Betsy / Eminence Alpha 15 A

Update: These were dismantled and replaced by a completely different design. After some critical listening I decided that neither bass response nor treble was to my full satisfaction. 

These are my current Open Baffle  speakers. The drivers are a Wildburro Audio Betsy and an Eminence Alpha 15 Woofer. Two bucket subs (not on the picture, see separate post) help below 45 Hz. 

The initial modeling was done using Martin King’s licensed worksheets. I then adjusted by ears. Betsy is high passed at 400 Hz 4th oder LR and lowered by 8db. The woofer is bandpassed 45 – 400 Hz 4th order LR and phase inverted. The sub’s work below 45 Hz and boosted by 12db. 


The speakers and the bucket subs (separate post) are driven by:

  • A small Line Driver with a volume control from Abacus Electronics
  • A Behringer DCX 2496 3-way digital crossover
  • A Behringer iNuke NU3000 DSP for the sub woofers
  • A DIY Gainclone (see separate post) for Betsy
  • A DIY Chipamp (see separate post) for the Alpha
  • The disc player is a Denon DVD 3910
  • At the bottom you see  Marantz Tuner



2 thoughts on “Betsy / Eminence Alpha 15 A”

  1. Hi Michael. I have built speakers using some of the same drivers as you (JX92S, Betsy, and Alpha 15A). My ongoing project is a open baffle loosely based on Troels Gravesen’s OB11 but usling Betsy and different dome tweeters. I have cheaply placed thme in a 2′ X 4′ MDF panel from Home Depot. What did you make your baffle board from? It looks like it could have been fabricated from a kitchen cabinet door of the right proportions or you may have made all by hand. I’d like to upgrade my baffle to something like you have. Thanks, Chris.

    1. Hi Chris,

      This just 26mm thick solid beech wood I got from a local shop. Nothing special. There is also a lot of bracing on the back of the baffle around the entire outside and horizontally across the middle. I used 44 * 44 mm beech wood for those.
      I think birch ply wood should also work well. On my next iteration I will try to laminate different types of timber as each kind reacts differently to resonances and provides different damping.

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