I guess I neglected to mention last night - there is a whole lot more story behind my L/C/R's than just what I posted. Perhaps I should do up a short separate thread..
I don’t know if any of you are familiar with Joseph D’Appollito and James Bock’s “Swan IV” DIY speaker system.. It started out as a High powered Satellite speaker in 1984, then morphed into a full range double box system with the satellite sitting on top of the woofer module (containing a pair of 12” woofers) in 1988. The whole development, and analysis was very thoroughly documented by joe and James in Speaker Builder articles…
The only thing I am able to find online as a description comes from DIYAudio member Leadfinger:
“The Swan IV was designed by Joe D'Appolito and published in Speaker Builder 4/88, 5/88 issues. It is a 4 box system consisting of two 100 Liter woofer boxes each containing dual 12 in woofers and two mtm satellites each containing dual 5.25 dvc mids and a tweeter. The system is bi-amped at 200 hz between woofers and satellites. The satellites have a passive 2000 hz crossover between the dvc mids and tweeters. The article recommends 4 amplifier channels of 200 watts each.
The Pedal Coupler is the 200 hz bi-amp crossover with bass boost. There were no further articles on the project, just some discussion in reply letters and responces published is subsequent issues the following year.” Posted here:
Anyway, the Swan – IV speaker system used a Dynaudio D-28, coupled with MTM arranged 5.25” Focal 5n412db – (later updated by various people to different drivers), and a pair of ~~either 5mm or 6.5mmx-max 12” woofers. Active crossover for woofer/satellite – with baffle step compensation for the monitor section, and bass boost for the LF section. It was a 115dB capable speaker (per each) from 25hz through 20khz. Joe and James agreed that to reproduce modern music at the time – especially with the advent of digital recording and deep bass encoding - 115dB SPL was the minimum necessary to achieve something akin to “realism” for reproduced sound in a home.
PET PEAVE ALERT: TO THIS DAY MFR’s absolutely SKIRT the biggest issue with home speakers recreating lifelike sound at home. Dynamic range. Dynamic compression happens to be one of the biggest distortions in your music systems playback wheelhouse – and is almost NEVER addressed commercially.. (off my soap box now) The Swan-IV speakers were incredibly dynamic in their time – and exceptionally detailed…. THAT system is what ended up cementing my need to become a professional in the audio industry…
My journey here started when I was 9 – after my father built himself a speaker system for our home “stereo.”. I was amazed - couldn’t believe my OWN FATHER built SPEAKERS!! Man, I JAMMED Billy Joel Glass Houses / 52nd street, Survivor Eye of the Tiger, miscellaneous Fleet-wood Mack, Stevie nicks, Janis Joplin, Styx albums (and waaay more more, but that should tell you the era) till I blew those woofers. Pop’s made me replace them. So began my journey.
Anyway, I can’t tell you how many times I doodled up variations of HT rooms / systems using the Swan-IV system as a 5.1 surround system in school… My current mains are just a modern interpretation – almost tribute to Joe’s Swan IV. I doubt anybody ever implemented them as HT speakers, this was the era of Stereo's still, before HT had become mainstream – but they would have been a near perfect home theater speaker system... Well the center would need to go lower – but in the day….
OK so maybe I a few more dB available, am using better drivers which I got to design and launch myself, the whole system goes lower – etc…but figure it’s also been what, almost 3 decades since Joe and James started on the original high powered satellite? I probably spent $300-$350 per month on phone bills with Joe D’Appollito and James Bock (he was hard to get ahold of) during the late 80’s early 90’s (before James passed) over a 2-3 year period... They are also very much to blame for my becoming ‘industry’.
The mid center to center distance on mine is less than 1.5x wavelength at the crossover (inside of Joe’s original D’Appolitto array guidelines), crossover is 24dB octave acoustic He first advocated 18dB, and modified it to 24dB L/R). Reason for the transducer offsets side to side is to get the mids as close together as possible vertically. C-C distance is 12”s (~~1120hz 1 wavelength, or 1,680hz for 1.5x 1 wavelength at cross) The drivers are also offset at a ratio of 1.41 to 1 from the sides – to help defray external cabinet diffraction effects. L/R cabinet round overs 0 .5” on horn side and 0.75” on mid side. Ideally these would be closer to 0.75, and 1.5” – but I didn’t have those bits handy, and as you can see from the un smoothed F/R in the links – and low mid low-pass – the net effects are entirely acceptable. The baffle step is taken into account through the asymmetric (electrically) network & horn level..
The back inside of the mid-range driver cutouts have varied depth and width scallops cut into them to eliminate large internal ‘tube’ edge diffraction effects inside the cabinet face, behind the drivers. Diffraction from this is significant – especially with thin cone faces (high efficiency drivers HAVE to be light weigh). Too many miss the importance of internal cabinet reflection / diffraction. They will go to great lengths to ensure the cabinet face is smooth outside the enclosure and forget the insides – IE: external edges are well rounded over – then load the transducer into a short tube with a perfectly concentric diffractive edge ¾" to 1½” ” behind the cone. Circular diffraction edges create the worst possible constructive and destructive interference reflections. There are greater aberrations in measured frequency response from this shallow diffraction tube than just about ANY surface diffraction from the front of the cabinet where the edges are 180degree’s from the piston’s face and 6 to 8 inches from the drivers centers....
Inner mid enclosure dims = 18.5” x 7” x 10” = 0.74 cubic feet or 21.2 Liters.. QTC is 0.54. 3dB down on mids in their sealed enclosure is ~~ 120hz.. Where they hand off to the woofers. Woofer enclosures are braced with moderate bracing where my accelerometer told me the cabinet 'talked' the most..
Originally Posted by chrapladm
Amazing finish. But I would expect nothing less. You always amaze. How are you getting by with no sub-woofer? Or do you have a little something?
Well, considering the main speakers are ~~~-3dB in room at my chair at 20hz, 6dB down at 16hz….……. Some would consider the L.C.R.’s themselves “sub-woofers”. (they contain “woofers” to me, and are what I call proper “Full Range” speakers ) Each cabinet has 2x the total measured volume displacement capability in the LF of any single THX certified 12” sub-woofer driver I have competitively bench marked. Essentially each L/C/R contains a sub-woofer capable of meeting THX specifications. (Yes I have Commercial THX Ultra2 specifics due to above mentioned ‘involvement’ with a famous makers THXu2 system . And I worked exhaustively on said system with THX to develop the drivers, and help work on the polar/power response of the finished system… They also have more real watts going to each than Most THX Ultra2 sub-woofers. Basically the main “woofers” do alright . Truth be told, these LCR’s without external sub-woofers exceed the THX Ultra2 specification in everything but lowest impedance allowed in every way for THX certified LCR’s Plus sub-woofers...The LCR’s also have better pattern control, vertical and horizontal off axis response, lower distortion at any given level, and more peak SPL capability than any THX u2 system I’ve bench marked. Call them THXu2 + 15dB at THX prescribed distortion levels, with better power/polar radiation.
And just in case you missed the title of this thread…… I do have a ‘sub-woofer’. These photos were taken before theHouseWrecker was completed.Edited by dB-Kicker - 1/25/13 at 9:02pm