Owner`s manual

METER DS GR CAL
VU METER = +4.0 dB
EQ = UNITY GAIN
METER GR ZERO SET
LINE
IN
INSERT
IN
PRE
OUT
EQ
OUT
POWER
TRANSFORMER
12V FILAMENT
REGULATOR
+15V & -15V
REGULATORS
MIC
IN
EQ CAPS AND
INDUCTORS
COMP AUDIO CAL
3
1
7
6
EQ IN SELECT & MUTING
E
M
M
EE
L
GND
OPTOS
DS / LIM CAL
5
4
2
ON
D2D1
D1 ON = No mute
METER COMP GR CAL
D1,D2 OFF = Factory default
mute timer ON
D2 ON = Shorter mute time
Power turn on delay
OPTOS
MULTICAP
OP COUPLING
MULTICAP
OP COUPLING
6414 / 12BH7
6414 / 12BH7
12AX7 / ECC83
Low noise graded
12AX7 / ECC83
SUPER YELLOW LED LIGHTS
(remove 2 small phillips screws on
meter back to access)
TUBE & TRIM LOCATIONS
18
TUBES: We use 4 tubes in the VOXBOX. The substitutions listed just might work in a pinch but may not
give optimum performance. Get selected tubes from Manley Labs. A tube that does not glow or
has turned white inside needs to be replaced. A tube that makes too much audio noise when tapped
(microphonic) or is causing increased hiss should be replaced. The life of these tubes averages
more than 5 years but individual tubes cannot be predicted and may work 3 weeks or 30 years.
Let the tubes cool before handling to prevent burns. The list is:
12AX7EH MIC PRE GAIN STAGE, very low noise tube, a good quiet, 12AX7WA or
ECC83 may work but expect more noise & microphonics and uncalibrated
gain.
12AX7EH EQ GAIN STAGE,bettter 5751, ECC83 or12AU7WA may work OK
6414 LINE DRIVER, high current, 12BH7A may work OK but are hard to find now,
12AT7A is the next best choice but does not have as much "poke".
TRIMS: Each VOXBOX has been factory calibrated and tested at least four times. These trims should not
be re-adjusted unless absolutely needed and should only be done by a qualified technician. The
function of each trim is labeled on the diagram above each trimmer and the order is below. The
complete procedure is on page 19. The technician will need these pages.
DIP SWITCHES: D1 if on, bypasses the turn-on delay. May be desired for live gigs or mobile recording.
D2 if on, shortens the turn on delay. If the unbalanced outputs are not used, then this setting will
be OK. There is only a small and "quick" thump that gets through the transformers to XLRs.