4" fullranger (SN4-60F)
I've had the drivers for this project since 2014. I really need to get it done. Instead, I build endless test horns, scrap my prototypes and get distracted on other projects. Sometimes I think I should just buy an Azura horn for the mid-high section, build a simple ply / painted box for the bass drivers, and just call it a day.
Pictured (gallery format - click to expand the photos):
Pictured (gallery format - click to expand the photos):
- 3 (of many) drivers I tried
- An Ikea "Sekin" bowl is a nice match for 4" drivers
- Prototype enclosure using the Sekin
High efficiency (JBL) rig
This entry is more about shopping and horn theory than DIY. I'm waiting on delivery of a pair of horns and a 2nd driver (I have driver A, and am waiting on a diaphragm for driver B). Basically, it's a cheap version of the 2445J + 2386 horn combo (using a no-name horn which just happens to look a lot like the 2386).
The 2445J are big & beefy 13.8kg units. JBL claim they can handle 100 watts > 500Hz.
The 2386 horn is 45 cm across - about as wide as I am - and 36 cm long. JBL have stated that these can be used to 350 Hz.
My horn preferences are:
1) flare rate (throat angle) should match the driver
2) smoothly expanding (no slots, odd angles or parallel walls)
3) big enough to cross at 500 Hz
4) wide mouth (elliptical or rectangular - not round)
5) can be mounted on a baffle
The 2445J are big & beefy 13.8kg units. JBL claim they can handle 100 watts > 500Hz.
The 2386 horn is 45 cm across - about as wide as I am - and 36 cm long. JBL have stated that these can be used to 350 Hz.
My horn preferences are:
1) flare rate (throat angle) should match the driver
2) smoothly expanding (no slots, odd angles or parallel walls)
3) big enough to cross at 500 Hz
4) wide mouth (elliptical or rectangular - not round)
5) can be mounted on a baffle
Flare Rate
The 2445J (and similar) drivers have a low flare rate, stated by JBL to be <200Hz::
180Hz, in this interview
160Hz, in this technical note, which says (the underlining is mine):
"By our calculations, the initial flare rate in the older driver design was approximately 160 Hz, reflecting the need to drive the very large horns that were used in early motion picture systems"
This implies that nobody working at JBL can remember or find their original design specifications. This is forgotten lore for many users, too. Often an assortment of horns are recommended for use with a given driver, with no consideration given to which horn has the most suitable throat angle.
My own low accuracy measurement of a 2445J, (taken by sticking a ruler into the driver's throat), is a 5 degree throat angle.
Exponential flare (using the Hornresp software to give throat angles):
160Hz is 4.25 degrees
180Hz is 4.75 degrees
190Hz is 5 degrees
The 2445J (and similar) drivers have a low flare rate, stated by JBL to be <200Hz::
180Hz, in this interview
160Hz, in this technical note, which says (the underlining is mine):
"By our calculations, the initial flare rate in the older driver design was approximately 160 Hz, reflecting the need to drive the very large horns that were used in early motion picture systems"
This implies that nobody working at JBL can remember or find their original design specifications. This is forgotten lore for many users, too. Often an assortment of horns are recommended for use with a given driver, with no consideration given to which horn has the most suitable throat angle.
My own low accuracy measurement of a 2445J, (taken by sticking a ruler into the driver's throat), is a 5 degree throat angle.
Exponential flare (using the Hornresp software to give throat angles):
160Hz is 4.25 degrees
180Hz is 4.75 degrees
190Hz is 5 degrees
Smooth expansion
JBL literature for the 2386 horn decries " the performance disadvantages of horns that feature sharp flare transitions and flat sidewalls".
Some well regarded people who have contributed a lot of time to horn theory (e.g. Le Cleach and Geddes) agree, and have really hammered this point. Diffraction & discontinuity = bad.
Big enough
The bigger the better, but the JBL 2386 is approaching my upper limit ... 60*40 cm is about the largest frontal dimension I'm willing to use. The 2386 has a good depth - many horns for 2" drivers are 20 cm or less, too short to play down to 500Hz.
Rejects
The most common JBL 2" horns (2380 and 2385) are too short to work well, with very sharp flare transitions.
All of the 2386 examples I can see for sale (eBay, Parts Express), and in people's systems (from a Google image search) have flawed throats. I may as well buy a clone if the premium product looks poorly made / doesn't match it's own sales pitch.
There are many other poor options: P Audio are offering direct clones of the 'bad' JBL horns 2380 and 2385. Other manufacturers have horns with similarly bad throats or that are much too short.
JBL literature for the 2386 horn decries " the performance disadvantages of horns that feature sharp flare transitions and flat sidewalls".
Some well regarded people who have contributed a lot of time to horn theory (e.g. Le Cleach and Geddes) agree, and have really hammered this point. Diffraction & discontinuity = bad.
Big enough
The bigger the better, but the JBL 2386 is approaching my upper limit ... 60*40 cm is about the largest frontal dimension I'm willing to use. The 2386 has a good depth - many horns for 2" drivers are 20 cm or less, too short to play down to 500Hz.
Rejects
The most common JBL 2" horns (2380 and 2385) are too short to work well, with very sharp flare transitions.
All of the 2386 examples I can see for sale (eBay, Parts Express), and in people's systems (from a Google image search) have flawed throats. I may as well buy a clone if the premium product looks poorly made / doesn't match it's own sales pitch.
There are many other poor options: P Audio are offering direct clones of the 'bad' JBL horns 2380 and 2385. Other manufacturers have horns with similarly bad throats or that are much too short.
Hot contenders / eye candy
The Azura horns appear to be a good design. The maker is in Australia ("only" a 35 hour drive away) - they can be shipped fairly cheaply. The downsides to these are:
- $750 AUD / pair + shipping
- round mouth
Large fibreglass Iwata horns made by Auto-Tech, Poland. These tick most of my boxes, the downsides being:
- over $1000 AUD / pair (inc. shipping)
- shipping and customs delay (from Poland to Australia)
- extremely difficult to mount in a baffle
The elliptical style that Faital are selling look perfect, would mount easily, cheap clones are available. The huge downside:
- they don't make them big enough (none with a 2" throat)
Pictured below: Azura AH-340, Iwata 300, some $25 knock-offs that appear to be identical to Faital LHT142
The Azura horns appear to be a good design. The maker is in Australia ("only" a 35 hour drive away) - they can be shipped fairly cheaply. The downsides to these are:
- $750 AUD / pair + shipping
- round mouth
Large fibreglass Iwata horns made by Auto-Tech, Poland. These tick most of my boxes, the downsides being:
- over $1000 AUD / pair (inc. shipping)
- shipping and customs delay (from Poland to Australia)
- extremely difficult to mount in a baffle
The elliptical style that Faital are selling look perfect, would mount easily, cheap clones are available. The huge downside:
- they don't make them big enough (none with a 2" throat)
Pictured below: Azura AH-340, Iwata 300, some $25 knock-offs that appear to be identical to Faital LHT142