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Tube & trim locations – Manley VOXBOX - MVBXA 4/2003 User Manual

Page 19

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L

LINE

IN

E

PRE

OUT

M

TUBE & TRIM LOCATIONS

INSERT

IN

E

E

EQ

OUT

M

EQ IN SELECT & MUTING

6414

6414

Low noise graded

12AX7 / ECC83

OPTOS

MIC

IN

MULTICAP OP

COUPLING

METER GR ZERO SET

3

METER DS GR CAL

12AX7 / ECC83

OPTOS

7

6 DS / LIM CAL

SUPER YELLOW LED LIGHTS

(remove 2 small phillips screws on

meter back to access)

D1 ON = No mute

D2 ON = Shorter mute time
D1,D2 OFF = Factory default

mute timer ON

ON

D1 D2

Power turn on delay

MULTICAP OP

COUPLING

1

EQ = UNITY

GAIN

GND

METER COMP GR CAL

COMP AUDIO CAL

VU METER = +4.0 dB

12V FILAMENT

REGULATOR

5

4

2

POWER

TRANSFORMER

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:

12AX7

MIC PRE GAIN STAGE; very low noise tube; a good quiet, ECC83 may
work but expect more noise & microphonics and uncalibrated gain.

12AX7

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 20. The technician will need these pages.

DIP SWITCHES: D1 if on, bypasses the turn-on delay. May be desired for live gigs or mobile record-

ing. 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 trans-
formers to XLRs.

19

EQ CAPS AND

INDUCTORS

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