Wood Horns
square tractrix horn
s for compression driver


SYNOPSIS

Design:
- Wood
- Square tractrix
- Cross 500Hz@18dB

Goals:
- Complete main system and match up with 515C/TL16H
- 4" Compression driver
- 100dB+
 

Weird story... I was already contemplating getting back into audio and wondereing what to do with the remainder of my system. Having looked around and not wanting to spend a fortune straight away, I had kind of set my sights on the Tangband W8-1772 to replace the AER units and Oris horns I sold a while back. It would be a shoe-in for a future upgrade back to AER or something else. While skipping over google and youtube for info about the 1772, I happened on a youtube video by Kenrick Sound in Japan featuring a 3-way system using a 15" bass cabinet, a wood fronthorn with JBL 375 and a plasma tweeter on top. It was playing "Moroder by Giorgio" by Daft Punk... and I was sold.... Love at first sight. It was the right song, the right looks and the right sound as far as you can use a youtube video to judge.

Still having my bass cabinets with 15" Altec 515Cs and a pair of Visaton TL16H, I was 2/3 of the way there to a similar setup already. The heart wants what the heart wants, so I did a binge search on info about the JBL 375s that Kenrick used only to find that this is a collector's item now, going for insane prices. Asking around the 375 was the commercial version of the JBL 2440 and most people actually preffered the 2441 or newer versions. The 2440/2441 are the AlNiCo magnet versions to the 2445 Ferrite and 2450/2451 Neodymium. The higher numbers just refer to a newer version and not a lot has changed to the phase plugs, meaning the newer versions would be attainable within a 500 budget, as that is about what the 24450/2451 are going for on the used market. After some checking the 2451 has the same magnet as the 2450, but no longer has the long throat of the 2451 (dating back to the old AlNiCo units with longer pole pieces/motors. The 2450 has a longer throat going from the 1.5" phaseplug opening to the standard 2" opening; the 2451 does away with this long throat and exits right after the phase plug at 1.5". I will need to keep this in mind if I am to use existing designs for this project.

Besides the neo magnet and short throat, the new units all use titanium diaphragms, which almost everyone seems to hate because of the way they sound when they break-up over 7-8kHz. The reason the 375/2440 is so popular seems to be the aluminium diaphragms that were used originally. As there is no alu replacement from JBL that I am aware of, most people seem to go for a replacement offering by Radian. Not as expensive as original JBLs, but quite a bit more expensive than the 25 diaphragams on ebay.


LOG


16-0-2017

Scouring E-Bay I found a clean pair of 2451s for around 300 and before I knew it there was a "thank you for your purchase" message on my screen. Dammit!!!!! Cool!!!!  You know that mixed emotion of guilt and pleasure ;)   A set of Radian 1245-16 alu diaphragms were ordered soon after to complete the set of compression drivers at just over 500.

 

29-09-2017

The JBL 2451s arrived today. These suckers are stil pretty big and heavy, I'd hate to see the 2445 or 2441 if the 2451 is anything to go by. 

 


Jim de Kort