TRACE ELLIOT AH1200-12 User manual

Untitled-1 1 17/10/2008 16:47:57

Untitled-1 1 17/10/2008 16:48:40

CONTENTS
Warnings & Cautions.........................................................................................................................................2
Important Safety Instructions.............................................................................................................................3
Introduction........................................................................................................................................................4
Basic Comparison Of Features...........................................................................................................................5
Quick Start..........................................................................................................................................................5
In Depth Guide...................................................................................................................................................7
Front Panel..........................................................................................................................................................7
(1) INPUT socket...................................................................................................................................8
(2) HI/LO switch...................................................................................................................................8
(3) INPUT GAIN rotary control............................................................................................................8
(4) Signal level LEDs............................................................................................................................8
(5) TUNER socket (7 Band)..................................................................................................................9
(6) PRE SHAPE switch.........................................................................................................................9
(7) VALVE switch (12 Band)................................................................................................................9
(8) DRIVE rotary control (12 Band).....................................................................................................9
(9) BLEND rotary control (12 Band)....................................................................................................9
(10) DI OUT XLR socket (7 Band).....................................................................................................10
(11) PRE/POST switch (7 Band).........................................................................................................10
(12) GRAPHIC EQUALIZER switch & sliders..................................................................................10
(13) COMPRESSOR switch and rotary control (7 Band)...................................................................11
(14) COMPRESSOR switch (12 Band)..............................................................................................12
(15) LOW BAND rotary control (12 Band)........................................................................................12
(16) HIGH BAND rotary control (12 Band).......................................................................................13
(17) SEND socket (7 Band).................................................................................................................14
(18) RETURN socket (7 Band)...........................................................................................................14
(19) LOOP switch (12 Band)..............................................................................................................14
(20) MUTE switch...............................................................................................................................14
(21) OUTPUT LEVEL rotary control..................................................................................................14
(22) Multipurpose red LED above OUTPUT LEVEL.........................................................................15
(23) LINE OUT socket (7 Band).........................................................................................................15
Rear Panel.........................................................................................................................................................16
(24) EXTERNAL CONTROL 8 pin DIN socket(s)............................................................................16
(25) DI EARTH LIFT switch..............................................................................................................17
(26) SEND-LO PASS, FULL, HI PASS sockets (12 Band)................................................................17
(27) SERIES/PARALLEL switch (12 Band)......................................................................................17
(28) RETURN-LEFT, MONO, RIGHT/MONO sockets (12 Band)...................................................17
(29) LOOP LEVEL rotary control (12 Band).....................................................................................18
(30) TUNER socket (12 Band)............................................................................................................19
(31) BALANCED DI OUTPUTS-LEFT, RIGHT, PRE EQ XLR sockets (12 Band)........................19
(32) OUTPUTS-LEFT & RIGHT sockets (12 Band).........................................................................20
(33) SPEAKER OUTPUT(S)..............................................................................................................20
(34) FRONT PANEL BRIGHTNESS rotary control...........................................................................21
(35) POWER switch............................................................................................................................21
(36) IEC socket and fuse holder...........................................................................................................21

ADDITIONAL INFORMATION.....................................................................................................................22
Power Amplifi ers..............................................................................................................................................22
Anti-clipping circuit.........................................................................................................................................22
Combos.............................................................................................................................................................22
Help..................................................................................................................................................................23
Suggested Settings............................................................................................................................................24
7 Band block diagram-Basic signal fl ow..........................................................................................................25
12 Band block diagram-Basic signal fl ow........................................................................................................26
Specifi cations....................................................................................................................................................27
Glossary of terms..............................................................................................................................................29
Trace Elliot • Great Folds Road • Oakley Hay • Corby • Northamptonshire • NN18 9ET • England
Phone [phone] • Fax [phone] • www.traceelliot.com
Trace Elliot • Great Folds Road • Oakley Hay • Corby • Northamptonshire • NN18 9ET • England

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Congratulations on your purchase of a Trace Elliot product. Our experience in design and quality of
manufacturing will ensure that you will be able to rely on this product to deliver the solid professional sound
you deserve, whether in the studio or on stage.
ThisTrace Elliotrange isthelatestevolutionofalineofproducts thatwere alwaysknownfortheirsophisticated
features, high quality construction, use of state of the art technology and reliability. Many of the original ideas
have become industry standards and are included within this range, however, around these are even more
features to inspire musicians to create the music that they want to hear.
The range features two types of preamp simply called 12 Band and 7 Band. This refers to the number of
frequency bands of control within the graphic equalizer. There are several differences between the two preamp
sections which are outlined below. In addition to the preamp, different models have different rear panel
features, different power levels and, in the case of the combos, different speaker con gurations.
High quality parts have been used throughout. In keeping with traditional Trace Elliot ampli ers, the INPUT
GAIN and OUTPUT LEVEL controls use parts that have ‘detents’ to give a professional feel.
All the switchable features on these ampli ers are split into two types: pre-set and performance.
➢ Pre-set functions are those which will be set at the start and are unlikely to be changed again during a
performance. These all use latching type switches which means they have an ‘in’ and an ‘out’ setting and will
click when changing settings.
➢ Performance functions are those which it is likely the user will want to switch on or off throughout a
performance. These all use non-latching type switches which ultimately control FETs to switch the particular
function on or off. The switching is extremely quiet and therefore will not be heard during a performance. The
front panel switch does not click when pressed and only needs to be pressed lightly to operate. In all cases the
appropriate LED for that function will be lit/unlit as it is switched. All these functions are also conveniently
footswitchable using the supplied footcontroller.
When a part of the circuitry is switched off then that particular part is completely bypassed, retaining signal
integrity. Also, correct signal phase is maintained from all outputs regardless of which functions are switched
on or off.
Caution: Please look over this guide and read any caution or warning statements found within. Following
these warnings is crucial to your personal safety and the safety of your Trace Elliot product.
TRACE ELLIOTAMPLIFICATION
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BASIC COMPARISON OF REATURES:
7 Band 12 Band
LED level indication Yes Yes
HI / LO sensitivity switch Yes Yes
TUNER OUT Yes Yes
PRE SHAPE circuit Yes Yes
DI OUTPUT on front Yes No
VALVE DRIVE circuit No Yes
7 BAND GRAPHIC EQUALIZER Yes No
12 BAND GRAPHIC EQUALIZER No Yes
COMPRESSOR Yes No
DUAL BAND COMPRESSOR No Yes
SERIES EFFECTS LOOP Yes No
MULTI OPTION EFFECTS LOOP No Yes
DI OUTPUTS on rear No Yes
MUTE switch Yes Yes
4 function footcontroller Yes No
6 function footcontroller No Yes
Brightness Control for front panel Yes Yes
QUICK START:
This section is for people who are either too excited or too impatient to read the whole manual before using
their new Trace Elliot. Please at least read this rst section thoroughly and return to the rest of the manual
later, lest you don’t get the full potential out of your new amplier.
(1) Once you unpack your Trace Elliot, plug the power cord into the socket on the rear panel and connect to a
mains socket supplying the proper AC line voltage for your unit. This is located on the rear of the unit, near
the mains inlet and power switch.
(2) If your unit is an amplier head (e.g. AH600-7, AH1200-12, etc.) then connect the speaker output to your
speaker cabinet(s). (More information on this is provided in the Owner’s Guide for the cabinet).
(3) Turn the OUTPUT LEVEL control to the “0” position.
(4) Connect the footcontroller (included) to the EXTERNAL CONTROL socket on the rear panel using the
eight-pin DIN cable (included).
(5) Plug your instrument into the INPUT on the front panel using a high quality shielded instrument cable and
turn the INPUT GAIN control to the “0” position.
(6) Flip the power switch on the rear to the “ON” position to turn the unit on.
(7) Set your instrument to your normal settings and while striking a string hard turn up the INPUT GAIN
gradually. While doing this observe the level indication LEDs above the control. When the red LED starts to
be lit, turn the INPUT GAIN control back one or two clicks so that it only lights up very occasionally.
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(8) Now gradually turn up the OUTPUT LEVEL control. Do this slowly to avoid any sudden level changes
that could damage your hearing; these are loud amps! Set this at the desired playing volume.
(9) You will notice that the unit will have defaulted to a setting of everything off except the PRE SHAPE
circuit. This is so that whenever the unit is turned on it will power up with a good basic tone.
(10) Make music! Feel free to turn on and off the other features on the unit, either by the footcontroller or
the front panel, and make adjustments to the other controls to get an idea of the exibility of the unit. While
making adjustments keep an eye on the level indication LEDs; some extreme settings of the Graphic Equalizer
will increase the signal level into clip, if this happens simply re-adjust the INPUT GAIN control as mentioned
above.
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IN DEPTH GUIDE
Well done! The very fact that you are reading this section means that you are serious about getting the most
out of your Trace Elliot ampli er. Although fundamentally easy to use, this guide will hopefully explain
the features of your ampli er in a way that will unlock all sorts of sonic potential that may have otherwise
remained hidden.
This operating guide covers the features of all the contemporary 12 Band and 7 Band range of ampli ers. If a
feature is only applicable to particular units then these are shown in brackets next to the heading. Therefore,
if (12 Band) is shown, this section applies to all 12 Band products and not to any 7 Band products.
Where a speci c model is shown in brackets, e.g. (AH1200-12), then this applies only to that product. The
feature being explained is shown in upper case, the type of control is shown in lower case. If there are any
terms you do not fully understand then please refer to the glossary at the back of this manual.
FRONT PANEL
There are two different front panels used for the range. Aesthetically they are very similar, however closer
inspection shows there are several differences. The 7 BAND has all its primary features on the front, with very
little on the rear, whereas the 12 BAND has many of its features moved to the rear to make space for other
features on the front. Basically the operation is very simple. The signal  ow runs from left to right through
the functions on the front panel. The status of each function is clearly shown by the corresponding controls
and LEDs, which also match the LEDs on the footcontroller.
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(1) INPUT socket
This is to connect the 1/4” jack lead from your instrument. Alternatively, if any effect units are being used
before the amplier then the output from the last unit is connected here. When the INPUT is not in use the
amplier is automatically muted to prevent any unwanted noise.
Experience has shown us that not all 1/4” jack plugs are made equal, therefore, we recommend the use of only
high quality 1/4” jack leads for best sonic performance and reliable connection.
(2) HI / LO switch
This switch has two functions; to set the sensitivity and the impedance of the INPUT stage. In the out
position it is set HI for high sensitivity and high impedance (1MΩ). The in position is the LO setting for lower
sensitivity and lower impedance (100KΩ).
The difference in sensitivity is 10dB. Actual sensitivity is dependent on the setting of the INPUT GAIN
control.
Generally, this switch should be set to HI for passive instruments, which are usually high impedance and have
lower outputs, and LO for active instruments (those with batteries built in), which are low impedance and
often have higher outputs. However, either can be used as long as the INPUT GAIN is set correctly.
(3) INPUT GAIN rotary control
This is to set the gain of the input stage of the amplier. The setting of this control is the single most important
on the whole unit, hence why the control knob has a red cap.
(4) Signal level LEDs
The level indication LEDs are included to help the user set the INPUT GAIN control. The circuitry monitors
several strategic points throughout the preamp to determine if clipping (distortion) is occurring.
The 7 Band units have 3 LEDs; green, yellow and red. Green will be lit for very low signal levels, yellow
will also come on when higher levels are present, and the red will be lit when the level is clipping or close to
clipping.
The 12 Band units have 5 LEDs. An extra green LED shows low to medium signal levels and the additional
red LED is a peak indicator that remains lit for a few seconds, even if the signal has dropped in level. This is
to show where clipping is occurring momentarily and might otherwise be missed.
Ideally, the INPUT GAIN control should be set as high as possible with the red LED(s) only lighting very
occasionally when playing the instrument at its hardest.
The basic procedure is as follows:-
1) Set the OUTPUT LEVEL to 0. Connect your instrument to the INPUT.
2) Set the HI / LO switch as appropriate for the particular bass being used.
3) Set the Volume control on the instrument to maximum.
4) Play the instrument as hard as it would be played during the performance.
5) While playing gradually turn up the INPUT GAIN.
6) The LEDs will begin to light up starting from the left.
7) Continue to turn up the INPUT GAIN until the (rst) red LED is momentarily lit on the hardest strokes, then
back off slightly one or two clicks on the control.
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If an active bass is being used with the HI / LO switch set to LO and the INPUT GAIN control is turned
fully clockwise without the red LED lighting at all, then switch to HI and follow the same procedure. This is
because not all active basses have high enough outputs to require the LO setting to be used.
While making adjustments to the rest of the controls keep an eye on the level indication LEDs. Some extreme
settings of the graphic equalizer will increase the signal level into clip. If this happens simply readjust the
INPUT GAIN control as mentioned above.
(5) TUNER socket (7 Band)
This is an output for connecting to a tuner. It is a buffered version of the input signal. Simply connect a 1/4”
jack lead from this to a tuner and you will be able to tune up easily at any time without degradation to the tone.
The signal from this socket is present all at times regardless of any other settings including MUTE.
(6) PRE SHAPE switch
This activates the circuit for the classic Trace Elliot ‘Mid Pre-Shape’ that all users of previous Trace Elliot
graphic style ampliers will recognise immediately. As it is our ‘signature sound’, these ampliers are designed
to default to this setting when initially turned on. When this is activated the yellow LED is lit.
The actual effect of this circuit is to boost the low and high frequencies (55Hz and 2kHz to 5kHz respectively)
and to cut the mid frequencies (centred around 400Hz), giving an instant, clearly dened, punchy sound. It
can be switched on and off using the front panel switch and also from the footcontroller. Both have a yellow
LED to show its status.
(7) VALVE switch (12 Band)
This switches the VALVE circuit on or off.
(8) DRIVE rotary control (12 Band)
This sets the signal level that is sent into the VALVE circuit.
(9) BLEND rotary control (12 Band)
This controls the mix between the normal sound and the sound from the valve.
The VALVE section uses both halves of an ECC83/12AX7 thermionic valve and is congured to be in parallel
with the normal signal.
Low settings of the DRIVE control will remain basically clean but with valve warmth added due to the
harmonics generated by the valve. Higher settings will drive the valve harder and will result in overdrive
sounds being created.
The BLEND control can then be used to literally blend together the two parallel signals to achieve the desired
effect. With the BLEND control fully anti-clockwise only the normal signal will be present; turning clockwise
will reduce the normal signal and increase the valve sound until, with the control fully clockwise, only the
valve sound is present. This means that in all positions, other than maximum and minimum, the sound of the
valve is blended together with the normal, clean signal which prevents the bottom end losing denition.
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By using the two controls a wide range of valve sounds can be dialled in, from vintage warmth to heavy
overdrive. Bearinmindthisisnotsimulation,thisisarealvalvedoingarealjob. Werecommendexperimenting
with both the PRE SHAPE and GRAPHIC EQ in various settings while the VALVE circuit is switched on.
With PRE SHAPE selected and a low to medium amount of DRIVE, the sound takes on the character of a
vintage valve bass amp due to ‘shaping’ the signal before the valve. With higher DRIVE settings the tone
often benets from some sound ‘sculpting’ by the GRAPHIC, a little boost in the high mids helps the attack.
Also the COMPRESSOR can be used to further shape the tone. The HIGH BAND is of particular use when
lots of overdrive is being produced due to the extra high frequency content in the sound.
Basically, this is a very versatile circuit that can produce various valve tones, from demurely subtle to wantonly
lthy! Experiment and enjoy.
Once a particular sound is found, the user can switch to the normal, clean sound and back again by pressing
the associated switch on the front panel or by using the footcontroller, both of which have a red LED to show
its status.
Please note: to drive the valve hardest the INPUT GAIN control needs to be set correctly as described above.
(10) DI OUT XLR socket (7 Band)
This is a low impedance balanced output for connecting direct to a stage box or mixer for live or studio use.
It gives the engineer a strong, clean signal without any overspill from other instruments. The XLR socket is
wired as normal: pin 1 = Ground, pin 2 = Signal +, pin 3 = Signal –
(An ‘Earth Lift’ switch is featured on the rear panel - see below).
(11) PRE/POST switch (7 Band)
This switches the signal that appears at the DI OUT from PRE with the switch out, to POST with the switch
in.
PRE is before any EQ is applied, therefore a higher level, buffered, version of the input signal. POST is after
the EQ, COMPRESSOR and effects loop, but before the OUTPUT LEVEL control. Therefore, any sound
shaping that is applied within the amplier will be heard on the DI signal as well. Different applications will
determine different settings. If in doubt choose POST as this will be basically the same sound that will be
heard from the cabinet / combo speakers.
Both settings should have similar general output levels. Neither will be affected by adjustments to the OUTPUT
LEVEL, so turning up on stage will not overload the mixing desk once it is set. In either setting the output will
be muted if the MUTE function is used.
(12) GRAPHIC EQUALIZER switch & sliders
When switched on the GRAPHIC EQUALIZER will be inserted into the signal chain. The green LED above
the sliders shows its status. It can be switched on and off using the front panel switch and also from the
footcontroller.
The graphic equalizer is the centre piece, both functionally and quite literally, of a traditional Trace Elliot
amplier, so much so that the actual name for each part of the range is derived from the number of frequency
bands within each one, i.e. 7 Band and 12 Band. Both types are very powerful tools for controlling the tone
of your instrument. The design of a Trace Elliot graphic equalizer is very different from a standard sound
reinforcement EQ. 15dB of cut or boost is available for each band, but instead of being spread mathematically
over the frequency range they have been set at carefully selected frequencies of particular use for bass guitar.
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Therefore, there is more control in the lower frequencies. Another difference is that each slider controls a
much wider frequency range than normally found. These design differences are in common with traditional
Trace Elliot ampliers and are part of the sound.
With the controls all set at 0dB (their mid ‘click’ position), no change is made to the signal. Moving a slider up
will progressively increase, or ‘boost’, the frequencies centred around the frequency marked above the slider.
Moving a slider down will progressively decrease, or ‘cut’, the frequencies.
Due to the exibility and massive cut and boost available, it is important to know how to get the best from the
circuit.
➢ Do not boost or cut all frequency bands. This will have the same effect as increasing or decreasing the
overall volume level without affecting the tonal characteristic of the sound.
➢ Do not use excessive bottom (30Hz to 40Hz) boost on the graphic unless your speakers can handle it.
Very few speaker systems are capable of handling frequencies as low as 30Hz and 40Hz with any degree of
efciency. Boosting at 30Hz, for instance, will not add to the perceived amount of bottom end in the sound,
it will only make your speakers ap to no useful effect. In fact, boosting at 100Hz or 180Hz will have the
apparent effect of adding far more bottom end than boosting at 30Hz, 40Hz or even 60Hz. The 30Hz slider has
been provided on the 12 Band to allow precise tailoring at very low frequencies. This slider should be used to
cut (not boost) the 30Hz to a level that allows the speaker system to work at its maximum efciency.
➢ Do not use excessive top (10Hz to 15kHz) boost, this will add mostly hiss to the sound as there is very little
signal output at this frequency from a bass.
➢ Try to keep the graphic sliders balanced around 0dB and in a smooth owing curve from one slider to the
next, and remember that after adjusting the graphic you may need to re-set the INPUT GAIN.
The fundamental frequency range of a regular, 4-string bass guitar is from 41.2Hz (bottom E string) to around
392Hz (two octaves up on the G string) - not a very wide range. Obviously a lot of harmonics are produced
when playing and these can extend up to 5kHz and more.
The attack portion of the note also produces other high frequencies when the string is rst struck. This attack
can be emphasised by boosting the top end. However, because of the fairly small range of frequencies from
a bass, by top end we mean between 2.5kHz and 5kHz. You will nd that by boosting at 5kHz the attack
will be emphasised, whereas boosting at 1.3kHz and 2.6kHz will bring out the harmonics in the note. Above
this frequency range you will nd it is better not to boost the signal as this will mainly emphasise any hiss
present.
If the VALVE circuit on a 12 Band unit is used at quite high DRIVE settings, you will nd the GRAPHIC EQ
extremely useful in shaping the overall tone due to having far more precise control than a simple bass, middle,
treble arrangement found on many other ampliers.
(13) COMPRESSOR switch and rotary control (7 Band)
Pressing this switch will add the COMPRESSOR to the signal chain. The blue LED above the switch shows
its status. It can also be switched on and off using the supplied footcontroller. The rotary control adjusts the
amount of compression applied to the signal; the further clockwise the control is set, the more the dynamic
range will be squeezed.
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The compressor in the 7 Band series uses studio quality, dedicated dynamics controller integrated circuits and
has been specically designed for bass guitar due to the common problems often experienced when using a
normal, single band compressor in this application.
With a standard compressor, the transition from non-compressed to compressed, i.e. crossing the threshold,
can often be abrupt and unnatural sounding, especially at high ratio settings. Also, the normal pre-set attack
and release times always have to be a compromise between having it work fast enough to catch rapidly
changing signal levels (i.e. transients such as slapping techniques) or too fast which can cause low frequency
distortion.
To tackle these issues, the compressor on the 7 Band range has been designed as a soft-knee compressor with
programme dependant adaptive attack and release times.
➢ Soft-knee means that, above the threshold, compression is applied gradually, with the ratio increasing as the
input level goes up. The result is a smoother sounding compression than the normal hard-knee type.
➢ Adaptive attack and release means that these settings are automatically and constantly adjusted by the
circuitry depending on what is being played. It will adjust to be slow to prevent distortion at low frequencies
and then readjust to be fast to catch transients. It enables a bass player to switch between various playing
styles such as nger style, slapping or plectrum, and the compressor will self-adjust its attack and release times
accordingly.
The simple single control makes setting the desired amount of compression easy as it is effectively controlling
the threshold, ratio and make-up gain simultaneously. This is considerably less complicated than setting up
a studio compressor from scratch as most of the hard work has been done by our engineers and incorporated
into the circuitry.
The circuit has been tuned so there should be little nominal signal level difference when switching the
COMPRESSOR on and off, however this is dependant on the correct setting of the INPUT GAIN control. If
you nd that the level increases too much when switching the COMPRESSOR on, then slightly turn up the
INPUT GAIN. The opposite applies if the compressed sound is too low.
Compression is good for generally controlling the dynamic range and preventing distortion, and also as an
effect. It sounds great for slapping techniques, for making harmonics more prominent, and for fattening up
grooves or smoothing out notes in a run.
Please be aware that due to the nature of any compression circuit that then adds make-up gain to bring the
nominal level up, dialling in high levels of compression will increase high frequency hiss between notes.
This is not hiss added by the compressor circuit, but hiss that is already present in the signal and then being
amplied. However, as this is only really noticeable when not actually playing, if high levels of compression
are desired it is possible to prevent the noise from being heard too much by using the footcontroller to turn off
the compression or muting the signal when nothing is being played.
(14) COMPRESSOR switch (12 Band)
Pressing the switch will add the dual band COMPRESSOR to the signal chain. The blue LED above the
switch shows its status. It can also be switched on and off using the supplied footcontroller.
(15) LOW BAND rotary control (12 Band)
This adjusts the amount of compression applied to the low frequencies in the signal; the further clockwise the
control is set, the more the dynamic range of the low end will be squeezed.
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(16) HIGH BAND rotary control (12 Band)
This adjusts the amount of compression applied to the high frequencies in the signal; the further clockwise the
control is set, the more the dynamic range of the high end will be squeezed.
The compressor section of the 12 Band series uses two separate studio quality, dedicated dynamics controller
integrated circuits, and has been specically designed for bass guitar due to the common problems often
experienced when using a normal, single band, compressor in this application.
With a standard compressor, the transition from non-compressed to compressed, i.e. crossing the threshold,
can often be abrupt and unnatural sounding, especially at high ratio settings. Also the normal pre-set attack
and release times always have to be a compromise between having it work fast enough to catch rapidly
changing signal levels (i.e. transients such as slapping techniques) or too fast which can cause low frequency
distortion.
To tackle these issues, the compressor on the 12 Band range has been designed as a dual band, soft-knee
compressor, with different attack and release times pre-set for each of the high or low bands, and separate
controls for the user to set the amount of compression applied to each band.
Dual band means that the signal is split into the high and low frequencies, each of which then goes through
separate compression circuits before being reconstructed.
The amount of compression of each band can be set by adjusting the LOW BAND and HIGH BAND controls.
This is similar to the sophisticated type of compression that is used for mastering whole tracks to prevent
unwanted pumping and breathing effects.
Soft-knee means that, above the threshold, compression is applied gradually, with the ratio increasing as the
input level goes up. The result is a smoother sounding compression than the normal hard-knee type.
Different attack and release times are pre-set for each band so that the low band works slow enough to prevent
distortion at low frequencies and the high band works fast enough to catch transients.
Thesimplesinglecontrolforeachbandmakessettingthe desiredamountof compressioneasyas itiseffectively
controlling the threshold, ratio and make-up gain simultaneously.
This is considerably less complicated than setting up a studio compressor from scratch as most of the hard
work has been done by our engineers and incorporated into the circuitry.
The circuit has been tuned so there should be little nominal signal level difference when switching the
COMPRESSOR on and off, however, this is dependent on the correct setting of the INPUT GAIN control. If
you nd that the level increases too much when switching the COMPRESSOR on then slightly turn up the
INPUT GAIN. The opposite applies if the compressed sound is too low.
In this application a dual band compressor has several uses. If used solely for controlling the dynamic range,
it enables the bass player to switch between various playing styles, such as nger style, slapping or plectrum.
The circuit will compress as directed without distortion to the bottom end, or transients taking hold of the
whole signal level and causing pumping, which is very obtrusive on bass guitar.
Applyingcompressiontojustthelowbandwillfattenupthebottomendwithoutlosingtheattackcharacteristics.
It is a less processed sound than full range compression and works well in controlling the low frequencies,
allowing higher volumes without stressing power amps or speakers. It can also help to add denition to notes
within a run without loss of the attack dynamics.
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Compression applied to the high band will directly effect the attack portion of the note and should be used
carefully. However, even extreme settings can produce some interesting effects for both slapping and fretless
techniques and will help to make harmonics jump out in the mix.
If the VALVE drive circuit is being used at high settings then the high band compressor can be used to control
and smooth out the overdrive produced resulting in quite a processed, produced sound.
Experimentation with many different settings of the compressor will help to get the most out of it.
Please be aware that due to the nature of any compression circuit that then adds make-up gain to bring the
nominal level up, dialling in high levels of compression will increase high frequency hiss between notes.
This is not added by the compressor circuit, but is hiss that is already present in the signal and is then being
amplied. However, as this is only really noticeable when not actually playing, if high levels of compression
are desired it is possible to prevent the noise from being heard too much by using the footcontroller to turn off
the compression or mute the signal when nothing is being played.
(17) SEND socket (7 Band)
This is a 1/4” jack socket for connecting to the input of effects units.
(18) RETURN socket (7 Band)
This is a 1/4” jack socket for connecting to the output of effects units.
The effects loop on the 7 Band range is an easy to use, unity gain, series effects loop. The user can simply
connect effects units between the SEND and RETURN sockets and the effect will be applied to the whole signal.
The normal bypass on each effect unit can still be used to turn the effect on and off during a performance.
The nominal level has been set to -10dBV to be able to drive most commonly used effects units. If the
effects units have their own level controls, please ensure these are set correctly to prevent distortion occurring
anywhere in the overall system.
(19) LOOP switch (12 Band)
Pressing the switch adds the EFFECTS LOOPS in to the signal chain. Its status is shown by the orange LED
and it can also be controlled by the footcontroller.
All the connections for EFFECTS LOOPS are on the rear panel. See below for a full description.
(20) MUTE switch
Pressing this switch will mute all outputs, (speaker, line and DI) except for the TUNER output. Its status is
shown by the red LED above the OUTPUT LEVEL control which will ash when MUTE is selected. It can
also be operated using the footcontroller.
The MUTE function is useful for preventing unwanted noise between songs, when changing instruments or, if
a tuner is connected to the TUNER output, for tuning up silently without needing to make adjustments to any
other controls. The signal level indicators remain active when in mute so it is possible to change basses and
set up the INPUT LEVEL silently without turning the OUTPUT LEVEL to zero and therefore risk forgetting
the setting.
(21) OUTPUT LEVELrotary control
This sets the signal level sent to the power output stage and the LINE OUT(s). It should be set at “0” when
switching on the amplier and turned up to the desired playing volume slowly to avoid any sudden level
changes that could damage your hearing.
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The actual power level produced from the amplier will be dependent on the input signal and the settings of
the other controls.
Once set for a performance it can be left alone and the MUTE function can be used to turn the signal off
between songs or sets.
We also recommend turning the OUTPUT LEVEL control to ‘0’ at the end of a session, before switching
off.
(22) Multi-purpose red LED above OUTPUT LEVEL
This LED has several functions. Firstly, it will ash on and off if the MUTE function is selected. It will also
light momentarily if maximum output from the power stage is reached.
It also functions as a general protection warning light, illuminating if any of the following conditions occur:
power amp over-temperature protection, short-circuit protection, over-current protection. If this LED remains
lit please refer to the HELP section at the back of this manual.
(23) LINE OUT socket (7 Band)
This is an unbalanced jack output that can be used to send the output of the preamp section to another piece of
equipment, such as a power amplier, mixing desk or recording device.
The actual level is dependent on the setting on the OUTPUT LEVEL control, which means that if it is used
to expand the system with extra power amps and speakers, then the overall volume can still be set by a single
control.
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REAR PANEL
7 BAND
12 BAND
N.B. Within the 7 Band and 12 Band ranges the rear panels may vary slightly from those shown above.
(24) EXTERNAL CONTROL 8 pin DIN socket(s) – BFC-4 (7Band), BFC-6 (12 Band)
The socket(s) are for connecting to the footcontroller supplied with the unit. It should be connected before
the unit is switched on. Please ensure that the lead is inserted  rmly and securely into the sockets on both the
ampli er and the footcontroller.
7 Band units are supplied with a 4-function footcontroller (BFC-4) that enables the user to control PRE-
SHAPE, GRAPHIC, COMPRESSOR and MUTE.
The 12 Band units are supplied with a 6-function footcontroller (BFC-6) that enables the user to control PRE-
SHAPE, VALVE, GRAPHIC, COMPRESSOR, LOOP and MUTE.
The LEDs on both footcontrollers all correspond in colour and function to those on the front panel.
If a footcontroller is disconnected from the ampli er while it is on and then reconnected, it may display
different settings to the front panel.
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To re-synchronize the switching simply turn the unit off for 5 seconds and then back on. Both the amplier
and footcontroller will power up in the normal default state of PRE-SHAPE on, all other functions off.
The 12 Band units have been designed with two EXTERNAL CONTROL sockets. These make it possible to
use two footcontrollers, either of which can control the amplier. This is useful if performing on a large stage
where each footcontroller can be placed in a different location for the performer’s convenience. Alternatively,
one of the controllers could be placed on stage as normal and the other placed at the side of the stage to enable
a technician to control the musician’s amplier if necessary. Again, this is useful on particularly large stages.
Another use for both sockets is if two ampliers are being used. In this scenario the two ampliers can be
controlled by one footcontroller by connecting the spare EXTERNAL CONTROL socket on the rst unit to
one of the sockets on the second.
(25) DI EARTH LIFT switch
Pressing this switch in will disconnect the earth/ground connection from pin 1 on the DI output XLR
socket(s).
Usually this should be left in the out position however there may be certain situations when connecting from
the DI socket(s) to another device that a hum is produced due to an earth/ground loop. If this happens then
pressing the EARTH LIFT switch in should eliminate the problem.
EFFECTS LOOPS (12 Band)
(26) SEND – LO PASS, FULL, HI PASS sockets (12 Band)
These are all SEND outputs within the EFFECTS LOOPS section and are active at all times.
The FULL SEND will output the full frequency range of the signal. The LO PASS SEND will output only the
low frequencies and the HI PASS SEND will output only the high frequencies. The lters have been designed
so that when the LO PASS and HI PASS signals are reconstructed they will be identical in both frequency
response and phase.
(27) SERIES / PARALLEL switch (12 Band)
This congures the effects loops to be either SERIES, with the switch in where the whole signal passes
through the effects loop, out of the sends and back in the returns, or PARALLEL with the switch out, where
the signal is split, one part going through the effects loop and the other, dry, signal being unprocessed and
mixed in with the effected signal. The PARALLEL setting ensures that a part of the overall signal remains
pure and unaffected.
If the PARALLEL setting is chosen it is recommended that the dry signal in the effects unit is turned to
minimum if accessible.
(28) RETURN – LEFT, MONO, RIGHT/MONO sockets (12 Band)
These are all RETURN inputs within the EFFECTS LOOPS section.
➢ The MONO socket will route the signal through both channels of the rest of the preamp.
➢ The LEFT socket will route the signal to the left channel.
➢ The RIGHT/MONO socket will route the signal to the right channel if the LEFT socket is also in use, or it
will route the signal through both channels, i.e. in mono, if the LEFT socket is not used.
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