Powered Subwoofer


Discontinued, here for archive only

10" high excursion  subwoofer and 250 Watt dedicated amplifier designed for single subwoofer applications
in small listening rooms and subwoofer arrays in larger  listening rooms.


    The chicken, the egg, and the chicken coupe all arrived at once.

    The vast majority of subwoofers available today were designed using  existing drivers and plate amplifiers, hence the designers were unable  to take a system-oriented approach to engineering the product.

    The North Creek approach is to define the optimum parameters first, then design the system to meet those parameters.

    The North Creek Poseidon subwoofer was conceived of as a system. The driver, the amplifier and the cabinet were optimized together to fulfill our design goals, providing the cleanest, tightest, most  articulate deep bass we have heard. We feel the North Creek Poseidon to  be the ultimate statement in small subwoofers for today's most demanding applications.

    Design Goals:

    For a subwoofer to perform optimally in both two channel and home theater applications, it must:

  • 1) Be capable of considerable output down to 25Hz
  • 2) Reproduce high SPL at very low frequencies without overloading
  • 3) Not self-destruct under subsonic overload
  • 4) Cleanly reproduce mid-bass up to its high end cut off frequency
  • 5) Third order roll off at the top end to mate cleanly with the main speakers
  • Both the front-firing and down-firing version of the Poseidon share  the same driver, the Peerlexx XLS-10, a design with enormous strength  for a very low Qts, a self-cooling voice and extremely high excursion  capability. The combination of the and our acoustic suspension cabinet  yield a Qtc of about 0.30 in the neighborhood of 30 Hz. The central  benefit of acoustic suspension loading is that it provides the lowest  distortion at high excursion, hence the cleanest deep bass, while  limiting driver excursion below resonance. In this application, the  driver/cabinet combination is 10dB down at system resonance, and the low Qtc means cone motion is optimally damped.

    Matching this driver/cabinet combination is our 250 Watt dedicated  amplifier, which combines 6.5dB of bass boost at 25 Hz and a third order subsonic roll off. The product of the amplifier and driver/cabinet  transfer functions yield a system exhibiting frequency response that has a very gentle 2dB frequency contour from 75 Hz to 25Hz, a -3dB point of 25Hz, and a fifth order roll off below 20 Hz. The possibility of  overexcursion is eliminated by the amplifier high pass roll off, and the woofer motor is capable of thermal dissipation up to the amplifier's  power limit.

    The high frequency low-pass section of the amplifier is also third  order, switch selectable at fixed frequencies (55, 80, 100, 140 Hz,  bypass). Switch selectable is superior to "infinitely variable" low-pass crossover frequencies because it allows the left channel to be  precisely matched to the right channel, and incorporates much better  sounding discrete components. Likewise, the third order slope is a good  match to acoustic suspension satellites and a perfect match to aperiodic and first order high-passed satellites.

    All told, the North Creek Poseidon subwoofer system provides  exceptionally dynamic, clean deep bass, a tight mid-bass, and rolls out  quickly to allow the satellites to perform at their best. The system design approach has yielded a subwoofer that surpasses all of our  design goals while eliminating the shortcomings of subwoofers designed  using existing drivers and amplifiers.

    The Poseidon kit includes the Peerless XLS-10" driver, dedicated  amplifier, cabinet stuffing, NCMS soft glue, Big Toe spikes, and all  required mounting hardware. Everything except the wood.


Discontinued, here for archive only

  • Driver Features Poseidon_and_amp
  • Heavily Ribbed Cast Aluminium frame
  • Reinforced Paper/polymer cone
  • Half-roll Rubber
  • Massive Motor Structure
  • High Excursion
  • Extremely low resonance
  • Suitable for Acoustic Suspension applications only
  • Poseidon Woofer Theile-Small parameters:
    Re = 3.40 W
  • Fs = 18.9 Hz 1.5 Hz
  • Qts = 0.17
  • Qes = 0.18
  • Qms = 2.63
  • Vas = 3.17 cubic feet (89.73 liters)
  • Sensitivity = 88.4db (2.83V, 1 meter)
  • H = 33mm (voice coil height)
  • G = 8mm (gap height)
  • Xmax = 25mm p-p
  • Suggested alignments:

    Acoustic Suspension, Vab = 1.5 cubic ft., Qtc = 0.30, fc = 33 Hz.
    This alignment is optimal for most plate amplifiers that offer 6dB of  bass boost below 30 Hz in smaller rooms where extreme volume levels are  not required. Vented box alignments are not suggested for the downfiring version of this woofer as no overexcursion precautions are taken - the  cone travel is linear all the way to the back plate.

    Amplifier Features

  • 250 Watt class AB amplifier.
  • Heavy Aluminium Plate with Large Heat Sink
  • Plastic sub-enclosure isolates amplifier from acoustic chamber
  • Fixed third-order high pass with 6dB of boost at 25 Hz.
  • Switchable third order low pass (55 Hz, 80 Hz, 100 Hz, 140 Hz, bypass)
  • Switchable Absolute Phase
  • High and Low Level inputs

"Hi, George..Moonhawk_Subs_and_Ikemos

Here's a photo of my finished Ikemo's and Poseidons. It was a long haul getting them done, but well worth it.

I'm currently running the Ikemo's as mains and side surrounds, while I contemplate  which kits to build for the mains and center channel, but even running  what is probably your lowest priced speaker, the sound is fabulous. I'm  inclined towards the Vision Signatures and Vision-C Signature, so I  imagine the upgrade will be remarkable.

These are just as advertised...Musical, large soundstage, well balanced, and  great full range sound with the addition of the Poseidons. The level of  detail is wonderful. It's nice to enjoy listening to music again, and  the home theater experience is terrific.

It is a pleasure to work on a project where you can communicate so readily with the designer, and get help with questions that arise in the course of construction. The woodworking aspect was great fun, and the reward  at the end beyond satisfying.

Looking forward to future projects,

Dave C.

La Madera, NM"