Inlow Sound 15-A
I fell in love with the You Tube videos of the Western Electric 15-A last year. I heard passion in the music as never before; the artist practically reached through my computer screen and poured out his heart to me.
I HAD TO HAVE A PAIR OF THESE HORNS!
Of course, wouldn't you know it, they're hard to find, and when you do find them, they're expensive. Being a DIY type of guy, I knew that if I applied my gifts of observation and perseverance, and spent enough time tinkering, I'd come up with an Inlow Sound version of the fabulous Western Electric 15-A!
The spiral horn you see in the above picture took a year to fabricate. First I had to design the beautiful creature, then create a mold to cast the paper mache. All this had to be learned on the fly, as it's a completely different beast than my durable, little 400 hz paper mache horn. Then came the mouth... should it be paper mache, or wood? Turns out, paper mache is too flimsy for the mouth unless you use a ton of epoxy instead of glue to bond the paper. Then you have a plastic horn... not my favorite cup of tea. I opted for a twenty petal conical mouth. It's quite elegant looking and sounds perfect.
My version of this horn is being operated between 150 Hz and 8000 Hz--hence the smaller mouth. At the moment, I'm using my Spiral Bass Horns from 20 Hz to 80 Hz, and my mid bass horns between 80 Hz and 150 Hz. I top the system off with a pair of JBL 2404 (baby butt cheek) compression drivers that carry the load from 8000 Hz to 20k.
In the future, there will be a 40 Hz to 400 Hz bass horn available , I call it the 15-B (following page) that will cradle the 15-A. The Spiral Bass subwoofer horns will reproduce the first octave 20 to 40 Hz, then the 15-B bass horn kicks in to cover 40Hz to 200 Hz, followed by the 15-A.
I drive this horn with a hot rodded JBL 2446 loaded with a TruExtent beryllium diaphragm.
For now, I'm using a miniDSP processor for a four way crossover, EQ, and time delay.
Listening impressions? Here's a cut from Mannheim Steamroller Fresh Aire ll (1977). It's taken with my iPhone/Shure MV88 mic at a distance of fifteen feet from the horns. The 2404s weren't hooked up at the time, so the top octave is soft. As usual, the bass octave is not as strong as live listening. Still, this is a fair representation of what a good horn setup can do.
I discovered that I can shorten the horn:
This horn is fairly large, and when coupled with the solid Maple 15B, it's larger than necessary. The 15B bass horn is excellent sounding and is rock solid to 250 hz, so why not reduce the mouth of the 15A and optimize for the same cutoff of 250hz? Of course you can, so on to my next portion of this adventure. To make things interesting, my customer purchased a pair of the famous Ale P-7550 midrange compression drivers. They have a 1 3/8 throat exit, so I shortened the 15A's throat section as well as the mouth.
Below: Here's my assembled, truncated 15A sitting pretty on its perch. I'll be staining the maple with a tinted, white wash pickling stain that matches the color of the 15B. I'll also use a sponging/ragging technique on the paper mache portion of the horn using amber shellac.
Oh, and those wood clamps and the rear support are temporary. They'll be replaced with a custom, brass turnbuckle. This feature allows me to adjust the horn so that it's aimed at the listener.
Below, I'm using a laptop computer and Spotify with my little 1 watt Darling tube amp to demonstrate the truncated version of my 15A.