|
High Efficiency Speaker Asylum Need speakers that can rock with just one watt? You found da place. |
|
|
|
High Efficiency Speaker Asylum Need speakers that can rock with just one watt? You found da place. |
|
In Reply to: 4435/4350 posted by djk on May 12, 2003 at 16:45:50:
Hi Dennis!Sounds like a great solution. I'm fond of a similar system, a three-way using the JBL 2245, 2123 and 2426 or a 2142, 2012 and 2426. Using the 2206 in place of the 2012 or 2123 would be excellent too. There are a few guys running Professional Series three π 's, which are a 2206 and a 2426, and when this is combined with the 2245 sub, it's exactly the same system you described. So I'm with you on this one all the way. I like the simplicity of the large-format two-ways, and they're very popular. But splitting the band out to form a three-way or four-way has advantages too.
On the slot loaded subs you're talking about - You got me thinking about something though. I'm very familiar with the JBL and Eminence product offerings, and I like 'em both. I've built lots of systems that have similar drivers paired on the same baffle, but I'm not familiar with slot loaded or isobaric configurations.
It's easy to see that increased diaphragm decreases excursion requirements in a baffle mounted configuration. I would expect the same for the slot loaded configuration you've described. Perhaps it might emulate a stronger motor by improving force to weight. It certainly reduces distortion by reducing excursion requirements, but this improvement is similar to what would be expected by reducing power by 1/2. It's not like a 10dB change, more like a 3dB, and the distortion difference is a small percentage of that.
How does the slot loading mechanism suppress distortion greater than a pair of baffle mounted drivers? Have you seen evidence of this somewhere?
That gets me thinking of another interesting configuration - Isobaric. Seems like when two similar woofers are connected in an isobaric configuration, the diaphragms are coupled so that they act as one with increased mass. They're usually situated "face-to-face" and driven out of phase, electrically so that their cones move in unison, but I suppose they can be installed any way that has a common chamber between the diaphragms that doesn't become pressurized as the cones move. Seems like that one would make deep bass possible in a smaller cabinet, and power handling might be improved a little bit. But I wouldn't expect distortion performance to be considerably better. Do you know if that's the case or not?
I can see how some of these configurations can reduce distortion by virtue of reducing excursion requirements, but I don't expect they would be able to reduce the distortion caused by the motor's magnetic structure. Every reputable source I can think of indicates that low frequency distortion from voice-coil driven woofers is mostly caused by the magnetic structure and not the diaphragm, suspension or even the cabinet.
I suppose this could be largely due to the fact that the magnetic structure is modified by the voice coil's presence when the mechanical structure is in resonance, so maybe that's key here - If the cabinet can damp the diaphragm sufficiently, perhaps this will reduce distortion caused by the magnetic structure. Then again, I've seen data over and over again that shows distortion rising dramatically down low, regardless of the acoustic load. That would seem to indicate that while you can damp or shift the resonant frequency, this doesn't change the distortion performance of the magnetic structure. You see a lot of this in work discussing Faraday rings and the like.
Where I'm going with all of this is that I'd like to know specifically what kinds of distortion improvements you've found with dual woofers in this slot loading configuration. It "squeezes" the pressure built between the two. Have you seen anything that compares it with two woofers connected the same way but baffle mounted? What about the opposite connection, the isobarics? I've always treated dual (baffle mounted) drivers as having double the surface area and double the impedance if connected in series, or half the impedance if connected in parallel. But I've never given any thought to the other configurations, and I'm curious about their performance.
Wayne
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- Subwoofer configurations - Wayne Parham 05/16/0302:49:27 05/16/03 (10)
- PPSL - djk 17:26:18 05/16/03 (9)
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
