Hey X, it's not going...yet.
Just after you did the work for me I've ended up very busy with work and family travel, but I hope to get re-started soon. Next week I leave again for a week and a half, then I'm back for the long haul. So I'm hopeful I'll finish something up in early September. Who knows, though? If it's easier than I'm imagining, I might be done sooner.Carl
OK, back in the game. I'm starting to pull this together SLOWLY, but had a question for X.
You mention an "aperature or wing" and I'm wondering what you mean by that? Is that the curved opening on the front panel/baffle? Also, "the slot on the wing starts at 3/8" wide and 3 in from the end" (which I assume means starting 3" from the top based on your scaling). Assuming I'm right, the 12" original has the slot starting at the top at 1/4" wide. Is yours different just to handle the scaling which would make it very small?
Finally, you mention a "top vent piece." What do you mean by this? I see an internal structure that leaves a slot opening at the top, which in the original 12" appears to be 1 5/8" high and opens to the back chamber which looks a bit like a horn. Is that the vent you're talking about?
Many thanks again, X!
Carl
You mention an "aperature or wing" and I'm wondering what you mean by that? Is that the curved opening on the front panel/baffle? Also, "the slot on the wing starts at 3/8" wide and 3 in from the end" (which I assume means starting 3" from the top based on your scaling). Assuming I'm right, the 12" original has the slot starting at the top at 1/4" wide. Is yours different just to handle the scaling which would make it very small?
Finally, you mention a "top vent piece." What do you mean by this? I see an internal structure that leaves a slot opening at the top, which in the original 12" appears to be 1 5/8" high and opens to the back chamber which looks a bit like a horn. Is that the vent you're talking about?
Many thanks again, X!
Carl
CarlP,
Yes, the aperture and wing is the same thing. I guessed the aperture shape and slot width. You can experiment but 3/8 in works well. You will feel air pumping through the narrow channel and the thinner you make it the more bass extension there is. Easy to play with. The top channel that connects the back and front is what I call the vent. You have it correct. Good luck and looking forward to hearing about your progress. Which drivers are you using?
Yes, the aperture and wing is the same thing. I guessed the aperture shape and slot width. You can experiment but 3/8 in works well. You will feel air pumping through the narrow channel and the thinner you make it the more bass extension there is. Easy to play with. The top channel that connects the back and front is what I call the vent. You have it correct. Good luck and looking forward to hearing about your progress. Which drivers are you using?
OK, started cutting pieces tonight and glueing a few. One question. The driver baffle (the doubled panel) is only about 9.5" when scaled down by 0.67. Since the driver is 4.5", that means there isn't much between the two.
1. Does that sound correct?
2. Think I should further brace that panel, or will the doubling do the trick?
I notice that the original 12" driver version has that panel at 14", which isn't a ton bigger, so I suppose my measurements are probably OK, but I'm just wondering.
Thanks.
1. Does that sound correct?
2. Think I should further brace that panel, or will the doubling do the trick?
I notice that the original 12" driver version has that panel at 14", which isn't a ton bigger, so I suppose my measurements are probably OK, but I'm just wondering.
Thanks.
Carl,
There should be just enough room for the two drivers with a 1/4 inch gap between them. I brace the baffle to the internal divider after both are glued in place with a couple of braces to the sides of the drivers. I think I may have braced the baffle to the bottom panel too, look at the photos in the mini Karlsonator thread. In fact, you may want to switch to that thread for future discussions so folks can see what you are doing relative to the posted plans and photos. Of course post link on this thread to finished speaker from that thread. It sounds like you are coming along nicely and I can't wait to hear from you how it sounds. Bracing lots of panels wherever you think there is a large flat surface that is free to vibrate like a drum head. That will increase SPL from the main TL output rather than radiating out through the walls.
X
There should be just enough room for the two drivers with a 1/4 inch gap between them. I brace the baffle to the internal divider after both are glued in place with a couple of braces to the sides of the drivers. I think I may have braced the baffle to the bottom panel too, look at the photos in the mini Karlsonator thread. In fact, you may want to switch to that thread for future discussions so folks can see what you are doing relative to the posted plans and photos. Of course post link on this thread to finished speaker from that thread. It sounds like you are coming along nicely and I can't wait to hear from you how it sounds. Bracing lots of panels wherever you think there is a large flat surface that is free to vibrate like a drum head. That will increase SPL from the main TL output rather than radiating out through the walls.
X
Well, I thought I'd post a few pics, but ended up finishing it today (kids are home and I needed to be too, watching over them). So here are a few pics of the build. Played it just briefly, and it sounds quite nice. No real low end (my test song is I Love You by Sarah McLaughlin, which has a low series of notes that is felt as much as heard, and that was a bit, um, thin), but the upper bass and mids are quite nice. As for efficiency, I wouldn't say they are especially high. I'd guess lower 90s (close to the same as my Pioneer BOFU in a Pass designed TL, just below the Karlson in the last two photos). Oh, and I didn't use the 700+uF cap yet. No trouble with excursion on my 1.5wpc SE Pentode amp (strapped to triode).
I had built a wood BD Pipes with these drivers (not optimized) and I like them a lot for mid range and above - vocals, etc. Even the bass is reasonable in them. I need to hook that speaker up and demo the two together to get a comparison. I suspect the Karlson will beat it pretty readily.
This was a complicated build, but pretty reasonable using foam core. I wouldn't have wanted to try it first with wood!
Many thanks, X. I'll post in the other thread too, with a link to these photos. Maybe more impressions when I get a chance to really listen.
A few notes: The build is rough, but everything is reasonably well sealed (except drivers to the driver baffle, which I hope to try later). I drew the arc of the vent baffle using a thin piece of wood bent to some approx measurements taken from the original drawing. Borrowed a technique from boat building, which I've done a small bit of. Lastly, I did not brace the driver baffle other than a single 1.5" piece between the two drivers (see second photo).
I had built a wood BD Pipes with these drivers (not optimized) and I like them a lot for mid range and above - vocals, etc. Even the bass is reasonable in them. I need to hook that speaker up and demo the two together to get a comparison. I suspect the Karlson will beat it pretty readily.
This was a complicated build, but pretty reasonable using foam core. I wouldn't have wanted to try it first with wood!
Many thanks, X. I'll post in the other thread too, with a link to these photos. Maybe more impressions when I get a chance to really listen.
A few notes: The build is rough, but everything is reasonably well sealed (except drivers to the driver baffle, which I hope to try later). I drew the arc of the vent baffle using a thin piece of wood bent to some approx measurements taken from the original drawing. Borrowed a technique from boat building, which I've done a small bit of. Lastly, I did not brace the driver baffle other than a single 1.5" piece between the two drivers (see second photo).
Attachments
Nice work Carl! 
As for the thin bass, try this with the speakers - they are meant to be placed on the floor next to the wall right behind them - this should bring the bass up noticeably and is how they are placed in the sims which IIRC gets down to 50 or 60 Hz. Not deep but good enough for most music like pop or jazz.
Do you have a stereo pair? Not bad for 1.5 wpc.
Again, very nice work and thanks for trying it.
Regards,
X
As for the thin bass, try this with the speakers - they are meant to be placed on the floor next to the wall right behind them - this should bring the bass up noticeably and is how they are placed in the sims which IIRC gets down to 50 or 60 Hz. Not deep but good enough for most music like pop or jazz. Do you have a stereo pair? Not bad for 1.5 wpc.
Again, very nice work and thanks for trying it.
Regards,
X
Thanks, X, but I wouldn't have done it without your help! I'll definitely try it on the floor, as I recall that's best but didn't have room to try that today. May also try it with my SE transistor amp that puts out about 5wpc.
I only made one so far, though may try a second at some point. This build used up most of my stash of foam core (almost all re-purposed from kids' display boards) and most of my remaining hot melt glue, so it'll be a while before I try again. But I'll report back.
Carl
PS - this really is a fabulous technique to prototype builds. And I have a few designs of my own I hope to try at some point using foam core to proof them. Thanks for sharing this technique.
I only made one so far, though may try a second at some point. This build used up most of my stash of foam core (almost all re-purposed from kids' display boards) and most of my remaining hot melt glue, so it'll be a while before I try again. But I'll report back.
Carl
PS - this really is a fabulous technique to prototype builds. And I have a few designs of my own I hope to try at some point using foam core to proof them. Thanks for sharing this technique.
Anybody ever try Homasote for an enclosure? I picked up; a 2'X4' sheet at Menards yesterday. Its made of pressed scrap paper 1/2 inch thick. It cuts easily with any type saw. It is very dense, and yet light weight, and can be nailed and glued like wood. I can see it being used as both a material for experimental builds and then finished projects when covered with 1/4" or 1/2 inch plywood. I intend to build a test box and will report in its performance.
I think Homasote is basically the same is what we called Celotex on the west coast. Different brand, and AFAIK, Celotox no longer makes celotex. Anyway, it's also called sound dead board, insulation board, bulletin board backer, etc.
David Weems published a design using using insulation board with an outer shell of ceramic tile back in the 80s. (IIRC)
David Weems published a design using using insulation board with an outer shell of ceramic tile back in the 80s. (IIRC)