matched preamp tube
Preamp tubes 12AX7, 12AT7 and 5751
are dual triodes in which the A and B sides are closely matched for use
the phase inverter or driver position of musical instrument amplifiers.
A single 12AX7/12AT7/12AY7/12AU7/5751 contains TWO circuits within the tube. These tubes are tested to find the INDIVIDUAL SINGLE TUBES in which these two circuits are MATCHED - 1 tube contains two circuits.
We are matching 12AT7,
12AX7, 12AU7, the " 5751 Tone
secret tube" and the "Blues Cool" 12AY7.
We found our suppliers could not provide us with enough high quality
Matched Preamp Tubes so we designed and built our own Tube
accurate to .00002A measurement - super accurate.
Now we can provide super accurate "Torres Matched" high
quality preamp tubes all the time.
The benefit of this tube in a guitar or bass amplifier is having a
matched power tube output section. Equal drive to both sides of the
With a matched triode the upper and lower portions of the output
waveform will be much more equal.
When this waveform is not equal, differences are cancelled out in the
feedback loop of class A/B amplifiers and are noticed as a lack of
sustain or apparent "dead spots" in areas of the fret board.
At high levels at all frequencies, sustain will be improved. The
"grainy" nature that is often present with a regular tube disappears
too. You will hear it right away!
This is even more critical in Class A amplifiers such as the Torres
Class A Models, Vox AC-30's, Matchless and other Class A amplifiers.
Improvements are heard in both Class A and Class AB amps.
Use the Torres
Matched tubes in any application where a phase
inverter / driver of the ECC81/12AT7 or ECC83/12AX7 tube is specified.
The phase inverter / driver position of a guitar or bass amp is a
current driving position, and not part of the tone generation stage.
Use of a
"Torres Matched" 12AT7
in place of a 12AX7 will give you more clean headroom in
your output section. Using a "Torres Matched 12AY7"
will have still more headroom and a sweet bluesy tone.
Using the "Torres Matched" 12AX7
will give you the highest gain from the driver/phase inverter of your
amp. It can be used in place of a 12AT7 for an INCREASE IN GAIN at the
cost of some extra distortion.
Using a "Torres Matched" 5751
in place of a 12AX7 will also give more clean headroom, but has a bit
lower gain for a warm, rich tone.
Replace a 12AT7 with a
Matched" 5751 for more drive and warmth or a "Torres Matched 12AY7"
for a sweeter tone.
The tube types are interchangable without any
adjustment required, so feel free to experiment!
It has long since been a great improvement to use matched preamp tubes
in all positions in HiFi/stereo preamps for a very balanced tone.
They are a very noticeable improvement in tone in your amp!!
Gain comparison chart:
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