What Horn should I use? When distance mater

Introduction

We strongly recommend to read the Acoustic Q/A section before reading this article.

The guide diagram can help you too:

Here we will see how to choose a type of horn and an opening coverage according to our listening distance.

As we said in Q/A section, in a room around half of the energy comes from the reflection on walls, that means if we aren’t at 50/50 or 60/40 between the direct sound from the speaker and the walls reflection that will not be optimal.

We have at our disposal several Constant Directivity horns, we will choose them according to listening distance and usages.

In one words more we are close more we will “open” the coverage angle and more we are far more we will “close it”, of course we stay in Constant Directivity in all cases.

Close distance, aka Monitoring usage

We are here bellow 2 or 2.5m (7 or 8 feet), we need to open the coverage to 110° or 100° with a device that can go low without need to be “loaded”.

So we use a tweeter in a wave-guide with a phase plug, we have developed our own FEA driven phase plug technology, ReShape© :

Use with tweeters for 6.5/7.5/8/10" wave-guide.

Medium distance

Here we enter in compression horn usage with a 90° coverage for a listening distance between 2.5m and 5/6 m (from 8 to 17/20 feet).

Accessible solution:

The OS horn is relatively accessible, it can be completely printed or partially with a direct integration in the front baffle, we can use 1" compression driver from BMS or 18Sound with a 8 or 10" woofer from Wavecor or PURIFI.

We use our specific integration of the OS formula, there is a custom curve vertically for improve loading and the round to rectangle transition is FEA driven.

state of the art solution:

The bi-radial horn with fins will bring here several advantages: We can cut lower and we have a constant SPL behavior. It’s a high end solution, the lower control of the horn, the usage of a 1.5" horn with pinch and the constant SPL behavior will completely change the listening experience.

We will use 1.4 or 1.5 compression driver such as 18Sound ND3N, TAD TD4003, TAD TD4002, JBL 2450SL. We can use 12/14/15" woofer with it, the speaker will be a lot bigger.

2 ways with a 15 or 14" woofer with a subwoofer or 3 ways with 12+18" without subwoofer like this :

Note : TH-4003 horn can be used here in some particular cases.

Long range distance

From 6m (20 feet) we need to restrict radiation, 70° or 80° horn is used.

We have developed an improved version of the TH-4003 and we can generate any size/throat and use a coverage of 70 or 80°.

It can be Apaxial (different coverage angle between top and bottom):

Ideally with 1.4/1.5" compression drivers and it can also be used as a pure medium horn with the JBL CMCD 8" in this case of usages:

These big 3 ways will be use at a further listening distance, after 9/10m (30 feet). The 2 ways with subwoofer will work perfectly for 6m (20feet).

Stadium usage, Music Festival

Use Line Array :).

Tiny line array cannot be cross low with the subwoofer line, as the height of the line define how low the plane wave radiation will be, so the bigger the better.