One box concept for Pluto+: 'Plu-Tosh'

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Dear DIY Audio community:

Presented for your appraisal is my solution for a one box enclosure for the Linkwitz Pluto+. The Plu-Tosh main enclosure has only two different parts: A 6 inch outer diameter half-cylinder and a triangle. The tweeter enclosure might be a short pipe covered with a foam sphere (like a microphone cover or similar). It can be rotated around the mounting hoop so it always remains at the correct orientation to the mid-woofer for good flexibility in locating the main enclosure in the room. There is ample room inside the enclosure for the active crossover and amps (but I would still build these in a separate box). A partition is needed between the mid-woofer and 10 inch woofer, and there's (mostly) room for it to run parallel to the front half-cylinder and in behind the woofer. I'll leave the details to your imagination. For scale, the 'floor mat' is 24 inches in diameter.


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Hello Tosh

Interesting ideas! As I own Plutos, I think there are some things you should consider: as shown, the tweeter and woofer will not respond as if they were in regular Plutos - they need the pipe's enclosure volume/stuffing behind them. Otherwise, the active circuitry will have to be totally redone. Similarly, the pipes SL used play an important role in preventing the enclosure from acoustically radiating. I don't know anything about the sub, but would assume it would have to be housed in a physically separate air cavity than the woofer, otherwise they will interfere with each other. I'd assume you own the plans if you were thinking of building them. What I would suggest is to try and build the pipes into the enclosure you've drawn. But I don't know how to add the sub, as the pipes would not allow you to place the sub underneath them (the whole thing would be too tall).

A tip too - the active circuitry in my Plutos picked up EMI noise from the environment because they were not housed in a metal container. I set two different pairs in a number of different locations, but the hum/hiss didn't go away till I put the electronics in a metal chassis. I would suggest trying to house the container in the speaker cabinet (somewhere you can get them easily). Having them hang off the back of my speakers is not a plus..

Good luck,

I should have made clear that the partition between the mid-woofer and 10 inch woofer runs the full height along the front parallel to the front half-cylinder, creating the volume and length of pipe needed for the mid-woofer (and obviously separate from the 10 inch woofer). The partition could even be made from another half-cylinder to create a complete pipe for the mid, if you insist on a circular cross section.
The tweeter only needs a small damped volume behind it, as its cross-over point is ~1kHz. SL used the pipe for simplicity and as a convenience to locate the tweeter, not for the length or volume it provides.

The Plutos (not Pluto+) I heard had nice depth of soundstage. Maybe yours need adjusting, cuibono.
Great looking speaker Tosh - I really like the look of everything blended together - gives a cohesive feel to it, as opposed to everything looking like a bunch of separate components thrown together. Very organic with the smooth curves. I would only try to blend the tweeter into it more, with another pipe as you alluded to, which I think would give it an even more seamless look.
Tosh said:
The Plutos (not Pluto+) I heard had nice depth of soundstage.

I tried lots of different things. I've lived with them in at least 5 different rooms, some quite different. Nothing changed. SL has said several times that the Plutos have less depth than the Orions, and compared to my other speakers, the Plutos have truncated depth. Not massively, but I enjoy depth, so I take notice of the loss.

Please keep us up on your work!
sdclc126 said:
I would only try to blend the tweeter into it more, with another pipe as you alluded to, which I think would give it an even more seamless look.
Thanks, SD!
Regarding the tweeter housing, I was trying not to block the upward radiation from the mid-woofer, and chose a sphere rather than pipe to mount it in. Perhaps instead of the tweeter hanging from a hoop, it should sit on top of a hoop or bracket so it maintains the correct orientation to the mid-woofer and can still rotate? Then at least there would be nothing protruding above it.

For a completely smooth appearance, I've thought of enclosing the whole tweeter assembly in a wire-supported grill dome, flush with the main enclosure, but I'm not a grill person. (And I fear it might end up looking like the tip of a carpenter's pencil.)

y8s: A downfiring woofer configuration would have a larger footprint and wider front profile. Also, if the main enclosure were a perfect cone, the 10 inch woofer would interfere with the pipe underneath the mid-woofer. (And my calculations show this shape would be 48 times more complex to build.)
Few said:
Do you have a plan for constructing the curvaceous enclosure? Laminated thin sheets? Fiberglass? Park your car on one end of a Sonotube overnight?

The straightforward construction of the Plu-Tosh is why I'm so proud of myself: The main enclosure consists of only two duplicate half-cylinders of 6 inch outer diameter material (cut at an angle) and two duplicate flat triangles. Four pieces! Mix and match plywood, MDF, or whatever. Use your favorite butt joint (tongue and groove?). Slide in a flat partition from underneath. Slight fuss with clearing room for 10 inch woofer basket at bottom of partition. Mount a bottom cap. Cut hole for 10 inch woofer. Decide how to mount tweeter. Move on to electronics.

That's only six pieces (four different pieces) to cut (plus tweeter housing). I think the hardest part is finding the 6 inch diameter half-cylinders and accurately cutting them to length. And I've seen online suppliers of both plywood and MDF half-cylinder shapes in the US and the UK.
Few said:
Got it. Pretty slick, and a good reason to feel proud of yourself---although I try to avoid using "butt" and "tongue" in the same sentence:clown:. I'll look forward to seeing some construction photos!
Yeah, but I neutralized that by also using "groove," "favorite," and "joint" in that same sentence.

Sorry, but I won't be in a position to build these for many months (maybe longer depending on the tweeter supply).
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