(These are not for sale separately).

Horns are the tough part and the hardest thing to build to make full use of the TAD TD-4001 driver.
This is were most projects fall short and where I started this blog.
A compression driver and a horn should be seen as one piece, and are designed together, it is illusory to think that things can be mixed and matched. The requirements for the TD-4001 are very specific and there is next to zero lee-way. Both have to 'clic' acoustically and mechanically like two matching puzzle pieces.

The throat contains vertical fins that will dampen and control the behaviour of the diaphragm (The 'load' in 'horn-loaded') and prevent resonances and distortion but this very specific curve will also flatten the frequency response.

The fins give very good dispersion of the high frequencies and remove the narrowing of the beam at high frequencies that makes most horns tiring to listen to. These horns will give a comfortable listening position over a wide area, not just a single chair perfectly centred. I call them 'four-seaters'.

The solid plywood construction is non-resonant, very heavy and doesn't have the acoustic reflexions found on horns with a hard surface like metal or even plexiglass.

CNC helps doing the heavy lifting of cutting hundred of small parts and I created files with dowell-pin registration so that parts stay positioned while glueing and under clamping force. Each throat is hand sanded to match the mounting plates. Any imperfection in the throat can cause distortion.

The fins are necessary to realise the full potential of the TAD TD-4001.

Bi-radial profile: The sides are curved not flat, making the horn hard to build.

The fins are a lot of work but essential.

Sides are reinforced with a vertical panel, note that the inside profile is a curve.

Fins will distribute high frequencies over a wide listening area.