DCAudioDIY.com

woodcrafters club is pretty expensive.
what I just talked about can be accomplished with hand tools, some sweat, and time.
a 2 foot section of 2X4 and be ripped with a hand saw in 5 mins or less.
I am willing to help anyone, but I live in crime and death ridden Baltimore City

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Walt

If I could ever get everything cleaned up I would offer my shop facilities to the DIY fanatics -


Note the shop shares the room with my man cave. The table in the center of the shop is actually a table saw.

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Walt

Walt
since you live 15 mins from me any woodworking tidbits you would like, my shop and or assistance is available

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Walt

Paul,

I am not too hung up on the Altec Cabinet anymore. Since you were here last time, I made a couple of changes to the compression driver which yielded excellent results.

Altec compression drivers have a bug screen, a brass mesh, within a quarter of an inch from the phase plug. Since the Altec gear is originally designed for theater use, the bug screen is needed to keep the bugs from crawling into the compression drive. I decided to remove it completely. Unfortunately, my horn and CD is inside the sealed enclosure, so I tried the 511s without the bug screen sitting on top of the cabinet. Liked liked the effect very much. Next, taking Walt's suggestion to the extreme, removed the dust cap on the compression drive. Eliminating the diaphragm resonances by removing sealed dust cap is a revelation. I also loved the effect of raising the horn and tilting it down towards the ear on the soundstage, so decided to leave them that way permanently. Need to build a stand for the 511Bs and an acoustic baffle behind the compression driver.

Unlike present day full range speakers which stand out on their own, Altec made home and studio monitors less than 30" tall overall. Their idea is to make Altec speakers part of home furniture/decor. Downside is, cabinets are smaller and horn is far below the ear level.

I am going to try damping the cabinets and stiffening the back wall like Walt did first and they go for building a bigger cabinet just for the woofer of around 12-14cft. My problem, I dont have any woodworking experience or woodworking gear.

so only the woofer can come out not the horn?
I see the possibility of six braces
four front to back and two across

If you give me accurate inside dimensions I can over cut the six pieces, and trim to fit at your house

Actually I am think 1 dowels might work.

If you are not worried about looks, the braces along the walls can be placed on the outside. The onlything that will be needed inside will be cross braces between opposite walls to transfer bending moment into tension and compression in the braces. Wood is much stronger (as are most materials) in tension and compression than in bending. An I beam essentially converts bending moment into tension and compression in the upper and lower parts of the "I".

Hey Sashi,

You might see if anybody got different results but:

Modeling your woofer with the specs Tom gave you in the 7.5cuft box, I get a rolloff (f3) of 57 cycles.

going to a bigger box of 9.1cuft, I get 59 cycles.

Going a little smaller to 6, I get 55 cycles

The lowest I got was 4 cuft, at 53 cycles, but cone displacement was severely curtailed.

The variation in the rolloffs of these 4 boxes, as far as I can tell is insignificant.

The box resonance does go a little bit lower as you go bigger. I got 33 cycles for the biggest box, and 49 cycles for the smallest, but I don't think that will contribute that much to the overall results.

If you ask me which one I like best if you are going to build a new box, I would say 6 cuft., but focus your attention on the quality of the construction. 6 cuft is right on the cusp of Infinite Baffle, and should give you all the performance your woofer was designed to deliver!

Also, bassbox suggests that adding stuffing to any of these four, will do very much other than raising the rolloff by about 10 cycles.

I think the best mod for your existing cabinet at this point is what Paul suggested: add some bracing, and try gluing some tiles on the inside of the cabinet walls.

You might be able to get to 39 cycles with a 6 cuft Transmission Line, but it's just a theory!

Chris