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Old 18th September 2003, 07:21 PM   #11
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Default Re: Re: Re: reply to MatttCattt

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I might try this, but the reson for isobarik configuration is size. (500l instead of 2000l )
I missed that (even after looking twice)

I'm still of the conviction that isobarik has advantages beyond halving the box size.

Still the big box, push-push will very likely give better performance.

dave
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Old 19th September 2003, 05:07 PM   #12
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Default Re: Re: Re: Re: reply to MatttCattt

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Originally posted by planet10


I missed that (even after looking twice)

I'm still of the conviction that isobarik has advantages beyond halving the box size.

Still the big box, push-push will very likely give better performance.

dave
i know, but i dont have a room to devote to my subwoofer.
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Old 23rd September 2003, 07:39 AM   #13
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I have some questions about crossover (before amplifier).

1) Which order should i use? 1st? 2nd? 4th?

2) I want to use the linkwitz transfor circuit. I also want to have a low pass filter at ~120Hz, and a high pass filter at ~20Hz. Should I put the filters before or after the linkwitz transform circuit?

I think it should be:
LP 120Hz -> Linkwitz -> HP 20Hz
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Old 23rd September 2003, 11:52 AM   #14
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Hi Matt,

As no-one else is answering...

Probably best 2nd order, apparently if it's too steep it won't integrate with the main speakers as well. 1st order is probably not steep enough.

As for where to put each filter stage, I don't think it makes any difference. I think I read that on a LT guide page the other day...

When you choose how much gain to use in your LT circuit, keep it as low as possible, or you'll probably run out of excursion on those (not that great) woofers.

Also, why not start the rolloff at about 25hz, as you can hardly hear much at all below this frequency anyway. (or at least I can't with my sub, which is -3db <20hz - even when turned loud there is little to hear, just a bit of distortion from my main speakers and a few things rattling ;-) )


-Simon
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Old 23rd September 2003, 03:14 PM   #15
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Quote:
Originally posted by SimontY
Hi Matt,

As no-one else is answering...

Probably best 2nd order, apparently if it's too steep it won't integrate with the main speakers as well. 1st order is probably not steep enough.

As for where to put each filter stage, I don't think it makes any difference. I think I read that on a LT guide page the other day...

When you choose how much gain to use in your LT circuit, keep it as low as possible, or you'll probably run out of excursion on those (not that great) woofers.

Also, why not start the rolloff at about 25hz, as you can hardly hear much at all below this frequency anyway. (or at least I can't with my sub, which is -3db <20hz - even when turned loud there is little to hear, just a bit of distortion from my main speakers and a few things rattling ;-) )


-Simon
ok
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Old 20th January 2004, 07:53 PM   #16
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OK, time for an update. i have changed the design lightly: i have built 1 ~150L box (50cm cube).

i have not finished assembly, and i have not added the braces yet.

i will post some pictures ASAP, probably this weekend.

i am very excited, and cannot wait to get it running.
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Old 24th February 2004, 04:46 PM   #17
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At last, I have had the time to take and host some pictures of my subwoofer. (See pics 1/2)

I was so eager to finish the construction that I did not take any pictures whilst I built it.

I have not painted it yet, and I am thinking of painting it matt black, when I have time/funds.

It adds lots of bass to my current setup. (See pic 2) Hopefully I will get flatter response when I finish the Linkwitz Transform Circuit I am building for it.

I have also taken the opportunity to show off my humble HIFI system. (See pic 3)

Sorry about the quality, I am really bad a taking photos, and I have compressed the image as I only have a limited amount of storage space online. Also, sorry about the wait. Enjoy.

[edit]: Forgot some details. It is a 50cm cube, made from 18mm think MDF. It has an internal volume of approximately 98l, and i have changed this to 93l when working out response etc, to alow for the driver, an Eminence (Spelling?) Beta 15. Thanks to SimontY who gave me the driver. The graph (made with WinISD) is shown below (See pic 4), along with the graph for the Linkwitz Transform Circuit (See pic 5)

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.
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Old 24th February 2004, 07:57 PM   #18
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Hello there!

Good to see that old driver being put to good use. I really like your chunky look! Hope your Linkwitz transform works out ok...

I'm sure you'll let us know how that goes
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Old 24th February 2004, 09:29 PM   #19
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Quote:
Originally posted by SimontY
Hello there!

Good to see that old driver being put to good use. I really like your chunky look! Hope your Linkwitz transform works out ok...

I'm sure you'll let us know how that goes

Chunky?

I really hope it is worth the effort in the end. I put in over 120 screws. The battery in my electric screwdriver went flat after the first 30 or so. I did the rest by hand! Then I removed them, glued the panels together, and put them all back in! At least it was fun to build.
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Old 25th February 2004, 01:20 AM   #20
Bull is offline Bull  United Kingdom
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Looks good is it a sealed box, or is there a port somewhere round the back???
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