Stratocaster Tubes, Les
Paul Tubes, and Losers.
Perhaps the best "all-around" 6L6 tube in this competition would be the GE 6L6.
The GE showed great (cleaner) Strat playing coupled with great clean and
distorted Les Paul playing. The next "all-around" runner-up would be the Ruby
STR007. To me, the Ruby seemed like a less-professional version of the GE.
The Ruby catered to decent Strat and Les Paul playability.
The Stratocaster guitar definitely preferred certain 6L6-types. The most
notable were the PhilipsEGC and Svetlana. Hands down, these were the best
tubes for clean and dirty Strat playing. Runners up included the GE, 6L6CRC,
and Ruby STR007, in order of preference. I should note that the runners up
didn't always play well in distorted settings - most were splotchy in certain
positions.
On the other hand, the Les Paul guitar definitely preferred certain 6L6-types.
The most notable was the GE. Runners up included the AudioGlassic 6L6, Ruby
STR007, and 6L6GC STR415, in order of preference. The AudioGlassic 6L6 was an
all around Les Paul winner, the STR007 seem better geared toward distorted
tones, and the STR415 was better suited for cleaner, jazz comping, voicings.
I'd hesitate in buying the Russian 5881 and 6V6HD. These tubes didn't seem to
offer any decent sound, whether clean or distorted. Of these, I preferred the
Sovtek 5881, but again, I'd purchase a different 6L6-type altogether.
Thanks for your attention,
Mook
*-Special thanks to Miles O'Neal for lending me the AudioGlassic 6L6s for the
Taste Test.
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