Box-tuning magnet-to-magnet construction - Page 2 - diyAudio
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Old 31st May 2009, 04:14 PM   #11
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Well, then I won't bother cutting holes for the port and all that :-)

What about my thought of dividing both of the two cabinets on the drawing into two each, dividing them between the magnets that unfortunately won't come any closer to each other than about 15 cm.

Dividing the boxes should increase the width:depth ratio which is preferably - if I get it all right?
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Old 31st May 2009, 04:21 PM   #12
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Originally posted by Mr_Oasis

I won't be able to have the magnets physically touching each other, as the box then won't get deep enough to store my battery. The closest I'll be able to mount the magnets to each other is approx. 15 cm.

When I can't get the speakers touching - and need to make the cabinet as wide as possible compared to the depth, would it then be worth the effort to omit the magnet-magnet solution and instead divide the cabinet into two between the drivers? Even thought they probably are intented for 'leaky' enclosures in a car, the reflex-port won't be a good idea?
You can and should still couple them with a spacer or a brace that runs the height of the enclosure. There are many drawings of this type of brace in the FullRange section. The brace needs to be offset, not centered in the enclosure or on the magnet. If the magnets are heavy a lip can be incorporated to help support the back of the driver as well. This is more work but worth the effort.
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Old 31st May 2009, 05:27 PM   #13
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Okay, I think I get what you're talking about. Is it possible that you can drop a link to such a brace - just to be sure?

Thanks a lot for the help by the way, it's really apreciated :-)
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Old 31st May 2009, 05:45 PM   #14
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The 42 liter push-pus box is pretty much what your will look like only smaller. The brace will need to have cut-outs so as to not act as a baffle, only a brace. A lip may not be necessary as the magnet can't be that heavy on a 6 x 9 and will be supported from the contact with the brace. This will also tighten up the whole box as the baffle will not have to span as far.
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Old 31st May 2009, 06:04 PM   #15
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Great, thanks a lot!

I think I'll just have to get my hands dirty working :-)

If there's any trouble, I'll come back asking more dumb questions. This is my first build, so I'm learning all the time.
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Old 1st June 2009, 01:46 PM   #16
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Col, I don't think I'll be able to get my hands on any 400F capacitators, but I should be able to get some 470F. Based on my calculations with 4 ohm speakers - that will cut somewhere about 80-85 Hz.

What voltage does these caps need to be as a minimum? I'm running the amp on 12V.

I have a few electrolyt capacitators at home already that is 470F, but just 6.3V. I'm quite certain that these aren't big enough, but what values would I need to be sure I'll work out best?

Would it be something like these:

...they are 470F 35V?

I won't be able to get those before next week and I'm going to do the building and construction the next few days, so will I be able to maybe just test at a low volume with the capacitors I mentioned above - 470F 6.3V?
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Old 1st June 2009, 05:24 PM   #17
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Note that the cap needs to be non-polar.

As well due to the resonant peak in the impedance, the calculation of cut-off is no-where near text book.

community sites,, ........ commercial site planet10-HiFi
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Old 1st June 2009, 06:58 PM   #18
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Hmm, for me it doesn't seem possible to find bipolar 470F caps anywhere?

I don't want to cut off all the bass - just whats nessesary in order not to get the distortion. I think I'll just mount the speakers without any caps, and see how it goes. Then maybe I can use a tone-generator to find out what frequency to cut at.
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Old 1st June 2009, 09:10 PM   #19
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I've used 1000u caps back-to-back before. But as Dave says, it's a bit naff.
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Old 1st June 2009, 11:08 PM   #20
col is offline col  Australia
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I got my caps from here:

I guess you could mail-order, would have them too, probably cheaper.

Also, a PLLXO crossover might be more appropriate. You can adjust the input on the amp6 with resistors so adding a PLLXO might be a good option.

I think Dave knows better about this option though?

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