11 September 2011

BK-12m Folded Horn Kit - Fostex FE126En

There is a new high-sensitivity folded horn speaker kit being offered by Madisound.  The new BK-12m is a single-driver folded horn speaker kit that follows in the lineage of the BK-16 and BK-20 designs.  The BK-12m uses the Fostex FE126En full-range speaker driver in a custom folded horn enclosure while the driver is run full range with no filters whatsoever.  The Fostex FE126En driver is 4.7" (120 mm) in diameter with a rated sensitivity of 93dB/W(m).  This high-sensitivity means that the BK-12m speakers will be suitable for use with low powered amplifiers.

BK-12m Folded Horn Kit - Fostex FE126En
The enclosure panels are made using high quality 5/8" (16 mm) thick Baltic Birch multiplex cut using a CNC machine and bundled as a flat pack.  Once completed the speaker cabinets have overall dimensions of 31-5/8" x 7-1/4” x 14-1/2" (800 x 185 x 370 mm).  The Birch plywood is unfinished so you can finish the speakers how you like.

The BK-12m speaker kit includes:
  • 2 x Fostex FE126En 4.5" Full Range Drivers;
  • 2 x Unassembled, unfinished Baltic Birch Cabinets;
  • 3 oz. Acousta-Stuff internal damping material;
  • 5 ft Supra Classic 1.6 15 AWG speaker wire;
  • 4 x QC187 Quick Connects (2 red, 2 black);
  • 8 x 8X1 Socket Head Wood Screws (8x Philips Head wood screws also included);
  • Assembly Instructions.
To put the kit together you will need just a screwdriver, wood glue, sand paper, bar clamps and binding posts.  An inside view of the folded horn speaker enclosure is shown in the photo below.
Inside - BK-12m Horn Speaker Kit - Fostex FE126En
 The BK-12m kit is available from Madisound for $315US + shipping.  For full details about the BK-12m speaker kit see the product page at Madisound.

More single-driver speaker kits and projects:

05 September 2011

DIY 2-Way Tower Speakers - Ion

Adam has put together a fantastic looking pair of tower loudspeakers and he has shared his design with us.  The speaker design uses a Tang Band 25-1372SC 1" inverted titanium dome tweeter combined with a pair of Audax HM170CO 6" woven carbon fiber mid-woofers and used in a TMM configuration.

DIY 2-Way Tower Speakers Audax HM170CO Tang Band 25-1372SC

The loudspeaker enclosures are constructed using 1.5" thick MDF with solid oak side panels. The overall dimensions of the tower speakers are 37.5" x 8.5" x 11.5" with each weighing about 60 pounds.  The MDF is painted with a textured graphite spray and the side oak panels are stained.

Speaker Box Assembly with Straps
Test Fitting the Drivers
A 2-Way passive crossover dividing network consisting of a 3rd order Butterworth filter at 4000 Hz is used along with an impedance correction network.  The nominal impedance of the speakers is noted at 4 ohms and the loudspeaker covers a frequency range of about 60 Hz to 20 kHz.  In-room you will get some additional bass extension (shown on the in-room measurements).  The total cost for the pair of tower loudspeakers was about $900 US.

Adam reports that the Ion speaker build is his favorite so far.  "The Audax HM170CO woofers produce very warm natural tones up through the upper midrange. With the TangBand 25-1372SC tweeter the highs are crystal clear, detailed but far from harsh.  The Ion speaker is a very challenging build but it comes with a huge payoff! These have quickly become my favorite loudspeakers."  Great work Adam and thanks for sharing your work.

For the full details of Adam's speaker project see the Ion - DIY 2-Way TMM Tower Loudspeaker Project page.

More DIY Speaker Projects by Adam