NOTE: This effects loop operates 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.
If connecting an effects unit to THE GREG causes
hum, a ground-loop may be the cause of it.
[9] COMBO SPEAKER OUTPUT:
For connecting the
internal speaker(s) of the Combo.
[10] EXTENSION SPEAKER OUTPUT:
For connecting an
8 ohms extension speaker cabinet to THE GREG. The
output impedance of the amp switches automatically to the
correct impedance of 4 ohms. (see also CONNECTION
DIAGRAM page)
WARNING: Never play THE GREG without a speaker
connected. This may cause serious damage to either
the power tubes and/or the output transformer.
AND ALWAYS USE SPEAKER CABLE.
[11] REC/PA OUTPUT:
This jack provides an unbalanced
mono output suitable for recording or PA. Its signal is
derived from the speaker output so the typical tube
saturation of the power amp is included; it also includes all
effect signals. This signal is at line level (-10 to 0 dBV) and
is shaped by a special filter that emulates the typical
recording characteristic of a microphone placed in front of
a guitar speaker.
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)
BEFORE REPLACING THE POWER TUBES,
REMOVE THE CE SAFETY CAP FIRST.
AFTER REPLACING THE POWER TUBES, PUT THE
CE SAFETY CAP BACK IN PLACE.
NOTE: Always have the amp rebiased after replacing the
power tubes.
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 GREG’s best
performance. Tubes behave like strings, they lose highs,
lows and dynamics and after a period of time they have to
be changed. 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 both channels.
- Excessive noise on one or both channels.
POWER TUBES (EL34):
- 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.
Please always use two matched EL34 (= one duet)
replacement tubes to obtain the amps best
performance.
Again, if you have any doubts, please take no risks
and consult your dealer and/or a qualified technician
