After seeing the new QSC product go up, with what looks to be lab12 drivers (with 3" vc's) forum member MRGSR brought up the idea of a possible group buy on a 3" VC lab12. Minimum order is 50 from eminence for any OEM design.
First things first, how do we think this "upgrade" will effect TS parameters? what other changes to the driver will need to be made to accommodate (obviously different spider)?
My initial hunch (and this is coming from someone with admittedly very little knowledge of actual driver design, beyond a basic understanding of T/S specs), is that we will see an increase in LE, and possibly a rise in FS (smaller spider would likely be stiffer?) and a possible decrease in xmech due to said smaller spider size. The dustcap is already ginourmous, so cone topology would likely stay the same.
The big question. would this be a drop in replacement for lab12s in popular present day designs (labsub I'm looking at you and your thermal failure rate), and will it work BETTER (ie, more thermal powerhandling, better thermal dissapation rate)
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I've considered perhaps pursuing a lab12 that keeps the same VC, but adds a copper tube around the pole piece (a la, AE TD18h, which boasts a 2.5" coil and 1000 watt PE, granted a much higher xmax as well for better cooling). This would theoretically lower LE as well (although for sub use this is arguably a non issue with the labs already low 1.41 LE).
What do you guys think?
First things first, how do we think this "upgrade" will effect TS parameters? what other changes to the driver will need to be made to accommodate (obviously different spider)?
My initial hunch (and this is coming from someone with admittedly very little knowledge of actual driver design, beyond a basic understanding of T/S specs), is that we will see an increase in LE, and possibly a rise in FS (smaller spider would likely be stiffer?) and a possible decrease in xmech due to said smaller spider size. The dustcap is already ginourmous, so cone topology would likely stay the same.
The big question. would this be a drop in replacement for lab12s in popular present day designs (labsub I'm looking at you and your thermal failure rate), and will it work BETTER (ie, more thermal powerhandling, better thermal dissapation rate)
footnote:
I've considered perhaps pursuing a lab12 that keeps the same VC, but adds a copper tube around the pole piece (a la, AE TD18h, which boasts a 2.5" coil and 1000 watt PE, granted a much higher xmax as well for better cooling). This would theoretically lower LE as well (although for sub use this is arguably a non issue with the labs already low 1.41 LE).
What do you guys think?
The easiest way to do that would be to minimize effects on T/s Parameters.
3" is not a giant voice coil. also, note that I also listed methods to improve driver cooling, sans increasing VC size (copper pole piece sleeve).
Keeping the voice coil dia same. Consider upgrading voice coil material such as fiber-glass former and modified winding material such as 4 layer flatwound copper wire or a different winding technique, such as inside/outside winding.
End result will be lower power compression at higher temperature.
Flatwound aluminum wire coil will also bring VC inductance down.
End result will be lower power compression at higher temperature.
Flatwound aluminum wire coil will also bring VC inductance down.
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The greater gap width allows the use of round-wire voice coils, and gives lots of room for thermal expansion before things go haywire. But you get lesser performing drivers than you do with ribbon-wire VCs and tight tolerances. A lot less expensive, too. Look at Chinese drivers - they are even more extreme in this regard. And the stupid-high Qts values show it.
It would be interesting to see the result of a Lab12-form-factor driver with a more modern motor, and see if a pair ends up more useful than a single 18 of equivalent Sd.
It would be interesting to see the result of a Lab12-form-factor driver with a more modern motor, and see if a pair ends up more useful than a single 18 of equivalent Sd.
Similar rated and coil sized drivers with round wires are built with much lesser gap width than Eminence and are not Chinese. eg: RCF, 18Sound, Celestion, Meyer Sound/ Ciare and many others. And their faliure rate is lesser than Eminence.
and I had referred to flatwound ribbon voice coil not edgewound ribbon coils.
I totally agree with you on that.
An upgradation to a newer 3" coil will also cost more.
But there certainly are cheapo drivers out there with much bigger gaps (typically Chinese) that make Eminence look like precision machines. It can get worse. And of course it can get better - that's why you pay $400-600 for a driver.
I haven't had a lot of Eminence failures. I've had them so hot you can smell it 10 feet away without failure, but by then they're 10dB down. If you did THAT with a tight tolerance gap you'd be scraping the coil against the pole piece and have a ruined driver.
That's not what we're talking about here. My PAL12 has the magnet directly exposed to ambient air. That's not the issue.
Exactly. We would be targeting the driver that is in the Danley cabinets. He is using custom eminence 12" drivers, cone appears the same as well as basket. But with a 3" motor.
This is the whole reason I brought this up in another thread.
Why else would you need a larger voice coil - for heavily loaded designs that are low excursion and have poor cooling, like the lab-sub? Most modern designs have good woofer cooling.
Power compression happens even on a design with great cooling and a large VC. You just want to minimize it.
More surface area will be a good thing; hence the desire for a good small driver such as the LAB12 with a larger VC.
Danley saw a need to upgrade from the factory lab 12. I figured if there was enough interest here we could get a group buy and benefit from this. I figure at around $200 the 3" LAB12 wouldn't be a bad deal at all.
More surface area will be a good thing; hence the desire for a good small driver such as the LAB12 with a larger VC.
Danley saw a need to upgrade from the factory lab 12. I figured if there was enough interest here we could get a group buy and benefit from this. I figure at around $200 the 3" LAB12 wouldn't be a bad deal at all.
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I dunno, but there's something about those big-coil subs that makes them sound different, in a better way. The old 1200GTi for example, also equipped with a 4" coil, remains one of my favourite subwoofer drivers.
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