Adjustable port design suggestions ??

Hello,

Looking for any suggestions on the design of adjustable ports - any photos or drawings would be great. I am in the process of building up some 620 cabinets for my 604 drivers (re-purposing some quite tattered Magnificents i found locally), and would like to have the flexibility to alter the port size to properly tune the cabinets. I have the information on recommended port size for 9 cu ft cabinets, but I am sure mine will not be exactly 9, and it is likely all 9 cu ft cabinets are not created equal...... Trying to cut the port larger after the fact, or putting in 'shims' to decrease port size, seems a bit haphazard. I would like to design some flexibility in, if possible.

I also have a few bits that may be of interest to others, such as the bass horn woodwork (which came out quite cleanly). Probably do a post once I have done both sides, and have a better idea of what is there..... All of the drivers and crossovers were long gone, do no need to ask about those.

regards -- Roger

Quote:

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Originally Posted by rogerh113

Hello,

Looking for any suggestions on the design of adjustable ports - any photos or drawings would be great. I am in the process of building up some 620 cabinets for my 604 drivers (re-purposing some quite tattered Magnificents i found locally), and would like to have the flexibility to alter the port size to properly tune the cabinets. I have the information on recommended port size for 9 cu ft cabinets, but I am sure mine will not be exactly 9, and it is likely all 9 cu ft cabinets are not created equal...... Trying to cut the port larger after the fact, or putting in 'shims' to decrease port size, seems a bit haphazard. I would like to design some flexibility in, if possible.

I also have a few bits that may be of interest to others, such as the bass horn woodwork (which came out quite cleanly). Probably do a post once I have done both sides, and have a better idea of what is there..... All of the drivers and crossovers were long gone, do no need to ask about those.

regards -- Roger

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I like to use 6in. PVC pipe which can be cut in various lengths and
joined with a PVC pipe coupling to facilitate tuning.

There is no need to glue the pipe to the coupling as they grip sufficiently
in this application, and can be removed for tuning.


A lathe is ideal for cutting the pipe and couplings.

............GC

I would mount the flange (screw in place) on the front of the speaker so that the duct sticks out into the room. That way it will be easy to change ducts to differing lengths until you find the one that works best. Once you've determined your optimum duct length you can then mount the flange on the inside of the cabinet and glue the duct permanently in place.

Thanks very much for the suggestions. Helps in planning for the port.....

regards -- Roger

Quote:

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Originally Posted by rogerh113

Thanks very much for the suggestions. Helps in planning for the port.....

regards -- Roger

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Roger, what version of 604 are you going to use ???
...........GC

I have the 604-8G, and am planning on building up some Markwart crossovers. Cab is Altec 620 ish at ~ 9.3 cu ft calculated without deducting the 604, bracing, port, etc, etc.....

Thinking of using a 6" Precision Port in each of the cabs, since they are flared and adjustable. Other options are out there as well, and I am still considering options.

regards -- Roger