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
Close up
Note the cone breakups at 950 Hz and 2300 Hz.
Regards / Petter
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
An externally hosted image should be here but it was not working when we last tested it.
Close up
An externally hosted image should be here but it was not working when we last tested it.
Note the cone breakups at 950 Hz and 2300 Hz.
Regards / Petter
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.
http://www.quarter-wave.com/General/Lowthers.pdf
My pair of PM2A's seem to be a little bit different.
Yup, that's a PM2A! It's not my favorite
Not mine either. That´s 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 it´s to late.
There are a big differences in the Bl product between my sample
and those at quarter wave.
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...
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...
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.
It´s the old version, and theay are probably reconed aswell since they the cone structure differs from the other PM2A I've seen.
An externally hosted image should be here but it was not working when we last tested it.
Have you considered reconing with the new frame and cone/whizzer? Does Lowther still have the trade in policy? The magnets are probably fine so if the bolting pattern matches a new front might be a step up in performance. Worst case you sell them later with the updated cones.
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