5 1/4" Benthic Passive Subwoofer

5 1/4" Benthic Passive Subwoofer

from 495.00

The 5 1/4" Benthic passive subwoofer receives its input power via a single speaker wire connected to the binding posts of an Outboard Subwoofer Amplifier (sold separately).

Whatever suits your intended room placement for your Outboard subwoofer amplifiers, your Benthic subwoofers will sound great because they get separated by a long speaker wire which allows them to be placed in the most space saving or acoustically advantageous spot in the room. Any place you put it, keeping the subwoofer amplifier and passive subwoofer in separate enclosures also keeps the subwoofer controls conveniently hidden from plain view, but still accessible to the stereo system owner for basic adjustments.

The outboard subwoofer amplifier inputs typically get driven by the main stereo amplifier by thin speaker wires. However, I suggest using the Anchor Chain high level input cable which gets biwired to either end of your existing pair of speaker wires going to the fullrange speakers (Marlins, Orcas, or Tritons).

Alternatively, you could feed the inputs of your outboard subwoofer amplifier’s RCA inputs via RCA cables like the Bowline RCA cables from any standard LFE outputs or the RCA outputs from any preamp. 

If your preamp is of the ultraminiature type like the original PS Audio Sprout I, and it only has a minijack pre level output, you can use any length of high quality RCA to 1/8” Minijack convertor cable like the Hammock line cable for this connection.

However you chose to drive it, Each Outboard Subwoofer amplifier has a single (mono) set of binding posts. A single Main sheet speaker cable should be used to connect the Outboard subwoofer amplifier to the Benthic Bass Unit passive subwoofer. 

Design notes:

The single Mainsheet speaker cable connection between each outboard subwoofer amplifier and passive subwoofer can sound good even if it is an abnormally long connection (above 30 or even 60 feet). Typical cable runs for the subwoofer speaker wire are between 8-12-16 feet of speaker wire running to each subwoofer. 

A single outboard subwoofer amplifier can power 1, 2, or even 4 separate benthic subwoofers. This allows you to stack benthic subwoofers on top of a component plinth for use as short or tall speaker stands underneath the Orca, Marlin, or Triton Fullrange speakers for a floor standing system.

*In order to get true stereo subwoofer bass support with any Blumenstein full range speakers, it is necessary to purchase at least two Benthic passive subwoofers and two corresponding Outboard subwoofer amplifiers.*  

With Orcas or Marlins, recommended power input is the 25 Watt Outboard subwoofer amplifier. 

With Tritons, the recommended power input is the 70 watt Outboard subwoofer amplifier.

An isolation plinth is recommended to go underneath with your Benthic subwoofer for optimal results with room loading.

60 day in home trial period. 1 year warranty.

Price is for a single passive subwoofer.

Ships worldwide from Seattle, WA.

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The flexible passive subwoofer system that facilitates flawless sonic integration with Orcas, Marlins, or Tritons.

Full range speakers have unique needs in terms of mating to any kind of subwoofer - active or passive. By mimicking the hookup methodology and cabinet construction practices for the sake of pure acoustics, putting large format passive subwoofer type performance into a smaller, compact, real-world package, attaining the kind of performance and seamless sonic integration from a compact unit that is typically reserved for much more expensive subwoofer setups. Like the Orcas, this subwoofer is designed for great bass at any volume level - even extremely low volume levels. This is by virtue of their unconventionally small paper cone subwoofer driver that has been taken to the extremes in terms of cabinet rigidity and carefully tuned acoustics.

All this combined effectively addresses the common issues of poor subwoofer sound quality by considering that subwoofers are important speaker enclosures in and of themselves, even though they are only covering the one or two octaves that the full range speakers (Marlin, Orca, Triton) don't cover.  Furthermore, the specific models of outboard subwoofer amplifiers offered fully support the sound quality possible from this passive subwoofer with the full range speaker models (listed separately).   


  • 11 3/4" x 6.5" x 8.75"
  • Passive subwoofers are compatible with any external subwoofer amplifier including the Outboard Subwoofer Amplifier models.
  • ~34hz response on the low end.  High-frequency roll off is set by the external subwoofer amplifier to mate with the acoustic roll off of the full range speaker.
  • (45hz for Triton, 90hz for Orca, 100hz for Marlin)
  • works well in either small rooms or large spaces
  • Can be networked into 4 pair arrays of subwoofers off of a single subwoofer amplifier 
  • Selection of any cabinet material will yield nearly identical acoustical qualities due to internal bracing

Design background

The New Benthic Bass Unit passive subwoofer is a completely redesigned Dungeness Deluxe+Dungeness Max combination model released in November, 2016. The Benthic Bass Unit now has solid Douglas Fir internal bracing, near golden ratio box proportions, A new, high excursion 5.25" subwoofer driver, and is a passive unit - which is acoustically ideal. 

All Benthic Bass Units are outfitted with a subwoofer-adapted full complement of parts found in the Depth of Field Enhancement Kit that goes into the full range speakers, as well as other enhancements native to this speaker design. These components were 10 years in development as of November 2016, but are applicable to older Blumenstein models via the Kit found here.

On the Benthic

The Benthic Bass Unit is named after the ecological region at the lowest level of any body of water. The Benthic region can extend very deep into the ocean, into its lowest depths. 

The Benthic Bass Unit subwoofer model attains a new level of performance and acoustic integration from a bookshelf subwoofer. Mainly, this happened by making them passive cabinets, with the same quality solid wood internal bracing as is found in the full range speakers. Additionally, the new Benthic Bass Unit's upgraded 5.25 inch woofer driver works with this passive, stiff-as-concrete-cabinetry to give an even quicker and more liquid presentation to the lowest regions.

The Benthic Bass Unit is really a "Best Of" Blumenstein Audio subwoofer.  

In mid-2016, I decided that I needed to make an ultimate, super compact, lower power subwoofer model in order to keep up with the recent enhancements to the sound quality in the rest of the full range lineup. So I went back, looking forward and borrowed my favorite features from the best Blumenstein subwoofer models from the past. I found an even more prodigious sounding and lighter woofer driver with an improved magnet, with stronger, lighter cabinet stiffening technologies borrowed from the Marlin, Orca, and Triton full range bracing topologies.  

Passive subwoofers are cleaner. Period. 

Passive Subwoofers are acoustically clear of any smear or drag to the mid-bass and lower midrange because of the dead weight of a subwoofer amp chassis is missing. A passive subwoofer can be hooked up to any commercially available subwoofer amplifier via the binding posts on the back of the enclosure (just like the Blumenstein full range speakers can be hooked up to any commercially available stereo amplifier).

Hassle Free Subwoofer Amplification

When hooked up to one of the new higher power Outboard Woofer amplifiers, the Benthic Bass Unit will completely disappear into the mix while simultaneously astonishing you with all those low notes you've never heard/felt so clearly. The point is, that because the Benthic Bass Unit is a passive, acoustically purist enclosure, it can only make the most out of any subwoofer amp that it is hooked up to.

Enhanced Active Crossover compatibility

The Benthic Bass Unit can be used to support a wide variety of loudspeakers and has been specifically voiced to be able to mate its prodigious bass support seamlessly with any of the full range speaker models (MarlinOrca, and Triton) when the Outboard woofer amplifier is given its appropriate recommended settings. (Recommended settings are supplied with each model upon purchase).

While the physical size of the Benthic subwoofer is the smallest of any we have ever built, its bass sound quality, power, convenience, ergonomics, longevity, and suitability to almost any environment is by far the best I've ever offered in the lineup. This is the one tiny subwoofer that does it all!

Additional Design notes:

The single Mainsheet speaker cable connection between each outboard subwoofer amplifier and passive subwoofer can sound good even if it is an abnormally long connection (above 30 or even 60 feet), and no other specialized cabling or setup is necessary to run such a long length.

**I recommend going long enough length for the subwoofer speaker wire, which in a typical room runs between 8-12-16+ feet of speaker wire running to the/each subwoofer. This allows you to go shorter for the sub amp input cables (like the Anchor Chain high level input cables - or the Bowline RCA cables - depending upon how your subwoofer amplifier's imputs are configured).

A single outboard subwoofer amplifier can actually power 1, 2, or even 4 benthic subwoofers. To power two Benthic bass unit cabinets, you'll need a second mainsheet speaker wire (*pin-banana terminated* for bi-wiring to the single set of output binding posts of the Outboard subwoofer amplifier) And for 4 Benthic passive subwoofers, you'll need a custom cable harness (Email to inquire).

*In order to get true stereo bass, it is necessary to purchase at least two Benthic passive subwoofers and two Outboard subwoofer amplifier monoblocks.*

-With Orcas or Marlins, recommended power input is the 25-Watt Outboard subwoofer amplifier. 

-With Tritons, the recommended power input is the 70-watt Outboard subwoofer amplifier.

-I recommend using an isolation plinth with your Benthic subwoofer for optimal results with room loading.