Poor Plumber's Pluto, a novel DIY project

[speakerdoctor]

Some of you may be familiar with Siegfried Linkwitz's web site and his Pluto loudspeaker system.
Pluto specs

The Pluto design has garnered quite a following with many having built or bought his design outright. A user/builder forum also exists.

I've developed a novel TL design utilizing the PLuto drivers with powered sub to fill in the low end that can be built for about 10% of what the Pluto sells for assembled. Some have called it but* ugly. Others have expressed an interest.

Pluto+ from Wood Artistry

Attached is a picture of the PPP pair. PM me for details, more pics and test data. Some of the test data shows direct comparisons between published Pluto data and the PPP. You'll be surprised how similar the PPP data is!

If you're interested in building your own PPP, contact me.

 

[roger_lew]

Cool! Would you be willing to upload your test data? I'm sure it would garner some interest.

Roger

 

[speakerdoctor]

My test data shows comparisons with SL's Pluto data which is copyrighted. PM me with your email address and I'll glady send it privately.

Here is one test done with HI which may be of interest. It' s on axis @ 50 inches.

 

[tubesguy]

The Pluto is an omni-directional speaker isn't it? Isn't that the feature that makes it unique, and, presumably, worth the extra cost?

 

[speakerdoctor]

I suspect the omnidirectional feature is the result of the driver configuration. The extra cost would seem to come from the highly customized electronics to manage the response and power the drivers.

OTOH, my polars look very much like what SL shows for the Pluto with my more conventional directional configuration.

 

[norman bates]

nice job

 

[roger_lew]

The Pluto is omni out to 3kHz. Being able to cross the Aurasound NSW2 mid/tweeter at 1kHz allows the woofer to operate in its pistonic band. So having the woofer facing forward shouldn't really mess with the polar response.

Is that frequency response gated?

Does having the TL terminus off to one side of the woofer asymmetrically affect the polar response? Would it make sense to make the left and right channels symmetrical for peace of mind (and possibly aesthetics).

Roger

 

[speakerdoctor]

The test I show is not gated and thus the favorable results below 150 hz.
Having the terminus asymetrical isn't affecting the polar response significantly. The terminus power response is down about 10 dB from the mid/woof.
I could easily make them symmetrical with a few adjustments of the pipe fittings which BTW, are not glued (yet).

PM me with your email address for the polars I show compared to SL's.

 

[Brisso57]

A Destitute Plumber's Pluto?

Just wondering if - for reasons of impecunity - one could utilise (say)
HiVi drivers like the B2S and either the M5N / M6N / M6A?

All with a cute copper-coloured face. (WAF)

The xMax is down in all cases, but perhaps that wouldn't matter in a smaller room?

The freq ranges are suitable, same impedences, and you could blank off a section of your pipe to account for the differing woofer Vas, right?

As I say, just a thought experiment ...

cheers

Doug

 

[speakerdoctor]

The Seas bass/mid driver was used for two important reasons. It's Qts is about 0.6 which is in the ideal range for TL's.
Second, its size allows the back side behind the flange to fit nicely into the rubber coupling.

You'll have to check the HiVi drivers for proper fit. Also recommend you visit www.quater-wave.com for info. in TL design to size the pipe's diameter and length.

I used 4 inch ABS easily available here in the states at the local Home Depots or plumbing supply houses.

 

[6.283]

The Pluto is an omni-directional speaker isn't it? Isn't that the feature that makes it unique...

and minimum diffraction...

 

[454Casull]

and minimum diffraction...

A diaphragm on the end of a circular pipe experiences the worst diffraction of all.

 

[badman]

A diaphragm on the end of a circular pipe experiences the worst diffraction of all.

Not really. The frequencies at which diffraction would happen in this configuration are high enough that the driver is producing a very narrow beamwidth- thus the "edge" is minimally illuminated.

 

[TerryO]

Not really. The frequencies at which diffraction would happen in this configuration are high enough that the driver is producing a very narrow beamwidth- thus the "edge" is minimally illuminated.

I'm also not sure that diffraction is necessarily a problem, however baffle step would occur at a fairly high frequency and should be pretty easy to compensate if it was felt to be a problem. Perhaps I shouldn't say easily, but it would be realitively inexpensive as the components would won't cost as much as those that would be needed for lower frequencies.

Best Regards,
TerryO

 

[sdclc126]

I've developed a novel TL design utilizing the PLuto drivers with powered sub to fill in the low end that can be built for about 10% of what the Pluto sells for assembled. Some have called it but* ugly. Others have expressed an interest.

For aesthetic reasons, could the TL pipe originate at the bottom rear of the primary pipe and then ascend straight up and terminate behind it (preserving length of course)? It might make the design a little sleeker looking without the TL pipe on the side. Just a thought.

Also, any reason not to go with a passive/active sub or subs? The system would have a little more oomph in larger rooms and the total cost would still be very reasonable (plus you'd have a single straight pipe, and shorter too).

 

[gainphile]

Nice work!

But you should name it "The Divorce" 🙂

 

[speakerdoctor]

For aesthetic reasons, could the TL pipe originate at the bottom rear of the primary pipe and then ascend straight up and terminate behind it (preserving length of course)? It might make the design a little sleeker looking without the TL pipe on the side. Just a thought.

Also, any reason not to go with a passive/active sub or subs? The system would have a little more oomph in larger rooms and the total cost would still be very reasonable (plus you'd have a single straight pipe, and shorter too).

The woofer/mid is located approx. 25% along the TL length is one way to mitigate response ripples - the biggest battle a TL designer has to fight. Since my pipe was small to start with, I couldn't realistically, taper the pipe at the end like many TL wooden cabinet designs do, so I went with the location of the woofer mid as shown.

One of the bases houses a 100 watt plate amp and a ten inch down-firing sub. See attached pic.