TT eXtended Matching
TT Tone-Selection
TT Standard Matching
TT V1-Selection
TT Audio-Selection
TT Balanced
Tube-Town eXtended Matching
TT eXtended matching is an optimized test and matching
system for powertubes. The system is standardized and computer-controlled,
and avoids common problems which normally arise when testing
and matching tubes.
Power tubes are often tested and matched under one or more
unrealistic conditions; for example, low plate voltage,
low current, strapped triode mode, or an unregulated measuring
voltage.
Tubes normally are operated under very high voltage, often
close to their operating limits, often far higher than that
which can be supplied by test devices. As a result, the
tubes are tested at an insufficient voltage or low power,
leading to inaccurate results.
The testing instruments may also use unregulated measurement
voltages, another potential source of error.
More sophisticated testing devices may avoid these pitfalls
and test extensively, but at great expense. Note that there
are also producers and suppliers who claim to test up to
140 parameters without specifying what those parameters
are or how they are tested. Often these claims are little
more than a marketing device to justify horrendous and unrealistic
prices.
Our test methods
Our measurement method avoids the inadequacies of most
tube testing equipment, while at the same time avoiding
drastic cost increases. We measure and test the tubes at
voltages equal to or greater than those found in real-world
equipment. EL34 and 6L6 tubes are tested at 450 volts on
the plates; most of the common amplifiers using these tubes
run between 420 and 430 volts.
By testing the tubes under realistic conditions, the real
behavior of the tube is measured, and this data is the basis
for the matching.
We measure several other parameters which are important
for rating the tube. Screen grid current is normally of
secondary interest in matching tubes, but if it is too high,
problems can arise. As such, we reject any tube which draws
too much screen current. Cathode current leakage and the
residual gas in the tube are also measured. These values
are indicators of the quality and reliability of the tube.
Any tube which measures unusually high values for one of
these parameters is rejected.
The entire measurement and test procedure is computer controlled.
Because the process is standardized and fully automated
it may be performed reliably, repetitively, and economically.
What we do not or cannot test
We can't measure the life expectancy of a tube! Tubes are
subject to wear and tear and must at some point be replaced.
Although many factors determine the lifespan of a tube,
the most important factor is the operating load. Overloading
or otherwise abusing a tube will shorten its life significantly.
And no series of tests, no matter how complex, can completely
exclude the possibility that a tube will fail prematurely.
However, with our special measurement and test process,
most of the suspect tubes can be detected and rejected.
Our testing procedure results in a rejection rate which
is 5% - 10% higher (depending on tube type and manufacturer)
in comparison to other methods, a result which highlights
the quality and reliability of our methods.
We can't test the environment in which a tube will be used.
The often very high tolerance of some components used in
the construction of an amplifier directly affects the lifespan
of a tube. An asymmetrically wound output transformer; highly
fluctuating mains voltage; as well as variations in
the screen resistors can all reduce tube life.
Our testing environment with its regulated voltages represents
an ideal environment which is not present in any real-world
amplifier, but experience shows that tubes tested successfully
in this environment will
continue to perform reliably when used in those real-world
amplifiers -- as long as they are correctly installed and
the amplifier is not defective in some way.
Our warranty:
Although a tube is a part which has a limited lifespan,
and which wears out and must periodically be replaced, our
measurement and test ensures a high level of quality and
reliability. For this reason, all tubes which have been
tested with TT eXtended Matching are guaranteed 12 months
against premature failure and aging. Abuse, inappropriate
use, and filament burnout are explicitly excluded from this
warranty.
Tube-Town Tone-Selection
Tubes from the Tone Selection are multiply matched and
selected tubes which are intended for the following uses
and amplifiers:
1. Amps without adjustable bias (non-adjustable bias) such
as Mesa amps. Because the bias is fixed at a specific voltage,
and no adjustment of the sound is possible, tone tuning
can only be achieved by use of tube sets defined by required
current. As such, a „softer“ set consumes less
current, whereas a „harder“ set consumes more
current.
2. Amps whose bias is set for a particular selection grade,
and in which no bias adjustment is desired when swapping
tubes. (Nevertheless, we always recommend – as far
as possible – that the bias be checked and set when
replacing tubes).
3. Amps in which the bias range is limited; for example,
Marshall and similar amps. It could happen, depending on
the tubes, that the range of the bias pot is insufficiently
wide so as to permit correctly setting the bias. In such
amps we recommend the use of a „standard“ set,
which normally can be used without a problem.
4. Users who wish to extract the maximum performance from
the tubes. In this case, ‘hard’ or ‘extreme’
sets are recommended. These tubes measure 30% - 50% over
the ‘standard’ sets.
Classification
The classification is performed under conditions of constant
bias, anode, and screen voltage. A change in the bias voltage
would shift the definition accordingly.
Soft: a tube set with soft tone and gentle
attack, without a particularly high output. Useful for low-gain
amps or to attain a slight output reduction. Also good to
warm up a harsh, cold output stage.
Standard: A set with this classification can be used in
any amp designed for the tube type without problems. A balanced
tonal spectrum will be produced, which provides a clean
fundament for diverse uses. Recommended for all guitar and
bass amps.
Hard: these tube sets will consume more
current, sound harder and more sharply defined, but also
slightly ‘analytic.’ Depending on the amp, they
can sound cool. Interesting for audio/hi-end applications
where clear reproduction is required; as well as in modern
hi-gain amps.
Extreme: Tubes in this classification
are rare, and have a very high current consumption and transconductance,
far beyond that of the standard tubes. These tubes are used
in applications where the absolute maximum performance is
required. The tone is very clear, defined, and highly dynamic.
Application examples:
A Peavey 5150 is shipped with a cold bias voltage. A set
of ‘hard’ or ‘extreme’ tubes results
in a higher current flow; which in turn will produce a harder,
sharply defined tone, with excellent dynamics.
Tonal differences:
It is difficult to describe and measure the tonal differences
in any real-world application, as these differences are
dependent upon many factors. Basically, any amp which is
designed for a relatively neutral tone, and which uses high-quality
components – especially the output transformer –
and which is also powering a neutral and well matched speaker
cabinet, will show a greater change than amps built from
inferior parts and circuitry, or with a poorly dimensioned
output transformer or a poorly matched speaker cabinet.
Tube-Town Standard Matching
Most of the powertubes we offer are matched by us. The tubes
are matched based on the plate current (and Transcundaction
if nessesarry). To get the best result we messure the plate
current a tube draws at ca. 400 Volt plate voltage. All
tubes not machted by us are matched by the manufactor and
check by us. We match the tubes within 5% - which means
that the tubes won't differ from each other by more than
5% plate current
Preamptubes
We offer some of the preamp tubes as “Selected Versions"
for special purpose:
V1-Selection
These tubes are selected for use in the first gain stage
of guitar amps. These tubes are tested for gain, mikrophonics
and low noise and highly recommended for any "HiGain"
amp.
Audio-Selection
These tubes are tested like the V1-tubes except that the
noise of the tube must be much less than with the V1-Selection.
These tubes are recommended for audio/highend-Applications
and studio amps
Balanced Selection
So called “Blanced” tubes are selected for
use in phasesplitters and driversections of a tubeamp.
In addition to the “Audio”-Selection these tubes
are also tested for symmetry – this means that both
triode systems of the tube do have the similar electrical
properties; they are balanced.
These tubes are recommended also for use in headphone amps
and studioequipment
