Basshorn (Pt III) – construction and completion

Low frequencies carry most of the energy and power in music, so a Basshorn needs to be constructed as rigidly as possible, with the minimum of resonances that colour the music.

This Basshorn is large, so very thick panels would be heavy and even more impractical.

In principle I prefer to brace & stiffen thin panels, rather than use thicker & heavier sheet material.

Plywood is lighter with better strength-to-weight ratio than MDF or ‘chip-board’ – in my experience, it sounds better too.

The design in principle: (see also Midhorn + Basshorn (Part 2).)Mid-Basshorn-061115b

This Basshorn is made in 2 parts – (1) bottom Basshorn Mouth, (2) upper Folded Horn-Driver Chamber-Throat.

1)  Basshorn Mouth:

True corner loading – floor + 2 walls.




Side panel double-wall, box-construction with internal ‘skeleton’ frame – 12mm plywood.



The bottom bend is curved 90 degrees in 3 directions – using Bendy Ply (see below).


The ‘Bendy Ply’ (flexible, bendable plywood) is 9mm thickness (used in single & double layers).

Bendy Ply

2)  Upper Folded Horn:




First layer, 9mm Bendy Ply.


Second layer, 2 x 9mm Bendy Ply


Driver Rear Chamber (throat chamber) + first horn section.




Front panel added – with driver mounting hole. Note that the internal horn cross-section is kept as ‘square’ as possible throughout.


Rear panel access-hole for Driver Rear Chamber.


Driver Rear Chamber (throat chamber) – with front and rear access holes.


Side panels added – 18mm plywood.


Double layer top curve (2 x 9mm) Bendy Ply) + sloping front panel.


The sloping front panel is stiffened internally and….


…also to form an internal curved horn flare.


External Stiffening Ribs were added to the large rear panels – top and bottom.

DSC00875 crop

Test assembly of the top & bottom parts.


The completed Basshorn (hypex), with Midrange Horn (tractrix) attached – and tweeter later added.

11 thoughts on “Basshorn (Pt III) – construction and completion

  1. Hi there
    Great work here! I’d love to find out more about this project as I’m about to embark on my Horn Adventure….
    Could I possibly email you direct to discuss more?

    Regards Dave

  2. Owen, now that you have lived with these horns for a while, do you notice any “phasey” sound or issues in the region where front horn transitions to the delayed sound from rear horn? I understand it’s around 150hz? How does the sound of SEAS FA22RCZ compare to Lowther in that horn? Very interested because I’m planning of starting a similar design.

    • Hi Herman – no problems with bass output, to my ear – I think the idea of the LF response lagging behind is not what is heard IMHO – my explanation is that sound waves inside the basshorn do not travel as in free air, the horn air is pressurised & I think that the basshorn output is thus not delayed as one might think.

      (I do have a response dip at ~1kHz which may be a cancellation between front horn output & basshorn out-of-phase output.)

      The front horn has a design Fc of 140Hz – however the output tends to start rolling off around 1/3 octave higher, ie. 180-200Hz. The basshorn upper roll off I think starts from 140-150Hz – but I need to measure it, with REW I hope soon.

      The Lowther technically is suitable than the SEAS for horn loading, however I find that the SEAS works very well. I gave up on Lowthers because of cost, maintenance required, foam surround deterioration. The SEAS has noticeably warmer tone. These drivers with whizzers can have an upper mid resonance, intermodulation(?), slight ‘glare’ at loud peaks & I have slightly damped the SEAS whizzer with a small pc of foam plastic. The FA22RCZ is great value, a h quality driver, I’m still happy with it.

      Keep me advised about your progress – happy to learn from others!

  3. Pingback: Midhorn + Basshorn (Part II) | D a r k L a n t e r n

    • Hi Kenny – Thanks for visiting!
      Check modelling also with varying throat size/horn length, to optimise LF response for your driver. Also rear chamber vol. Interested in your construction & results.
      I am using SEAS FA22RCZ drivers presently & larger throat/shortened basshorn would be a better fit for these.
      Cheers, Owen

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