sbe4kdr said:
I know the early screws were too long, this has been changed.
The glue squishing out from between the boards is also expected, you can just cut it off or sand it.
But the hole for the woofer being wrong - nobody else has said that. Was it the inner hole or the outer one? Since you are overseas did you buy your own drivers? Did you use the identical B&C?
How would you make the waveguide/baffle which is all one piece? It could be done, but wow, what a lot of work. Initially I had the baffle made in glass and made the rear part myself in wood. But the large radius corners took forever to do and so I had the rear made in glass too. The cost of the fiberglass parts is far less than the time and materials for doing it in wood.
Several people have tried to make the Summa enclosure in wood, but none have suceeded to my knowledge. To do the baffle right it has to be CNC'd and unless you have one of those and are very good at using it the cost of a single baffle goes up to about $1500. In the end everybody just gives up because the costs are too high.
I am willing to help you do one however you want, but no matter how you go, it is expensive. If you feel very competent then I can get you the fiberglass parts. But thats not like doing a wood project.
Several people have tried to make the Summa enclosure in wood, but none have suceeded to my knowledge. To do the baffle right it has to be CNC'd and unless you have one of those and are very good at using it the cost of a single baffle goes up to about $1500. In the end everybody just gives up because the costs are too high.
I am willing to help you do one however you want, but no matter how you go, it is expensive. If you feel very competent then I can get you the fiberglass parts. But thats not like doing a wood project.
1", the Summa15s are 2". There are no 2" router bits. Its the roundovers that led me to MDF. A smaller one makes MDF viable. 2" and its not worth the trouble - just do it in glass.
I did see where you can buy 2" MDF roundovers pre cut. That is very interesting. But the bottom line is there just isn't a lot of interest in the bigger Summa - not with the cost increases that come with this size.
I did see where you can buy 2" MDF roundovers pre cut. That is very interesting. But the bottom line is there just isn't a lot of interest in the bigger Summa - not with the cost increases that come with this size.
gedlee said:
How thick is the waveguide/baffle? Do you cast this currently (using a mold) out of fiberglass?
I might have access to a cnc machine. would you machine it out of say, aluminum?
What about machining the waveguide out of aluminum and setting it a concrete baffle? Or maybe make the whole thing out of concrete using an aluminum mold....???
Anyway, the thickness is a major determinate I suppose....
Thanks again,
The current baffle is molded in a fiberglass skin then backfilled with dense polyurethane foam to 2" thickness throughout and the waveguide about 8" thickness.
Molds are only cost effective if you are going to make many parts. To cut the baffle or a mold in aluminum would easily cost $5000.
Trust me here, I have looked into all of this and I do what is the most reasonable given the volume.
You would end up spending more to copy a pair of Summas than they would cost from me. So unless you LOVE to do things yourself that is not a good choice.
I could sell you a baffle in fiberglass with polyurethane filling for about $800. Then you could make the rear enclosure yourself, just like I did in the begining. A pair of baffles, drivers and crossover parts would be about $3000. But then you'd still have to make and attach the rear enclosure, finish and add the back panel. About 100 hours of work (best case).
Molds are only cost effective if you are going to make many parts. To cut the baffle or a mold in aluminum would easily cost $5000.
Trust me here, I have looked into all of this and I do what is the most reasonable given the volume.
You would end up spending more to copy a pair of Summas than they would cost from me. So unless you LOVE to do things yourself that is not a good choice.
I could sell you a baffle in fiberglass with polyurethane filling for about $800. Then you could make the rear enclosure yourself, just like I did in the begining. A pair of baffles, drivers and crossover parts would be about $3000. But then you'd still have to make and attach the rear enclosure, finish and add the back panel. About 100 hours of work (best case).
As Dr. Geddes mentioned earlier though, the larger waveguide does have the advantage of better directivity control to a lower frequency. This is an advantage over the smaller versions. If you are crossing over too high, say above 1khz, then I could see you not feeling there is an advantage, but otherwise, I don't really understand how you don't see the advantage of a larger waveguide. I can't speak to the HOM supression, thats Dr. Geddes deal, as I have no experience, but the better pattern control over a broader range is the most fundamentally understood part of changing a waveguides size. While I haven't seen measurements of the 12" and 15" versions to know this, I would estimate that there must be atleast a 200hz lowering in pattern control, say down to 800hz, with much better control at 1khz.
I think that what Patrick is saying is not that the 15" waveguide wouldn't work better, its just that the Abbey is a much more palatable choice than the full 15" Summa. From my limited experince of direct listening I would say that is true. The 15" does sound better, but the Abbey is very close and the size and cost difference is substantial.
I'm still looking for that "sweet spot" of the design, maybe a 12" woofer and 15" waveguide, maybe a 12" woofer and a 15" x 10" elliptical, I don't have enough data yet to know. But of the data I have the Abbey is the clear leader in terms of best compromise.
I'm still looking for that "sweet spot" of the design, maybe a 12" woofer and 15" waveguide, maybe a 12" woofer and a 15" x 10" elliptical, I don't have enough data yet to know. But of the data I have the Abbey is the clear leader in terms of best compromise.
pjpoes said:
Yeah, I should have clarified that. Law of diminishing returns is in full effect with the big Summas - the expense of the larger unit may not justify the incremental improvement in performance.
Just for fun I'm building another Unity, should be interesting to see if the bigger waveguide makes any audible difference. Originally I was going to make it 28" across, but settled for 24". It's still B-I-G.
It will be a while before it's done.
Another Unity Horn
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