Basswitch Classic Boost Manual
Ruppert Musical Instruments
User Manual
Ruppert Musical Instruments • 20a, rue de Bascharage • L - 4995 Schouweiler • Luxembourg
Tel./Fax: 00 352 691 379050 • Web: • E-Mail: [email protected]
With the Basswitch Classic Boost you have purchased a super compact
high-end bass preamp gently voiced for passive P, JJ and PJ type basses
that gives you the confidence to be adequately prepared for any situation,
be it in a live performance or in a recording studio.
carefully so that you can consult it at any time.
Your Basswitch Classic Boost package contains the following items:
- Basswitch Classic Boost
- User manual
When developing the Basswitch Classic Boost we focused on the needs and
wishes of the professional bass player who is not willing to compromise
on either sound or the technical quality of the equipment. The Basswitch
Classic Boost is manufactured, assembled and tested in Germany to the
highest quality standards using only the best brand components available
to ensure optimal treatment of the electrical signal from your instrument.
Please check that all these items are there as soon as you unpack. Should
something be missing, please contact your authorised dealer.
The Basswitch Classic Boost is built to last, but if you nonetheless experience problems or have any questions do not hesitate to contact us.
Please take your time to read this user manual carefully before you start
using your Basswitch Classic Boost. You will find lots of useful information
on the pedal and the various ways it can be used. Keep this user manual
I wish you every success with your Basswitch Classic Boost. Yours, Jacques Ruppert
Tech Talk
Technical data
Why a specific Booster for bass instruments? The reasons are obvious: the
frequency range of bass instruments goes from very deep fundamentals
(e.g. 30.87 Hz for low B or 41.20 Hz for low E on an electric bass) to very
high overtones that have a crucial impact on the timbre of the bass instrument even though they are approaching the upper limits of the audible
spectrum (from 18 Hz to 20 kHz). On top of this, bass instruments have a
characteristic attack with a very steep initial transient followed by a weak
electrical signal.
Boost can drive a power amp, an active monitor, an active bass speaker
cabinet or an in-ear monitoring system.
Additional features
- Lehle “True Sound Technology” (for details please consult the chapter
“Tech Talk”).
- Specially designed to protect the controls from damage and to prevent
inadvertent changes to the settings.
- The design of the housing permits easy installation: the ultra‑flat base
and removable rubber feet allow the unit to be securely attached to the
pedal‑board using Velcro or similar.
These characteristics of bass signals make enormous demands on the
electronics, with the result that the handling of bass signals by most
equipment is unsatisfactory and inconsistent in quality. Only equipment
specifically designed for the purpose is able to handle such a demanding
signal pattern adequately.
1. Input IN
Connect your first instrument here.
This is the standard input for all instruments. The input is designed to
accept active and passive instruments.
Functions and applications overview
- The Basswitch Classic Boost used as a booster
The primary application field of the Basswitch is the one as booster with
an adjustable EQ. Used as such the Basswitch Classic Boost puts at your
disposal a louder tone and/or a second sound setting for your instrument
at the push of a footswitch.
Note: The Gain control has a volume cut and boost function to allow
a perfect match of the desired tone levels.
2. Output OUT
Connect your bass amp or power amplifier or active monitor here.
If the Basswitch Classic Boost is used in its function as booster upstream
of a bass amp, it should be in “straight through” mode (LED lights white)
when the settings for the basic sound are made on the amplifier. Only after that the tone for solos, a second sound or a second instrument should
be set on the Basswitch Classic Boost.
If the Basswitch Classic Boost is used as a preamp upstream of a power
amp to drive a power amp, an active monitor, an active bass speaker
- The Basswitch Classic Boost as a high-end preamp
The Basswitch Classic Boost features a high-end preamp and a 3-band
EQ specifically designed for bass instruments and featuring bass, mids,
and treble controls. As a stand‑alone preamp, the Basswitch Classic
8. Footswitch
Push this switch to activate the booster.
Pressing the footswitch turns the Classic Boost on or into ‘straight through’
cabinet or an in-ear monitoring system the Booster must be activated
(LED lights blue). The basic sound is set up using the preamp/EQ section
of the Basswitch Classic Boost.
3. External power supply
Connect your external power supply here (9-15V; min. 60 mA) with a
standard 5,5 x 2,1 mm connector.
Because of the uncompromising design, the quality of the components
and the switching technology used, the power consumption of the Basswitch Classic Boost is too high to run it satisfactorily on batteries. The
external power supply should provide not less than 9V and not more than
15V. Either alternating (AC) or direct current (DC) sources can be used
and the polarity is not relevant. The voltage supplied is internally rectified,
filtered, stabilised and then brought to 18 V.
Note: To get the best out of your pedal set-up we recommend that
you use high quality power supplies with isolated output sections
in your set up!
Warning: The Lehle power supply (item no. 7014) with the connector
acc. to DIN 45323 is not suitable.
9. Status LED
This LED turns blue when the Classic Boost comes on and white in the
Tech Talk
True Bypass and True Sound
Today more and more effect pedals feature true bypass switching to completely bypass the pedal in the signal routing when the pedal is switched
off. The target of this design is to ensure that the pedal does not affect
the electrical signal when it is switched off. This way the sound is left
unaltered - in theory.
In practice, however, connecting several pedals featuring a true‑bypass
design in series does not improve the sound or keep it unaltered at all.
Long runs of cable and multiple connections lead to a weak and lifeless
sound. On large pedalboards the overall length of the cable is enough for
the capacitance of the cable to have a negative effect on the sound. The
capacitance of the cable acts as a low‑pass filter (= the low frequencies
pass through the filter while the high frequencies are filtered out). The
price and quality of the cable you are using will not change this physical
A solution would be to use only devices with buffered bypass design instead of true bypass. This, however, is only a good solution if the buffer is
of very high quality. If several units with buffered bypass are connected in
series it only needs one buffer to be noisy, to cut the dynamics of the sound
signal or to negatively affect the sound in any other way for the sound of
the whole effect chain to be spoilt. As the saying goes: „a chain is only as
strong as its weakest link”. In addition, the noise of the individual buffers
adds up to produce audible noise (It is a fact that every buffer produces
some noise, even if it cannot be heard when only a single buffer is used).
The ideal solution is to have a very high‑quality buffer at the beginning
of the chain that brings the signal down to a very low impedance. This
makes the signal insensitive to the length of the cable. It is important,
however, that this buffer is of the highest quality with the dynamic range
and headroom necessary to ensure that all the details of the bass signal
stay are retained unaltered.
The effect pedals in the downstream should then ideally have true bypass
so that they will not have a negative effect on the now buffered signal,
as the true bypass design does not reduce dynamics and headroom or
produce any noise.
Conclusion: Having a True Sound Lehle buffer at the beginning of your
effect chain combined with good true‑bypass‑equipped effects in the loop
guarantees the best sound.
4. GAIN Control
Use this control to adjust the volume of your Classic Boost.
To permit optimal matching of signals this control enables you to boost
and to cut the signal, the neutral position is at 12 o’clock. The high‑end
preamp of the Basswitch Classic Boost allows you to connect the Basswitch Classic Boost directly to a power amp (see also point 2).
5. M (MID) Control
Use this control to adjust the amount of mids in your tone.
This control boosts and cuts the lower mids. The technical design used
enables a good sound to be maintained even when applying major adjustments to the signal, but we suggest however to use this control with care,
the intention being more to subtly modify the sound than to fundamentally
change it.
6. B (BASS) Control
Use this control to adjust the amount of bass in your tone.
This control has been designed with the deepest frequencies of the bass
instruments in mind to permit a targeted cut and boost of these frequencies. This control is very useful with passive basses, for instance, to give
them more depth and substance. The technical design used enables a
good sound to be maintained even when applying major adjustments to
the signal, but we suggest that you use this control with care to avoid a
bass‑heavy sound.
7. T (TREBLE) Control
Use this control to adjust the amount of treble/presence in your tone.
This control enables you to create interesting sounds like the classic slap
sound („Slappers delight”). Boosting the treble control brings life to dull
speaker cabinets and new life to old strings. When using new strings, especially new round‑wound steel strings you can get the aggressive highs
under control by cutting the upper frequencies a little. It can also help, if
needed, to reduce the annoying rattling of the strings.
What is Lehle True Sound Technology?
Lehle True Sound Technology is a combination of several electrical design
measures with only one aim in view: to transmit the sound and the character of the instrument without altering it.
The voltage supplied to the Basswitch Classic Boost is internally rectified,
filtered and stabilized and then brought to almost 18 V. This gives enough
Working principle of the Basswitch Classic Boost footswitches
Footswitches are pressed thousands of times during their long lifetimes
- sometimes sensitively but some times more brutally depending on the
situation and the musician’s temperament. An ordinary footswitch will
switch up to 20 000 times before wearing out mechanically or electrically,
which means that either it will stop working altogether or the signal will
start to lose transparency and dynamics.
The Basswitch Classic Boost is equipped with high‑quality Lehle
footswitches. Here the foot of the musician does not press an ordinary
footswitch but an actuator button that activates a pushbutton inside the
Basswitch Classic Boost via a metal lever. Because the actuator button
and the internal pushbutton are not directly connected, the load exerted
by the foot is absorbed by the actuator button and the housing, preserving the circuit board from mechanical stress. The design is as robust as
possibly and the actuator button mounted in a special socket making for
easy and silent operation.
Inside the Basswitch Classic Boost the impulse from the pushbutton
activates special gold‑plated relays via discrete logic circuitry. This way
the switching is done only via high-quality relays and thus guaranteeing
absolutely reliable and loss‑free switching of very sensitive signals. The
switching technology and the gold‑plated relays in the Basswitch Classic
Boost are designed to operate for up to two million switching cycles!
headroom to guarantee an open and dynamic sound in all situations without losing any detail, even when confronted with pickup power peaks from
plus 7 to minus 7 volts.
The buffers are designed to effortlessly handle signals reaching the
megahertz range. At the output, the frequency bandwidth is limited to the
audible frequency range to prevent HF interference, disturbing the electronic circuitry. This guarantees optimal transient response by the circuitry
and is key to obtaining a sound that is transparent and, above all, cuts
For switching, Lehle True Sound Technology uses exclusively gold-plated
contact relays and/or gold-plated switches. The decaying signal from a
string is so weak that contact materials with lower conductivity have a
negative impact on the sound. Ordinary footswitches use contact materials developed to switch high voltages (e.g. electrical power tools) as this is
their main field of application. This can be heard, for example, when, after
a switch has been in use for some time, a decaying tone starts to break off
abruptly. Relays and switches with gold-plated contacts do not have this
problem and even the smallest electrical signals can be transmitted for
years without being negatively affected. In addition, the relays used in the
Basswitch Classic Boost have a lifetime about 100 times as long as those
used in ordinary footswitches.
Together with typical Lehle electronic circuitry to reduce the switching pop
of relays, the combination of the above design features represents today’s
state-of-the-art solution for an uncompromising preservation of the signal and hence the sound and character of the instrument.
Technical data:
Overall height:
Voltage range:
Power consumption:
Frequency range:
Input impedance:
Output impedance:
Signal-to-noise ratio:
Max. level:
Max. gain:
390 g
14.9 cm
6.0 cm
4.4 cm
9-15 V AC/DC
max. 60 mA
30 Hz – 150 kHz (+1/-3 dB)
0.002 %
2 MOhm
150 Ohm
-96 dB @ 1 kHz, 0 dBu
15 dBu (with 12 Volt power supply)
+/- 15 dB
Bass:  +15/-11 dB @ 45 Hz (peaking)
Mid: +/-12 dB @ 640 Hz (peaking)
Treble: +10 dB @ 5 kHz/-12 dB @ 10 kHz (shelving)
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