BSC and New Crossover
lydan01,
Hi, as you have noted, the new 35" MLTL requires very little BSC, a few dB goes a long way when it is located near a corner and toed in as is consistently noted for the JX92S! Enjoy...
I found that a few dB is quite pleasant, so 0.5 mH to 0.75 mH with about 3 ohms should be optimal.
As far as adding a ribbon, I put together a new crossover for that! It uses a 2nd order Linkwitz Riley configuration, with 3 dB of BSC rather than the traditional 6 dB from the mini-monitor.
It is equally well suited to 7.5" or 8.5" enclosure widths, uses easy to obtain parts and a much smaller inductor for the JX92S. It also offers the benefits of LR constant phase....
The schematic and parts list can be found here: http://documents.jordan-usa.com/2nd-Order-LR-2Way-Xover.pdf. Enjoy
If you need some assistance in getting components just email me.
Mark at Jordan USA.
Thanks Jim - looks like the P-E website is still a bit flaky, at least from here. And, CSS have as much stock of the Aurum Cantus as the local reseller. Seem's like it'll be straight Jordan's for awhile yet. Not a bad thing...
lydan01,
Hi, as you have noted, the new 35" MLTL requires very little BSC, a few dB goes a long way when it is located near a corner and toed in as is consistently noted for the JX92S! Enjoy...
I found that a few dB is quite pleasant, so 0.5 mH to 0.75 mH with about 3 ohms should be optimal.
As far as adding a ribbon, I put together a new crossover for that! It uses a 2nd order Linkwitz Riley configuration, with 3 dB of BSC rather than the traditional 6 dB from the mini-monitor.
It is equally well suited to 7.5" or 8.5" enclosure widths, uses easy to obtain parts and a much smaller inductor for the JX92S. It also offers the benefits of LR constant phase....
The schematic and parts list can be found here: http://documents.jordan-usa.com/2nd-Order-LR-2Way-Xover.pdf. Enjoy
If you need some assistance in getting components just email me.
Mark at Jordan USA.
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Thanks Mark!
The PE site came good earlier this week and I've ordered the G2Si's. All of the bits and pieces for both crossover designs and BSC have already arrived from a local supplier so I'll make a start on those over the w'end...
All going well I should be in a position to also take some measurements in the near future.
Cheers!
Dru
The PE site came good earlier this week and I've ordered the G2Si's. All of the bits and pieces for both crossover designs and BSC have already arrived from a local supplier so I'll make a start on those over the w'end...
All going well I should be in a position to also take some measurements in the near future.
Cheers!
Dru
My 48" Jordan MLTLs put out 35Hz at a respectable volume and gave the whole sound a nice weight. If anything, it put out slightly too much bass in my room.
Bass is a question of enclosure design with these drivers. But no, you won't go to ear-shattering levels. To use at very high levels, you need a horn or separate bass units.
Bass is a question of enclosure design with these drivers. But no, you won't go to ear-shattering levels. To use at very high levels, you need a horn or separate bass units.
Mark,
Thanks for providing this nice new design - I have all of the bits now and am just about to build.
To get the best possible results, I want to have some substantial bracing between the the front & back panels - I have allowed for this with my dimensions but I have one question . . .
If I have a solid front to back brace all the way from top to bottom, instead of having one line I will now have two 1/2 sized parallel lines that amount to the same volume.
Will this arrangement completely change the behavior of the air in the line and thus demand a complete re-design or will it work pretty much the same as a single line ?
If the answer above is that it will be different can you recommend the best method to front to back bracing without disturbing the operation of this design.
many thanks
mike
Thanks for providing this nice new design - I have all of the bits now and am just about to build.
To get the best possible results, I want to have some substantial bracing between the the front & back panels - I have allowed for this with my dimensions but I have one question . . .
If I have a solid front to back brace all the way from top to bottom, instead of having one line I will now have two 1/2 sized parallel lines that amount to the same volume.
Will this arrangement completely change the behavior of the air in the line and thus demand a complete re-design or will it work pretty much the same as a single line ?
If the answer above is that it will be different can you recommend the best method to front to back bracing without disturbing the operation of this design.
many thanks
mike
A full length brace may be overkill, especially as MLTLs don't suffer from cabinet resonances in the same way as a reflex box. Being a quarter wave, the MLTL will have resonances at specific points along its length rather than pressurising the whole enclosed space, as in a reflex.
Elsewhere on the forum, Earl Geddes has recommended a cross-brace - two pieces of timber (25mm square oak, for example) joined and connecting front-back and side-side panels. I've done this on my gen 1 Jordan MLTL and it seems to work with a solid feeling enclosure (despite being made of MDF rather than stiffer birch ply).
Hope that helps.
Elsewhere on the forum, Earl Geddes has recommended a cross-brace - two pieces of timber (25mm square oak, for example) joined and connecting front-back and side-side panels. I've done this on my gen 1 Jordan MLTL and it seems to work with a solid feeling enclosure (despite being made of MDF rather than stiffer birch ply).
Hope that helps.
Surprisingly, absent ( or in spite of ) thorough test data on the subject, there's no consensus among commercial or DIY builders on the subjects of "best material" or bracing
I personally use only BB or similar plywood, with full length braces on many of my builds, but would offer the suggestions to align slightly off centre line, and to cut sufficient holes to open at least 40% of the surface area. Also, in an MLTL, try to keep the CSA of lateral or front to back brace members as narrow as possible ( i.e. 3/4" x 3" or more oriented lengthwise)
I personally use only BB or similar plywood, with full length braces on many of my builds, but would offer the suggestions to align slightly off centre line, and to cut sufficient holes to open at least 40% of the surface area. Also, in an MLTL, try to keep the CSA of lateral or front to back brace members as narrow as possible ( i.e. 3/4" x 3" or more oriented lengthwise)
Thanks for your replies.
Colin, I know the MLTL will be quite low pressure inside the cabinet. I was more thinking about vibration transmitted directly from the driver exciting the natural resonance of the cabinet - I really don't want the cabinet to vibrate at all
Chris,
Many thanks for your advice - I have carefully studied some of your designs and they have informed my thinking on cabinet design.
For this design I was thinking about a 6mm aluminium front baffle with everything else in 3/4" baltic birch ply.
Can you think of any reason why this would not be a good way to proceed ?
mike
Colin, I know the MLTL will be quite low pressure inside the cabinet. I was more thinking about vibration transmitted directly from the driver exciting the natural resonance of the cabinet - I really don't want the cabinet to vibrate at all
Chris,
Many thanks for your advice - I have carefully studied some of your designs and they have informed my thinking on cabinet design.
For this design I was thinking about a 6mm aluminium front baffle with everything else in 3/4" baltic birch ply.
Can you think of any reason why this would not be a good way to proceed ?
mike
First - credit for the design work to Dave and Scott Lindgren
Second - were it not for the extra cost and complexity of machining the aluminum, I'd be all over than myself. With some nice CNC milling and powder coating etc, the results could be outstanding.
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