DaytonClassicRevival
The Repository->DIY->Dayton Classic Revival
The Dayton Classic Revival is a small floorstanding speaker with a "Classic" paper/silk sound that is comfortable on both high-quality, and not-so-high-quality recordings. They have been my living room speakers for several years now, and despite all the designs that go through my house all the time, I always enjoy coming back to these.
Drivers
The bottom end of the Dayton Classic Revival is deftly handled by a pair of DC160-8. Wired in parallel, they bring a healthy amount of sensitivity, and in this 30 Liter cabinet, they reach a very satisfying -3 dB point of 34 Hz.
The mid here is the Dayton DC50F. It is a silk dome midrange, which is something we don't see too often in speakers these days. While dome mids perhaps experienced their heyday in the 70s and 80s, they are still useful in some situations, and can sound quite good, depending on the model, and its implementation in a crossover.
I initially chose the Dayton ND20FA6 for this project for two important reasons: it's very small, and it's cheap. The picture on the left is way out of scale, so you'll have to take my word on that first issue. The price, unfortunately, has gone up quite a bit over the last few years, with the skyrocketing price of Neodymium magnets. If I were to do this design again, I might still use it, though, because it puts out a pretty nice sound, and its compact size makes placing it close to another driver a simple matter.
Enclosure Design
The enclosure for the Dayton Classic Revival is none other than my much-overused "Amiga" cabinet. It's 30 Liters, and is made of 3/4" stock. You can build your own, or purchase a CNC-cut flat pack from Parts Express. (Note: the PE flat packs come with blank baffles, so you would still need to cut and/or route holes for the drivers). The reason I keep coming back to this cabinet--aside from my desire to not fill up my house with floorstanding speakers--is that it's relatively small, narrow, and unobtrusive for a floorstanding speaker. This design is vented, tuned to approximately 38 Hz. It uses a 2" dia pipe that is 4" long. You can get as plain or fancy as you'd like with the vent; anything from hardware-store-bought PVC to Precision Port is perfectly acceptable. You can mount the vent on the front or the back. The rule-of-thumb I use with regards to port placement is that the openings of the vent should be at least the diameter of the vent away from any boundaries, inside or outside of the cabinet.
Standard cabinet "cutaway" diagram here
Metric cabinet "cutaway" diagram here
Crossover Design
OK, this is definitely not one of my simpler crossovers, however there's not a whole lot of black magic going on here, either.
The tweeter is 3rd order. The mid uses a 3rd order highpass and 2nd order lowpass. The woofers have probably the most unusual filter of all, sort of a 2nd order with R4 used to shape the response, and C6 used to notch out a bit of unnecessary treble. Put it all together, and what do you get? A very well-balanced speaker that's not fatiguing to listen to, yet can still present a fine amount of detail in a recording.
There are a few things to take note of with the Frequency Response and Impedance graphs. First, since I used MLS measurements, there's pretty much nothing to see below 250 Hz on the top graph; don't worry, the bass is there, it's just a real PITA to measure anechoically, so it's not shown. OK, the next thing to notice is that the Frequency Response seems to rise slightly between 300-800 Hz. This is intentional, as I found that the woofers' proximity to the floor was giving me some bonus reinforcement of 2 dB or so. When I was initially designing this speaker, I found that a flat graph was creating too much of a "closed-in," "heavy" sound. Once I eased up on the mids and treble a bit (to the astute reader, what I really did was reduce the Baffle Step Compensation), the soundstage opened up tremendously, and the speakers came to life. Bingo!
Finally, the impedance load of these is probably what would be considered a "4 Ohm" design. However, I will say that I've run them on a wide variety of amps without problems. In fact, one of my favorite uses for them is hooked up to a "T-amp," with a laptop or smartphone playing tunes!
Final thoughts
I've had this project finished for over 2 years, but I never got around to formally publishing it. Every time I looked at the DCRs--which was frequently, since these are some of my favorite speakers to keep hooked up--I'd think to myself, "I really gotta publish these things." So here we are, finally. It's a small-size, small-budget speaker with a very large sound. If you build them, please enjoy! I know I have, and will continue to do so for years to come.
Here's me, at InDIYana 2011, standing next to the Revivals, showing that, either I'm a giant (I'm 5'11"), or these are relatively small speakers.