Here's the result:
I'll get to the little box on the top but first, how do they sound? I've been reading this site for a few years and had built 2 of Bill's designs (AutoTuba and T39), but nothing full range. Frankly, I was pretty skeptical piezos could do the job. I've been around PA equipment and "HiFi" for a long time and the thought of using piezos seemed a little...out there. Well, I'm happy to say I was proven wrong. I'm sold - hook, line, and sinker. The clarity of a 6 piezo straight array was very surprising, to say the least. Cymbals were clear and not harsh, brass and wood instruments came through clearly, and vocals were clear and intelligible.
The Deltalite 2512 is not a cheap 12" speaker, but it has 2 things going for it: it's extremely light (5.1lbs) and extremely efficient (sensitivity is 99.9db). Pop that into one of Bill's horn designs and the thing shines. At war volume, you will not get foundation rattling bass, but my guess is that was never the original intent (low, loud, and small - you only get 2). As the name suggests, this cabinet does a lot of things well and that's exactly what I needed.
The chosen design for my particular application (high school drama club sound reinforcement and whatever else they could think of) called for a very versatile design: one that could perform well in many situations, be easy to use, and be easy to move around. The Jack 12's fit the bill (pun fully intended
) and then some. The drama club just finished its yearly musical, utilizing the Jacks for spoken word, singing, and recorded music (unfortunately, the auditorium has NO sound dampening to speak of and the brick surfaces prevent any kind of volume without feedback). I had a chance to crank some recorded music and was impressed with the overall clarity of the speakers. Tight, punchy, and clear. Now, onto the little box at the top of the picture...I'd originally thought of making the Jack's self-powered but, during my build thread, was wisely talked out of it. Basically, the amp's 12lb weight would've thrown off the balance of pole mounts, moving the center of gravity into the back chamber where the mount would potentially be VERY close to the woofer - not good in my book. I decided to build a separate box, install a vent near the transformer, and wire a jack to the top near the handle. At 4 Ohms, this amp will put out 250W. Not much, you say? While testing out the little darling prior to a play rehearsal, I was asked to turn it down. The beauty of these designs is the efficiency (ie: very few watts needed). The other benefit of this little beauty is versatility, just like the Jack's. Not only was this plate amp capable of being hooked up to the mono output of the auditorium's soundboard, but it will be used for recorded music during the dance team's recital (1/4" connector into the line level input with a microphone in mic 1) AND it will be utilized for a party for the president of the school committee. Oh, did I mention the whole thing can be moved around on a dolly?
IMO, a great build satisfies the end user's requirements to a "T" and puts a smile on their face. This certainly accomplished that and more. 3 boxes, great sound, 1 dolly. Gotta love it. Thanks to Bill for such a great design and the many folks who contributed in my build thread. Now, I gotta figure out what's next...
On the 1/4", I was going for lowest common denominator (re: a school), but when buying speaker cables at the local music store that is notorious for low end, they had an abundance of speakon and had a hard time finding a 1/4". There's my answer - speakon has now become mainstream; time for a retrofit on these babies. And definitely balanced on the XLR, even if it's a short run and "technically" doesn't matter.
Gotta love that girl.