hi dave. im pretty new here but i was looking at this link a couple days ago. about the billfort speakers. hope it helps. those stonehenge V plans are a bitch to find.
Billforts Audio Obsession
Greetings All. I have recently retired, and as my first "project" I am going to build my own speakers! I've built a lot of Bottlehead, Audio Note Kits, and DIYHiFiSupply kits over the years, but never speakers. Years ago I had Altec 604-8G speakers in 620 cabinets. Never should have sold them, but we live and learn!
To keep things simple, I'm going to start out with a Duplex speaker--probably the GPA 604-8H-III. I have also seen that a crossover from Selah Audio is highly recommended rather than the stock crossover, so I'll probably contact them too.
As far as a cabinet goes, I think I will either attempt Billfort's cabinet or a Stonehenge V. Todd: if you are still willing to send out cabinet plans, I would be most grateful to receive them. A friend is going to help me build them, since I'm not much of a woodworker. He is a cabinet worker/home remodeler and wants to look at any plans before offering advice.
Looking forward to participating on the Forum, and returning to Altecs!
Dave
hi dave. im pretty new here but i was looking at this link a couple days ago. about the billfort speakers. hope it helps. those stonehenge V plans are a bitch to find.
Billforts Audio Obsession
Hi Dave ! Welcome to the forum ! Try this.It is the Stonehenge III cabinet.Same as the Stonehenge V.The only difference was the drivers.
http://home.earthlink.net/~jmarkwart...iles/3577a.pdf
Thank you. Those are some one of the nicest, clearest cabinet plans I've seen! However, my understanding was that one might want to consider the Billfort and SH V cabinets since in both of them, the drivers were more nearly at ear height, and the internal cabinet volume closer to 9 cu ft (for somewhat lower bass response).
Dave
If my calculations are correct, the internal volume of the SH III is 17.25 x 13.25 x 42.5 = 9714 cubic inches, which is about 5.6 cubic ft. What I don't know is to what degree the smaller cabinet volume will decrease the low end frequency response. Altec's specs for the SH III, however, list the lower end of the freq response to be 50 Hz. If I could get an extra 10-20 Hz lower, I'd prefer that. Having said that, my wife would almost certainly prefer the smaller cabinet!
Dave
Hmm, I thought this cab was the SHV, which IIRC was listed as being 9 ft^3 and the one Todd had the drawings of, or is it an Iconic Manufacturing custom?
GM
DemoRoom_4.jpg
- - - Updated - - -
As a general rule, the point of diminishing returns is Vas/1.44, though if driven with a high output impedance, up to Vb = Vas is desirable due to the increase in effective Qts and why cabs tended to be relatively huge way back when.Originally Posted by dth31
Tuning to Fs is desirable, so with a large enough cab it can often be ~flat in room all the way down due to room's contribution and/or with some form of EQ to trade some efficiency for tonally balancing it.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Not so sure about this. AFAIK the V is larger than the III - I have seen external measurements of 121cm tall x 56cm wide x 45cm deep (47.625" x 22" x 17.75), which would be ~9 cu ft. once you subtracted for internal measurements and bracing. DJK has posted that you get an additional 5hz from the size.
Edit: See the Iconic page - Iconic Speaker Manufacturing - Stonehendge Page
"The Stonehenge Model III - This system consists of a Iconic's new 16"compound loudspeaker, the 704-8A, a custom crossover, and a hand-crafted 6 cubic foot enclosure (interior volume), which gives it excellent frequency response down to 50 Hz. This is an excellent choice for smaller living environments, and systems that employ subwoofers.
The Stonehenge Model V - Our premium system, and the one that has proven to be the most popular. This system consists of a Iconic's new 16" compound loudspeaker, the 704-8A, a custom crossover, and a hand-crafted 9 cubic foot enclosure (interior volume), which gives it excellent frequency response down to 30 Hz. This is an excellent choice where full-range, point-source sound reproduction are desired."
I've drawn up some preliminary plans for a larger cabinet with an internal volume of about 9 ft 6 in (before any internal bracing). Briefly, internal dimensions of W 26 in x H 43.5 in x D 14.75 in. This will result in a W 27.5 in x H 46 in x D 16.25 since I will use 3/4 in Baltic Birch plywood all around and will sit the speakers on 1 in spikes, or maybe a 1 in pedestal. The GPA datasheet for the 604-8H-III also recommends 2 round ports of 5.25 in diameter x 2.3 in long ducts, so will try that to begin with, too. Will place the ducts on the back panel approx 16 in above the internal floor, which results in the center of the port being approx 17.25 in below the center of the speaker.
Billfort had remarked in some of his posts that he wanted to keep the front baffle width 26 in, b/c with narrower baffles he felt like he lost some bass. Because my wife was more concerned about keeping the speakers from sticking out too much from the wall, I went with a slightly wider internal width, resulting in a front baffle width of 27.5 in instead of 26 in. I don't think the wider baffle will be a problem, but I'm not really sure, either.
These cabinet dimensions will result in the center of the speaker being 35 in above the floor, which may be a little low since my ears will be about 42 in above the floor. I figure I can always tilt the speaker back a bit if this seems to be a problem. This also leaves 3 in from the edge of the speaker to the top of the cabinet.
If anyone sees any "fatal flaws", or has any comments/suggestions, would be glad to hear about them!
Dave
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