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Old 26th January 2007, 09:55 PM   #111
tinitus is offline tinitus  Europe
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Order the softest surround he has

What are efficiency of all drivers - what are your goal fore overall sensitivity
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Old 26th January 2007, 10:54 PM   #112
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Quote:
Originally posted by richie00boy
You've either got your Qes, Qms and Qts all mixed up or there's something wrong. Box Q can never be lower than Qts.


Sorry Rich I got the decimal place in the wrong spot, those should have read:

Qts: 0.329
Qes: 0.4
Qms: 1.85
Fs: 25hz
VAS: 40ltrs
Mms: 70g

Qts: 0.381
Qms: 1.6
Qes: 0.5
Fs: 33hz
VAS: 40ltrs
Mms: 40g

Quote:
I would aim for Qts around 0.35-0.45. Qms and Qes will have to be juggled according to motor and suspension requirements/constraints. It might also be worth specifying a target BL range, I feel a highish (>8) BL gives more slam and control to the sound which is what I think you're after.

As you know your box volume you can then work back to what Vas would give you the desired box Q.

The trouble is a lot of parameters interact. For instance Vas will be influenced by Fs.
Yeah its a tough job to make changes, is there any sort of auto calculate utility that will do all the lot instead of having to work through the formula's?
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Old 26th January 2007, 10:57 PM   #113
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Quote:
Originally posted by tinitus
Order the softest surround he has

What are efficiency of all drivers - what are your goal fore overall sensitivity
Its looking very likely that I'll be going active again as things have gotten more complicated since the initial idea I had for use with passive. So sensitivity isn't really that much of an issue anymore but the treble is around 95 and the mids around 94. Its going to be impossible to get an 8" to extend to an F3 of 50hz in a 20ltr sealed enclosure whilst simultaneously have a sensitivity of 90dB+. So what I'm going to have to do is take a knock and look at around 85dB+. The largest flexunit motor for the 8" is an 200mm magnet on a 230mm frame which should have a formidible field strength, if I make it overhung and go with a 4" voice coil then that will help things once the driver Fs and VAS start to drop.
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Old 26th January 2007, 11:16 PM   #114
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Can anyone tell me what effects changing a 3" coil to 4" one has? Is it just Qes, Qts, BL, mms, re and fs or are there more?

This is way over my head. I just fail to see the all the relationships between the parameters. Really need a bit of guidance here.
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Old 26th January 2007, 11:18 PM   #115
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Well, I cant help but thinking that 4 x 10" (Beyma 10BR60 ?)pr side would be the right thing to deal with 40-300 hz

and the result would be a much simpler construction
and they would be able to take some EQ
and without the side woofers you would have less phase problems to deal with
and end up with much better efficiency

edit... or 4 x 8" AT with good Xmax and low Fs, if thats preferable
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Old 26th January 2007, 11:57 PM   #116
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Quote:
Originally posted by tinitus Well, I cant help but thinking that 4 x 10" pr side would be the right thing to deal with 40-300 hz
Are you saying ditch the subs and just go with a speaker that does 40hz+?

BTW The only drivers left to order are the 8" so at this point I've made my bed and will have to lay in it.

Quote:
and they would be able to take some EQ
10's that would elegantly run upto 300hz and storm down to 15hz after EQ don't really exist or at least I haven't found any yet. Running 20hz at fairly high SPL's on a 10" would knock the s**t out of IMD.

Quote:
and without the side woofers you would have less phase problems to deal with
Phase problems? If you consider the subs blending in around 40hz then that frequency has a wavelength of about 8.5m. All 4x side firing 10's would effectively couple as the 1/2 wavelength rule applies, the dispersion will be omni at those frequencies so the same coupling will apply between the 8's and 10's, there's also the delays to refine things further. If anything, more room modes will be excited and more evenly since your working with 4 woofers and 4 subs working in different planes and they still remain consistent in distance from the listening spot.

Quote:
and end up with much better efficiency
Deep bass is always inefficient, you either have to build a horn the size of a garage or you make up with numbers, displacement and amplifier power if your wanting things more manageable. Thats pretty much why I decided on the 4 side firing XLS10's, they only have a very limited but demanding range to work in. The rest of the range can be optimised with the use of more suited drivers.

It all looks pretty ambitious at the moment and there's a hell of a lot of hearsay on my part - it could turn out to be the biggest POS ever to grace this good forum. But my gut feeling says that this is the best way to go about what I'm really after, the others designs were me compromising, this is the one I really wanted to build from the start. Much will depend on the XO and I've been well prepared with all my active experiments on the Perceives.

Thanks for the input.
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Old 27th January 2007, 12:56 AM   #117
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I think I've nailed the internal partitions:

Click the image to open in full size.

Blue = mid enclosure (7ltrs)
Green = bass enclosure (20ltrs)
Red = sub enclosure (20ltrs)

All volumes are after bracing.

The problem is maintaining the relative cabinet dimensions/driver positioning and distributing the relevant volumes between the drivers. Its a bit convoluted but gets the job done. Really could do with about 25-30ltrs for the bass driver to work in, might have to widen and make the cabinets slightly taller to do this. The XLS10 is more than happy with 20ltrs and yields a critically damped alignment with this.
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Old 27th January 2007, 08:11 AM   #118
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Quote:
Originally posted by ShinOBIWAN Its a bit convoluted but gets the job done.
We wouldn't expect anything less
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Old 27th January 2007, 12:34 PM   #119
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Quote:
Originally posted by ShinOBIWAN


Hi Marc

I've bit the bullet and am paying for image hosting now. This will allow to host all images and not have to keep deleting older ones to make way for the new, you should find that the majority of the images in the Perceive 2 thread are working again. The early ones in that thread I can't fix because they where hosted on a different server but the rest should be OK from about page 30 onwards.

They're pretty spread out though because the thread is quite large. Here's a couple if you can't be bothered to hunt through:

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.
Very very beautiful realization

Angelilo

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Old 27th January 2007, 12:34 PM   #120
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Very very beautiful realization

Angelilo
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