I am gearing up to build a two ELAND cabinets using MarkAudio Alpair 10.3 drivers (already purchased).
My question regards lining ("lagging") the cabinet with Ultratouch insulation.
The first schematic from DIYaudio states and shows that all surfaces should lined
https://www.diyaudio.com/community/...audio-fostex-tb-dayton-seas-etc.323051/page-3
While the schematic posted on MarkAudio.com states and shows that one of the sides should NOT be lined.
https://www.markaudio.com/eland-alpair-10-3-compact-mltl/
The first depiction is attributed to Scott and the second is not (or forgotten). Otherwise the dimensions appear similar. So my question is obvious, do I line all surfaces or not?
Before someone responds: "try it both ways ....", the manner construction does not allow for a removable back in order to "experiment".
Thanks, -Tom
My question regards lining ("lagging") the cabinet with Ultratouch insulation.
The first schematic from DIYaudio states and shows that all surfaces should lined
https://www.diyaudio.com/community/...audio-fostex-tb-dayton-seas-etc.323051/page-3
While the schematic posted on MarkAudio.com states and shows that one of the sides should NOT be lined.
https://www.markaudio.com/eland-alpair-10-3-compact-mltl/
The first depiction is attributed to Scott and the second is not (or forgotten). Otherwise the dimensions appear similar. So my question is obvious, do I line all surfaces or not?
Before someone responds: "try it both ways ....", the manner construction does not allow for a removable back in order to "experiment".
Thanks, -Tom
Tom,
Since this is DIY, you can use wooded slats to create a frame where you can can screw on a removable back like a Pensil cabinet (image courtesy of KJF Audio). 🙂
You might have concerns about the reduction of internal volume that these additional pieces of wood will result in; in that case, if we assume that the slats that you will use are 3/4" thick and 1" wide, and cut to according to the internal height and width of the cabinet, increase the cabinet internal depth by 1/4" and you should be fine.
Since this is DIY, you can use wooded slats to create a frame where you can can screw on a removable back like a Pensil cabinet (image courtesy of KJF Audio). 🙂
You might have concerns about the reduction of internal volume that these additional pieces of wood will result in; in that case, if we assume that the slats that you will use are 3/4" thick and 1" wide, and cut to according to the internal height and width of the cabinet, increase the cabinet internal depth by 1/4" and you should be fine.
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Zman - I appreciate your thoughts. However, ..... the inside dimensions are only about 6 inches (width and depth) so there is not much room to play with (the insulation itself is almost an inch thick). Second - the back and sides of the cabinet are visible and the structure is mean to have a "pillar -like" appearance of oak columns.
I assume Scott had his reasons for how he specified the lagging (of course he did). Why the specs changed between the two two schematics is confusing me. Was this a case of a simple cognitive hiccup?
-Tom
I assume Scott had his reasons for how he specified the lagging (of course he did). Why the specs changed between the two two schematics is confusing me. Was this a case of a simple cognitive hiccup?
-Tom
I simply changed it between the two uploads, since the non-opposing faces is 'good enough' for most builders, many of whom prefer a slightly less well-damped alignment.
Thanks for the clarification, Scott. I get what you are suggesting, Zman.
I will go ahead and build the cabinets and lag all the walls.
The only modifications I will make are positioning the port to the front (vertical geometry will not be altered). This is to avoid having the port firing into a semi-open stairwell behind the cabinets. The floor in front of the cabinet will need to suffice as the boundary to help with the low freqs.
The other is to make the baffle about 8% wider. This will preserve the internal volume since I will be adding three (possibly four) window braces to stiffen up the cabinet (one a few inches above the driver, one a few inches below the driver, and one several inches above the port). These will NOT be dividing the vertical dimension into exact thirds.
The only trick will be due to the fact that the driver diameter comes close to width of the baffle and I need to leave room for the bolting the driver to the baffle (I'll probably use inserts (hurricane nuts) and also some room to chamfer (at least certain portions) the back of the speaker hole so the driver can "breathe".
All in all, careful planning is needed since it could be a snug fit.
I will go ahead and build the cabinets and lag all the walls.
The only modifications I will make are positioning the port to the front (vertical geometry will not be altered). This is to avoid having the port firing into a semi-open stairwell behind the cabinets. The floor in front of the cabinet will need to suffice as the boundary to help with the low freqs.
The other is to make the baffle about 8% wider. This will preserve the internal volume since I will be adding three (possibly four) window braces to stiffen up the cabinet (one a few inches above the driver, one a few inches below the driver, and one several inches above the port). These will NOT be dividing the vertical dimension into exact thirds.
The only trick will be due to the fact that the driver diameter comes close to width of the baffle and I need to leave room for the bolting the driver to the baffle (I'll probably use inserts (hurricane nuts) and also some room to chamfer (at least certain portions) the back of the speaker hole so the driver can "breathe".
All in all, careful planning is needed since it could be a snug fit.
Cool! Perfect opportunity to expand a little on what I've posted over the years with a little recent helping locals that comes 'close enough' to 'critically' damping the port/system (to my old ears anyway); i.e. I wish we standardized on either the pioneer's top, one side, back to max out vent performance and/or Bozak's top + hanging 'blanket' except diagonally oriented to reduce the need for wall covers that I wound up preferring overall due to them literally wanting to use old blankets, comforters and linings out of old Winter jackets!
Sounds good to me! I've shifted more & more to the top / back / one side over the years, & these days I'm only adding more if I'm using it 'actively' to adjust the alignment e.g. in the pensils, or here, where the longitudinal is a bit excessive & I didn't want to make too many changes to the proportions. I like the Bozak curtain / blanket approach too -I haven't played with that as much as I should, apart from when we were doing more with the pipe-horns. Diagonal makes sense for that -multiple birds down with one stone, plus a bit of 'creative recycling'! 🙂 I'm going to have to do some more with this...
As you can probably see above, not what GM or I would actually recommend, but YMMV as always!
Eland isn't actually a boundary loaded design so it shouldn't make any audible difference -some might even feel happier with the extra space behind it!
No real need, I provided a little extra Vb in the design as I expected some builders would want to add the recommended bracing, & 3 window braces (ensure they don't block the longitudinal standing wave -since this is an MLTL it forms a functional part of the alignment) was the 'default' assumption.
Your choice; the supplied screws should be fine though given the modest torque needed, assuming you're using the designed doubled baffle & it's full-width rather than having the side panels running full external depth. You can use the extra cover or not -it does provide a bit of extra stiffening, but most people have tended to use them as frisbees. 😉
Upon further consideration ............, today's plan, and subject to change, is to only line the top, back and a single side. The bottom will have a cleat on the inside so that the bottom assembly (two boards thick) is now removable. In doing this I can experiment on whether more dampening is required (probably using fluffy/teased fiber glass shoved through the bottom and bottom-most window brace).
This would only allow extra dampening in the bottom third of the cabinet. If more is required I can stuff more of it using the driver hole as access. This should be doable but certainly involve a certain amount of finesse and swearing since the inside cavity is not very large.
Question: When I have built bass reflex cabinets in the past (I understand these are not strictly analogous), I noticed the amount of dampening (using rock wool) seem mostly to change the the apparent "volume" of the cabinet. This in turn changed the vent tuning as revealed by the before-and-after impedance measures. Audibly, the differences were subtle and I noticed and measured nothing in terms of differences in resonances.
So my question is: if I run an impedance measure, what is the ball park vent tuning I should expect? Let's not stop there ..... How useful is an impedance measure (the location of bumps) in determining whether remaining resonances in the cabinet are sufficiently (or insufficiently) damped? Personally, I have better luck on getting repeatable impedance measures than frequency response measures at lower end of the spectrum.
I appreciate you guys keeping me on course. It is educational for me and I hope it is helpful for others also. -Tom
This would only allow extra dampening in the bottom third of the cabinet. If more is required I can stuff more of it using the driver hole as access. This should be doable but certainly involve a certain amount of finesse and swearing since the inside cavity is not very large.
Question: When I have built bass reflex cabinets in the past (I understand these are not strictly analogous), I noticed the amount of dampening (using rock wool) seem mostly to change the the apparent "volume" of the cabinet. This in turn changed the vent tuning as revealed by the before-and-after impedance measures. Audibly, the differences were subtle and I noticed and measured nothing in terms of differences in resonances.
So my question is: if I run an impedance measure, what is the ball park vent tuning I should expect? Let's not stop there ..... How useful is an impedance measure (the location of bumps) in determining whether remaining resonances in the cabinet are sufficiently (or insufficiently) damped? Personally, I have better luck on getting repeatable impedance measures than frequency response measures at lower end of the spectrum.
I appreciate you guys keeping me on course. It is educational for me and I hope it is helpful for others also. -Tom
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Impedance minimum is at Fb, which is 40Hz in Eland's case per the sketch plan (assuming undamaged / broken in drivers & built to spec.). As a forced MLTL you'll see a minor secondary peak above the usual double-saddle impedance; in a Helmholtz you'd want to damp that out for paper accuracy, although many per the above prefer the results without doing so. As a quarter-wave variation, leave well alone. Otherwise, not much. The lagging will kill lateral eigenmodes easily enough -short wavelength, easily absorbed.