The Dual Filter Modular pre-amp is available in 3 different configurations.

DFM 4K

Stack one: Volume/Blend.
Stack two: Low-pass filter for the neck pickup plus push/pull switch to activate the low mid boost. The lower ring is the filter frequency, with 41 detents. The upper ring is the overshoot peak level.
Stack three: Low-pass filter for the bridge pickup plus push/pull switch to activate the upper mid boost or Attack Boost. The lower ring is the filter frequency, with 41 detents. The upper ring is the overshoot peak level.
Stack four: Sweepable mid/treble.

DFM 4K/AP

Same features as the DFM 4K but with a passive tone control in lieu of stack four, the sweepable mid/treble.
The single pot passive tone features a push/pull active passive switch. The tone control works in both active and passive modes. Passive is a full bypass even when the battery dies the passive section will still work.

DFM 5K

Same features as the DFM 3K with the addition of:
Stack four: Sweepable mid/treble.
Single five: Passive tone with active/passive on the push/pull

When the active/passive/tone pot is added, the volume/blend continues to work in both active and passive modes. When the bass is put into passive mode, the filter stacks have no effect on the sound. The passive tone pot can be used to shape the sound in both passive and active modes. The passive section completely bypasses all active sections in the pre-amp, so even without power the bass will continue to work in passive mode.

Note: When the DFM 4K/AP or the 5K/AP are used with the MC range of pickups the passive mode operates as normal. However should you lose power, the bass will no longer produce any sound. This is because the ACG IB1 board that connects the pickups to the pre-amp requires power to mix the pickup signal. So, if the battery dies there will be no output from the pickups.

The push/pull switches on stacks 2 and 3 activate a low-mid and hi-mid boost/attack boost that is independent of the filter positions and work globally so both can be active at the same time. Internal dip switches allow you to chose between two frequency settings on each stack. There are also trimpots to adjust the level of the boost from very subtle to a very pronounced boost.

Details on the frequencies and levels, and how to set them can be found in the instruction bundle at the bottom of the page.
The DFM pre-amp is now standard on all Custom and Über range basses in whatever configuration best suits you requirements. The EQ03 has now been discontinued.
Instructions for the DFM can be found at the link below.

The Dual Filter Modular pre-amp is available in 3 different configurations.

EQ01 4K

Stack one: Volume/Blend.
Stack two: Low-pass filter for the neck pickup. The lower ring is the filter frequency, the upper ring is the overshoot peak level.
Stack three: Low-pass filter for the bridge pickup. The lower ring is the filter frequency, the upper ring is the overshoot peak level.
Stack four: Global high-pass filter for both pickups. The lower ring is the treble frequency, the upper ring is the treble level.

EQ01 4K/AP

Same features as the EQ01 4K but with a passive tone control in lieu of stack four.
The single pot passive tone features a push/pull active passive switch. The tone control works in both active and passive modes. Passive is a full bypass even when the battery dies the passive section will still work.

EQ01 5K

Same features as the EQ01 4K with the addition of:
Single five: Passive tone with active/passive on the push/pull

When the active/passive/tone pot is added, the volume/blend continues to work in both active and passive modes. When the bass is put into passive mode, the filter stacks have no effect on the sound. The passive tone pot can be used to shape the sound in both passive and active modes. The passive section completely bypasses all active sections in the pre-amp, so even without power the bass will continue to work in passive mode.

Instructions for the EQ01 can be found at the link below.

Uni-Pre – Passive Mode

• Active/Passive mode is selected via the push-pull toggle switch on the tone control.
• In Passive, the active circuit is bypassed and the signal is passed directly to the jack.
• When active is selected this brings preamp circuit into operation.

Uni-Pre – Active Mode

• Volume Knob sets the output level for both active and passive paths.
• The Blend Knob sets both the active and passive blend mix for the pickups: ACW for bridge pickup alone and CW for the neck pickup alone. A click midway gives and equal mix of both pickups if they are balanced. Internal Gain Trims, 0-12dBs, allow the pickup levels to be adjusted and/or matched.
• Bass Boost/Cut or Boost only – set according to Jumper Link on circuit board. Controls the level of low end content according to the ‘Bass Window’ settings on the on the circuit board, described later. A centre click is included.
• Treble (Pull for Bright)/Cut knob, controls the higher frequency spectrum according to the setting of the internal Treble Shelf Frequency adjustment. Pull for Bright, adds ‘high end sizzle’ sheen. A neutral setting is provided with a centre click.
• Mid controls the level of Mid Boost/Cut at frequencies according to the setting of the Mid Frequency knob. A neutral setting is provided with a centre click on the upper Boost/Cut knob.
• Tone Roll-off, set CW for no effect. Adjust ACW in order to mellow the treble and fully backed off for the ‘darkest’ sound. Push-pull google switch, pull for the Passive Signal path which consists of the Volume, Blend and Passive Tone. Push in the full Active Signal path.