In WinISD, I put the T/S parameters from the Mark Audio Alpair 10.2 into an 8 liter sealed cabinet and got a pleasant surprise. It says the F3 should be about 72 Hz, -6dB at 56Hz, -10dB at 43 Hz, with a Qtc of 0.74. 87dB sensitivity. That's pretty darned good, I'd say.
Did I do that right? Am I missing something? That all seemed too easy!
I have a pair of 8 liter cabinets I can start out with, so I can actually afford to do this...
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Did I do that right? Am I missing something? That all seemed too easy!
I have a pair of 8 liter cabinets I can start out with, so I can actually afford to do this...
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Hmmm... Even so, F3 = 77Hz is still acceptable for a start. That's as low as many small bookshelf 2-ways, and better efficiency than many.
I pulled the trigger and bought a copper pair from Madisound. This should be fun.
In WinISD, it doesn't show much improvement by going vented in that small a box. I just want to give these drivers a fair audition. I've heard Jordan's and loved them. I'm hoping these will be in the same family. If so, I'll be one happy audiophool.
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don't let a computer sim dissuade you from trying a "vented" enclosure (there's far more latitude in that genus than with sealed)
use the existing cabinets as break-in boxes while you hike the trail of pursuing a different design?
be aware that due to their basket / flange design, all Alpairs share the characteristic of needing a larger enclosure than the modeling would suggest as minimally acceptable, just to fit in the box
let me elaborate - it's the extra wide composite resin flange of Mark's drivers that causes some fun when it comes to making a box wide enough to fit, while keeping the net volume on target for some designs - this is what prompted the trapezoid shaped boxes such as:
Should be fine - it only starts to get really hairy with something like the narrow trapezoid shapes, in which case there's not a lot of margin between the flange and chamfered edges ( i.e approx 6.5mm each side if using the extra bezel ring, and 8.4mm per side if not)
yup, depending on the angle of light and grain on individual blocks, they either almost disappear, or stand out - Bernie's a far more patient guy than I
Fir, eh? Hmmm... That's different. Fir would be a softwood, like spruce, pine, etc?
I got my Alpair 10.2's today. They're a bigger driver than I imagined. Very impressive. Can't wait to hear 'em.
I have a pair of old B&W DM100 8.5 liter cabinets. I'll be happy to use them as a start, especially since I can't afford $200 for a pair of cabinets at the moment.
The B&W cabs are made of 14mm (approx 1/2") particle board. Not very beefy, no. Would it be useful to clamp and glue an additional 1/2" MDF board on the front, as an additional layer of baffle?
I have several project panels of 1/2" MDF from Home Depot, left over from making some shelves. I was thinking of making sandwich baffles out of the MDF. I could cut the 139mm mounting hole in the first 1/2" baffle layer, with the driver front mounted on that.
Then, I could make a second baffle layer, firmly glued to the first layer. In that second layer, I'd cut the 165mm hole to fit around the 139mm diameter hole, and around the driver mounting ring.
I see in the drawing that the driver mounting ring + basket total depth is 13/32". I wouldn't get away with another 1/2" MDF layer, would I? I could check to see if I can get a 3/8" thick sheet of birch ply, or maybe MDF.
So in the end, I'd have three 1/2" layers for the baffle, the original cabinet, the first 1/2" added baffle layer, and the second 1/2" added baffle layer.
Would it be better to have a constrained layer of damping in between two of the baffle layers?
It doesn't seem too difficult, even for me. It's the joinery that would cause me trouble. But I'm sure there's something I'm missing, because it seems there always is. OK, what am I missing?
Thanks...
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I got my Alpair 10.2's today. They're a bigger driver than I imagined. Very impressive. Can't wait to hear 'em.
I have a pair of old B&W DM100 8.5 liter cabinets. I'll be happy to use them as a start, especially since I can't afford $200 for a pair of cabinets at the moment.
The B&W cabs are made of 14mm (approx 1/2") particle board. Not very beefy, no. Would it be useful to clamp and glue an additional 1/2" MDF board on the front, as an additional layer of baffle?
I have several project panels of 1/2" MDF from Home Depot, left over from making some shelves. I was thinking of making sandwich baffles out of the MDF. I could cut the 139mm mounting hole in the first 1/2" baffle layer, with the driver front mounted on that.
Then, I could make a second baffle layer, firmly glued to the first layer. In that second layer, I'd cut the 165mm hole to fit around the 139mm diameter hole, and around the driver mounting ring.
I see in the drawing that the driver mounting ring + basket total depth is 13/32". I wouldn't get away with another 1/2" MDF layer, would I? I could check to see if I can get a 3/8" thick sheet of birch ply, or maybe MDF.
So in the end, I'd have three 1/2" layers for the baffle, the original cabinet, the first 1/2" added baffle layer, and the second 1/2" added baffle layer.
Would it be better to have a constrained layer of damping in between two of the baffle layers?
It doesn't seem too difficult, even for me. It's the joinery that would cause me trouble. But I'm sure there's something I'm missing, because it seems there always is. OK, what am I missing?
Thanks...
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No botanists in this thread, I see.
Fir and pine are both members of the pine family pinaceae, but different genera. Fir is abies, pine is pinus.
Douglas-fir is a crazy one. Its genus is pseudotsuga (false hemlock) and it's actually a member of the larch subfamily (Laricoideae)! Douglas-fir is not a member of the abies (fir) genus at all. The common name is totally misleading.
Common names are confusing enough, but I love how the lumber industry made up names for species that don't exist. For instance, Yellow Pine. What is that? Actually, it can be Black, Jack, Jersey, Longleaf, Loblolly, North Carolina, Oldfield, Slash, Shortleaf, or Virginia Pine. It basically means that it isn't Eastern white pine (pinus strobus).
Sorry for the thread drift... and that was a doozie. But my surprise was at why a softwood would be preferable to birch ply.
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Fir and pine are both members of the pine family pinaceae, but different genera. Fir is abies, pine is pinus.
Douglas-fir is a crazy one. Its genus is pseudotsuga (false hemlock) and it's actually a member of the larch subfamily (Laricoideae)! Douglas-fir is not a member of the abies (fir) genus at all. The common name is totally misleading.
Common names are confusing enough, but I love how the lumber industry made up names for species that don't exist. For instance, Yellow Pine. What is that? Actually, it can be Black, Jack, Jersey, Longleaf, Loblolly, North Carolina, Oldfield, Slash, Shortleaf, or Virginia Pine. It basically means that it isn't Eastern white pine (pinus strobus).
Sorry for the thread drift... and that was a doozie. But my surprise was at why a softwood would be preferable to birch ply.
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Of course, softwood doesn't necessarily mean 'soft' either. I well remember GM discussing some boxes he made a few years back from pine that had spent the best part of 150 years seasoning as part of a barn in Georgia. Stiffness-weight ratio was extremely high; apparantly getting on for aluminium / sheet metal levels from its resonant behaviour.
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<chuckle>
So... A hard layer bonded to a softer layer. If I have a softer layer already (1/2" of particle board), then a harder MDF layer bonded to it might be a good thing.
No?
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