Please note: you may find that some pre amp tubes, whether newly manufactured, used, or even
n o s , may be too "micro honic" for the first gain stage (V1) of a Komet amplifier A
microphonic preamp tube is a condition in which a tube will absorb mechanical vibration and
amplify it into the audible range In this scenario, a tube can "feed back", or give off a loud, high
pitched squealing noise Feed back can occur intermittently, even without an instrument plugged
into the input of the amp This does not mean that the tube(s) are completely unusable One
possible solution you can experiment with is moving the microphonic tube to the V3 phase
inverter socket where microphonics are not as noticeable The microphonic 12AX7 may be
quieter in the V3 position as opposed to the V1 or V2 position
Please note: a small amount of "hiss" is normal for high gain amplifiers An excessive amount
of hiss, especially when the volume control of the amplifier is all the way down and with no
instrument plugged in the amplifier’s input, usually denotes a bad pre amp tube Some n o s
audio tube suppliers offer "select", or hand picked pre amp tubes, which are superior in all
aspects of quality, especially when it comes to being quiet and non-microphonic
Please note: your amplifier produces heat Prolonged gigs, outdoor or non-climate controlled
venues, only multiply that factor We suggest (after extended periods of play) that you allow for a
sufficient amount of time to pass so as to let your amplifier cool down prior to moving or
loading This action will help protect and extend the lifespan of the audio tubes and internal
components from excessive vibration or damage
Caution: please pay close attention when extracting and installing the power and pre amp tubes
The pins of the tube - must align perfectly - into the tube’s socket Bent pins, especially when
forced into a tube socket, will cause serious damage to an amplifier’s tube socket pin inserts
99% of the time this results with the tube socket needing to be replaced To avoid this
contingency, we recommend that you purchase a miniature pinned, nine hole, pre amp tube pin
straightener These can be found online from many vintage tube retailers This easy to use device
guarantees that your 12AX7 pre amp tube power tube pins will be straight and aligned for socket
insertion Note: Komet Amplification’s warranty will not cover damage done to a tube socket’s
insertion pins from forced or accidental mis-alignment / and or bent / crimped insertion pins
TUBE REPLACEMENT
A noticeable deterioration in your amplifier’s overall sound is an indication of an imminent tube
replacement You may notice symptoms such as "muddy" or "saggy" power chords, a loss of
tightness or "unch", a weak sounding treble and bass, and loss of certain sonic frequencies or
note "bloom" We suggest that you first start by replacing your KT88 power tubes We suggest
that you purchase your KT88s from a reputable dealer that matches and selects each power tube
for plate voltage and plate current
The pre amp tubes can last a very long time, and do not necessarily need to be replaced as often
as the power tubes However, we do recommend that you have them properly tested by a
technician between servicing
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