Koch Supernova - Manual (Page 7)

All four FX loops (S1, S2, P1, P2) can be switched ON/OFF with the switches [29-32] at the
front panel.
The serial loops S1 and S2 are relay bypassed when switched OFF.
The parallel loop P1 is relay muted on the FROM FX (return) jack when switched OFF.
The parallel loop P2 is relay muted on the TO FX (send) jack when switched OFF, thus
enabling delay effect signals to fully fade out.
NOTE: The effect loops operate on a -10dBV signal level which guarantees compatibility with
both instrument-level effects like floor-pedals and guitar-processors, as well as line-level
effects like professional 19 inch rack mount devices.
NOTE: If connecting an effects unit to the SUPERNOVA causes hum, a ground-loop
may cause it.
[19, 20, 21] SPEAKER OUTPUT JACKS: Provided for connection of speaker(s) or speaker
cabinet(s) with an impedance of 1x4/2x8 ohms, OR 1x8/2x16 ohms, OR 1x16 ohms. (see also
CONNECTION DIAGRAM page)
WARNING: Never play the SUPERNOVA without a speaker connected. This may cause
serious damage to either the power tubes and/or the output transformer.
Always use speaker cable.
[22] STEREO/MONO SWITCH (Model 6060 only): Provided for switching the R(ight)
Channel ON (STEREO) or OFF (MONO). In the OFF position the R(ight) Channel speaker
outputs do not have to be connected to a speaker cabinet or a Loadbox.
POWER TUBE OPTIONS
Each type of power tube has its own distinctive sound character, therefore changing to a
different type (or mix of types) of power tubes will also change the SUPERNOVA’s overall
sound.
Due to special bias control circuitry, the SUPERNOVA is able to accept almost any type of
power tube, for example: EL34, 6CA7, 6L6, 6550, KT66, KT77, KT88, KT90 and KT100.
The SUPERNOVA is provided with two separate bias control trimmers (located inside on the
PC board)
6060 STEREO VERSIONS
One trimmer is for the two left power tubes and one for the two right power tubes, therefore
either one quartet (=4 matched tubes) or two duets (= 2 matched tubes) of power tubes can
be used. Also different types of tubes can be used for each side, for example the two left
tubes may be EL34’s while the two right tubes are 6L6’s or 6550’s.
120 MONO VERSIONS
One trimmer is for all four power tubes, a quartet (=4 matched tubes) of power tubes must be
used. Also different types of tubes can be used, for example 6L6, KT66, KT88 or 6550’s.
REPLACING TUBES

SAFETY FIRST: DISCONNECT THE POWER CORD FROM ITS POWER SOURCE
AND LET HOT TUBES COOL.

CHECK THE ‘TUBE LOCATION DIAGRAM’ ON THE CHASSIS FOR THE CORRECT
TYPE NUMBERS AND LOCATIONS.

REPLACE TUBES ONLY WITH ORIGINAL KOCH HIGH QUALITY TUBES. [IF OTHER
TUBES ARE USED THE WARRANTEE OBLIGATION EXPIRES]
NOTE: Always have the amp rebiased after replacing the power tubes. Biasing instructions
can be found inside the amp. Rebiasing the amp is not necessary only if KOCH power tubes
are used with the same type and bias-class number.
If you have any doubts, please take no risks and let a qualified technician do the job.
Preamp and Power tubes wear out and have to be changed from time to time to maintain the
SUPERNOVA's best performance. Tubes behave like strings, they lose highs, lows and
dynamics and after a period of time they have to be replaced. Exactly when is hard to say but
this is an indication: if you play almost every day change tubes each year, if you play once or
twice a week change tubes every 2-3 years.
Tubes rarely fail. If they are bad, these might be the symptoms:
PREAMP TUBES (ECC83, 12AX7, 7025):
- Microphonic whistling or squealing on one or both channels.
- No or low amp volume on one or more channels.
- Excessive noise on one or more channels.
POWER TUBES (EL34, 6550):
- Loud crackling that is not affected by front panel controls.
- Intermittent or regular blowing fuses.
- Weird amp ‘distorting’.
- Hum.
Changing a tube is a simple and quick fix for most problems in your amp.
In case of failure, just one bad power tube can be replaced without re-biasing only if a KOCH
tube with the same type and bias-class number is used.
If power tubes with a different or unknown bias-class number are used for replacement, the
two inner and/or the two outer tubes have to be replaced and the amp has to be rebiased.
Always use a set of four (one quartet), or two sets of two (two duets) matched
replacement power tube sets to maintain the amp's best performance.
Again, if you have any doubts, please take no risks and consult your dealer and/or
a qualified technician.
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