ACI DV12

[kingfisher]

Old school dual voice coil woofer.. ACI DV12 circa 1995
I have a pair of these from an old project and I am wondering if each of the coils can be driven at different cut-off frequencies? I am planing to use as the bass augmentation for an O.B. project supporting a dual concentric JBL woofer model 2452H as upper mid to Hi-fr.
Any thoughts, suggestions or advice?
Francis

 

[Brian Steele]

I see no reason why you can't do that.

 

[revboden]

Old school dual voice coil woofer.. ACI DV12 circa 1995
I have a pair of these from an old project and I am wondering if each of the coils can be driven at different cut-off frequencies?

What do you hope to achieve by driving the coils with different filters? It's an interesting idea, strange but interesting. I'm not sure if going to half field strength at a set frequency will do much good unless you have a very specific need.

You may find some odd phase interaction when the first filter starts to delay the field of one coil while the other is constant.

 

[kingfisher]

Thanks for the replies to this...Sub terrain-ian idea. I was mostly curious from reading an article reaching back to 1992 in speaker builder.
My objective is to use the JBL 2152 as mid-and hi range in an open baffle situation and have the DV12 in a powered sub-woofer enclosure....

Francis

 

[djk]

Focal used to drive the coils with different crossover components to shape the midrange response.

Infinity did something similar to what you want to do in the bass, they had a bandpass filter driving the second coil in parallel, tuned to the resonant frequency of the driver in the box.

"What comes out of the
Dual-Drive Woofer ‘M is
a new bass experience.
Everybody knew for years it
was impossible to get acceptable
efficiency, good transient response,
enough power, and extended bass
range out of any enclosure of reason-
able size. So every speaker system
in the world represented a serious
compromise of one or more of those
desirable characteristics. Until . . .
William Watkins found the
solution to problems of the speaker’s
fundamental resonance, back-EMF
and the resultant impedance peak.
He invented a woofer with two voice
coils. Right down where rising imped-
ance and falling response were inevi-
table before, his second voice coil
takes over, presenting a low impedance
path to the amplifier in the region of
resonance"

 

[djk]

Attached Images
File Type: jpg Watkins White Paper1.jpg (147.0 KB, 79 views)
File Type: jpg Watkins White Paper2.jpg (146.0 KB, 52 views)
File Type: jpg Watkins White Paper3.jpg (149.5 KB, 47 views)
File Type: jpg Watkins White Paper4.jpg (149.0 KB, 44 views)
File Type: jpg Watkins White Paper5.jpg (146.0 KB, 57 views)
File Type: jpg Watkins White Paper6.jpg (17.4 KB, 28 views)

 

[kingfisher]

Hi djk, I am unable to open the attached files. Your previous reply is very interesting and now I have renewed interest.... Can you post again? I will google Walkins name in the mean time!
Francis

 

[bjorno]

Hi,

FYI, The 'Watkins *DVC' is IMO very sensitive to aging and driver(component) tolerances.
When compared to an active design like ACE-bass,actually doing the same tricks without the shortcomings: I would not Rec. the former approach to any DIY:er.

http://www.diyaudio.com/forums/subwoofers/104447-ace-bass-amplifier-design.html

Take a look at the picture showing simple 'Watkins' tweaking a DVC coil without changing Mmd.

Note:
In the example: One of the coils of a normal DVC is tweaked by cutting the coil in half an re-winded. This operation conserves the air-gap clearance and the weight of the coil.

IMO, better use of the ACI-DV12 driver : The second of submitted pictures.

*
http://www.davidsaudio.com/Infinity_Renaissance_Technical_Summary0001.pdf

b 🙂