How we get
that Groove Tubes sound:
Guitarists both yesterday
and today can be linked by one piece of equipment: The tube
amp. With all the strides in transistor amp technology, guitarists
still prefer tube amps. Why do tube amp designs sound and
feel differently from solid-state? Simply, tubes work differently.
is a tube? A
tube is an electronic device consisting of a minimum of four
active elements: a heater (filament), a cathode, a grid and
a plate. All sealed in a vacuum glass enclosure to prevent
parts from burning. Once heated, the cathode begins to emit
electrons, which flow from the cathode (which is negatively
charged) toward the plate (which is positively charged). The
grid's purpose is to control this flow, in effect, acting
as a valve.
do Tubes Work? When
the guitar's pickup produces a small voltage (the result of
the string vibrating in the pickup's magnetic field), this
signal is applied to the grid, which causes a large current
flow from the cathode to the plate.
Because of this, a correspondingly
large voltage now appears at the plate. A portion of the amp's
electronic circuitry, the grid bias control, adjusts the proper
voltage setting of the grid. When the grid bias is properly
set, the tube is balanced to the circuit, and therefore produces
a clean, powerful signal. The plate is connected to an output
transformer, which matches the impedance to that of the speaker.
do Tubes Distort? As
the signal emitting from the plate approaches its maximum
potential, the tube gradually begins to react less and less
to the original input signal. This results in a type of compression
of the signal, and the signal becomes cut off or "clipped."
Tube distortion ("clipping") occurs gradually, producing
low order distortion which compliments the original signal,
creating a warm sound. This is also why it's easy to move
between clean and distorted tones.
Groove Tubes Process:
and Selecting tubes.
We literally go through thousands
of tubes, rejecting more tubes than we accept. We put every
tube through a rigorous performance test, one at a time, in
real amp circuits. The preamp tubes are rejected for adverse
microphonics, low output or high noise. Power tubes are more
involved, and they go through additional analysis. Here's
what we're looking for:
- Grid Leakage. Causes tube
to burn out quickly, and worse yet, to short out and wreak
lots of havoc. We throw these tubes out.
- Weak Vacuum. Tube will
act deceptively normal, then just burn out on you (usually
at the worst time!). These tubes don't make it past the
- Gain to Distortion Ratio.
The center of all Groove Tube magic! This measurement tells
us if the tube will distort early or later in its power
range. Since the tube distortion is rich in harmonics (That's
why we love 'em!), the tonality of each tube will vary according
to this ratio. Only Groove Tubes sets have been measured
and matched to insure longer sustain, wider frequency response
and a more musical amplifier!
and Matching Tubes.
We translate this gain to
distortion ratio into a performance scale that can range up
to 100 points, then match up the tubes to within 1 point of
each other. To simplify things, we reduce the scale to 1-10
before the tubes leave our shop. All tubes are exactly matched
into duets, quartets, sextets and even octets.
than just Great Tone.
The Groove Tubes Process
produces many welcomed improvements:
- Dramatically Improved
Sustain by eliminating phase cancellation (which occurs
when dissimilar tones coming from unmatched tubes are combined
and cancel out certain frequencies.)
- Improved Harmonic Balance-
All the notes you play will have the same amplitude. (No
more dead spots or dull notes!)
Life Span by 1st) eliminating faulty tubes. 2nd) Our balanced
sets reduce stress that occurs when a stronger tube is working
too hard to make up for its weaker partner, and 3rd) because
our sets drive the output transformer evenly it actually
do Tube Amps all Sound Different?
- Types and quality of tubes
vary, some tubes amplify more than others.
- The amount of gain
a tube produces varies with the each amp's circuit design,
some tubes amplify more than others under similar conditions.
4 amp stages:
- Preamp Stage - Amplifies
an incoming guitar or mic signal for tone shaping.
- Signal Processing Stage
-This is where you add the effects, reverb, tone controls,
- Power Amp Stage -The real
workers in your amp. Most amps over 10 watts use an alternating
push/pull power amp design- when one tube is on, the other
is off. Your amp may have two, four, six or possibly eight
- Rectifier Stage -Converts
AC wall electricity to the DC electricity inside your amp.
Most modern amps have sold state rectifiers.
Should You Replace Your Tubes?
Glass, metal, lots of little
parts... tubes are subject to mechanical problems and are
not meant to last a lifetime. Actually, the harder you work
your tubes, the faster they wear out. Which means that from
time to time you will need to replace your tubes. More reasons
to replace your tubes:
- When one starts to go,
it drags the others down with it, decreasing the over all
efficiency of the amp.
- The better the tube, the
better the tone. Simply put, the best reason to replace
your tubes with Groove Tubes is that they'll make your amp
Pay attention to your amp's
performance. When you hear the sound begin to deteriorate,
it's time to change your tubes. Your amp will last longer.
Your tone will always be at its best. Think about it, you
don't wait until the strings break before you change them,
do you? Look for these signs that Your Tubes May be Deteriorating:
- Loss of highs or
lows, Muddy chords
- Poor balance in
the output of various notes
- Lacks punch, Makes
- Amp starts sounding
- Power fading up
- No sustain, or fast
long will Groove Tubes last?
Groove Tubes will last longer
than other tubes but they won't last forever. The usable life
of any tube will depend on how hard it's actually used in
the circuit. Some circuits will use tubes harder than others
and we all know some players are play harder and louder than
others. Power tubes can last years in a light duty situation
while lasting only six months in another. Preamp tubes will
generally last much longer than power tubes unless used in
the driver stage where they wear out as fast as the power
set they are driving.
The only thing certain is
that the performance of all tubes will wear down and out eventually.
So naturally we don't warranty them forever. We do warranty
them plenty long enough to expose any manufacturing faults
that would reduce the normal wear cycle.
Tubes. It all Comes Down to Tone.
When you go into a store
and buy other tubes, it's a crapshoot. Without The Groove
Tube Process, there's absolutely no way of predicting how
a tube will sound. When other tube suppliers claim to have
"matched" sets, they're referring to the meaningless
measurement of the tube's power. As we learned in the beginning,
it's a waste of time to measure power because you simply can't
hear variations of power (unlike variations in harmonic distortion).
And even if you could, the power measurement is always changing
as the tube wears (This measurement wouldn't stay "matched"
anyway, but ours do!). Buying Groove Tubes will save you money
and a great deal of aggravation, while turning you on to the
best tone you're ever heard coming out of your amp! Groove
Tubes are more expensive than most other tubes. Now you know
Tube-Tone Phenomenon. The next time you're experimenting with
your tone, and before you shell out more bucks on effects,
gadgets, guitars, another amp! ... check your amp head and
try out a new set of Groove Tubes.
Warranted to be free of
burn out, excessive noise or microphonics for
180 day from date of purchase.
Warranted to be free
of burn out for 90 days from date of purchase.
If one tube fails, the whole set will be replaced
to insure proper matching.
GT-Solid Rectifiers & Substi-tubes:
Warranted for 3 years
from date of purchase.