T&S Lowther PM2A

Petter Persson · 11th February 2009, 06:10 PM

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

Nelson Pass · 11th February 2009, 07:26 PM

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.

MJK · 11th February 2009, 07:34 PM

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.

Petter Persson · 11th February 2009, 07:51 PM

Quote:

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.

Scottmoose · 11th February 2009, 09:02 PM

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...

hornophile · 11th February 2009, 09:22 PM

your pm2A is the old version or the new one ?

I have the old version. It's on the shelf too...

MJK · 11th February 2009, 09:39 PM

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.

Petter Persson · 12th February 2009, 06:25 AM

It´s the old version, and theay are probably reconed aswell since they the cone structure differs from the other PM2A I've seen.

CLS · 12th February 2009, 07:30 AM

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.

jdunham · 12th February 2009, 08:55 AM

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

11th February 2009, 06:10 PM	#1
Petter Persson diyAudio Member Join Date: Sep 2007	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 Close up Note the cone breakups at 950 Hz and 2300 Hz. Regards / Petter

11th February 2009, 09:22 PM	#6
hornophile diyAudio Member Join Date: Dec 2007	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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11th February 2009, 07:26 PM	#2
Nelson Pass The one and only Join Date: Mar 2001	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.

11th February 2009, 07:34 PM	#3
MJK Account disabled at member's request Join Date: Feb 2002 Location: Clifton Park, NY	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.

11th February 2009, 09:02 PM	#5
Scottmoose diyAudio Member Join Date: Mar 2005 Location: UK	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...

11th February 2009, 09:39 PM	#7
MJK Account disabled at member's request Join Date: Feb 2002 Location: Clifton Park, NY	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.

12th February 2009, 06:25 AM	#8
Petter Persson diyAudio Member Join Date: Sep 2007	It´s the old version, and theay are probably reconed aswell since they the cone structure differs from the other PM2A I've seen.

12th February 2009, 07:30 AM	#9
CLS diyAudio Member Join Date: Jun 2005 Location: Taiwan	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.

12th February 2009, 08:55 AM	#10
jdunham diyAudio Member Join Date: Oct 2003 Location: Near London	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