4.5 Inches of Fury- My Single Driver Speaker Project

strider

After stumbling across the Frugal Horn site one day, I decided it would be a cool project to build a set of single driver speakers. Initially I wanted to do one of the double mouth Nagoaka style horns, but couldn't justify the 2 or 3 sheets of birch ply I may waste on my first attempt at a speaker build. Let the idea slide until I came across a guy on Audio Circle selling a pair of gently used Fostex Fe127e 4.5" full range drivers. With the drivers on their way to my house, I decided it would be the right time to find some plans.

Enter the Fonkens. They're near aperiodic monitors 13" tall and about 11 inches deep, using about half a 4x8 sheet of natural birch poplar core ply. The Fe127e is flanked on either side by 3 vertical ports set in the chamfered edge of the cabinet. Being a single driver full range speaker, there's no crossover, resulting in an efficient design without the phase shifts associated with a crossover. At least this is what I read, I liked them because it looked like I may be able to build them.

When I was done, I had about 3 weekends invested in building the cabinets and matching stands, another month and a half of weekends and evenings in finishing them. The baffles are natural birch finished with clear brush on Deft lacquer. The rest of the cabinet would have been the same had my wife, the interior artist and faux finisher, not commented that the end cuts of the ply visible on the chamfered edges made them look unfinished. Five coats of primer, four various color coats, and 7 coats of lacquer later, they're woodgrained to match my equipment stand. She hasn't looked at them since, but I can sleep better knowing my **** matches.

Anyway, on to the sound. Going in, I'd never heard a set of single driver speakers. I was interested at first because they're just about 180 degrees opposite in design from my SDA's (which I still have, everybody relax), and I really wanted to experience something different. Eminent lifestyle changes added fuel to my quest; my wife's pregnant with our first kid so a design that has a bit more finesse and nuance at lower volumes will help me from attaining eunuch status as quickly. First thing I noticed was how revealing they are. I was ready to ditch my turntable the first time I spun some vinyl through them. The sound I had loved was now flat and lifeless, like listening to a poorly recorded cassette tape. Turns out the tracking force on my cartridge was set way too low using the cheeseball system on my entry level Pro-ject table. Setting it with a digital gauge did the trick. Next was the imaging; the soundstage width of the SDA's was gone, but the imaging is so precise. In vocal duets, voices are easily discernable from one another, I can pick out which stringed instrument is playing where much easier in bluegrass numbers. The imaging does get a bit congested as the number of electric instruments increases, which I guess is a drawback attributed to having a single driver playing everything. Bass, while not vibrating your pants, is super clean. Not much information below 60hz or so, though. Anyway, a fun project. I'm still going to do the big horns, I'll just have to bolt them to the walls in the case the not yet born little Washington decides to go King Kong on them.

hoosier21

very cool project, I have to finish my project (workshop/bark) and get a speaker project of mine going.

mhardy6647

Vurry nice! :-)

Dave Dlugos' sites have some cool ideas and projects; see also www.t-linespeakers.org
You might also want to consider one of Bob Brines' folded, mass loaded TQWTs. I've muchly enjoyed mine. These are loaded with R/S 40-1354s adorned with Dave's phase plugs.




The Fostex FE-207E is another nice FR; refined and articulate. Qts is high enough (barely) to get away with a simple BR cabinet.

ben62670

Very nice. I tried a sigle driver, but ran out of time. Some day I'll get her done. DIY is fun for sure. Congrats on the new one on the way:)
Ben

MillerLiteScott

They look awesome.

Nuf small talk.

Now invite me over to hear them.:D

Scott

Systems

Those look great.

Fongolio

Cool project. I love that brick wall mounted turntable shelf too. No floor resonance on that baby. BTW have you got the book yet? Let me know when it arrives and what you think of the read.
Kelvin

ShinAce

Wow! That is gorgeous. I love birch; such a smooth wood.

I wish you had some pics pre-stain though.

Ricardo

They loook great; nice job. Someday I'll have to try a single driver speaker.

Face

Nice job!

strider

ShinAce wrote: »

Wow! That is gorgeous. I love birch; such a smooth wood.

I wish you had some pics pre-stain though.

I should have taken pics along the way in general. Next time, I'm going to follow my instincts and do a satin finish lacquer on the entire cabinet. The woodgraining takes so many steps to look right, not to mention the fact that I need to have my wife apply them. It sucks doing something all day long, then coming home and having to do more of it. Plus I don't think the area where the lacquered baffle and the painted edge meet integrated as nicely as I'd hoped.

strider

mhardy6647 wrote: »

Vurry nice! :-)

Dave Dlugos' sites have some cool ideas and projects; see also www.t-linespeakers.org
You might also want to consider one of Bob Brines' folded, mass loaded TQWTs. I've muchly enjoyed mine. These are loaded with R/S 40-1354s adorned with Dave's phase plugs.

......


The Fostex FE-207E is another nice FR; refined and articulate. Qts is high enough (barely) to get away with a simple BR cabinet.

Thanks, I was hoping you'd see them. I think it was you that had posted a link to the full range driver forum, another source of inspiration for me. It's so cool that talented people like Dave at Planet 10, the guys at diyaudio and the full range forum share there designs and experience so freely. I find that I understand the concepts behind the designs so much better when I build the design and see how it works first hand, rather then reading white papers, et. al.

The little 4.5 inchers have really surprised me. From what I'd read, I assumed the midrange would be done very well, and they haven't disappointed. I wasn't expecting any type of bass out of them; after getting used to how clean and tight the bass was, I feel that the output is surprising for such a small driver. I've got my eyes on the Saburo next, which is a double mouthed, back loaded horn designed for the Fe126e. With the combination of the cabinet design and the extra 2db of efficiency of the 126's, I'm hoping to get a bit more bass output. I think there more directional and have a smaller sweet spot, but I'm looking forward to comparing the 2 designs.

Jim Shearer

Strider,

Nice looking pair!

I built a pair of Fonkens this summer (my third single full range driver build.) I veneered mine in red oak w/ satin polyurethane finish, matching the solid oak stands I also built. As in previous builds, I use a Baffle Step Correction circuit (BSC) -- in this case, a 5.5 ohm 10 watt Mills resistor in parallel w/ 1 mH air core inductor. In the photo you can see the inductor peaking out from behind the stand. Note that a change of just 0.5 ohm in the resistor will make a very significant change in response. For my set up, 5 ohms is just a bit too bright, while 6 ohms will kill it dead. (I really need to build a box for the BSC now.)

I know some purists refuse to put anything between the amp & the driver, but I prefer to tame the rising high end w/ BSC. Since I use SS amps, the loss of a couple dB in sensitivity is of no significance.

As for the low end: I had expected the Fonkens to get down, at best, to about 60 Hz (as you indicated.) To my great surprise, mine get down to 40 Hz. Measured in room, the output at 40 Hz is the same as at 2 KHz; using a Stereophile test CD and a Radio Shack spl meter. (In the interest of full disclosure, there is a room effect bump in the response at 80 Hz.) I did deviate slightly from Dave Dlugos’ plans: I used Parts Express 0.5” thick acoustic foam (w/ adhesive backing) as lining, rather than the recommended 0.5” wool felt. I doubt that would make any real difference though. None the less, I still supplement the low end w/ a sub woofer. My speaker building experiences have taught me that I won’t be satisfied w/ a system unless it gets down to 30 Hz.

I would describe the Fonken as colored, but very musical. And they are very sensitive to the quality of the amp and upstream components! This is a whole different world from that of the typical commercial speaker. For those who haven’t tried this yet, be warned: for a couple hundred bucks you can build a speaker that will make your friends green w/ envy, but it’s almost impossible to stop at one build. My wife is already becoming concerned about the number of speakers in the house--and I have at least four more builds planned!

Cheers, Jim

zingo

Those speakers look great! You did a very nice finish job on those, and the ports integrate very smoothly into the cabinet design. And I would assume that you made those stands as well by how well they integrate into the design.

ShinAce

Now I realize you stole the cabinet design.

Here I thought it was 100% original. Silly me.

Still a beautiful build.

strider

ShinAce wrote: »

Now I realize you stole the cabinet design.

Here I thought it was 100% original. Silly me.

Still a beautiful build.

Thanks, I guess. As are most of the designs on the Frugal Horn and Planet 10 sites, they're open sourced plans, meaning anyone is welcome to build them as long as they aren't doing it for profit.

themuskr

Wow those are great looking