A very good friend of mine recently moved into a new house with an unfinished basement. There’s nothing that cries out Home Theater like a big empty basement with nothing in it. So naturally I offered to build this friend of mine a set of speakers to go into his soon-to-be-rocking new home theater. With a tight budget and the only criteria that the speakers had to pretty much rock for movies, I set out to design a medium-end LCR (left-center-right) speaker system to go into his wall next to his 78″ screen.
He had already cut out holes in his wall to accommodate a pair of speakers I had mentioned wanting to build. The design changed since then but we were left with the same size cutouts in the wall, so I was on a hunt to pick out some drivers that would still fit in the allotted space – which was basically 8″ wide by 40″ high by as deep as we need. I originally was planning on doing an MTM design with a pair of Dayton 6″ Reference Woofers and 1″ reference tweeter. But when I ran the cost numbers it was a bit on the expensive side (we’re doing 3 sets of speakers so the final cost = everything needed to build times 3, and it adds up fast). In addition, we weren’t really looking for an audiophile-esque sound, since the speakers will probably never get used for any kind of dedicated 2-channel listening, and my friend just wanted something that plays movies, sounds decent, and plays loud enough to mate with his big 78″ screen.
I looked at every 6″, 6-1/2″ and 7″ woofer Parts Express carries with an intent to buy one of the lesser expensive drivers, but didn’t want the cheapest one’s either. That’s when I ran across Dayton’s 7″ aluminum cone woofers which despite being only $18 a piece, really had some decent specs, low fs at 37Hz, a modern, clean look with a silver aluminum cone, nice rubber surround and some healthy Xmax at 4.25mm. PE recommends a 0.76 cu.ft. box tuned to about 32Hz for an f3 of 35Hz. I’ll double the box volume for our MTM design. The frequency response of these drivers looks very good up to about 1.5kHz, where there’s a slight dip and then the infamous cone break-up modes kick in at around 5-12kHz. It will be critical to get rid of everything above 2kHz in order to achieve decent sound out of these budget drivers that isn’t harsh and fatiguing. So with the right crossover, this driver should sound great and with a pair of them, our efficiency is up 3db from a single driver, as well the power handling doubles, so they should play nice and loud with his Onkyo receiver. More on the crossover design later.
For the tweeters I did the same thing with the woofers, I looked at them all (this is where having PE’s catalog really comes in handy). Clicking around the Internet can be tiresome, even at cable modem speeds, but a catalog I can browse specs of multiple drivers all at a glance and with ease. Some of my favorites tweeters I’ve used on several speakers are made by Vifa and Morel. They offer low-cost, high-performance tweeters and have detailed data sheets including FR and Z plots, which are critical for designing any kind of decent crossover. So after going back and forth for days on Vifa and Morel, I settled on the popular Morel MDT-20. It’s a 1-1/8″ soft dome tweeter with the high efficiency I need to match up the the pair of 7″ woofers, has a very low fs (650Hz) which will allow me to set the crossover point below 2kHz without damaging the tweeter and keep those woofers operating in their optimally flat region. The cost of the MDT-20 is just right for our budget and should be a great tweeter for this set of MTMs with a flat, on and off-axis, frequency response.
Anyway, I’ve gone on enough about that, here’s a quick picture of the box of goodies that showed up on my doorstep today. The 7″ aluminum woofers look great. The stamped steal frame is cheap, I would have preferred cast baskets, but aesthetically they look great. And the Morel MDT-20 really looks sharp with its super delicate fabric dome and large rear cavity. The plastic faceplate isn’t quite as fancy, but again for the cost, it should be a great tweeter and should sound really good when mated up with the pair of woofers. Just as long as I don’t completely screw up doing the crossovers, I think we’ve got a great set of speakers in the making. More to come!
Getting new speakers and crossover parts is always fun.
This will give you some idea into the crossover I’ve concocted up.
The cutouts in the walls of the basement where the Left Center and Right speakers will soon go.
www.aktiondan.com – 2007 – This is my most recent .com domain registration which at the moment is nothing more than a landing page which points visitors to www.danmarx.org. I guess I’ve always been kinda bummed that I couldn’t get my name in a .com, and the guy who did register www.danmarx.com hasn’t done anything with the name in almost a decade and has the domain registered for at least decade more. So www.aktiondan.com was my way of picking up a .com that was still unique to me. I may do something with it later on, but for now it’ll be placeholder, until I come up with that single really great idea.
www.floppy2cd.com – 2003 – I woke up one morning and decided that the entire world had hundreds of floppy discs that were collecting dust on a shelf and that if given the chance would love to have converted to CD for easy access and preservation. This idea stemmed from the small pack of 3.5″ 1.44mb floppies I had on my shelf collecting dust that contained old journal entries, school projects, lab reports, that I thought would it be great if I had all these on one CD instead of wasting away and never getting used. Using all that sophisticate mathematics I learned in college I had determined that I could fit over 450 floppies onto one compact disc. Who had that many floppies lying around? I have no idea, but if someone did, I was going to copy them all to a CD for them. I would have a shipping service come pick them, I would pop them in my massive array of floppies drives and one by one (or ten by ten) start transferring all of Joe Shmoes old love letters onto a single CD which would then be mailed back to him in a single envelope and all for a very reasonable fee. Well the idea never made it out off the runway (my fancy-pants spreadsheet basically said the concept needed to convert an unrealistic amount of floppies in an unrealistically short amount of time to even make anything) and pretty much crashed and burned the same week it was born but not before I snatched up what I thought was a clever domain name and made some really lame logo.
www.aktionrc.om – 2003 – A few years ago I got back into RC cars via a little popular car called the Micro RS4. I got so hooked on this little 1/18th scale car that my desire to make it faster and faster just wouldn’t quit. After trying out just about every motor and battery I could find, I knew the end all big-block conversion would be to stuff a whopping 540-sized motor into this car and then surely, no one could top it. Several prototypes later and the Micro Hybrid 540 Conversion Kit was born. During that time I had met up with another fanatic named Chris who helped fine-tune the design and a couple of months later Aktion RC was formed. I registered the name and we’ve been selling 540 conversion kits ever since. If you’re into RC then you should check out this site, we’ve got some pretty cool videos of this tiny car hitting over 51mph as well as a small history of all the different kits we created over the years. This was at least one of my domain names that didn’t completely flop.
www.hostmypics.com – 2002 – Picture hosting back in the day was extremely limited. Nobody let you direct-link to pictures for placing in forums, blogs and web sites, and bandwidth was so limited that half the time the hosting provider had cut off the offending bandwidth abuser and placed some lame marketing image its place. I decided it was time to change the way hosting providers treated customers images. I figured I could offer up picture hosting that uncapped all the rules of traditional picture hosting by allowing embedded images with no watermarks, giving everyone a whole bunch of bandwidth and only charging them $5 a year. There were only about four other sites doing this same thing, and they all charged way too much and didn’t offer all the untethered use of images like I was going to do. And then shortly after the idea fell into the toilet. Without going into the details, I just decided I didn’t want to do it, to have to deal with everything that would have been involved to maintain such an endeavor, seemed like a huge hassle. But again, not before registering the domain and actually making a full-fledged working web site that never actually went live. These days picture hosting is much better (Flickr, Picassa), and the most popular providers offer all the things I wanted to, but they even one-up my original idea – it’s free.
www.audioinnovation.com – 1999 – This was the first ever domain name I registered and to this day I still kick myself for letting it go. I know it seems stupid now, but at the time when registration was actually $37/year and me being a starving student, decided I needed to pay rent one month instead of renewing my domain. The site had already ranked fairly high on Google when searching for DIY subwoofers as well and I (not knowing anything about how Page Rank worked) didn’t think anything about moving the domain to my newly registered site at www.danmarx.org/audioinnovation, which as far as Google was concerned, didn’t even exist. It didn’t take long for someone to snatch up my expired domain and of course do nothing other than use it to advertise real estate. What’s that got to do with audio? Well apparently nothing since the domain was later sold to a domain reseller who has been holding it hostage ever since. They’re offering it up to anyone willing to fork over $3,338. Boy that $37 sure seems like chump change now. Ah well, it’s all in the past, but I did regain my Page Rank status, if you type Audio Innovation into Google and hit I’m Feeling Lucky, you’ll be taken straight to my site. Take that you lame domain reselling place.
