Exodus DPL-15 IB/Dipole Driver
Jan 30, 2008 12:41:24 GMT -7
Post by diycable on Jan 30, 2008 12:41:24 GMT -7
This one is done and I'm placing my PO for it this week. Expect availability in late March or April.
The design idea was a simple one. We wanted a high output Dipole/IB driver that not only broke the value barrier in terms of $$/L of displacement, it had to utilized Dan's XBL^2 motor design and the AlCu inductance tricks to minimize inductance non-linearities and flux modulation under dynamic peaks in the program material. Its a tall order to both hit the value mark and still produce a world-class motor design but we managed only slightly over budget coming in @ $125 each. Slightly less in 4 & 8 packs. Expect to see shipped pricing in the $30/L of displacement range.
This is a single 8 Ohm VC design, in most cases being used in pairs to achieve a nominal 4 Ohm load. The VC is a 2.4" all copper design with black anodized aluminum former for maximum power handling. This is huge overkill for this design as it doesn't take much power to get it to full stroke in its intended application, but what the hell, it didn't cost much more and power compression will be a non-issue. Figure 200W per driver to get full output from them. That will get you to full excursion @ 20Hz in an IB install and you probably won't be able to bottom them due to the healthy X-mech.
The motor is good for about 22mm X-max, that being the 30% down point. The 10% down is out to 18mm so we have plenty of linear BL. Why not more? For three reasons. First, in dipole designs low noise is important. As you design a driver with more and more stroke the noise generated by the suspension & air movement around the basket and through the pole vent start to become an issue. There are practical limits to what can be done to minimize these effects and we find that designing a driver with more stroke gains you very little when the mechanical noise starts to become a limit for dipole use. The second reason has to do with Sd. For high stroke designs you need a larger roll surround, which eats away at some of your cone area. By keeping the stroke reasonable we could use a relatively small roll surround keeping Sd high while keeping self-noise under control. The third factor was the driver weight. We wanted a driver that was light weight, under 20lbs to keep shipping cost low. These drivers are going to come in around 18lbs so shipping for 4 & 8 Packs is HALF the cost of shipping the same number of Tempest-X in many cases and with the higher Sd, the total swept volume is 3.65L which is still a healthy number for a 15" driver.
Another question we will probably get is why not an 18" driver? Good question, our aim was for something that is usable in a typical IB install. Most IB installations are manifolds, for good reason. The manifold allows you to mount the drivers to help cancel vibration and provide an easy stealth install. The rule for manifolds are that you want the opening to be close in size to the Sd of the drivers. If you get it too small you create a bandpass device. Mounting four 18"s in a manifold not only prevents you from sticking it between standard stud spacing, it creates a situation where the Sd of the drivers gets too big for reasonable sized manifolds. Four of these will require a big manifold and four 18"s would require a ridiculous one. We feel 15"s are the right size for the job and for anyone who needs more output, just keep adding manifolds.
Pre-Production Parameters:
Re: 6.1 Ohm
Le: 1.7 mH
Fs: 19.5 Hz
Qms: 3.27
Qes: 0.84
Qts: 0.67
Mms: 271g
Cms: 0.23 mm/N
Vas: 232L
Sd: 830 cm^2
Vd: 3.65L
BL: 15.67
SPL: 85.2 1W/1M
X-max: 22mm
X-mech 29mm
These parameters give you an anechoic F3 of about 20-21Hz in an IB install. Not too shabby.... no need for bass boost. ;D
Motor Design:
And here is a rather crude picture that needed a lot of Photoshop work to even post. :oops: The red cast is because the background was red in the original picture. It was hurting my eyes so I changed it to blue with some PS work.
The design idea was a simple one. We wanted a high output Dipole/IB driver that not only broke the value barrier in terms of $$/L of displacement, it had to utilized Dan's XBL^2 motor design and the AlCu inductance tricks to minimize inductance non-linearities and flux modulation under dynamic peaks in the program material. Its a tall order to both hit the value mark and still produce a world-class motor design but we managed only slightly over budget coming in @ $125 each. Slightly less in 4 & 8 packs. Expect to see shipped pricing in the $30/L of displacement range.
This is a single 8 Ohm VC design, in most cases being used in pairs to achieve a nominal 4 Ohm load. The VC is a 2.4" all copper design with black anodized aluminum former for maximum power handling. This is huge overkill for this design as it doesn't take much power to get it to full stroke in its intended application, but what the hell, it didn't cost much more and power compression will be a non-issue. Figure 200W per driver to get full output from them. That will get you to full excursion @ 20Hz in an IB install and you probably won't be able to bottom them due to the healthy X-mech.
The motor is good for about 22mm X-max, that being the 30% down point. The 10% down is out to 18mm so we have plenty of linear BL. Why not more? For three reasons. First, in dipole designs low noise is important. As you design a driver with more and more stroke the noise generated by the suspension & air movement around the basket and through the pole vent start to become an issue. There are practical limits to what can be done to minimize these effects and we find that designing a driver with more stroke gains you very little when the mechanical noise starts to become a limit for dipole use. The second reason has to do with Sd. For high stroke designs you need a larger roll surround, which eats away at some of your cone area. By keeping the stroke reasonable we could use a relatively small roll surround keeping Sd high while keeping self-noise under control. The third factor was the driver weight. We wanted a driver that was light weight, under 20lbs to keep shipping cost low. These drivers are going to come in around 18lbs so shipping for 4 & 8 Packs is HALF the cost of shipping the same number of Tempest-X in many cases and with the higher Sd, the total swept volume is 3.65L which is still a healthy number for a 15" driver.
Another question we will probably get is why not an 18" driver? Good question, our aim was for something that is usable in a typical IB install. Most IB installations are manifolds, for good reason. The manifold allows you to mount the drivers to help cancel vibration and provide an easy stealth install. The rule for manifolds are that you want the opening to be close in size to the Sd of the drivers. If you get it too small you create a bandpass device. Mounting four 18"s in a manifold not only prevents you from sticking it between standard stud spacing, it creates a situation where the Sd of the drivers gets too big for reasonable sized manifolds. Four of these will require a big manifold and four 18"s would require a ridiculous one. We feel 15"s are the right size for the job and for anyone who needs more output, just keep adding manifolds.
Pre-Production Parameters:
Re: 6.1 Ohm
Le: 1.7 mH
Fs: 19.5 Hz
Qms: 3.27
Qes: 0.84
Qts: 0.67
Mms: 271g
Cms: 0.23 mm/N
Vas: 232L
Sd: 830 cm^2
Vd: 3.65L
BL: 15.67
SPL: 85.2 1W/1M
X-max: 22mm
X-mech 29mm
These parameters give you an anechoic F3 of about 20-21Hz in an IB install. Not too shabby.... no need for bass boost. ;D
Motor Design:
And here is a rather crude picture that needed a lot of Photoshop work to even post. :oops: The red cast is because the background was red in the original picture. It was hurting my eyes so I changed it to blue with some PS work.