FractFins Bi-radial: Next Gen Bi-Radial Horn

Our next-generation bi-radial horn with fractional fins is designed for 1" and 1.4"/1.5" compression drivers, including models like the TAD 2001/2002/4002/4003, JBL 2450SL, and 18Sound ND3N/4015BE.

The Constant Directivity control pattern extends to higher frequencies, achieved through a slight, smooth constriction in the throat adapter, eliminating the need for a super-tweeter.

This horn follows the Hypex formula surface law and was developed using in-house Finite Element Analysis (FEA) simulations.

Older designs saw a reduction in the use of fins, which influenced our approach. As a result, the number of fins, the overall shape, and the throat adapter in this design differ from traditional horns like the Arai 480/290 or TH-4001.

This innovation resolves the “finger response” issue and incorporates our proprietary FractFins technology to further enhance energy distribution.

The FractFins technique allows precise tuning of energy in the initial degrees of high frequencies, ensuring a perfectly balanced tonal response.

This makes the horn our most complex design yet, addressing all the challenges of previous models.

Measurements show a horizontal Constant Directivity behavior. The dip and drop at 15/16 kHz are due to the breakup of the JBL 2450SL compression driver, not the horn.

A compression driver will lose its plane wave radiation behavior when the diaphragm breaks up, creating a cancellation at a specific frequency on its polar map. It will rise up again if enough energy is sent.

With JBL 2450SL, 1.5" :

With ND3T, 1.4" :

1.5 adapter + specific ND3 adapter to 1.5" :

1.4 adapter :

48cm version

Measurements were conducted using a HF1440 1.4" compression driver, which has a 3.4" diaphragm, The HF1440 exhibits a breakup frequency around 12kHz, which create to a slight dip at 12kHz on horizontal polar.

The horn can be made in this dimenssion either in 1" or 1.4".

Recommended crossover and drivers for 1" version:

18Sound 1095N: 900hz
TAD TD2001 or TD2002: 800hz

Recommended crossover and drivers for 1.4" version:

Faital HF1440: 750 hz

1.5"/1.4" 48cm version

Horizontal polar:

Vertical Polar (50° coverage at 5kHz) :

SPL before and after EQ:

The HF1440 will exhibit a similar response pattern when used with various constant-directivity horns.

Distortion at 95 dB SPL after a flat EQ across all bandwidths

1" 48cm version

Horizontal polar :

Vertical Polar (50° coverage at 5kHz) :

SPL before and after EQ:

Distortion at 95 dB SPL after a flat EQ across all bandwidths

How it compet versus Arai A480, Arai A290 and TAD TH-4001 ?

Here is a comparison of the horizontal polar patterns of the A480 and A290 under the same conditions.

The polar pattern is significantly improved on our next-generation bi-radial:

We can see throat and fin reflections on the Arai that are absent in our design. Additionally, the well-known midrange narrowing and beaming that are prevalent in Arai and TH 4001 horns, primarily due to the lack of full return and outdated fin management techniques, are not present in our design.

A290 (2" 64cm wide)

A480 (1" 44cm wide)

TAD TH4001 (2" 60cm wide)

Features

Respect ADAPT principle (Acoustic Constant Directivity Adapted to Psychoacoustic Technology)
Constant directivity behavior 90° on horizontal
huge loading capacity
No High-Order Modes (HOMs) due to hyperbolic horn expansion.
End of profile optimized for removing midrange narrowing/beaming
Throat 1" or 1.4"/1.5"

Specification:

Usage for free-air, an in wall/in-box version exists.

Width: 48 to 60cm
throat size: 1" or 1.4/1.5"
Total Length: depending on width, 30/36 cm
Horizontal coverage: 90°
Effective crossing area: 500/700hz depending to size

Wood finish

Each horn is divided in sides and top/bottom parts, mixing wood/finish is a good idea to have sides darker than the rest of the horn (fins are black), otherwise you can choose to have the horn in full dark or light color.

Our recommendation is to use in EU or US wallnut for sides

From lighter to darker :

Birch Plywood Varnish