Lastly, I finally decided to just suck it up and rebuild my 20 year-old Acoustic Reality Avinci Studios (that I'd build on my hands and knees in my apartment in Zurich) as clean white towers to better fit the room. They're 10" rather than 13" deep now, and have about 35 pounds of sand in them, with the capacitorless crossover accessible in the bottom 3" of the 39" towers.
Here they are together, sounding great!
Here they are together, sounding great!
Thanks! I appreciate the feedback. For me, the height isn't a bother... in fact, I deliberately made it a little above my eyes so that the upper driver and light strips wouldn't be visible.
The force cancellation works very well, even with the separate chambers etc. You can feel a tiny bit of vibration, but not much. This was important to me because our living room is a suspended floor and I didn't want the drivers to be shaking the house with their movement. I also find the principle very elegant from the engineering perspective. 🙂
If you keep your drivers on axis, and have enough support around the drivers and to each other with the kind of bracing you mentioned, you should get a very good result. I might even work in some sand for good measure, but it's likely unnecessary. @MalVeauX has tried some measurements as well and videoed a glass of water sitting on his cabinet, which was a fun test.
I would probably break it into 2 chambers if it's that long. Only 10" drivers? 😉 Sounds like a fun project.
Yes, I believe so. That said, having successfully gotten the second layer of laminate to stick to the exterior, slippery surface of the first layer, I'd be surprised if its removal were actually necessary.
I tried to sand the first layer of laminate and was amazed at how tough it is! So I mostly focused on the ends and the seams with the best 3M 60 grit I could buy, cleaned it up with mineral spirits, put on 2 layers of cement as well as the heat and slippery substrate allowed, and hoped for the best.
The second layer seems to be holding fine, but is a little bumpier/less even to the hands than the prior layer due to glue variation etc. You'd see it with a glossy surface, but the matte completely hides it.
A lot of people hide the tube with some fabric, but while it took some work, the laminate really leaves a clean (and robust!) finish without lots of filling and sanding or whatever. I'm sure people have used wood veneers as well.
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You definitely could do it that way, and is how I'd build them for a HT system.
However, as noted in a comment I later added, you don't want leads that long for Rythmik's servo amps since the time delay eventually is enough to mess things up. I didn't want a box sitting on the floor the way the OB servo subs are often done, and since I had some volume to spare by virtue of having the baffles 5' apart, I was able to hide the big plate amp in the middle section. It's Hypex so seems to still get enough ventilation for the modest heat output at the levels I listen to.
I forgot to take a picture of this, but in that central section I have the power cable going to an outlet. The outlet has a short hard-wired tether to the standard power socket for the amp. The light strip's wall wart is just plugged into the lower outlet, leaving me with a spare outlet for future ideas like wild lights for parties or whatever.
Thanks, appreciated! I'm sure I need to dial it into the room a bit better, but so far... wow! It's absolutely effortless, deep, articulate, musical. Seems to give exactly what's there in a very confidence-inspiring way. I have no idea how loud the output can go since I don't listen at over 100 db levels, but it's easily handling everything else.
I did try a 10 Hz test tone and the driver excursion was getting so large that it was blocking the light strip at the top, making it look like it's flickering! So again, it doesn't compete with huge HT subs for infrasonic output, but for everything else I'm really pleased so far.
Extremely nice. An outstanding job. Thanks for posting the info!
I can attest it looks extremely nice, because not only did I see it as it was loaded into the truck for the trip home, but I got to touch it. The finish is very professional, actually. It has a modern Ikea like vibe but looks much better put together than anything from Ikea ( lasts two years and then falls apart ).
Unfortunately, I missed hearing it.
Oh, cables.. yes, servos. Like my Entecs, the amps have to be placed really close to the hardware. The sound of servo woofers is really good, they're fast enough to blend with Maggies.
I can attest it looks extremely nice, because not only did I see it as it was loaded into the truck for the trip home, but I got to touch it. The finish is very professional, actually. It has a modern Ikea like vibe but looks much better put together than anything from Ikea ( lasts two years and then falls apart ).
Unfortunately, I missed hearing it.
Oh, cables.. yes, servos. Like my Entecs, the amps have to be placed really close to the hardware. The sound of servo woofers is really good, they're fast enough to blend with Maggies.
Wow, you did a lot of very nice work! The original stand mounted speakers looked good, but the white tower look more swish. 😉
10" Dayton subwoofers because I already have them. SBA 12" woofers on hand would also work, but the increased low bass power would probably be overkill.
You kept drivers in separate chambers w/o additional bracing to each other, right?
Often, dual opposed force cancellation subs are mechanically joined inside the enclosure. KEF actually made a single dual-opposed driver with a shared motor in their K62 -- for a very small enclosure.
I can't do that, obviously, but will try bracing the speaker backs against each other with a rigid metal or wood pole between them. I think this is what I will need to do to keep sub-bass vibrations low enough to use it as a TV stand.
4' 8" is the width of the TV, and we're not going to go any bigger in the near future, so that would be the ideal length. 17" is a perfect height, but with the 14" depth the resulting internal volume is actually too big. I could put in a single shelf with a 4-5" vertical space that goes across the 56" length, a convenient place for electronics. That would reduce the volume to under 4', which is good for a <0.7Q closed box for the 2 woofers.
10" Dayton subwoofers because I already have them. SBA 12" woofers on hand would also work, but the increased low bass power would probably be overkill.
You kept drivers in separate chambers w/o additional bracing to each other, right?
Often, dual opposed force cancellation subs are mechanically joined inside the enclosure. KEF actually made a single dual-opposed driver with a shared motor in their K62 -- for a very small enclosure.
I can't do that, obviously, but will try bracing the speaker backs against each other with a rigid metal or wood pole between them. I think this is what I will need to do to keep sub-bass vibrations low enough to use it as a TV stand.
Gosh... swish! I haven't heard praise that high in ages! 😀
In my subwoofer, the driver flanges are mounted very close to the tube wall, and my central chamber also has lots of bracing. So while the driver chambers are separated, they're structurally tied together quite well. I didn't want the sub to directly shake the floor or otherwise do its own dance, and this implementation fortunately seems to be fully sufficient.
Have you considered adding accent lighting on the underside? 😉
Since you have volume to spare, maybe consider hidden power and cable management, and/or storage for remotes and similar?
Looking forward to seeing your design!
P.S. No idea how the bigger drivers could be overkill. This is audio... that's crazy talk! 🙃
yeah, overkill is not a thing except for those enormous SBA frames! Would probably need 16" sonotubes for those.
With say 14" square ends, no problem making them fit. I will not be using sonotubes. I made a sub enclosure with one already and found it more difficult to work with than sheet wood. The latter I have lots of tools for. Precise cutting of a cardboard tube? I had to devise ways. Even to make a clean square cut (from the 16" diameter 10 or 12' length I bought) was difficult.
Another reason the OP's project is so impressive.
Thanks, Tony, and sorry we somehow missed each other until literally the last minute at Burning Amp!
I appreciate the generous thoughts and if you have questions about any aspect of the build, feel free to DM me.
Couldn't you stuff the sonotube INSIDE a square cross section box? The wood is much easier to finish than the round sonotube. So build the sonotube to house the drivers (good sounding and stiff) and then hide it inside the box without worrying about making it nice. The wooden cabinet wouldn't have to be heavy duty, just thin sheets covering up the frame. So, I guess the whole thing could be 14" to house the 10" drivers?
Easy...
It won't have the mid-century, modern look though.
That's definitely one option... the other is to paint the sonotube, that will simplify the build. Any idea as to how Nelson Pass finished El Pipo? He also used Sonotube.
Actually, I was thinking that the sonotubes could be build in two pieces, say 30" long. Stuffed into the tall wood box, you could create a cavity to install the amps with a rear access panel for maintenance. You could even possible install a fog machine and lights in there so it could be like a Space X Sub-O-Matic, ready to take to the skies.
The 3rd option to build involves taking a lots of good beer to the Bay Area and.....
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Hmmm... maybe, but that sounds more complicated than just building a well-braced long rectangular box.
Yeah, my test is a square edge coin turned on edge and if it moves, the cab's not inert enough.
There are sonic advantages to the circular cross section when the driver is at one of its ends.
Back in '80 I built a pair of car speakers using Pioneer coaxials and large (empty) Chili Con Carne cans. The sound inside the car was really good. If it weren't for spousal considerations, I might start eating Chili Con Carne for a few months and collect 12 of those cans... tape them together with duct tape, screws and braces and go from there.
What kind of a speaker design software can I use to figure out a tube (sub) woofer.
I've been looking at #10 cans and the Purify 5" woofer... I don't see any servo woofers in that small size.
I've been looking at #10 cans and the Purify 5" woofer... I don't see any servo woofers in that small size.
For me it was interesting... having never worked with the concrete form / sonotube before, I definitely had my learning curve. Then you start to learn some tricks that make it much easier to work with... and then you've gone up that curve.
We all know that flat panels tend to be very suboptimal for many aspects of audio--wobbly resonating panels that need to be braced, parallel faces that also generate worst-case standing waves, worst-case stiffness for a given amount of material (for the desired shapes), etc. When budgets go way up in high-end speakers, most of the enclosure designs jettison flat panels for many good reasons. But... flat material is relatively cheap, easy to procure and goes straight through the table saws and circular saws. Case closed? No.
Now that I've worked with these light cylindrical cardboard forms that can hold hundreds or thousands of pounds of concrete with many feet of hydrostatic pressure, I absolutely will continue choosing them when I can. They make so much sense it blows the mind! But each person will work with their own equipment, needs and sensibilities... one of the joys of DIY. 🙂