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Old 20th September 2007, 09:28 AM   #1
jev is offline jev  Netherlands
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Default Lowther satellite

Currently I have Wilson Watt clones as satellites that reside on top of two subwoofers. I would like to construct two satellite speakers with my PM2a Lowther driversI have lying around. Any ideas?

The Kawaguchi enclosures look nice. http://www10.big.or.jp/~dh/faq/kawaguchi/index.html

Requirements are size (~~ 35 cm wide, `` 40 cm deep, not too heigh).

PS the subwoofer filter is a DBC 12 Stereo (blueplanetacoustic.com)
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Old 20th September 2007, 10:25 AM   #2
hm is offline hm  Europe
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Default Horn -Sat

Hello jev,

look my 3 alternatives
HORN-, TRUMPET-, SCHALMEI-SAT

The moderator forbid me direct links, so please
use the link in my signature.
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Old 20th September 2007, 11:21 AM   #3
Pano is offline Pano  United States
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Lowther has a satellite? Cool!

Is it "beaming" back to earth?
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Old 20th September 2007, 05:37 PM   #4
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http://www10.big.or.jp/~dh/faq/kawaguchi/index.html

I have a feeling those Lowther cabinets are simply aperiodic. They drill out several holes and cork them up during listening tests to tune to taste. It’s an interesting idea that certainly will not squeeze the most performance from your drivers but maybe enough to mate nicely with your subs.

Here’s a site with some small bass reflex cabs for Lowther.

http://www.lowtherspeakers.com/bassreflex.html
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Old 20th September 2007, 06:24 PM   #5
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Quote:
Originally posted by Godzilla
I have a feeling those Lowther cabinets are simply aperiodic.
My 1st thot too... the driver mounting and protruding edges will cause some serious diffraction.

Martin might have real world parameters for your Lowthers, i'd be modeling a sealed box with an eye to making it aperiodic. Whether it will work is probably dependent on how high you can take your woofers.

dave
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Old 20th September 2007, 07:41 PM   #6
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Oooh -perfect for resonance and diffraction problems! Yeah, they're certainly aperiodic.

Looking at Martin's measured parameters, the IB performance of the PM2A rolls off rapidly below about 800Hz, so sealed and / or aperiodic isn't going to be ideal. About the best I can offer is a box 19in tall, CSA 64in^2, Zdriver 9.5in, 3in diameter, 2.5in long vent mounted 2in up from the base. (all dimensions internal). Line it with your favoured damping material. Excursion stays well within Xmax down to cutoff, 1w / 1m. FR plot attached.
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Old 20th September 2007, 07:48 PM   #7
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Quote:
Originally posted by Scottmoose
the IB performance of the PM2A rolls off rapidly below about 800Hz, so sealed and / or aperiodic isn't going to be ideal.
How big a box is that. What is the cutoff of a sealed box with a Q of 1.1?

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Old 20th September 2007, 08:46 PM   #8
jev is offline jev  Netherlands
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Quote:
About the best I can offer is a box 19in tall, CSA 64in^2, Zdriver 9.5in, 3in diameter, 2.5in long vent mounted 2in up from the base. (all dimensions internal). Line it with your favoured damping material. Excursion stays well within Xmax down to cutoff, 1w / 1m. FR plot attached.
If I understand this correctly this would be the following box:
- Height box = 19in ~ 48cm
- Internal volume = 64in^2 ~ 4 liters (this is not correct is it? What is CSA?)
- Diameter driver Lowther = 9,5in ~ 24cm (or is this the width of the box? What is Zdriver?)
- Vent = 3in diameter ~ 7,6cm / 2,5in long ~6,35cm
- Vent up from the base = 2in ~ 5cm

And the woofers are JBL 2203a. Very thick and heavy cones. Probably should not cross over very high (now below 100hz).
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Old 20th September 2007, 09:25 PM   #9
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CSA = Cross Sectional Area. So the surface area of the top & bottom is 64 square inches. The width and depth dimensions are up to you, so long as you preserve this area.

Zdriver = the distance from the internal top to the centre of the driver.

Sorry Dave, I got a value wrong when I entered the driver data in the sealed box sheet, hense the apparantly duff response. Anway, this is the best I can do with a sealed box, CSA=68.2in^2, 19in tall, Zdriver 7.0in

A box Q of 1.1 would be about 1.68 litres using Martin's measurements (& assuming I've remembered my sealed box math correctly[?]: Vb = Vas / ((Qtc / Qts)^2 -1) )which is too small for the driver to fit.
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Old 21st September 2007, 05:54 AM   #10
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Quote:
Originally posted by Scottmoose
driver data in the sealed box sheet
Where do i find the PM2a data on Martin's site?

dave
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