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Multi-Way Conventional loudspeakers with crossovers

MW16P-4 vs MW16P-8 & TW29R vs SB29RDC-C000-4
MW16P-4 vs MW16P-8 & TW29R vs SB29RDC-C000-4
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Old 1st October 2018, 02:29 PM   #51
rscamp is offline rscamp  Canada
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Join Date: Jul 2018
Location: Ontario, Canada
Quote:
Originally Posted by krivium View Post
Yes minidsp have a Linkwitz Transform biquad fonction ( you can apply it using other ways, usually it use one or two parametric eq band, sometimes more...).
You can simulate it using winISD ( the freeware have a dedicated tab in the eq/filter section and it will give you valuable simulation including xmax and power requirement). I suggest you try it (to have an idea of limitation and compromise)...
WinISD FR plot attached. The excursion is scary so it looks like this must be used in moderation to extend low frequency response. The transfer function looks good. As a first thought, might it be best to make a critically damped enclosure alignment and start from there?
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Old 1st October 2018, 03:30 PM   #52
rscamp is offline rscamp  Canada
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Originally Posted by krivium View Post
How high in freq your sub are acceptable quality wise?
Well that's a good question. I don't currently know!

The crossover is at 90Hz but this will be re-evaluated when I start using REW. There are two subs. I have some room treatment (a Helmholtz passive absorber for example) and have spent hours and hours finding good locations for the subs with respect to obtaining smooth audible LF chirps. The re-positioning effort resulted in a large improvement - so large it seemed like I had just invested $$$ in a new system. It was amazing how this alone improved the overall sound - seemingly not just the low frequencies. But anyways, the result is the subs are not close to the main stereo pair and will be localized if I cross over too high and/or have a shallow low-pass slope.
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Old 1st October 2018, 04:07 PM   #53
krivium is offline krivium  France
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Rscamp,
Ok you discovered the limits of LT in case of low end extension which is a worst case scenario.
Now lets contemplate this case: a satellite and sub use satellite down to 80hz and sub from there.
There is reason for that: below 80hz we have difficulty to locate sound ( and this is even more true in a room and given you are in modal zone it can even be true up to 150hz ime), so if you can locate your 'satelite' within 1meter from the sub center* everything should be fine ( as we are in the enviable position to be within 1/4 wavelength center to center where there is acoustical coupling, sub and sat behave as one and only source).

So try to simulate the satory 7" for 80hz and 0,577 Q and check for spl and excursion. You'll see this should give you much less scarying results and this will be all needed for the high pass part for a Harsch solution ( you'll need a bit of delay for your 'sat' and a 24db butt lp on the sub). The 60hz 0.5Q example is the response if you block your port on the 17l box without a LT.

* imagine a sphere 1 meter diameter from center of your sub: this will give you the possible locations for your 'satellite'.

Last edited by krivium; 1st October 2018 at 04:13 PM.
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Old 1st October 2018, 04:58 PM   #54
rscamp is offline rscamp  Canada
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Join Date: Jul 2018
Location: Ontario, Canada
Quote:
Originally Posted by krivium View Post
Rscamp,
Ok you discovered the limits of LT in case of low end extension which is a worst case scenario.
Now lets contemplate this case: a satellite and sub use satellite down to 80hz and sub from there.
There is reason for that: below 80hz we have difficulty to locate sound ( and this is even more true in a room and given you are in modal zone it can even be true up to 150hz ime), so if you can locate your 'satelite' within 1meter from the sub center* everything should be fine ( as we are in the enviable position to be within 1/4 wavelength center to center where there is acoustical coupling, sub and sat behave as one and only source).

So try to simulate the satory 7" for 80hz and 0,577 Q and check for spl and excursion. You'll see this should give you much less scarying results and this will be all needed for the high pass part for a Harsch solution ( you'll need a bit of delay for your 'sat' and a 24db butt lp on the sub). The 60hz 0.5Q example is the response if you block your port on the 17l box without a LT.

* imagine a sphere 1 meter diameter from center of your sub: this will give you the possible locations for your 'satellite'.
There are a couple of potential problems. I have a combination stereo/HT setup and I suspect the LP filter on the AVR for the subs is 4th order. I also can't position the subs within 1 metre of the stereo pair.
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Old 1st October 2018, 05:35 PM   #55
krivium is offline krivium  France
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There is no problem for the lp to be 4pole (in case of Harsch setup as this is what is needed for the lp on sub).
1m is text book once your speakers done done you could try it to see if you experience issue or not.
But this was just a suggestion from my part ( Lt and or Harsch filter) , there is many ways to skin a cat...
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Old 1st October 2018, 05:46 PM   #56
rscamp is offline rscamp  Canada
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Join Date: Jul 2018
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Quote:
Originally Posted by krivium View Post
There is no problem for the lp to be 4pole (in case of Harsch setup as this is what is needed for the lp on sub).
1m is text book once your speakers done done you could try it to see if you experience issue or not.
But this was just a suggestion from my part ( Lt and or Harsch filter) , there is many ways to skin a cat...
No problem. I really appreciate your input! It helps me discover new possibilities.

The shipment just arrived! I now have most of the items needed to build and test this project. I have to be disciplined though and finish off my current speaker project or it won't get done. I'll be able to play with REW a bit while the glue/paint is drying.
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Old 2nd October 2018, 06:23 PM   #57
rscamp is offline rscamp  Canada
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Well these practice speakers ended up sounding better than I expected.

I call the finish "MDF au naturel".
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