Hi everyone,
I'm currently using open baffles with 1 MarkAudio Alpair 12P and 2 Eminence Alpha 15a per side. The chipboard (these "prototypes" ended up serving me well for more than 2 years) was cut to closely mimic the dimensions of the Quad ESL. Add a MiniDSP and a pair of Quad 306: I like what I hear. Problem is depicted in image no. 3: They take up way too much space in my new, much smaller living room.
Since I already have and like the Alpair 12P, I thought about placing the woofers in storage and go with Scott's "Small Reflex" proposal. Hope it's OK to add the PDF. As far as I know it's been released to the DIY community, but somewhat hard to find on the web. Trouble is, nobody seems to use them. No matter if searching here or through Google, almost all results for Alpair 12P Small Reflex seem to refer to Abszero's build or his own blog entries about it. The only other (modified) build I found is that by shane h and his brother. I reckon the 12P is not loved by everybody here and in particular the low-end extension is not exactly its strong point, but is the Small Reflex really that bad?
If anybody has build them silently and in secret, please stand up and share your experience.
Strictly speaking, a 12P Pensil is taking up about the same space as the Small Reflex on its stands. But as alternative facts have become so popular lately, I have to say that the visual appearance is still heftier. Also the Pensil does not fit into my car, while the Small Reflex does.
As far as cabinet construction goes: I'm tempted by the idea to go with 18mm plywood for the baffle and back only and make the other walls from 15mm or even 12mm plywood. With addition of one vertical and two horizontal braces (12mm ?) I feel like this could still be stiff enough compared to the small panel sizes to deal with. What do you think?
Thankful for any thoughts and comments. Even if it ends up to be "just try it yourself" or "go with SuperPensils" or "ditch all your lowly equipment".
I'm currently using open baffles with 1 MarkAudio Alpair 12P and 2 Eminence Alpha 15a per side. The chipboard (these "prototypes" ended up serving me well for more than 2 years) was cut to closely mimic the dimensions of the Quad ESL. Add a MiniDSP and a pair of Quad 306: I like what I hear. Problem is depicted in image no. 3: They take up way too much space in my new, much smaller living room.
Since I already have and like the Alpair 12P, I thought about placing the woofers in storage and go with Scott's "Small Reflex" proposal. Hope it's OK to add the PDF. As far as I know it's been released to the DIY community, but somewhat hard to find on the web. Trouble is, nobody seems to use them. No matter if searching here or through Google, almost all results for Alpair 12P Small Reflex seem to refer to Abszero's build or his own blog entries about it. The only other (modified) build I found is that by shane h and his brother. I reckon the 12P is not loved by everybody here and in particular the low-end extension is not exactly its strong point, but is the Small Reflex really that bad?
If anybody has build them silently and in secret, please stand up and share your experience. Strictly speaking, a 12P Pensil is taking up about the same space as the Small Reflex on its stands. But as alternative facts have become so popular lately, I have to say that the visual appearance is still heftier. Also the Pensil does not fit into my car, while the Small Reflex does.
As far as cabinet construction goes: I'm tempted by the idea to go with 18mm plywood for the baffle and back only and make the other walls from 15mm or even 12mm plywood. With addition of one vertical and two horizontal braces (12mm ?) I feel like this could still be stiff enough compared to the small panel sizes to deal with. What do you think?
Thankful for any thoughts and comments. Even if it ends up to be "just try it yourself" or "go with SuperPensils" or "ditch all your lowly equipment".
Pictures not showing up, so I'm giving it another try. They did show in the preview ...
PS: I did find the semi-official thread on these enclosures in the meantime (which is impossible to find search for "small reflex"). Still reading.
PS: I did find the semi-official thread on these enclosures in the meantime (which is impossible to find search for "small reflex"). Still reading.
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Well, I like it. But then, I would. Here's my friend Colin Topps's build in birch burr; they now reside in Scotland IIRC. This little 12P reflex is one of my favourite small wideband speakers actually as it goes like a rat up a drainpipe without shrieking like a banshee after a visit from the VAT man. Best in smaller spaces of course, and if you want sub-bass you'll need something different, but it's nice otherwise.
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Greets!
Well, wouldn't call the plans somewhat hard to find as it and the [2] Pensil PDFs are on the Madisound order page, so in the public domain: MarkAudio Alpair 12P 8" Paper Cone Full Range
Alpair 12.2P Small Reflex Enclosure Plans (PDF)
Alpair 12.2P Pensil & Super Pensil Enclosure Plans (PDF)
Regardless, no experience with this driver, but just from looking at its specs I imagine a lot of folks would find it pretty bland if it has the published dips at ~2, 4, 8 kHz where our hearing peaks and 'edge', 'definition', 'sibilance' resides, though would be great for me and others that have a 'ringing' Tinnitus at ~the same octaves.
Yeah, with horn, PA and/or high output impedance amp driver specs, a small reflex cab tuned high would be pretty much my last choice for a cab alignment, but not knowing anything about your app beyond a small room and it's got to fit in your car while not looking 'hefty', can't comment further.
GM
Well, wouldn't call the plans somewhat hard to find as it and the [2] Pensil PDFs are on the Madisound order page, so in the public domain
: MarkAudio Alpair 12P 8" Paper Cone Full RangeAlpair 12.2P Small Reflex Enclosure Plans (PDF)
Alpair 12.2P Pensil & Super Pensil Enclosure Plans (PDF)
Regardless, no experience with this driver, but just from looking at its specs I imagine a lot of folks would find it pretty bland if it has the published dips at ~2, 4, 8 kHz where our hearing peaks and 'edge', 'definition', 'sibilance' resides, though would be great for me and others that have a 'ringing' Tinnitus at ~the same octaves.
Yeah, with horn, PA and/or high output impedance amp driver specs, a small reflex cab tuned high would be pretty much my last choice for a cab alignment, but not knowing anything about your app beyond a small room and it's got to fit in your car while not looking 'hefty', can't comment further.
GM
Thanks, Scott. That's the kind auf sound description that I understand!
And that's what I like about a good speaker: fast and fun, but not offensive. Sub-bass surely not needed here. My OBs do have some bass extension, but certainly not earth-shaking, so that's not what I'm after.Any experience or recommendation concerning the wall thickness? 12mm with bracing against 18mm without? It's more work, so much is clear.
GM, thanks for commenting.
The small reflex should be good, it is one of Scott’s designs. I also should really post the small Classic Golden Ratio (CGR) enclosure for the A12p (email me if interested)… it will be the same as the one for the metal cone A12 but the vent will be slightly modified Frugal-phile | Box Library / Mark Audio. It has a smaller volume than Scott’s box. The larger CGR with essentially the same volume as Scott’s has yet to be drawn (and will support A12p, A10p, and the FF165wk).
dave
dave
You will need a double thickness baffle to support the rebate for the fat bezel, but if well braced, 12mm would be my preferred construction (as long as you use good plywood). We would do it with braced 15mm as we have choosen that as a default material thickness. And find 18mm often overkill — braces make a big difference, particularily the brace that ties the driver to top/bottom/back.
dave
Maybe a slightly thicker front baffle? IIRC the Alp 12P bezel + frame thickness of 11 mm... a 21mm-25mm front baffle allows more material for fixing the driver.
I haven't built 12mm cabs yet; but Bob Brines did a floor-stander build for the Alpair 12P with 12mm baltic birch and put in longitudinal bracing, and it worked well enough.
M12-A12
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Thanks for your very helpful hints, Dave. I am aware of the fact, that I'm talking about one of Scott's designs, hence the (just slightly) provokative title, to attract his attention. That probably makes me a self-declared click-baiter.
Also I know your GR Mar-Ken for the original Alpair 12, but not the unpublished stuff of course. Surely another option. The beauty of Scott's Small Reflex lies not to a small degree in its absolute simplicity, concentrating on the most important working principles. For someone like me who's been living with butt-ugly chipboard OBs for so long, it might be a good idea to stick to a simple design (but use the right stuff right from the beginning).
Now, if I go fancy - either by following one of your more laborious designs or by fiddling with Scott's plan myself - I might never get the job done. But it's tempting, still. Especially the thin-wall approach ...
I absolutely agree to the importance of supporting the driver. I still own a 25 years old (gosh!) prototype speaker, roughly based on old British ARC 050 speakers. Actually very similar drivers to the original SBL. For this prototype we made a cabinet with internal birch plywood bracing and glued the magnet right on that bracing. I glued a wooden ring on the magnet to support the spider and finally build the whole mid-woofer right into the cabinet. No traditional basket at all. Not usable in a commercial design, but the difference was night and day, even just looking at the frequency response.
zman01, cool to hear about the material choice for Bob Brines' floorstanders. If it works well with this panel size, it should definitely do for my small stand-mounts. This further supports Dave's comment.
Bigun, only in theory. If I had already built my OBs nicely, I might consider giving them away as they are (Together with the MiniDSP? Or after making an expensive passive crossover for it?). But the way these babies look like, ripping them apart seems a much more sensible move to me. And as I already said, I really like the 12P a lot.
MarkAudio drivers are very expensive in Germany. As of today's exchange rate, one single Alpair 12P would set me back more than 267$ (plus shipping) if I would by it in Germany. Another reason to stick with what I already have. I actually got mine from Madisound, because even with shipping, customs and taxes it was still cheaper.
Also I know your GR Mar-Ken for the original Alpair 12, but not the unpublished stuff of course.
Surely another option. The beauty of Scott's Small Reflex lies not to a small degree in its absolute simplicity, concentrating on the most important working principles. For someone like me who's been living with butt-ugly chipboard OBs for so long, it might be a good idea to stick to a simple design (but use the right stuff right from the beginning).Now, if I go fancy - either by following one of your more laborious designs or by fiddling with Scott's plan myself - I might never get the job done.
But it's tempting, still. Especially the thin-wall approach ...I absolutely agree to the importance of supporting the driver. I still own a 25 years old (gosh!) prototype speaker, roughly based on old British ARC 050 speakers. Actually very similar drivers to the original SBL. For this prototype we made a cabinet with internal birch plywood bracing and glued the magnet right on that bracing. I glued a wooden ring on the magnet to support the spider and finally build the whole mid-woofer right into the cabinet. No traditional basket at all. Not usable in a commercial design, but the difference was night and day, even just looking at the frequency response.
zman01, cool to hear about the material choice for Bob Brines' floorstanders. If it works well with this panel size, it should definitely do for my small stand-mounts. This further supports Dave's comment.
Bigun, only in theory. If I had already built my OBs nicely, I might consider giving them away as they are (Together with the MiniDSP? Or after making an expensive passive crossover for it?). But the way these babies look like, ripping them apart seems a much more sensible move to me. And as I already said, I really like the 12P a lot.
MarkAudio drivers are very expensive in Germany. As of today's exchange rate, one single Alpair 12P would set me back more than 267$ (plus shipping) if I would by it in Germany. Another reason to stick with what I already have. I actually got mine from Madisound, because even with shipping, customs and taxes it was still cheaper.
Excellent, Dave! Thanks a lot (not just for my own good).
There is currently a slight typo in the link to the file. There's an additional "2" in front of the dot that is not in the actual filename.
Your OB design has two 15" side by side.
How about mounting the Alpair you have over one 15", offset a bit, and placing the second 15" behind, firing through a slot at the bottom, like in this design that would halve the whole speaker baffle.... Would that still be too big?
Oops, not on my computer right now and can't find the right page... I'll get back to you later.
How about mounting the Alpair you have over one 15", offset a bit, and placing the second 15" behind, firing through a slot at the bottom, like in this design that would halve the whole speaker baffle.... Would that still be too big?
Oops, not on my computer right now and can't find the right page... I'll get back to you later.
The Super Pensils are what I'd recommend (as I own a pair), but if you try the small stand mount boxes, you'll want a couple powered subs to fill in the bass.
jeff
A little info....
Hi to all!
Just to inform about one person (Me) who has been enjoying Alp12P for a long time - and in a small BR (which I modified according to drawings that I found on different sites, with the vent facing out on the side) Very good, but not as rich in bass as my FHXL downstairs. Today I play more on the Betsy in OB which is soundwise likened to Alp12P - but gives a better definition and fills the room better. I have also coupled a B&G Neo3 - which gives a spatial electrostatic presentation that I like.
It is all driven by a SIT preamp (homemade) - and two monoSIT Amp (homemade) - and it is a very lifelike sound in this medium room.
Best to all
Olav
Hi to all!
Just to inform about one person (Me) who has been enjoying Alp12P for a long time - and in a small BR (which I modified according to drawings that I found on different sites, with the vent facing out on the side) Very good, but not as rich in bass as my FHXL downstairs. Today I play more on the Betsy in OB which is soundwise likened to Alp12P - but gives a better definition and fills the room better. I have also coupled a B&G Neo3 - which gives a spatial electrostatic presentation that I like.
It is all driven by a SIT preamp (homemade) - and two monoSIT Amp (homemade) - and it is a very lifelike sound in this medium room.
Best to all
Olav
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I heard the cabinets Scott posted a photo of.
Nice little boxes. IMO, not the last word in bass extension, but the rest of the range is very good. I liked the slightly laid-back top end, but I can understand why some people add supertweeters.
With regards to your current system, try removing one of the 15"s. If you can live with that, you could almost cut the baffle in half.
I can see that the little bass reflex box has your interest, though, so it might be an interesting thing for you to try.
You could still use the 15"s in some kind of ripole to cover the very low frequencies.
Chris
Nice little boxes. IMO, not the last word in bass extension, but the rest of the range is very good. I liked the slightly laid-back top end, but I can understand why some people add supertweeters.
With regards to your current system, try removing one of the 15"s. If you can live with that, you could almost cut the baffle in half.
I can see that the little bass reflex box has your interest, though, so it might be an interesting thing for you to try.
You could still use the 15"s in some kind of ripole to cover the very low frequencies.
Chris
