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Old 11th February 2009, 06:10 PM   #1
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Default T&S Lowther PM2A

I measured T&S parameters of one om mine Lowther PM2A and thought it would be of general intrest:

Sd 209 cm2
Vas 36 liters
Fs 58 Hz
Mmd 12,9 g
Mms 14,7 g
Re 8,8 Ohm
Bl 20,2 N/A

Cms 0,588 mm/N
Rms 1,87 Ns/m

Qms 2,68
Qes 0,107
Qts 0,103


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Close up

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Note the cone breakups at 950 Hz and 2300 Hz.


Regards / Petter
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Old 11th February 2009, 07:26 PM   #2
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Yup, that's a PM2A! It's not my favorite - I'm currently trying to
decide on the PM6A (16 ohm, Ticonal) vs the PM5A (bigger magnet).

I have the PM4A's coming, and I'll let you know eventually.

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Old 11th February 2009, 07:34 PM   #3
MJK is offline MJK  United States
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Measurements of the T/S parameters for my Lowther drives can be found here.

http://www.quarter-wave.com/General/Lowthers.pdf

My pair of PM2A's seem to be a little bit different.
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Old 11th February 2009, 07:51 PM   #4
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Quote:
Yup, that's a PM2A! It's not my favorite
Not mine either. Thatīs why they are in the book shelf, using
compression drivers instead for mid and highs. My pair is for sale
and i thoudht i would measure them before itīs to late.


There are a big differences in the Bl product between my sample
and those at quarter wave.
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Old 11th February 2009, 09:02 PM   #5
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Ye Gods! I make that as a 1.126KHz Fhm. That's a unit demanding a front-horn if ever I saw one... or a very large dose of series resistance / current source amp.

One wonders just what level of unit-to-unit consistancy Lowther achieve. No offense to them (although they're not exactly my cup of tea), and other manufacturers certainly have issues in this respect too. But one wonders...
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Old 11th February 2009, 09:22 PM   #6
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Default new or old version

your pm2A is the old version or the new one ?

I have the old version. It's on the shelf too...
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Old 11th February 2009, 09:39 PM   #7
MJK is offline MJK  United States
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All of my drivers are the new version with the rolled whizzer cones. I used my pair of PM2A drivers in my large OB for quite a while and they sounded very good. Personally I like the DX drivers the best but I did not have any complaints about the PM2A's sound. I have also tried my PM2A's in my ML TL with a variable correction circuit and it sounded very nice, I prefered it to the PM6A's in the same ML TL. Based on the T/S measurements, there is something very different in my PM2A drivers and the ones in the original post.
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Old 12th February 2009, 06:25 AM   #8
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Itīs the old version, and theay are probably reconed aswell since they the cone structure differs from the other PM2A I've seen.

Click the image to open in full size.
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Old 12th February 2009, 07:30 AM   #9
CLS is offline CLS  Taiwan
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I'm no expert of Lowther, but the frames look like AER to me. And there're no raidal pressed marks on the main cone, some suspicious concentric marks instead.
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Old 12th February 2009, 08:55 AM   #10
jdunham is offline jdunham  United Kingdom
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Those are Lowther frames, not AER. They're the ones they used after the original square frames. I have some PM6A's with the same frames from the 1970's.

The cones look like they are from a "C" driver, not an A or DX driver. So probably are re-coned.

Cheers,

Jonathan
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