WmAx

WmAx

Audioholic Samurai
By the way some of you will wonder how this possible. Well the db scale. The Lowther PM 6 has a sensitivity of 96db 1 watt at 1 meter. Put two together and you have 102 db. Donald Cave used a total of 60 watts from tube amps. That's all there was then. However that would be equivalent of a little over 1000 watts power with conventional speakers.

In my fathers case 100 watts of amplification was used, which is equivalent to driving conventional speakers with 1000 watts of amplification.
With a high efficiency cone driver, comes certain limitations, some of which are usually a high Fs or very limited motor. The Lowether appears to make a substantial compromise in the motor; but seems to keep a reasonable Fs. In addition, while I have never seen these drivers put under a proper distortion analysis vs. low frequency vs. spl; I believe it unlikely they offer anything special in regards to such. So, while I don't have specific data for this driver, I'll base the following on expected general rules that should apply, give or take 10 percent for error. It may be this 6" driver worked sufficiently for the church PA application down to 70Hz or so. Perhaps 55Hz, assuming the church shape you make mention by some chance acted as a large extension of the horn mouth, and assuming moderate SPLs are required in that church. Low SPL of course, has lesser requirements. With increasing SPL at lower frequencies, I expect distortion to raise rapidly, as well as for compression to start setting in rapidly. As for this being a 'hi-fi' execution, as you claimed earlier, one might question what should classify as 'hi-fi'. A large, highly resonant system with very limited dispersion and limited LF response is not my personal definition of 'hi-fi', but that's just my viewpoint. With this driver, to get what I would classify as marginal SPL vs. distortion LF down to say 40Hz range, I will presume would require a massive horn loaded design with effective horn loading re-enforcement down to that low frequency. From what I recollect, Lowther drivers have extremely limited excursion. Somewhere in the realm of 1-2mm, I believe. I consider 30Hz to be the earliest any hi-fi system should roll off. And dynamics at 30-40Hz should be able to reach a minimum of 95db at the listening position without audible levels of distortion to account for semi-sustained semi-loud/dynamic passages while playing music at least at medium-moderate average SPL; probably in the 80-85dB slow averaged SPL range.

-Chris
 
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TLS Guy

TLS Guy

Audioholic Slumlord
With a high efficiency cone driver, comes certain limitations, some of which are usually a high Fs or very limited motor. The Lowether appears to make a substantial compromise in the motor; but seems to keep a reasonable Fs. In addition, while I have never seen these drivers put under a proper distortion analysis vs. low frequency vs. spl; I believe it unlikely they offer anything special in regards to such. So, while I don't have specific data for this driver, I'll base the following on expected general rules that should apply, give or take 10 percent for error. It may be this 6" driver worked sufficiently for the church PA application down to 70Hz or so. Perhaps 55Hz, assuming the church shape you make mention by some chance acted as a large extension of the horn mouth, and assuming moderate SPLs are required in that church. Low SPL of course, has lesser requirements. With increasing SPL at lower frequencies, I expect distortion to raise rapidly, as well as for compression to start setting in rapidly. As for this being a 'hi-fi' execution, as you claimed earlier, one might question what should classify as 'hi-fi'. A large, highly resonant system with very limited dispersion and limited LF response is not my personal definition of 'hi-fi', but that's just my viewpoint. With this driver, to get what I would classify as marginal SPL vs. distortion LF down to say 40Hz range, I will presume would require a massive horn loaded design with effective horn loading re-enforcement down to that low frequency. From what I recollect, Lowther drivers have extremely limited excursion. Somewhere in the realm of 1-2mm, I believe. I consider 30Hz to be the earliest any hi-fi system should roll off. And dynamics at 30-40Hz should be able to reach a minimum of 95db at the listening position without audible levels of distortion to account for semi-sustained semi-loud/dynamic passages while playing music at least at medium-moderate average SPL; probably in the 80-85dB slow averaged SPL range.

-Chris
The Lowther drivers are actually low Qts drivers designed specifically for horn loading. They have huge flux densities and are highly sensitive and efficient.

Here is a link to Lowther.

http://www.lowtherloudspeakers.com/

Here is a link to the driver my father selected, the PM6A

http://www.lowtherloudspeakers.com/homeindex.html

Here is a link to Lowther America.

Lowther are one of the oldest, if not the oldest Hi fidelity loudspeaker manufacturer. They still have a good following. In the days before computer assisted crossover design, they had a very big following. They sound very good, they just have a little too much mid range shout at 2.5 K for my total satisfaction. However I always give them a listen when I get a chance. The drivers do continue to improve. They have been known on a number of occasions to fill large spaces very well.

The original design was by Paul Voight who many consider the father of high fidelity. Pre WW II the driver had a huge electromagnet. I have seen one in a museum, but never heard one unfortunately. After WW II things were tough in the UK for individuals of German extraction. Lowther was sold to Donald Chave who developed the business into a formidable speaker company. He also produced a nice line of tube amps. Since Donald's death the company has held a good niche position. There are a number of companies around the world producing speakers using these full range drivers. Among the most well known is the German Klein horn.

Paul Voight emigrated to Canada and lived the life of a somewhat eccentric recluse. There was a fascinating interview with him just before his death, that was published in speaker builder. We still have a lot to learn from those that blazed the trails. It's not really that long ago, but how we forget.

Don't dismiss it. They sound very live and engaging. Horns really fill a big space. The biggest installation I did was a large hall. I used a JBL 15 drivers in two gigantic back loaded horns with 3 ft horn mouths. Top end was 8 Jordan Watts modules a side. Biamped with 500 Hz crossover. The system is still functional after 30 years.
 
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