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Multi-Way Conventional loudspeakers with crossovers

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Old 4th July 2012, 11:09 PM   #81
tvrgeek is offline tvrgeek  United States
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Focusing on the Seas project. Got them into sanding sealer. The big 3/4 inch round over worked great. I still have a lot of crossover work to do.

I like the visual of the multi-ports on the side, but the measurements I did on diffraction with a moc-up was not much better than a square edge. I have some ideas to take his design to the next visual but with a different driver. I have two other projects that need front ports.

I use WinISD too. I'll pull a Fostex out of the box and do the measurements myself. We should not be getting different answers. I probably typed something incorrectly.
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Old 5th July 2012, 01:49 AM   #82
ODougbo is offline ODougbo  United States
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Thinking several 3/4" (to 1") strips would look different; going to tune low 60s.

When it was tuned at 61hz the sound just "disappeared" guessing about 1/2.
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Old 5th July 2012, 10:14 AM   #83
ODougbo is offline ODougbo  United States
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TVR, did find notes/pics on this box, it was 66hz before I went crazy and cut the sides off.

I also see 4 strips, which agrees with the previous post.

They didn't have much bass (and why I cut the sides off); I'm pretty sure it sure it should be in the low 60s - also Fostex recommends 57hz.

What did you put the sander sealer on; wood veneer?
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Old 5th July 2012, 09:06 PM   #84
tvrgeek is offline tvrgeek  United States
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MDF. Just did the first sand and a second coat. I am going to paint these. The last set I used automotive lacquer based primer. Easy to work with, quick drying, but i had a heck of a time getting it sealed so the top coats ( Dupont Centuri) did not go as well as I wish. Considering what a quart of that stuff runs, you don't want any problems. I am going to talk to the paint rep about that some more.

Boxes are drying, so let me look at the Fostex specs again and see why our sims looked different.
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Old 5th July 2012, 09:14 PM   #85
ODougbo is offline ODougbo  United States
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Oh Acrylic...yes that's what they are using these days on cars/trucks.

*
I think I'm going to go with the "comb" vent strip idea (might look cool).
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Old 5th July 2012, 10:00 PM   #86
tvrgeek is offline tvrgeek  United States
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Actually, new cars have to be water based acrylic. Never dealt with that stuff. As I don't have a powered suit, I have not played with Imaron either, but what a tough finish. The old standard non-activated acrylic is pretty forgiving. If you don't add accelerator, it does take days. I might spring for the extra this time. The brown metallic I used on my last set wound up being about $200 total for the paint. Brown is expensive. This time I think it is going to be green about two steps away from black. It looks like the water born has finally been worked out, so I should talk to the rep about it. The guys over in Beltsvillle are pretty patient with us non-tradesmen hacks.

As I suspected, I had some wrong values for the FF125WK. 9L, 63 Hz looks very good. Now I am going back to what I measured in your boxes and wondering why the response was not quite as solid.

I really don't see an advantage of tuning it lower. Another alignment would be 3L sealed for desktop speakers. (with sub). I bought some Fountek to play with like that too. All of them still need a tweeter!

When you get to using lots of small vents, calculations change as the friction in the ports becomes significant. It is no longer just cross section and length. Dynaco made good use of that years ago. Go for it. Anything to break up the square brown or black box!
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Old 5th July 2012, 10:03 PM   #87
tvrgeek is offline tvrgeek  United States
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Trick. Come Christmas, check all the paper wrapping paper tubes and see if any two fit snugly inside each other. Really cheap way to make adjustable ports for test. I don't do many ported boxes, but when I do, I put the port on the outside so changing it's length is easy and does not effect the box volume. When done, I build a new box taking the port volume into consideration.
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Old 6th July 2012, 09:40 AM   #88
ODougbo is offline ODougbo  United States
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That might be a long wait....haha PE has quite the selection of adjustable ports.

Friction in the ports,,,hummm that what this box needs, I think the vents are too thin now (having flashbacks). I'll be using the clamp-it-together-ploy to tune it, no calculations here!

The large 125wk boxes you have........if you add volume somehow (sand?) won't that drive up tuning frequency? I hope you have been breaking in your full range drivers.

Speaking of full range, my friend ended up with an vintage 80s McIntosh (mid level), I could probably swing a trade; it does work, would it need cap replacement?

Model MA6200

Last edited by ODougbo; 6th July 2012 at 10:00 AM.
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Old 6th July 2012, 05:22 PM   #89
ODougbo is offline ODougbo  United States
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More friction!!...don't want that with this box - now that you have informed me.

Second idea, use two strips and make a simple "<" in the slot, tune with clamps, adjust as needed. That will give me 2 small "horn" shapes on both sides. I guess I could curve them also.

A lot of small commercial speakers flare their ports.

A tweeter with Fostex; well that's a 2-way so I guess we are safe here

(-0;


Quote:
Originally Posted by tvrgeek View Post
When you get to using lots of small vents, calculations change as the friction in the ports becomes significant. It is no longer just cross section and length. Dynaco made good use of that years ago. Go for it. Anything to break up the square brown or black box!
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Old 7th July 2012, 04:34 PM   #90
ODougbo is offline ODougbo  United States
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Not much to look at, but did have some results; good - bad TBD.

The tuning is right around 60hz - 63hz. There is a noticeable increase in the bass around 55hz.
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