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-   -   Guidelines for cabinet extreme proportions? (http://www.diyaudio.com/forums/full-range/146358-guidelines-cabinet-extreme-proportions.html)

Brisso57 23rd June 2009 02:55 AM

Guidelines for cabinet extreme proportions?
 
I'm contemplating building a pair of sealed cabinets (for vintage 10" coaxials).

The proportions suggested in the design I have are for "old-style blocky" cabinets - ie wide, fairly deep and squat. 185L. (!)

I'd like to have them a little more modern looking, so I'm thinking less deep, and taller.

Assuming we don't have a suprabaffle, the minimum cabinet width is obviously constrained by the driver frame's diameter, a bit of "meat" either side of the driver cutout, and the ply thickness. (270mm + 50 + 2 x 18mm = 360mm)

I want to put the driver's axis at about seated ear height, so that would be between 1000mm and 1200mm above the floor. The top of the cabinet could be as tall as needed to accommodate the volume needed.

From what I've gathered in recent times, wide baffles have some advantages ... if WAF is ignored ... so maybe I should go much wider: 500mm? 600mm? 750mm?

The depth from the rear of the driver to the front of the frame flange is approx 150mm. This would be the minimum internal depth.

My question concerns the advisabilty (or otherwise) of building cabinets of minimum depth - "tombstone style" if you like.

I have also read of the supposed benefit of avoiding having the internal dimensions being simple multiples, and further, of using the Golden Ratio. All of that aside, am I likely to be happy with a minimally-deep cabinet? Say 1400 x 750 x180 mm internal dims.

fwater 23rd June 2009 04:51 AM

If you can tolerate these big cabs, have you considered open baffles? All the cool kids are doing it. You don't even have to commit to them, simply cut the panels and listen, and build an enclosure onto them if you are dissatisfied with the OB sound. What kind of vintage drivers? Any chance you know the specs?

Brisso57 23rd June 2009 05:11 AM

Quote:

Originally posted by fwater
If you can tolerate these big cabs, have you considered open baffles? All the cool kids are doing it. You don't even have to commit to them, simply cut the panels and listen, and build an enclosure onto them if you are dissatisfied with the OB sound. What kind of vintage drivers? Any chance you know the specs?
Peak 10CX50's (aka Coral 10CX501's)
I know some of the specs, but not all.
www.eastmarinedrive.com has some cabinet plans, on which I'm basing my thoughts.
I'm thinking I may be able to get the drivers tested, as the specs may well have wondered during their lifetime.

Re OB: Yes. I have tried OB and love it. But ... WAF!!! :-(

cheers

Doug

fwater 23rd June 2009 06:02 AM

I have a pair of OBs 20" by 40", considerably smaller than the 33" by 55" face you're proposing. Build the bases 8" forward and back (16" by 20") and keep them up against the wall when not in use. 25% smaller face, same depth to wall until pulled away for listenning, and you get the magic and voodoo of OB. I'm not railing against the idea of an enormous box, I'm simply for the idea of OB is you're already willing to put up with enormity anyway...

Brisso57 23rd June 2009 06:56 AM

2 Attachment(s)
Quote:

Originally posted by fwater
I have a pair of OBs 20" by 40", considerably smaller than the 33" by 55" face you're proposing. Build the bases 8" forward and back (16" by 20") and keep them up against the wall when not in use. 25% smaller face, same depth to wall until pulled away for listenning, and you get the magic and voodoo of OB. I'm not railing against the idea of an enormous box, I'm simply for the idea of OB is you're already willing to put up with enormity anyway...
Hmmm. You make a good point.
Much cheaper and faster to build than cabinets also.
I have a pair of OB baffles I liked with Peak 8CX50's fitted. Maybe I should just bore out the holes?

fwater 24th June 2009 02:44 AM

Enlarge the holes and give it a whirl. If they (the 10s) don't turn your crank, make an acceptable "beauty ring" for the 8s to return to their homes.

I am in love with the wide and low (JE Labs style?) OB. I have a pair of 8s on a face 24" tall by 36" wide with short wings. The baffle is leaned back 8 degrees and I feel I could go farther next time. The imaging was just a tad low, so I experimented with a 3" by 10" chunk placed horizontally across the back near the top; I had seen someone comment on this before. It makes a subtle difference in many ways, combining to make a big enough difference to be well worth it. Imaging didn't exactly move higher, instead the speakers disappeared a little more, they tended to be more involving. In addition, midbass improved, giving an overall improvement of what I was calling slow or a tad muddy bass. It appears that they are a little louder, too.

Build a big box, play with stuffing, and you're done. Build an OB, and you'll never be done, and have 5x the fun not getting there...

Brisso57 24th June 2009 03:19 AM

I quite liked the tonal balance I had with the 8's, but I wanted more bass, so hence I bought the 10's when I heard of some being available.

I played the 8's in OB for a local GTG some time back, and while the feedback was generally good, one person did comment that they found the soundstage too low. (Your description of your OB sounds much like mine ... which I got off a japanese site.)

I think I'll knock together some pieces of chipboard to make a temporary base on which to sit the existing OB's. If I like what I hear then I'll build some new OB's from scratch.

This may take a week or two to achieve, but I'll get back to you with opinion & pics.

cheers

Doug


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