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My New Line Array--It's a Modified CBT24
My New Line Array--It's a Modified CBT24
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Old 9th February 2018, 09:09 PM   #41
HankF is offline HankF  United States
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Join Date: Oct 2007
Location: Austin, Texas
Thanks guys. Jim, I'm looking at other drivers and noting their good parameters - I'll send you my spreadsheet. Those larger than the SB that have polymer frames, I can trim on my table saw using a jig - done that before. I don't mind the SB cost - I just want performance that won't require big EQ - like Minidsp. Maybe I'm dreaming...
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Old 10th February 2018, 12:20 AM   #42
Jim Griffin is offline Jim Griffin  United States
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Join Date: Jun 2003
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Hank, If you can afford the SBs, I would certainly go that way and cut to the chase. But I will review your spreadsheet for any gem we haven't seen. xrk971 had some positive comments on the SB65s and others have praised them. My main complaint about the SB65s are the plastic frame requires care but most small drivers like these suffer similar concerns.
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Old 14th February 2018, 06:26 PM   #43
HankF is offline HankF  United States
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I Jim, I'll PM you from home later - been busy with dress rehearsal, concert and new rehearsal last night. Actually, I've built lots of speakers with polymer frame drivers and really like them. If done right (right glass fiber fill, etc) the frames are very strong and don't ring like the cheaper small stamped steel frame drivers.
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Old 26th March 2018, 12:02 AM   #44
dtaylo3 is offline dtaylo3  United States
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Join Date: Nov 2004
Location: coloradao usa
Jim:

Great work, as always. From the one photo, it looks like you did not flush mount. So you just cut round holes and mounted? The square frame of those little drivers makes it a lot easier to place them in an array vs a pin cushion frame. Any EQ yet. Also, what kind of x-over are you doing to the woofer and at what frequency?
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Old 26th March 2018, 03:04 AM   #45
Jim Griffin is offline Jim Griffin  United States
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Join Date: Jun 2003
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The drivers are not flush mounted in my array. The trade I considered was whether the flush mounting (into 0.5 inch thick material with a 1/8th inch driver flange) was worthwhile considering the closeness to the side edges of the box.

The need for 0.5" thick material is such that a 36 degrees arc is possible without kerf cuts or more complex construction. Essentially the baffle can be laid out and cut on straight material and then mated with curved cut side panels which are glued with the aid of holding clamps.

I am finishing dedicated 12 inch active sub boxes in the next few weeks. I will be using DSP plate amplifiers with an anticipated crossover to the towers at 125 Hz. My current configuration uses my old passive 10" subs from an earlier project crossed over with a receiver sub out feed to separate amplifiers. No EQ yet but I will reconsider once I hear the final configuration.

Last edited by Jim Griffin; 26th March 2018 at 03:07 AM.
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Old 26th March 2018, 05:19 PM   #46
HankF is offline HankF  United States
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Join Date: Oct 2007
Location: Austin, Texas
Thanks for the update Jim. After I retire at week's end, I'll get serious about this and order drivers and talk with Kevin re enclosures.
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Old 2nd April 2018, 02:03 AM   #47
dtaylo3 is offline dtaylo3  United States
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So the front baffle does not need to be treated in any way to be curved, there is enough flex in the MDF so long as you keep thickness to .5 inch?
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Old 2nd April 2018, 12:01 PM   #48
wilbur-x is offline wilbur-x  Tibet
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A very interesting project! My main question if you could share the wiring diagram with us,
and how the banks are shaded and divided.
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Old 2nd April 2018, 12:54 PM   #49
arcgotic is offline arcgotic  Romania
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Join Date: Nov 2004
Location: Timisoara
Is Visaton FR7 good for this project?
The Fs is kindof high..
Visaton FR 7-4 2-1/2" Full-Range Driver 4 Ohm
Thanks!
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Old 2nd April 2018, 03:14 PM   #50
Jim Griffin is offline Jim Griffin  United States
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Join Date: Jun 2003
Location: Tennessee
Answers to recent questions:

Regarding curved front and rear baffles:

The front and rear baffles of my array are curved pieces of 0.5 inch thick MDF. This thickness permits the MDF to be curved over the 36 degrees arc of the CBT. Thus kerfing the material or other extreme handling techniques are not needed. The baffle hole cutting and such are done before it is curved in place. The side panels are cut with dimensions for the 36 degrees arc. Then the baffle and rear panels are glued and clamped/held by the side panels to effect the curved cabinet structure.

Regarding the weighting network:

I will submit a weighting network diagram in a future post.

Regarding the Visaton FR7:

This driver has several shortcomings vs. the SB Acoustics SB65 driver. You noted that the Fs is high which would raise the crossover from sub woofers or woofers. The frequency response is rough--sags in upper mid-range and lower treble regions--while the treble rolls off over the upper octave. These frequency issues necessitate EQ'ing. Also the Visaton driver has lower Xmax than the SB65.

The Visaton driver could be used if you intend to create a lower cost array with less performance than the SB65 array.

Last edited by Jim Griffin; 2nd April 2018 at 03:17 PM.
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