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Thread: JBL e120 in midbass horn application

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  1. #1
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    JBL e120 in midbass horn application

    Hi,

    I am planning to build a "proper" midbass horn to cover 100 to 500hz to replace my current 80Hz Edgar straight Horn (a compromised design). Efficiency goal is AT LEAST 103db, to match my other horns. The new midbass horn will have a 12" driver, full 100hz mouth area, and possibly 4:1 or 3:1 compression, flare shape not determined yet but most likely -- straight tractrix.

    Question:

    I have a pair of working JBL e120-8 drivers. Are these good in the above application or should I consider a better candidate (used or new)? What I mean by "good" is actually the best available for my application. If anyone tried e120-8 for "no compormise" midbass or compared it to other JBL models, TAD, Presicion Devices, etc.

    Thanks,
    Herman

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    I am planning basically the same as you are, but havn't built a horn yet.

    The E120 have a very light cone. It might break.

    Go for a 15" driver with a high BL instead, the horn will be shorter. Consider JBL 2220, 2227 and PD154. Include horn upper frequency dropoff in your filter design. 15" is better than 12" if 500 is your upper frequency.

    Make simulations in Hornresp and post them here.

    Lots of informations in http://www.audioasylum.com/cgi/etv.mpl?forum=hug

    Best regards

    Mårten

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    not 15" woofer

    Marten,

    I currently have an Edgar midbass with 15" EV driver. For whatever reasons, I am not happy with them. Maybe it's the 15", maybe not, maybe the horn itself. I do not believe any 15" can play music good with good resolution above 500Hz. And I plan to use 6db filters so practically the woofer will be audible to well above 1kHz.

    Maximum is 12" but 10" or 8" is also on the table. Even large compression drivers, still not ruled out. I am not interested in making the horn shorter, I am interested in making a proper, no compromise midbass horn 100-500 Hz.

    Regards,
    Herman

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    Senior Member Lee in Montreal's Avatar
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    Hi Herman. Isn't the e120 driver more suited for guitar, with its aluminum dome, and therefore designed to reach much higher frequencies than what you need (especially cut at 6db/octave)? Can you replace the aluminum dome with a felt one, or perhaps recone it as a 2202?

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    Here's a secret

    Quote Originally Posted by Lee in Montreal View Post
    Hi Herman. Isn't the e120 driver more suited for guitar, with its aluminum dome, and therefore designed to reach much higher frequencies than what you need (especially cut at 6db/octave)? Can you replace the aluminum dome with a felt one, or perhaps recone it as a 2202?
    I will be removing the alum dome completely. It will be replaced with a big phase plug to reduce the on axis beaming.

    Name:  DSCF5563.jpg
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    Because of this the 6 db/octave low pass filter will work very well and predictably, to integrate with my midrange horn.

    Herman

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    I believe you are right Herman. 12" will work better than 15" reaching 500 Hz. Ill do some simulations later in the week. The horns will be placed on floor away from any walls (2pi)?

    Will you replace the dustcap with a phase plug, attaching the phase plug to the cone?

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    phase plug

    the horns will sit on the floor. I will try to get them as far away from the walls as possible, not sure the exact distance yet.
    The phase plug does not attach to the cone, rather to the pole piece (part of the frame assembly). So the phase plug is static, like the speaker frame and horn enclosure.

    Herman

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    Senior Member ivica's Avatar
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    Quote Originally Posted by Herman Chigrin View Post
    I will be removing the alum dome completely. It will be replaced with a big phase plug to reduce the on axis beaming.

    Attachment 55408

    Because of this the 6 db/octave low pass filter will work very well and predictably, to integrate with my midrange horn.

    Herman
    Take care about E120, because it's voice coil length is shorter ( I think in order to enlarge 2'nd harmonic, to 'improve' guitar sound, or to say: music "production") then 2202 (which is much more liner,and i think better for music "reproduction").
    I have no idea about the membrane strength concerning its 'loading' because of 'phase plug' applied.

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    http://www.audioheritage.org/vbullet...l=1#post320687

    Figure 2C. E120 has an "equal height coil and gap". This is what Ivica is talking about I believe. In a horn the cone will not move much. Maybe not a problem?

    Very smart thing to attach a phase plug to the pole piece. What material will you use? Will yop glue it to the pole piece?

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