I wish I could find a white sheet like that for the Polk MM. That info is nearly 6 years olds, If Polk's technology hasn't gone anywhere since then I'll be a monkey's uncle!
Sounds to me like this spiderless design cannot center the voicecoil in the gap that well. I would think the clearances would be bigger as a result and therefore there would be less motor strength. If it's centered by the means of some funky surround that may take up the place of the spider in creating it's own distortion.Wonder what's your point of view regarding the SL10 and SL12 and their "Spiderless push pull suspension"...
Since you said that Alpine made a "motor structure that goes through the spider - making it king of the hill for it's depth" ; wouldn't a spiderless design be even better? Honest question really
The voice coil is usually centered in the magnetic gap by the use of a spider suspension that limits its excursion. Cones high forces are created and the non-linear elasticity of the spider causes distortion. For better control of the excursion most manufacturers feature a double spider suspension to provide better control. Wonder what a spiderless suspension does...
Here's a quote I found from a forum poster: "Specifically, they provide returning force and a little damping. However, they are never ideal springs, and this contributes to distortion. They do have the benefit of both returning and locating the coil former, though"
^ wouldn't that mean that RE found a way to lower distorsion?
Gonna try to e-mail RE Audio in order to have more infos regarding this.Sounds to me like this spiderless design cannot center the voicecoil in the gap that well. I would think the clearances would be bigger as a result and therefore there would be less motor strength. If it's centered by the means of some funky surround that may take up the place of the spider in creating it's own distortion.
I like that companies are innovating a lot nowadays, although I couldn't care less about the shallow subs given that all subs should have a minimum amount of room behind them. Sadly we don't have the tools and resources to test whether these new inventions work well. Look at all the tools the big boys are using:
Expanding Our Measurement Capabilities
I'm sure there are scientific ways to see the resonance in parts just like there are ways to check for their nonlinearities and they work quite well.
I'm not sure why the white sheet on the SR varies so wildly from the 3rd party test. In this case the 3rd party is well experienced too. Not big into conspiracy theories but it would be nice to get a second opinion here, maybe send one to Erin for testing.
Alpine publishes their xmech I think, if the Polk does to it should be easy to check which one got it better.
If they send Klippel results that would be good enough. You'll find that a lot of car audio brands simply do not have the overhead to test their drivers, no Klippel no AES power ratings etc. If they don't have these tools to optimize their speakers they will likely perform very bad as well, why test if you know it's not going to be good.Gonna try to e-mail RE Audio in order to have more infos regarding this.
Do you have questions I should ask on top of that? Regarding the design of the driver?
Am gonna ask if they have some klippel measurements (don't think they will send me anything regarding this though - one can hope :blush and what the spiderless suspension adds to the performance. Also want to know the voice-coil size/dimensions...
I looked at this again. Patrick at Red Rock A. was the tester, that guy really knows his stuff. Not sure what's going on. The white sheet gives about 14mm of linear BL, while the 3rd party is only at 9mm. Some of that is due to a motor offset, but even then there are 2 mm of BL missing if centered.Strange??? Coz I had that white paper for a long time and thought it was a pretty good sub: http://www.polkaudio.com/downloads/whitepapers/SR_WhitePaper.pdf
Quality control problem? Or just play lie? :worried:
Yet the SR is not the sub being scrutinized here, it's the Polk MM which is cheaper than the Dayton.I looked at this again. Patrick at Red Rock A. was the tester, that guy really knows his stuff. Not sure what's going on. The white sheet gives about 14mm of linear BL, while the 3rd party is only at 9mm. Some of that is due to a motor offset, but even then there are 2 mm of BL missing if centered.
Let's say the white sheet is the true performance. It's got 14mm of motor throw and about 11mm of suspension throw. Inductance isn't even tested but i'm guessing is very poor since no shorting rings are mentioned. A cheap Dayton RS sub, at only $130 has just as much motor and a bit more suspension throw. Add on top of that an intricate web of shorting rings to address inductance. The Dayton is flat out superior. I'm also basing this comparo on a 3rd party Klippel test on the Dayton. I tend to favor Patrick's results as more unbiased. The Dayton is far far superior anyway you put it.
This is everyday life in the car audio world, lots of $ spend on inferior product and shiny fat baskets. For better performance I would seriously look into DIY products, either the Dayton shallow sub or maybe this SB acoustics:
SB Acoustics SW26DAC76-4 Shallow 10" Subwoofer 4 ohm: Madisound Speaker Store
No dice, the BL will shift from one coil configuration to another but the shape will remain the same. It could be production variance, or maybe Polk tested a test version while RRA had an actual production unit. Concept vs production unit thing.The chart published by Polk may not show alot of throw but it is very symmetrical.
CA&E's test came from a DVC sub. Is it possible that the test report posted by Polk could've been a SVC sub and that might explain the difference in symmetry?
I know a speaker Q can vary widely from DVC and SVC, could the same be said for BL?