It's worth bearing in mind that the drivers like a little space around them inside the cabinet, which would deter me from building a design with too narrow a front baffle. The wider baffle helps the lower mid and upper bass, giving it a fuller sound. You can always compensate with BSC, at the expense of a little efficientcy.
Colin said:
That's one of the reasons why I went for the pentagonal MLTL - it's an attempt tp get the best of both worlds. I was also influenced by the section on cabinet shapes in Martin Colloms' "High Performance Loudspeakers"
See the attached PDF which shows how the JX92S "breathes" in this shape.
Has anyone tried them in some 6 inch diameter pipe? The CSA of the pipe is just over 90% of GM's design, so there would have to be some trade-off.
I located some 6 inch diameter cardboard tube used as the centres by the paper making industry. In the end, I didn't use them as the MLTL required a 9 inch diameter if I was to use half as a semi-circular cross-section cabinet. I've yet to go and see if tubes that size are available. The cardboard was good and solid and came in four foot lengths.
I am learning...Hi - Yes, I've compared my own triangular MLTL against both the 12 inch VTL and a narrow Augusperger TL. They all had their own characteristics but the comparison between the MLTL and VTL was the most interesting. The VTL sounded much fuller but didn't go as deep. The MLTL matched it better when BSC was added.
I haven't tried a properly adjusted BSC on the smaller TL yet. It's not a design I plan to pursue.
Of course, the MLTL and VTL are very different designs, so I'm sure some of the difference was down to factors other than the baffle width. But they did sound a lot closer in the lower-mid with BSC. It was particularly noticable on female voices.
I can see why Ted, among others, prefer the wide baffle approach, although I do like the appearance of the narrow designs. There is a quick way you can try it out with a narrow-baffle enclosure; place a board on one or both sides to temporarily extend the baffle and see how it alters the sound.
I haven't tried a properly adjusted BSC on the smaller TL yet. It's not a design I plan to pursue.
Of course, the MLTL and VTL are very different designs, so I'm sure some of the difference was down to factors other than the baffle width. But they did sound a lot closer in the lower-mid with BSC. It was particularly noticable on female voices.
I can see why Ted, among others, prefer the wide baffle approach, although I do like the appearance of the narrow designs. There is a quick way you can try it out with a narrow-baffle enclosure; place a board on one or both sides to temporarily extend the baffle and see how it alters the sound.
Hi,
I have started building the 31' Jordan MLTL and am ready to glue the panels. I am using 3/4' birch ply (13 layers, dense and strong, but am not sure it is "baltic") So, just one question:
I could still add one window brace (4.92' x 6.10 with a 4' hole) just below the drivers (which will also help to keep the damping material in place). It will take some box space and I do not know if bracing is factored in this design or if this does not matter.
Thanks
Antonio
I have started building the 31' Jordan MLTL and am ready to glue the panels. I am using 3/4' birch ply (13 layers, dense and strong, but am not sure it is "baltic") So, just one question:
I could still add one window brace (4.92' x 6.10 with a 4' hole) just below the drivers (which will also help to keep the damping material in place). It will take some box space and I do not know if bracing is factored in this design or if this does not matter.
Thanks
Antonio
I used a window brace (I believe Jim's design does too) but further comments from GM make me wonder if it is such a good idea. The design relies on the vertical resonance of the enclosure, so perhaps someone has a better solution? At any rate, if doing it again, I'd make the window 'frame' as narrow as possible.
Thanks Colin.
I read a lot about bracing the 48' version, where bracing is understandable because of the length. However the 31' might not need bracing or might be more sensitive to it as it is suppose to have the "right" size. Lets se if GM could give us his view.
I forgot to say that I am putting a double top by the way.
Antonio
I read a lot about bracing the 48' version, where bracing is understandable because of the length. However the 31' might not need bracing or might be more sensitive to it as it is suppose to have the "right" size. Lets se if GM could give us his view.
I forgot to say that I am putting a double top by the way.
Antonio
A Sanchez said:
Greets!
No, since when made from a suitably rigid material (no void 19 mm 11 ply plywood or higher MOE), pretty much any pipe with a < ~144"^2 CSA or any panels < 12" wide doesn't need any bracing except for the driver and until it gets really massive will benefit from additional top down mass loading such as from a heavy potted plant, barbell weight(s), etc..
While I have no scientific proof that window braces negatively affect pipe action, ~analogous high pressure water flow indicates there would be a strong disruption in pipe dynamics, so do not recommend them, instead preferring golden or acoustic ratio offset longitudinal braces on edge combined with dowel or similar 'X' braces staggered down the pipe to tie all six sides together.
That said, if the cutouts are large enough that they mimic the 'X' braces and rigid fiberglass insulation panels are used to the line the walls to fill in the perimeter flange to provide a smooth pipe perimeter, then you 'kill three birds': bracing, damping, and mass loading. Done this way, the pipe's CSA would be measured from the insulation wall's i.d. dims rather than the basic shell's.
Regardless of bracing scheme chosen, 'God' (or Devil, depending on your POV) is in the details, so any bracing/object out in the airstream should be damped to prevent any spurious reflections/eigenmodes (standing waves) IMO.
GM
Huh! When I copied/pasted my response I unintentionally left out this paragraph:
"Dave P10's vertical panel bracing scheme is obviously excellent from a structural POV, but I wonder about how the cutouts in them affect pipe action due to their high friction. Then again, the additional friction may be beneficial from a stuffing density POV, so as always YMMV."
GM
"Dave P10's vertical panel bracing scheme is obviously excellent from a structural POV, but I wonder about how the cutouts in them affect pipe action due to their high friction. Then again, the additional friction may be beneficial from a stuffing density POV, so as always YMMV."
GM
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.