Single Driver Loudspeaker featuring the DFR8 full range driver in an ultra-flex cabinet design.

Crossoverless wide range performance from 50Hz ~ 25kHz.

A true 99 dB 1w/1m efficiency!

Incredibly big and open sounding with no midrange shout.

Uncanny speed makes it comparable to a good electrostatic panel.

Good weight and balance make it more than usable on it's own without a sub.


If you've steered away from single driver speakers because of the typical tipped-up response and in-your-face sound, this is the exception you've been looking for.


 natural oak finish

The Nibbelin Ultraflex are similar in sound to an open baffle but have bass with good weight and tone.   In the midrange the cabinet design acts like a one-way valve (check valve) over a large band of frequencies.  Sound inside the cabinet exits instantaneously leaving little to no sound to reflect back to the driver.

High band frequencies are handled by foam spheres placed inside the cabinet in a vertical line to eliminate all parallel surfaces. The actual number of spheres can be adjusted to taste.

The result is simply the most non-congested sounding cabinet you've ever heard next to an open baffle.  Very nice balance, non-peaky, non-beamy, great tone and an absolutely huge wall of sound with excellent depth and no holes.

The efficiency is conservatively rated on this speaker making it a great choice with fine low power tube gear.  At the same time it does some pretty impressive things with bigger amps.



 NFX Ultraflex Speakers

  $1795.00 PR

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Natural Oak
Natural Walnut
Natural Cherry
Natural Maple



You may also request a custom finish such as exotic woods, or even painted white or black.

There is no 30 day trial or refunds on custom finishes.  Custom finishes typically add $250.


  • 99 dB with 1 watt at 1 meter
  • 58Hz ~ 20kHz flat
  • 48Hz ~ 25kHz -3dB
  • 8 ohm nominal impedance
  • Crossoverless
  • 2 ~ 60 watts
  • Max SPL 115 dB
  • Size 12.5" wide, 17" deep, 42.5" high
  • Ultraflex cabinet
  • Available in Satin white or black
  • No Grill
  • 5 way recessed binding posts on rear
  • 8 inch full range driver with phase guide
  • Shipping weight 45 lbs. ea.
  • 5 years on drivers and cabinets
  • 30 day money back trial




Even experienced woodworkers tear their hair out when building this cabinet but if you're up to the challenge we have the plans and the drivers!

Plans are available for instant download for $10

Get a redemption number
(used for your password)
to access the plans below.

(in .pdf format - requires Acrobat Reader to view and print)

NOTE: Your user name is the word "  private  " in all lower case.  Your redemption number is the password.





Please allow 6 to 8 weeks for delivery.  Speakers come with a 30 day money back trial.
Your card is charged when the order is completed and has shipped.

Oversees and custom orders are non-refundable.



Decware is a trademark of High Fidelity Engineering Co.
Copyright © 1996 1997 1998 1999 2000 2001 2002 2003 2004  2005 2006 2007 2008 2009 2010
by Steve Deckert