I have been working on a project to build a complete speaker for some time now and I have a final version. This is crude looking because it was my test mule to iron out all the bugs. Made with screws and no glue to be able to change the cabinet if needed by simply taking it apart.
The journey to making a complete speaker began with a desire to have another product to sell that could fit into both the Pro and homeowner markets. I picked basic cabinet dimensions and then with the capable help of Claude J who did the analyzing of the box and made an excellent woofer recommendation I was off to the races.
Of course modeling gives you a good indication of what you need with various drivers and defined goals but there comes a time when you must build and then dial it in. It is an eye opener to see the difference the port slot size makes in sound quality and what an additional couple of inches in ht can make. Then there is tinkering with eliminating resonance and standing waves through cabinet shape and acoustic foam.
I like two way systems a lot and to have a good one you need a good top horn. Taking the same basic cavity of the SMAHL and LMAHL tweeter bodies which are proven and known good I scaled it up to a horn made of stacked Baltic Birch. A mouth opening of 14″ x 7″ and 6.75″ deep from from face to driver proved to be the one and thankfully I needed only three attempts to get to a really fine sounding horn. I have had a few 1.4″ drivers I tried but the one that really excelled was the Faital HF146R-8. This produced a tremendously realistic high end with a crossover point at 900hz working quite well.
As an aside here the horn will be available before Christmas as a free standing horn on a sheet metal bracket that will fit helicoiled holes in the top of the bass bin in my speaker. They can also be used as freestanding units with any other bass bin or speaker you might have. It will also allow for rotation left and right and with horns, really with any speaker, positioning and aiming is key to finding your best result sweet spot. Believe me, being able to independently direct your HF sound brings a lot of improvement to the table.
Yes it is rough looking but is a complete finished product for sound and proves the concept admirably. One of the real bears to solve was the passive crossover. I wanted people to be able to plug and play. The basic second order Linkwitz Riley crossover has a couple of tweaks to it to dial it in better. No I wont tell you what. I started with an adjustable L-Pad which turned out to be a nightmare. They would drift and these speakers are sensitive enough that this made an audible difference and they were not consistent. I went through a bunch of these before I gave up and went with a fixed resistor setup. The Faital is 109db and the woofers are 99db so the mismatch has to be tamed. This too was done and let me tell you there were smiles all around as my visitors and I heard the final version for the first time.
That big ol black box behind the new unnamed as of yet two way is part of a set of Klipsch KPT 942/4 Cinema speakers with a set of 1st gen K-402 horns on top. One of the things I do is fix up old sets of Klipsch Pro gear. Great speakers with lots of headroom and surprising great fidelity these were made for 400 seat theaters. Being the crass mercenary that I am I will mention these are for sale.
A project I did for myself is the rather large brown wood things with a K-402 horn on top behind the two way. It will be the topic of a future post and it was built to give me an all horn speaker capable of getting all the low notes of Toccata in D Minor.
In any case the next day after the final combination was arrived at I decided to try the pro side of my two way. You see I wanted a speaker that could be used for pro use or right at home with audiophiles. So we rolled them to the big shop door and pointed them out. I use Crown xli 800 amps which provide 200 watts per channel. With each woofer in parallel being able to handle 400 watts plus the 150 watt horn driver I figured we would just crank it up all the way and see. From around 130 feet away they pegged the db meter at 85-86 db with the Allman Brothers live at the Fillmore and it was like you were there. Acoustic instruments like Cellos, which have become one of my favorite genres, have amazing depth and accuracy and I spend hours every week just listening. Pipe organs and Japanese fireworks can rock your world here and percussion is tight. I have become a big fan of 12 inch woofers now as I think they bring more definition and speed to sound then the bigger 15″ + ones do.
Cabinet construction will be of Baltic Birch and none of that odious crumbly prone to damage MDF crap in this shop. The finished version will be raw Baltic Birch with sanded finished surfaces. Crossovers mounted internally and the HF horn will be mounted in the aforementioned bracket.
Anyway that is it for now and some technical measurements will be forthcoming sometime soon along with pictures of the final finished and for sale speaker. Now it is my intent to offer this in the raw Baltic Birch which finishes up fine in my book with stain or Watco Oil or wipe on Polyurethane. Plus you ding it it is easy to fix and the birch is water proof so your friends sweaty drink wont ruin your veneer or dissolve your MDF. Believe me I have seen a ton of Klipsch (and others) MDF speakers with all kinds of problems and did not want to make something like that. And the best bonus is in this day and time of wildly expensive corporate offerings these will be quite reasonable for the superior listening experience they will provide.
If you are ever in Middle Tennessee get in touch with me through this site in advance and stop in. I always enjoy audio visitors.
Machined Audio Horn Lens 
Great article, Dave
Interesting and well written. Journos please note!
Good job you only have the turkeys to worry about when you turn up the volume.
Hi Alan, how are things and thanks for the comment. I have a bi-amped setup with DSP on my Super MWM set and figure 95 out of a 100 people would never volunteer to learn that so a passive was the way to go.
Still using SE though I let maintenance expire three years ago. Synchronous tech still my favorite and I miss the old days with the SE crowd. The way SE works with creating shapes and boolean removes led directly to the shape of the successful design for my tweeters and larger horn. Once I figured out how to do it that is. Last time I asked for help most of the good American techies had been replaced with Indians who had insufficient experience to answer my questions and I never went back and stopped my subscription.
Very exciting to finally see pictures and description of this speaker project. Appreciate all the design choices: Baltic birch, 2 way, 12″ woofers, passive crossover, and a most compact foot print suitable for any living room.
I built this like I would want it for myself. Everything I build has me as the first customer and if I don’t like it that is the end of it. While a fair amount taller the footprint is not much more then a Klipsch Chorus.
Eager to see this come to fruition. Do you plan a DIY version, say horn plus plans?
I am thinking about selling just the horn set. Otherwise I am leaning towards selling complete speakers and not flat packs or plans. I have a lot of time and a fair amount of money in this with the intent to sell complete speakers.
Forgot to mention I will be meeting with the CNC shop for cabinet building in early January so I will be testing an 18mm cabinet then. The 25mm Baltic Birch has been unavailable since a year ago August.
Are you familiar with Real World Audio on YouTube? He has a speaker, called Voice of Lancelot, about the same size as your two-way, using a single 15” Altec 515 woofer. What made me think of it is that if you are having difficulty with sourcing rigid enough plywood, have you considered trying his approach – with very thin plywood on a rigid frame that is intended to resonate at certain frequencies. Ocellia speakers use that approach also. Another guy on YT, Eduard Boekamp has built a couple prototypes and he discusses theory, results etc. quite nicely. https://youtu.be/VTOg2A77BKY
I think that 18mm Baltic will be more then enough. I will have a look at his site and see though I am skeptical of the claim of tuning resonance with this approach. I am in the camp of eliminating as much as you can. Now that being said I think that Baltic does add a better tone to all the sound produced from a speaker which is what I want.
Have you sold the K-402?
OK are you asking about the K-402 I have as part of a set of KPT-942/4’s listed with Craigslist Nashville,TN? They are the only ones I am likely to ever have for sale again as I have quit looking for pro gear and I am concentrating on new things I build.
I do have one more set but they are with my Super MWM’s and where they go will be my kids problem one day.