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I haven't find any clear photos show that how does a dual voice coil driver work. How do the two VCs arrange, does one have slightly bigger diameter and other smaller (in diameter) so the bigger one could "embrace" the smaller one?
it says in this datasheet, http://www.audioheritage.org/vbullet...p?33565-2216Nd
VC section, 0.8" each coil and 0.3" apart, what does that mean
Thanks folks
Hello
Page 2 of the referenced EDS has a cross section of the driver You can see the arrangement of the coils in the drawing.
Rob:)
I know that in the first place, problem is that image doesn't help anything.Quote:
Originally Posted by Robh3606
Cheers
???? These are the coils. Both coils are on the same voice coil form of equal diameter. The coils are wound in opposite directions
Rob:)
Hi Rob,Quote:
Originally Posted by Robh3606
It is regrettable that 2216nd VC is 3-inch diameter, instead of 4-inc VC, that have been applied on lot of 15-inc JBL bass drivers. I can imagine that 4-inc dual voice coil solution would be much better solution (as in 2269H), with not so huge production costs. I think that the result would be much better, relative to THD, then 2226 dual-layer VC, so VC length round double 0.75-inch section would produce almost the same BL factor as in 2226, and would reduce 2-nd HD, as on 2269H.
regards
ivica
Interesting comment
The 2216 does have low distortion according to the EDS.
A 3 inch VC to me means lower mms and lower inductance than a 4 inch coil
In a mid bass driver the lower mms of a long 3 inch former used in differential drive could be an important consideration for the mid band.
The power PE is divided across two coils and the negative coefficient wire means lower power compression over a single 3 inch vc
If you replaced the 2216Nd's 3-in VC with a 4-in version you'd lose the midrange magic that is at the heart of why this driver sounds so wonderful. Remember, it was designed for use up to between 800Hz and 1kHz in 2-way systems. If you're looking for a woofer to use in a 3-way system, I'd look elsewhere.
This type of dual voice coil driver/motor topography is much different that the typical dual voice coil driver, say for for car audio, where the dual coils are wound together on the former, have separate lead outs for multiple impedance options with two sets of terminals and share the same voice coil gap.Quote:
Originally Posted by johnhere
This is in the family of "Differential Drive" transducers that have two voice coils wound separately on the same former and have two voice coil gaps.
The idea is to separate the travel of each coil and magnetic field into two separate entities. When the one voice travels toward the direction of the opposite gap, a braking force is applied to that coil while the opposite coil is charged to move in the reverse direction. This is said to reduce motor induced distortion. Ferrite magnet models have a third coil that sets in between the drive coils and acts as a magnetic braking system to help stop the movement of the entire coil assembly before it reverses direction.
Hope the explanation helps. Here's the tech note on the technology.
https://www.jblpro.com/pub/technote/...-33%20rev3.pdf
Hi Ian Mackenzie,Quote:
Originally Posted by Ian Mackenzie
If You compare Mms or BL factor data for 2216Nd, 2226H, 2235H, 2234H it can be seen that they are not so different each others.
I can imagine that dual VC construction due to its 'symmetrical' construction could reduce THD, but it wold be the same results using 4 inch VC,
especially in the drivers where 2 layers VC are used (I think as 2241, 2226, or 2206).
Using 15-inch drivers over, say 800Hz, would introduce a kind of beaming, due to the geometry characteristics, so I can not see real reason why
JBL have not apply dual VC construction using 4-inc VC (except 2269).
regards
ivica
A 4 inch version of differential drive is good for some applications but as advised above not all applications.Quote:
Originally Posted by ivica
I think you are saying it’s a cost cutting issue.
Hi ivica,Quote:
Originally Posted by ivica
None of the JBL drivers you mention have dual layer voice coils. All edgewound voice coils are single stack, single layer.
I believe B&C has some drivers that have "inside/outside" coils where the former is sandwiched between the two layers of windings.
Hi edgewound,Quote:
Originally Posted by edgewound
Many thanks for the info. I was thought that 2226H has 2 layers VC as it has un-expectable large Le, relative to its size, and if compared to 2235H VC.
Regards
Ivica
Seem like it would be the J who's values (RE and LE) are twice that of the H. Also note that the J has the second highest BL of any of the JBL woofers.Quote:
Originally Posted by ivica
The description you use here seems inaccurate- the two coils are not in opposition to act as a braking force, but the shorted turns do, and act to prevent driver damage. With the actual voice coils, one is pushing, one is pulling, working together, not opposed. It's entirely possible I'm misinterpreting your meaning so apologies if so.Quote:
Originally Posted by edgewound
I'm a driver geek but I'd entrust you with JBL bits for service 100x out of 100 compared to my own hamfisting.
An interesting thing about the dual voice coil models is that they create no effective inductance (LE) that serves as a low pass filter. The two coils cancel each other out.