DVO User Manual
User Manual
Instrukcja obsługi
Version 1.2
Dear Customer!
Thank you for choosing our product.
Dual Vintage Overdrive (G LAB DVO) is the overdrive type stomp box
effect with two overdriven channels (independent setting of gain, overdrive type
and volume), SOLO volume boosting function and CLEAN tone. DVO can work
as a stomp box connected between a guitar and an amp or as the pre-amp –
connected between a guitar and the power amp.
Basic characteristics:
- classical guitar tube pre-amp emulated by selected FET transistors,
- passive equalizer: TREBLE, MIDDLE, BASS with typical tube amp
- two overdriven channels (CH 1, CH 2) with gain control (GAIN),
boosting and characteristics settable by BOOST A and BOOST B
switches, volume control (VOLUME), enabling to perform from almost
clean tone, through crunch one up to full overdrive,
- SOLO function with adjustable +3 dB or +5 dB boost,
- four working modes of footswitches (set by DIP switches),
- clean tone with volume control (CLEAN),
- independent guitar electronic tuner output (TUNER) with MUTE
- PRE OUT output with buffered direct signal from a guitar,
- FOOT PEDAL input for controlling by the G LAB GSC controller or by
a footswitch,
- possibility working in the parallel mode with amp channels and
overdriven channels (CH 1 or CH 2 of DVO), connected directly to a
power amp (skipping pre-amp),
- TREBLE and BASS boost switches post overdriving,
- backlighted footswitches,
- 9V DC power supply.
1 - DIP switches
2 - CLEAN tone volume control
3 - SOLO boosting mode switch
4 - 1st and 2nd mode - SOLO mode indicator (full volume),
3rd mode – clean tone indicator (CLEAN),
4th mode – bypass mode indicator
5 - 9V DC power supply socket
6 - Amp output (OUT)
7 - + 3dB TREBLE boosting (post overdriving)
8 - TREBLE control (pre overdriving)
9 - MIDDLE control (pre overdriving)
10 - BASS control (pre overdriving)
11 - FOOT PEDAL input
12 - + 3dB BASS boosting (post overdriving)
13 - First channel (CH1) GAIN control
14 - TUNER output
15 - First channel (CH1) boost switch (BOOST A)
16 - First channel (CH1) indicator
17 - First channel (CH1) VOLUME control
18 - First channel (CH1) boost switch (BOOST B)
19 - Guitar direct signal output (PRE OUT)
20 - Second channel (CH2) GAIN control
21 - Second channel (CH2) boost switch (BOOST A)
22 - Second channel (CH2) indicator
23 - Guitar signal input (IN)
24 - Second channel (CH2) boost switch (BOOST B)
25 - Second channel (CH2) VOLUME control
26 - Right footswitch
27 - Central footswitch
28 - Left footswitch
Power supply
DVO should be supplied from external regulated 9V (from 8.7V up to
9.6V) DC power supply, with 80 mA output or more. Before connecting
please check if the connector’s polarisation is proper. DVO is protected
against opposite polarity and overvoltage.
Mode of working selection
In the below table are given footswitches functions in four modes of
working. Mode of working selection is done by No.1 and No.2 DIP switches
located on the left-hand side of the casing.
Left switch
Right switch
CH 1*
CH 2*
SOLO (CH 2 with full
CH 1*
CH 2*
SOLO (active channel
volume change from lowered
to full - or reverse)
DIP switch
CH 1
with full
CH 2
with full volume
CH 1
with full
CH 2
with full volume
* - with volume -3 dB or -5 dB set by SOLO switch
DIP switch lower position is ON.
Operations of particular modes of working are graphically presented in the
next page table.
Mode 1
Mode 2
Mode 3
Mode 4
Connecting to a guitar amp
The way of connecting DVO to a guitar amp, an amp type and an amp
controls adjustment affect to a high degree of the final tone effect.
Connecting to the amp guitar input
In such case it is recommended to switch on clean amp channel and to set
flat tone characteristics.
This way of DVO connecting makes that overdriven tone is highly
dependent on an amp tone setting.
Connecting to the amp effects loop input
When the amp is equipped with the serial effect loop (LOOP), it is
recommended to connect OUT output to RETURN effects loop input. In such
case the tone is depending only on amp PRESENCE control if available.
Correction of the tone can be done post overdriving by +3dB BASS and
TREBLE boost switches. If such connected DVO allows to get a good
overdriven ton, you should use parallel connection to the pre-amp (see below).
Parallel connection to the amp
The connection with the amp is done by two circuits.
PRE OUT output signal is connected to the amp guitar input.
Output (OUT) signal from DVO should be connected to the amp effects
loop using Switching cable for DVO (product code 00804, ordered separately).
REMARK: In case of connecting Switching cable for DVO, it is required to
connect PRE OUT output to the amp INPUT by the Jack/Jack cable (this cable
assures proper grounding). DVO should be switched to No. 4 mode of working
and for work with Switching cable for DVO (No.3 DIP switch position should be
DIP switch
Connection to an amp
Without „ Switching Cable
for DVO”
Using „ Switching Cable for
In this case switching on the first CH1 channel or the second CH2 one will
affect in connecting DVO output directly to the RETURN input of the effects
loop (directly to the power amp skipping pre-amp section). Independence of
amp tones from the overdriven DVO channels is the advantage of such
solution. Tones from the DVO are independent from amp tone settings (except
of PRESENCE control if available).
Silent tuning function (MUTE)
Electronic tuner should be connected to the TUNER output. To MUTE
press at the same time left and central footswitches. All indicators will start to
blink. To exit MUTE function should be pressed any footswitch again. The
guitar signal is active all the time at TUNER output.
Connection to the Guitar System Controller G LAB GSC
DVO can be controlled by a typical latching type output two-switch foot
pedal connected to the FOOT PEDAL input.
Connecting the FOOT PEDAL input and SW1&2 (or SW3&4) output of
the GSC controller by a Jack/Jack stereo cable enables to control DVO
functions according to the below table.
Indicator is not lit
Indicator is lit
SW1 (or SW3)
CH 1
CH 2
SW2 (or SW4)
Lowered volume
Full volume
SW1 (or SW3)
CLEAN tone
CH 1 or CH 2
SW2 (or SW4)
CH 1
CH 2
SW1 (or SW3)
CH 1 or CH 2
SW2 (or SW4)
CH 1
CH 2
Considering the signal path, DVO can be connected between a guitar and
GSC (all effects connected to GSC will be placed post this overdrive), or
between GSC and an amp (all effects connected to GSC will be placed pre this
overdrive), or to the one of GSC loop (DVO can be bypassed and some effects
can be placed pre and some of them post this overdrive).
Rules of overdriving
Overdriven tone is one of the basic tone used by guitar players for playing
different kinds of music.
Slightly overdriven tone is the common used guitar sound. To get slightly
overdriven preset the BOOST A and BOOST B switches should be set to zero
and the GAIN control should be set to minimum. Equalizer controls should be
set at the central position (to “0” value). Tone testing should be done at the
medium volume. Guitar volume controls should be set to maximum. Playing
the guitar, test tone by increasing the GAIN. At some position of the GAIN
knob there will appear the effect of „cutting” sounds with higher amplitude
and later, the effect of adding harmonics to the tone what is the overdrive
effect. It can be clearly heard by programming for example: less GAIN on the
CH 1 than on the CH 2 and more VOLUME on the CH 1 than on the CH 2
(BOOST A and BOOST B switches on both channels should be set
identically) and during songs played these two channels should be switched.
In case of guitars with low signal converters (e.g. single type) this test may
require switching on BOOST A or BOOST B switches.
To get well-defined overdriven tone, one of the active channel BOOST
switches should be switched on. BOOST A and BOOST B offer different
overdriving characteristics. BOOST A supply the tone with more middle and
treble and BOOST B with more bass. To get more bass slightly overdriven tone
only BOOST B should be switched on and GAIN should be lowered to the
required level.
Then can be tested what is the influence of equalizer controls onto the tone.
You should realize that BASS and TREBLE boosting switches (+3dB) are
operating on the overdriven signal. Switching them on produce different effect
than using BASS and TREBLE controls. For typical guitars with humbacker
pickups the best results give setting TREBLE control at -3 dB to 0 dB and
setting on +3 dB TREBLE switch at the same time.
The main factor determining overdriven tone is a frequency characteristics of
amplifying elements between DVO and a speaker, as well as a speaker alone
(understood here as a speaker or a set of speakers in a cabinet). If DVO is
connected to the amp clean channel input, it is recommended to set tone
controls of this channel in the following way: BASS to maximum, MIDDLE at
the centre, TREBLE almost to minimum. If DVO is connected to RETURN
input of effects loop then controlling of tone at an amp is limited only to
PRESENCE control (if available).
The element determining tone is a speaker or are speakers (or rather
speaker/speakers model), their quantity, capacity and type of the cabinet.
The largest manufacturers of guitar speakers obtain in their offer wide range
of guitar speakers models. Specially are easily identified speakers
differences for overdriven tones because they obtain a lot of harmonics which
played lauder or more silently make reasonable tone difference. As higher
quantity of speakers as better performance of bass (even at the same amp
power). DVO was designed for working with speakers models usually used in
the high quality amps. The BASS +3dB boost switch allows to increase bass
level to the required one. It is recommended to switch on this boost switch
and eventual excess of bass correct by BASS control.
Some tips from G LAB web site: www.glab.com.pl
Too much bass at a neck pickup
Typical problem of many guitars equipped with humbackers is too high
level of bass from a neck pickup comparing with a bridge pickup. If a guitar is
connected to DVO or G LAB GSC it is recommended to correct this guitar
electronic circuit (see the diagram at www.glab.com.pl).
Treble disappearing while lowering a volume
Many guitars (with two volume pots) are equipped with an electronic
circuit enabling them to mix in any proportion signals from pickups (even
lowering to zero the volume of one of the pickup do not mute the guitar).
Such a circuit cuts treble while the guitar volume is lowered (as much cut as
longer is the guitar cable) and changes the guitar tone when its volume is
reasonably lowered (the resistance of the pot „short circuit” the pickup). To
solve this problem it is recommended to modify the circuit according to the
diagram at www.glab.com.pl. If after performing this step the effect of cutting
treble still exists, then the reason can be long guitar cable (e.g. 10 meters) or
high parasitic capacitance of this cable (over 1000pF).
EMC/EMI & Certificate of conformity
This device has been designed and manufactured to conform with directives and
standards in the field of safety operations and electromagnetic interference.
This device uses and can radiate radio frequency energy and, if not installed and
used in accordance with the instructions, may cause harmful interference to radio
communications. However in spite of performing below standards there is no
guarantee that interference will not occur in a particular installation. If this device does
cause harmful interference to radio or television reception which can be determined
by turning the device on and off, the user is encouraged to try to correct the
interference by one or more of the following operations:
● Reorient or relocate the receiving antenna.
● Increase the separation between the device and receiver.
● Connect the device into an outlet on a circuit different from that to which
the receiver is connected.
● Contact with the manufacturer.
● Consult the dealer for help.
Declaration of Conformity
ELZAB S.A., ul. Kruczkowskiego 39, 41-813 Zabrze, Poland,
declare under sole responsibility, that the following product:
Dual Vintage Overdrive (G LAB DVO)
conforms with requirements of the EC Council Directives:
● 2006/95/EEC Low Voltage Directive,
● 2004/108/EEC Electromagnetic Compatibility,
and holds CE mark. Above named product conforms with the following standards:
● PN-EN 60065:2004 /EN 60065:2002/ Audio, video and similar apparatus Safety requirements.
● PN-EN 55103-1:2000 /EN 55103-1:1996/ Electromagnetic compatibility Product family standard for audio, video, audio-visual and entertainment
lighting control apparatus for professional use - Part 1: Emission
● PN-EN 55103-2:2001 /EN 55103-2:1996/ Electromagnetic compatibility Product family standard for audio, video, audio-visual and entertainment
lighting control apparatus for professional use - Part 2: Immunity
Jerzy Biernat
President of the ELZAB S.A. Board of Directors
Copy of original EC declaration of conformity is available for download on our
webside http://www.glab.com.pl
This device is marked with a cross-lined waste container symbol according to
2002/96/EU Directive on Waste Electric and Electronic Equipment.
Such marking informs that after usage equipment can not be trashed together
with other household waste.
An user obligation is to return wasted equipment to a party collecting wasted electric and
electronic equipment. Parties collecting such equipment organise a system, including local
collection points, shops and other units, allowing to return such equipment. This Directive
assures an user free of charge utilisation of such delivered equipment.
This device is made of materials which can be recycled or utilised after becoming out of use.
Proper handling of wasted electric and electronic equipment reduce demand for row materials
and contribute in avoiding harmful consequences for environment and health of people caused
by dangerous components and not proper storing and utilising of such equipment.
Owner Manual, Drawing No. G03INA00
G LAB is a brand of ELZAB SA
ul. Kruczkowskiego 39, 41-813 Zabrze, Poland
phone: +48 32 272 20 21, fax: +48 32 272 81 90
Sales & Export Department ......................................
phone: +48 32 272 30 51 ext. 34, 39, 64
+48 32 272 20 21 ext. 308, 366, 468
e-mail: glab@glab.com.pl
Technical Support .....................................................
phone: +48 32 272 30 51 ext. 64
+48 32 272 20 21 ext. 308
e-mail: help@glab.com.pl
Nr rys. G03IN000
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