Custom Filters & Firmware Updates

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Installing a Custom EQ Filter:

To add a custom low-pass filter to your BalancedForce subwoofer:

  1. Download the appropriate zipped file to match your main speakers.
  2. Unzip and save the custom low-pass file in the root directory of a USB flash drive (a USB flash drive was included with your new subwoofer, but any flash drive 32GB or smaller should work)
  3. Insert the flash drive into the USB Input on the back of the subwoofer. The subwoofer will automatically find the file and load the custom low-pass filter.

To assure a successful upload to your subwoofer we recommend having no other files or folders on the flash drive—the subwoofer can only load one file at a time. Please review your subwoofer's manual for more information.

Why do some BalancedForce custom filters have multiple options?

One of the benefits of adding a subwoofer to a speaker system is to relieve your main speakers from having to play low bass. It has long been a common practice for MartinLogan to provide a bass control on our floorstanding speakers. Some early MartinLogan speakers adjusted bass by minus 3dB. More recent models with PoweredForce woofers allow adjustments of plus or minus 10dB.

The woofer sections of MartinLogan speakers are equalized to extend the bass response of their low frequency drivers. This equalization causes power from your external amplifier to be delivered to the woofers. Turning the bass control on the speaker to minus 3dB or minus 10dB (and letting the subwoofer fill in) relieves the load on your external amplifier, delivers more power for the upper bass and midrange, and allows the speakers to play louder. MartinLogan BalancedForce custom filters allow you to experiment and determine which method works best for you—letting the speakers play low bass to their fullest capability or letting the external subwoofer fill in. There is no right answer regarding which option to use. As always, we recommend that you try both options and trust your ears.

Model Filter File (click to download) Additional Description
Aeon Aeon(i).zip Aeon / Aeon i filter
Aeon i Aeon(i).zip Aeon / Aeon i filter
Aerius Aerius(i).zip Aerius / Aerius i filter
Aerius i Aerius(i).zip Aerius / Aeruis i filter
Ascent Ascent(i) -3dB.zip Ascent / Ascent i filter (with bass control set at -3dB)
Ascent Ascent(i).zip Ascent / Ascent i filter (with bass control set at flat)
Ascent i Ascent(i) -3dB.zip Ascent / Ascent i filter (with bass control set at -3dB)
Ascent i Ascent(i).zip Ascent / Ascent i filter (with bass control set at flat)
Clarity Clarity.zip Clarity filter
Classic ESL 9 Classic ESL 9.zip Classic ESL 9 filter
CLS II CLS2(a)(z)_BassAssist.zip CLS II / CLS IIa / CLS IIz filter (augmenting speaker's low frequency response below 80Hz)
CLS II CLS2(a)(z)_PlayBelow.zip CLS II / CLS IIa / CLS IIz filter (matching speaker's natural low frequency response)
CLS IIa CLS2(a)(z)_BassAssist.zip CLS II / CLS IIa / CLS IIz filter (augmenting speaker's low frequency response below 80Hz)
CLS IIa CLS2(a)(z)_PlayBelow.zip CLS II / CLS IIa / CLS IIz filter (matching speaker's natural low frequency response)
CLS IIz CLS2(a)(z)_BassAssist.zip CLS II / CLS IIa / CLS IIz filter (augmenting speaker's low frequency response below 80Hz)
CLS IIz CLS2(a)(z)_PlayBelow.zip CLS II / CLS IIa / CLS IIz filter (matching speaker's natural low frequency response)
CLX CLX.zip CLX / CLX Art filter
CLX Art CLX.zip CLX / CLX Art filter
EFX EFX.zip EFX filter
ElectroMotion ESL ElectromotionESL.zip ElectroMotion ESL filter
ElectroMotion ESL X ElectromotionESL-X.zip ElectroMotion ESL X filter
Ethos Ethos-10dB.zip Ethos filter (with bass control set to -10dB)
Ethos Ethos.zip Ethos filter (with bass control set to 0dB)
Expression ESL 13A Expression ESL 13A (Bass Augment).zip Adds deep bass to the 13A running full range. Augments the 13A’s output.
Expression ESL 13A Expression ESL 13A (Bass reduced 10dB).zip Designed to be used with the 13A bass control set to -10dB. Creates an actual crossover.
Impression ESL 11A Impression ESL 11A (Bass Augment).zip Adds deep bass to the 11A running full range. Augments the 11A’s output.
Impression ESL 11A Impression ESL 11A (Bass reduced 10dB).zip Designed to be used with the 11A bass control set to -10dB. Creates an actual crossover.
Monolith III Monolith IIIx 30Hz 0dB.zip Monolith III with IIIx Crossover (with 30Hz set at 0dB)
Monolith III Monolith_IIIp.zip Monolith III with IIIp Crossover (with bass contour set to Out)
Monolith III Monolith_IIIx_50Hz_-4dB.zip Monolith III with IIIx Crossover (with 50Hz set at -4dB)
Montage Montage.zip Montage filter
Montis Montis-10dB.zip Montis filter (with bass control set at -10dB)
Montis Montis.zip Montis filter (with bass control set at 0dB)
Mosaic Mosaic.zip Mosaic filter
Motion 10 Motion 10.zip Motion 10 filter
Motion 12 Motion 12.zip Motion 12 filter
Motion 15 Motion 15.zip Motion 15 filter
Motion 20 Motion 20.zip Motion 20 filter
Motion 35XT Motion_35XT.zip Motion 35XT filter
Motion 40 Motion 40.zip Motion 40 filter
Motion 60XT Motion_60XT.zip Motion 60XT filter
Motion LX16 Motion LX16.zip Motion LX16 filter
Odyssey Odyssey.zip Odyssey filter (with bass control set at flat)
Preface Preface.zip Preface filter
Prodigy Prodigy.zip Prodigy filter (with bass control set at flat)
Purity Purity.zip Purity filter
Quest Quest(z) -3dB.zip Quest / Quest z filter (with bass contour switch set to -3 dB for Quest or -5dB for Quest Z)
Quest Quest(z) Flat.zip Quest / Quest z filter (with bass contour switch set to flat)
Quest z Quest(z) -3dB.zip Quest / Quest z filter (with bass contour switch set to -3 dB for Quest or -5dB for Quest Z)
Quest z Quest(z) Flat.zip Quest / Quest z filter (with bass contour switch set to flat)
Renaissance ESL 15A Renaissance ESL 15A (Bass Augment).zip Adds deep bass to the 15A running full range. Augments the 15A’s output.
Renaissance ESL 15A Renaissance ESL 15A (Bass reduced 10dB).zip Designed to be used with the 15A bass control set to -10dB. Creates an actual crossover.
reQuest ReQuest flat.zip ReQuest filter (with bass contour switch set to flat)
Scenario Scenario.zip Scenario filter
SL3 SL3 -3dB.zip SL3 filter (with bass control set to -3dB)
SL3 SL3 flat.zip SL3 filter (with bass control set to flat)
Source Source.zip Source filter
Spire Spire -10dB.zip Spire filter (with 35Hz level control set to -10dB)
Spire Spire.zip Spire filter (with 35Hz level control set to 0dB)
Summit Summit 25-10dB.zip Summit filter (with 25Hz level control set to -10dB and 50Hz level control set to 0dB)
Summit Summit 25_50-10dB.zip Summit filter (with 25Hz level control set to -10dB and 50Hz level control set to -10dB)
Summit Summit.zip Summit filter (with 25Hz level control set to 0dB and 50Hz level control set to 0dB)
Summit X SummitX 25-50 -10dB.zip Summit X filter (with 25Hz level control set to -10dB and 50Hz level control set to -10dB)
Summit X SummitX 25Hz-10dB.zip Summit X filter (with 25Hz level control set to -10dB and 50Hz level control set to 0dB)
Summit X SummitX.zip Summit X filter (with 25Hz level control set to 0dB and 50Hz level control set to 0dB)
Theos Theos.zip Theos filter
Vantage Vantage -10dB.zip Vantage filter (with 35Hz level control set at -10dB)
Vantage Vantage.zip Vantage filter (with 35Hz level control set at 0dB)
Vista Vista.zip Vista filter

Firmware Updates

Updating your Subwoofer's Firmware:

Please note, the subwoofer will load whichever firmware revision is on the connected flash drive—even if the firmware revision on the flash drive is older than what is currently loaded on your subwoofer. The latest version of the firmware is available on this page.

To check which revision your subwoofer currently has installed, press the Custom Low-Pass button and hold it for 3 seconds. The Tone Sweep LED light will blink a number of times that is equal to the current revision number (e.g. two blinks = revision 2 firmware).

Please note, updating the firmware should not erase settings for PBK (Perfect Bass Kit) and the Custom Low-Pass filter. A notice will be posted on our website alongside the firmware download if, for some unforeseen reason, a specific firmware revision must erase these settings—otherwise, these setting should still be in place after a firmware update.

  1. Download the latest firmware file for your subwoofer model. Save the firmware file in the root directory of a USB flash drive (a USB flash drive was included with your new subwoofer, but any flash drive 32GB or smaller should work). To assure a successful upload to your subwoofer we recommend having no other files or folders on the flash drive—the subwoofer can only load one file at a time.
  2. Unplug the subwoofer from the AC outlet.
  3. Insert the flash drive into the USB Input on the back of the subwoofer.
  4. Reconnect the subwoofer to the AC outlet. The USB Status LED will continually blink red-green-red-green while the firmware is being updated—this blinking may pause momentarily during the update. Do not remove the flash drive until the LED stops blinking and shows a solid color for at least 5 seconds.

Please review your subwoofer's manual for more information.

Model Filter File (click to download) Additional Description

Uncompromising performance. Unflinching accuracy. Unwavering reliability. Harnessing the myriad technical advantages of electrostatic principles to recreate sound in its truest form—this is what MartinLogan is all about.