Classic Module Preamp - Overview
The Classic series is a small, fully wired configurable module preamp.
The preamp pictured
below has a 4 bands of EQ control in 3 sets of stacked knobs.
The Classic series is a more traditional design than our Z-Mode preamps.
The design uses a Mid Z-Mode input loading so it sounds like a traditional passive setup combined with
Active Mixing and features 2, 3, 3 + Mid Frequency Switch, or 4 EQ Bands.
The Classic series can be used with Active Pickups and
The bridge pickup channel input can be configured (at order time) for a Piezo pickup.
Below is a set of common configurations -
the preamp can be Custom Configured if what you need is
not listed in the tables but
these configurations are the most popular.
Pricing is simple:
Modules with 2 bands $99
Modules with 3 bands $114
Modules with 4 bands or 3 bands plus a mid-frequency switch are $129
Optional single knobs are $5 per pot
stacks are $10 and come in chrome, black, gold.
|vol = volume
||bal = balance
||b = bass
||m = mid on 3 band
||t = treble
|vn = volume neck
||mfsw = mid frequency switch
|vb = volume bridge
||lm = low mid on 4 band
||hm = high mid on 4 band
Most Common Configurations for 2 pickups,
volume and balance versions
||vol, bal, t/b
||vol, bal, t, b
||vol, m/bal, t/b
||vol, bal, m, t/b
||vol, bal, t, m, b
|3 + Mid Freq Switch
||mfsw, vol, m/bal, t/b
||mfsw, vol, bal, m, t/b
||mfsw, vol, bal, t, m, b
||vol/bal, hm/lm, t/b
||vol, bal, hm/lm, t/b
||vol, bal, hm, lm, t/b
||vol, bal, t, hm, lm, b
Most Common Configurations for 2 pickups,
volume and volume versions
||vol, vol, t/b
||vol, vol, t, b
||vn, vb/m, t/b
||vol, vol, m, t/b
||vol, vol, t, m, b
|3 + Mid Freq switch
||mfsw, vn, vb/m, t/b
||mfsw, vol, vol, m, t/b
||mfsw, vol, vol, t, m, b
||vn/vb, hm/lm, t/b
||vol, vol, hm/lm, t/b
||vol, vol, hm, lm, t/b
||vol, vol, t, hm, lm, b
Most Common Configurations for 1 pickup versions
||vol, t, b
||vol, m, t/b
||vol, t, m, b
|3 + Mid Freq switch
||mfsw, vol/m, t/b
||mfsw, vol, m, t/b
||mfsw, vol, t, m, b
||vol, hm/lm, t/b
||vol, hm, lm, t/b
||vol, t, hm, lm, b
We have pre-wired the electronic assembly to make installation as
simple as possible.
You will need to select
a spot for the Module install the controls into the Bass
body, and connect the pickup wires and ground wire.
The module will be custom wired based on your selections:
- • Your volume control selection - volume & balance,
volume & volume, and single.
• The EQ circuit based on Passive High Frequency Roll Off, 2, 3, 3 with a Mid Frequency switch, or 4 Band
• 9 or 18 volts of battery power.
The only soldering required is wire to wire joints
for your pickups and ground connections.
The controls are on high quality flexible wires to facilitate an easy installation.
Most controls can be single or stacked knobs to allow for a configuration corresponding to your available holes.
After we have wired your assembly together it is connected
to a bass pickup and then driven by a wide band magnetic field. All of
the controls are tested and a frequency scan is completed.
For more information see the Classic Installation PDF.
The Classic preamp module is just about the size of a 9V battery:
2.00"L x 1.05"W x 0.30"H.
The switches are mini toggle switches with bushings
of 1/4" diameter, 9.0mm length; the finish is chrome and each
switch comes with additional decorative washer and nut sets; in both
Black Nickel and Gold for versatile finishing.
The preamp is mounted with Double sided tape patches that are included
The true sound of your passive bass is available
with Tone controls in the center detentes.
Players often think they need an Active/Passive switch to get a passive sound
which is correct for many other types of preamps but not with Audere preamps.
Different reasons are stated for installing an A/P switch but the top 2 are:
1) Most preamps never sound like a passive bass due to distortion - our advanced design eliminates this distortion.
2) Many preamps never sound like a passive bass due to tone control curves -
our tone controls are flat in the center detent.
Due to the lower cost of this preamp and the requirement of 4 poles due to the DC pickup connection and
active mixing the classic is not offered with an Active/Passive switch
The active mixing design provides a broader range of usable sounds as
you adjust the pickup mix.
Our front end is a stereo design so the pickup signals are electrically separated from each other.
After buffering, the signals are mixed together by the balance control or the dual volume
controls depending on the preamp's control configuration.
This design is especially useful if you have 2 different types of pickups,
for example in a PJ
configuration, the P retains its classic P sound and the J retains its classic J sound.
Our balance (also known as a blend) control gets slightly louder as you move
toward soloing either the Neck or Bridge pickup.
This type of response curve makes soloing a pickup easier on stage as you do not need
the sound guy's help to keep your volume level reasonable.
In the Classic Module preamps you can select either a 2, 3, 3 with mid range frequency switch,
or 4 band tone control.
The active tone control pots contain a centered detent where the response is flat, giving you the uncolored sound.
Our tone controls are different than most preamps in the following ways:
1) The boost/cut amount changes slowly at first off the center detent and then the action speeds up
as the knob is rotated farther from the detent.
2) Mid-range controls use wide bandwidths - the issue with narrow bandwidths is the phase shift
changes too fast vs. frequency and they sound artificial while our wide frequency mid-range
controls is more musical.
3) The Bass and Treble controls are shelving which extends to lower and higher frequencies than other preamps.
The shelving control makes our specs look very different than most preamps.
Our spec is at the 1/2 boost or cut frequencies. You can think of our specs as all the frequencies
below 180 Hz or above 3.2KHz (for a 4 band example) have a significant level of boost or cut range.
The frequency response points:
Bass shelving Hz - dB
|180 +/- 16 dB
||200 +/- 16 dB
||200 +/- 18 dB
|1st Mid Peak Hz - dB
||250 +/- 10 dB
||500 +/- 10 dB
|2nd Mid Peak Hz - dB
||750 +/- 10 dB
|Treble shelving Hz - dB
||3.2K +/- 18 dB
||2.5K +/- 16 dB
||2.0K +/- 17.5 dB
The 3 band mid range frequency switch moves the frequency of the Mid range control to 250, 500 or 850 Hz.
In summary, we design very musical tone controls that are easy to use and give you lots of control of your sound.
The Audere preamps sounds the same when running on 9 or 18 volts in most cases.
Since our preamps do not add a lot of gain to the signal path in most cases they work exactly
the same with either voltage.
The output level does not increase with an 18 volt system unlike several common preamps.
We recommend you save some weight and space and only use 1 battery unless you already have an 18 volt battery box.
You will get more head room on 18 volts but the preamps are designed with parts which are fully qualified
to run at the lower voltages so unless you use your tone controls maxed out and play really hard,
you will not be needing the extra voltage.
You can always change the battery supply later and the preamps will automatically adjust in between 9 and 18 volts.
The Classic module preamps will run about 250 hours on a premium 9 volt battery.
If you are running 18 volts then the battery life will be longer.
Since we sometimes get asked:
1) Rechargeable batteries. Not recommended - their voltages tend to be different and
they self-discharge faster than normal batteries and when they die you get no warning.
2) Lithium batteries. Not recommend - they cost a lot more and do not work any better plus they have safety issues.
The output level when the tone controls are flat (in center detent) is the same as your passive bass.
Always connect a bass with an Audere preamp into the passive input on your amplifier.
We do not include excess gain, there are several reasons why:
1) This allows the preamp to run on a single 9 volt battery without distortion.
Lots of other preamps have added so much gain to the output that they are still clipping
with 18 volts of power which is why they never sound like a passive bass.
2) All bass heads work well with a passive jazz bass input levels since this is the most common bass.
When you plug into an active input on most bass amps they simply divide down the input level
(tossing away the extra gain) and then proceed through the amplifier like you plugged into
the passive input without the extra gain.
3) We make your bass to actually sound better as opposed to tricking your ear by making it louder.
If you turn up your bass sound intensity any where in the signal path it sounds better due
to how the human ear works as demonstrated by the Fletcher Munson curves.
You hear the bass (especially) and the treble better when the sound level is louder as shown in the graph.
A lot of preamp companies use this effect to trick players into thinking the quality of their
active sound is better by simply increasing the sound level but if you back it down to an equal
volume level you might not be very impressed.
Our design captures all the fine detail of your playing style and brings it out so it
really sounds better instead of just louder.
4) Most effects are designed to work with the passive bass pickup levels and
our preamp gives them the unamplified signal level they expect.
Our favored modes are series connections for hum-bucking and single coil modes.
Parallel connections are sometimes used for a passive bass as this configuration can drive a cable
to slightly higher frequencies but our preamp drives the cable so this is not a consideration and the sound is
often less interesting depending on your pickup's design.
The coil configuration switch comes before the preamp and the only restriction is do not connect
the pickup common to ground in any of the configurations.
If you see a connection to ground off an existing coil configuration switch then disconnect that
node of the switch from ground and connect it to the green/white (pickup common) wire off the Classic module.
Note using a separate coil configuration switch for each pickup is a nice option.
In addition to active tone controls we offer a passive tone control option which is a
traditional variable high frequency roll off control.
This control is like a tone in the 3rd position of a passive jazz bass and players either love them or
could care less about having this option.
In theory this type of control changes the frequency above which the
frequency response is reduced, or starts to roll off. In practice,
the frequency response curve is more complex (see the curves below).
This style of tone control can only reduce the signal level.
A typical Tone Control response is shown below.
High Frequency Response - TONE in Passive
Treble roll off position: Black - 100%, Red 66%, Green 33%, Blue 0%
These curves were acquired using a Nordstrand NJ5 pickup connected
with a 10' low loss cable into an Avalon U5 preamp.
The change in frequency response
at the top end depends on the pickup in passive mode. The cable and bass power
amplifier loading in both active and passive modes since the tone comes after the preamp in all modes.
At order time you can select to configure the Bridge Pickup Input for a Piezo.
Most Piezo Pickups require a High Impedance Load to sound natural and this can be built into
the classic circuit when we construct the PCB.
You will see this option when placing the preamp into the cart system.
To use this preamp you must have PASSIVE PICKUPS,
meaning that the pickup does NOT have a semiconductor component in the pickup or
add the coupling caps to your order at check out.
There is a lot of confusion among players and technicians about active pickups
- most pickups are passive but they are sometimes called active when they are connected to a preamp.
The connection to a preamp does not make the pickup active - it only makes the system active and
these pickups will work with our preamps.
The vast majority of basses have passive pickups. EMGs are the most common active pickups.
If you are uncertain about your pickups, Google them (fastest), check with the manufacturer,
or send Sales at Audere an email.
About 99% of the time you can also look at the red wire off the battery and see if it
goes to the pickup to supply power in which case it is an active pickup.
How long do I have to wait to get it?
How much is shipping?
Has my Custom Configuration been tested?
The most common installation problems.
How hard is it to install?
How big is the module?
Pickup wires 1 to 5
Why is the pickup ground separated from the jack ground?
How do I ground the pots?
Why remove the cable when not in use?
Why does it pop when I plug in the cable into the bass with the amp power on?
How is the module mounted?
What if I don't know anything about bass guitar wiring?
What type of wire is used?
Why so many wires?
What types of switches are used?
What types of pots are used?
What type of solder is used?
Too many knobs - I ALWAYS set my X control to the same position!
Do you provide knobs?
What colors of hardware can I get?
My bass has only 3 holes for controls - can I use this preamp?
What is heat shrink and why would you include any with my preamp?
What if my bass control holes are 0.4" diameter?
- How long do I have to wait to get it?
- All the module preamps require we take a pre-tested module and wire it to your configuration,
test it, pot it into a case, and test it again.
This process can take up to 1 week be most often we are faster.
Shipping is normally by USPS priority mail which is 2-4 days.
- How much is shipping?
- Add a preamp to your cart - the system will calculate the shipping
cost to you by different speed options.
Note in the US we recommend
Priority shipping as Express shipping is expensive will normally only saves you
a maximum of 1 day - sometimes it takes longer.
When shipping overseas Express is only a little more in many cases and can make
a big difference in speed.
- Has my Custom Configuration been tested?
- We test every preamp after construction and before potting.
Then after potting before shipping it.
We connect each preamp up to a real pickup and do a magnetic scan for both channels and
verify each control works correctly.
- The most common installation problems
- 1) Connecting the pickup common to the ground (scratchy controls, causes distortion, may shut down the preamp -
especially if you turn up the bass, and drains battery).
2) Not getting a good pickup connection (causes low volume and possibly distortion).
3) Not connecting the ground wire to the bridge (causes increased hum while playing).
4) Incorrectly wiring an output jack if you must move the wires to an existing jack.
- How hard is it to
- We have an example of an installation under Support/Documents or
follow the Install
We recommend that you have experience with a soldering
iron and installing simple electronics. A Luthier or repair shop
can do it for you if you are uncertain.
The Install example shows
how you can play test the unit early in the installation.
- How big is the module?
- The preamp is 2.00" by 1.05" by 0.30". This is the
same x by y size of a common 9 volt battery with a connector snapped
onto the top. The thickness is thinner than a battery.
- Pickup wires 1 to 5
- Pickups can have 2, 3, 4 or even 5 wires but most jazz pickups have 2.
• Every pickup has at least 2 wires, Hot and Common
must be connected to our board at the screw connector as shown in the installation
• If you have think you have only 1 wire, it's probably a coax (center is insulated from the outer braid)
- the center is hot and the braid is common.
• If you really have only 1 wire (very rare), this wire is the hot and you must pull up the pickup
and find the wire connection to ground - disconnect it and run a longer wire back to the pickup common.
• If you have a 3rd wire and it is a braided shield that wraps around the
pair of wires, this is a Ground wire and can be connected to the Cavity Ground.
• If you have a 3rd wire and it is red and goes to the battery - Stop - you have active pickups and
this type of pickup is not compatible with the preamp..
• If you have a 4 wires you have a dual coil pickup - see the manufacturer's site for how
to wire for series mode.
• If you have a 5th wire and it is a braided shield that wraps around the
2 pair of wires, this is a Ground wire and can be connected to the Cavity Ground and
see the 4 wire note above.
- Why is the pickup ground
separated from the jack ground?
- We create a split power supply so we can DC couple the pickup
signal to the input of the amplifier.
This allows us to move the
capacitive coupling to the output signal, which has a low impedance
drive source, instead of having it coupled at the pickup side which
is a high impedance signal.
Some pickups like Nordstrands have the pickup common connected to a shield ground by default - simply undo this connection.
The pickup's ground goes to Grey/White and the pickup's common is wired to green/white.
- How do I ground the pots?
- The barrel of the pot is metal and is normally grounded by pressing
against the shielded cavity.
Put the copper shielding down before the pot and connect a wire from the shielding to ground.
Traditionally in guitar electronics people soldered directly to the
back of pots. This was a poor idea for several reasons.
1) You need to use a very aggressive flux in the solder (acid core
was traditional). If the flux is not thoroughly cleaned off it will
reactivate when it gets humid and can corrode the metal and cause
the pot to fail.
2) You have to heat the heck out of the part. This often shifts the
resistance and permanently increases the noise of the resistance
element. Many pots have internal plastic parts that can be damaged
by this much heat.
- Why remove the cable when not in use?
- Most preamps use a stereo jack where one side of the battery is connected to the ring terminal.
When a MONO cable is inserted into the jack the ring is shorted to the body and the preamp powers up.
So you should remove the cable when not playing which removes the power from the preamp or you will
soon have a dead battery.
- Why does it pop when I plug in the cable into the
bass with the amp power on?
- Due to the standard power switching used for the battery connection the battery is connected to the input
of the guitar cable during the time the cable is sliding into the
Most players develop a habit of partially pulling out the other
end of the cable before inserting the connector into the bass jack
Some players use a guitar cable with an integrated disconnect switch.
Planet Waves and others have cables with this feature. Neutrik has
a "Silent Plug" (NP2C) out that we haven't tried but it
- How is the module mounted?
- We provide durable double-sided sticky pads to go under the module,
secure but still removable.
- What if I don't know anything about wiring
an electric bass guitar?
- Installation is simple if you have experience with installing music electronics.
However, typical hand tools for soldering wire connections
and assembly are required.
If you are uncertain about the installation
we recommend you have a guitar setup or repair technician or a Luthier
install it for you.
The module and controls are all pre-wired to
make it easy to install; you will need to:
1) connect the pickup wires
2) install copper shielding in front of the switches and pots
3) put the switches and pots into the body mounting holes
4) install the LED battery indicator
5) connect shielding and bridge grounding to the jack.
- What type of wire is used?
- The wire is a Mil-grade thin Teflon jacket over 24 AWG with 19
sub-strands for high flexibility.
Most of the wires have a base color
and a 2nd colored strip.
The advantage of using Teflon is the insulation
can be very thin and will not burn back from high heat during soldering.
The disadvantage is it is harder to strip unless you use a very sharp
- Why so many wires?
- 18 base configurations, not including all the control options. The good news is we'll
pre-wired it for you.
- What types of switches are used?
- We use SPDT (on/off/on) for the 3 band Mid Frequency switch.
- What types of pots are used?
- The pots we use are high end audio grade with low noise metal film
resistance elements (often called industrial controls).
are small 9mm units which provide you with more vertical space to
stack the electronic module and battery.
Our pots are all 100K ohms
with the volume pots having an audio taper
and active tone controls having a linear taper.
- What type of solder is used?
- We use lead free environmentally friendly solder for SMT processing and hand soldering.
The technical classification is SAC 305 which is 96.5% Tin, 3% Silver, 0.5% Copper - flux type is no clean
- Too many knobs - I ALWAYS set my X control
to the same position!
- If you want a quasi-fixed position control, for example, if you
always add/delete a little mid range, then we can wire up your unit
with a trimmer which is a small plastic part which stays hidden in
the control cavity. These controls are multi turn adjustments so you
have a very accurate set point.
The size of the adjuster is roughly 3/8" square by < 1/4" deep.
This allows you to setup the bass as desired then forget about that control.
If you change your mind later, then you can move the adjustment to a new setting.
The cost of this option is the same as a regular pot but you need
to put a note with the order to get it wired up this way, and include
an email address in case we have questions.
If you do not want one of the tone controls and you do not have room
to store the control in the body of the bass, you can remove the
control pot by cutting off the pot and insulating the wires.
That tone control section will default to a flat response.
- Do you provide knobs?
- We can supply knobs with the preamp but they are an optional item.
If you select a standard configuration in the tables on the main page then
we will offer a knob set to you when you put the preamp into the cart.
You can also knobs direction from the purchase menu under knobs.
You can also use your own knobs.
Single controls have a 6 mm shaft size.
Stacked controls have both a 6 mm and 8 mm shaft.
All knobs need a set screw to hold onto the shaft.
- What colors of hardware can I get?
- The switches are chrome and we provide a chrome, a black and a
gold washer/nut set so you can coordinate the look with your other hardware.
We also sell knob individually and in sets in these colors.
- My bass has only 3 holes for
controls - can I use this preamp?
- There are lots of options for what to do with your 3 holes. One
of the possible configurations is: 1st hole for a volume/volume;
2nd hole for a High/Low Mid tone control; and the 3rd hole for a Treble/Bass
- What is heat shrink and why would you
include any with my preamp?
- Heat shrink tubing is a plastic tube which is used to insulate
The tubing shrinks or reduces its diameter when you heat
it. It comes in various types of plastic, sizes and shrinking ratios.
You can shrink it with a hot air source (a match can be used with
care). Just be careful you do not apply too much heat to the tube
or other parts on you bass. We supply you with a few pieces so you
can insulate your wiring if you need to.
- What if my bass control holes are 0.4" in
- We supply rubber rings to fit over the switches and single pots
to expand the diameter. This works well for most applications. If
you require a special sized spacer ring then most Luthiers could
help you out.
Read the small print in our Satisfaction Guarantee but
the basic concept is you get 10 days from when you receive the preamp to try it out
and make sure it works in your bass for your playing style.