Posted by Roy on April 21, 2005 at 16:14:31:
In Reply to: Re: Re:More info posted by Lew on April 21, 2005 at 06:47:45:
Lew,
I must have missed something as I hadn’t realised that the factory had claimed that new stator
insulation + higher bias voltage = an increase in efficiency.
I mentioned stator to membrane distance being and important factor with regard to efficiency.
The two panels that I have used had different stator to membrane distances. This distance is a compromise between efficiency and the speakers ability to handle large bass excursions. I dare say the SL design in this respect has changed many times to reflect the requirements of users over time. That is one reason why one owner may find a slight increase in efficiency and another may not, it all depends when their particular panel was manufactured. My gut feel with my limited experience is that the variation with regard to stator to membrane distance will be worth 0.5 – 1.5dB.
To estimate the difference that the increase in stator wires may give is very difficult. I think you would need to compare a speaker that had been manufactured when a small stator wire to membrane distance was the norm, I think my panels are close to this and they were manufactured in 1994.
When I remanufactured my panels I was mindful that I had membrane stator slap previously on large bass excursions. To combat this I have fitted a dual thickness membrane. The lower third of the membrane is 4 microns thick with the remainder being 2.5microns thick, it works.
Roy