Pipe Dreams

[Mike B]

This is a new project just underway. I am going to simplify my office system (now 6.1) to 2.1 (like I need a HT in my office) and remove lots of wires.

Tang Band 4" bamboo drivers in a 3 liter box tuned to 80 Hz, -3 dB point at 80 Hz, so should be perfect for a sub.

I plan to make it of mostly PVC pipe (thus the name) and fittings, so the only wood in the project will be in the driver cones.

I plan to use a auto head unit for a control center with aux input for the sound card and a 3 channel car amp to drive it all.

[Dennis H]

The name has already been used.

https://web.archive.org/web/20070224102455/http://www.nearfieldacoustics.com/pipedreams.html

[Mike B]

Damn.

Well mine will be far less than 12 grand - :E

Ok, so to avoid copyright issues maybe "Plumbers Nightmare"?

[Jonasz]

"Plumbers Nightmare"

That's better! :B

[Mike B]

Plumber's Nightmare



Well these are just as hard to build as regular enclosures.

4" PVC Tees with caps. 1.5" elbow on top. Short pipe couplers inside on all ends to add strength and not take up too much volume. The one with the short pipe in the coupler should be close to how it will look when done. The 1.5" vent will be ~6" long for 80 Hz tune.

I am going to tape it up and check the volume by filling it with water - :P

Still need to order the drivers from PE, have been hoping they will come up with "free shipping over $99" again soon.

Have fun!

[ThomasW]

Those are great.... :T :B

[dyazdani]

Looks nice! Are you just using a 12v power supply for the HU and amp? 120V or like a computer PS?

[Mike B]

Thanks.

I am using a 35 amp linear regulated supply, Alinco DM-340MV.

Very nice, smart fan and small size.

[Mazeroth]

Mike, VERY cool idea! You're inspiring me here! I'm even envisioning a tweeter mounted much like the Linkwitz Pluto has.

[Mike B]

I taped 1 off and filled it with water and found (to my delight) I have about 3.5 liters.

Put it into win isd and looks even better. I got confused on the first data, 3 liters tuned to 80 Hz is -3 dB @ 100 Hz.

3.5 liters tuned to 82 Hz is -3 dB @ 92 Hz. Vent is now 4.5 inches long, so the pipe should be about even with the elbow. No problem, with this design port length changes are easy.

I am thinking of using the PE half inch "Sonic Barrier" foam with these instead of my usual poly batting. Any experiance here with this stuff?

[Hdale85]

Yeah its nice stuff expensive although with this design you don't need much

[here.now]

You might have a hard time getting the foam into the PVC. The tack is very sticky, does it's job well, but can be a pain in the neck. If you do go this route consider cutting the foam into smaller pieces or strips, it may make your life easier.

[Hdale85]

Just cut several smaller pieces, should make it easier.

[Mike B]

Drivers ordered along with the half inch sonic barrier foam. I am going to install the foam before I glue it all together. The cap has the elbow glued in place and a piece of pipe, but this is not yet glued into the T, so I will have access to all ends as well as the top of the cap.

I got some black marble bases for the bottoms. I will glue these on with silicone bathtub caulk, which adhears well to smooth surfaces. I think they look pretty cool.



Also planning to paint all the PVC with Krylon "Pearl"

I am getting excited! Have been thinking about this project for years now after being impressed with those little Logitech computer speakers that appear to use the 3" Tang Band drivers. Also wanted to try the single driver thing too, so here we go -

[Bent]

this thread inspired me to try a quick-and-dirty attempt at something similar.
I had built a pair of Zaph's B3S full rangers, but with the B3N instead - c/w his filter network

I then bastardized it by putting it in a 3" Straight PVC elbow on a small pedestal.
This is serving as my center channel on my upstairs tv.

[Mike B]

Well, how did it sound as compared to before?

[impala454]

Very neat idea Mike. Are you going to mud/paint them too or just leave them as is?

[Mike B]

I did sand off a lot of the mold marks, date codes, sprues and other artifacts, but there is a bit of concentricity error between the T and the cap that I am not certain how to deal with yet.

I sure am not going to attempt sanding them true. Maybe some tape or mask and paint a black ring...

Yes, going to paint pearl.

[Bent]

In mine, you can her the effects of the constricted driver (rear of driver doesn't breath too well in that tight space, so try to keep as much of a chamfer as you can get away with without loosing too much meat to mount the driver to)
Also, the B3N is only 83 dB/W, so with the filter network it gets even more power hungry, I need it to run 6dB louder than my Paradigm V2 Titan's to get equal output.

I'll try find time to post a pic this evening. It kinda looks like the periscope from teletubbies... ops:

[JonW]

Mike,

I just want to add my encouragement for this project. It looks very cool. :T

[Mike B]

Foam installed, holes drilled, ready for glue up & paint. I will paint first and then glue the T to the marble bases. Couldn't resist mounting 1 driver and trying a little cone thump. Sounds very encouraging and I clearly heard the differance with port length changes. Also making new mini shelves for the wall. These are not going on the desk but rather on the wall, so they don't get in the way. The desk is a corner unit, so the speakers are no more than 2 feet from my head. Near field indeed.



Have fun!

[Bent]

this is my project - not quite as ambitious...

I mounted the filter network (3 caps, 2 coils and 2 resistors) on a 3/8 oak dowel in the center of the base so it is hidden inside the elbow.



The bsc is for a baffle of approx 5" wide, so it sounds a bit goofy, but better than the tv's side firing speakers that are too close of a fit to the side walls of the cabinet it sits in).

[Mazeroth]

These look great!

Too many projects already. Must resist...

[Mike B]

Hey Bent,

That's cute!

One thing I have to warn you guys about. These 4" pipes are not like gluing up 3/4" stuff for irrigation. This stuff grabs fast. So get it lined up good before you insert because ya don't have much time.

I am off a couple of degrees on 1 because I just couldn't rotate it. You have like 2 seconds and then it's set hard.

[Bent]

I would suggest using "registration lines" to help ensure proper alignment.
just take a marker and make a line that crosses both surfaces at a seam - prior to applying glue. I've done lots of electrical work with PVC and that's one of the rules I try to follow.
The other, is to keep the silkscreening away from you - but that doesn't apply to loudspeakers.

Oh, PVC and ABS cement sets much slower if it's cooler out.

[Mike B]

Almost there.

There is no wood in the speaks, but I did make these cute custom shelves and the sleeve for the head unit. The sleeve will screw to underside of the desk to keep it out of the way. Made from solid red oak too, I love that stuff.

The paint is not pearl, something called "river rock" by Krylon. Went with that as it is supposed to be especially made to stick to plastic. It does stick to PVC real good. They should be up and running next weekend.

[Mike B]

All done.

The binding posts are hexagonal PC board spacers from the shack with heat shrink over. Grille is a 90 mm fan guard painted black.

The port was just a pipe flush fit with the elbow. The tuning was a nice plateau 82 - 76 Hz with -6 dB points at 50 and 170 Hz. Measured by close miking the port and a signal generator. While checking the port tuning, I couldn't help playing a few tunes and it sounds really good. Very clear and crisp, way better than the stuff I had in there before.

Now have to mount the shelves and the head unit and get it all buttoned up. I am very pleased, win isd was accurate as far as port length and volume and the drivers sound fantastic. With the sub dialed in, I am looking forward to a great little 2 channel system here in my office.

[impala454]

Very nice. I like how you used fan grills.

[Mike B]

Don't ya just hate it...

when stuff goes on sale soon after ya bought it?

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-846

I paid $50 and now they are $30.

So, I bought 2 more - :B , you know, just in case 1 blows or I need to build a couple more...

Along with some wire.

Free shipping too. Strike while the iron is hot guys, this driver is the real deal.

[JohnInKY]

Those are cool looking... maybe call them "Up Periscope"... :-;



John L.

[JonP]

With the sub dialed in, I am looking forward to a great little 2 channel system here in my office.

Very cool... I've played with PVC in various nefarious projects, haven't yet for speakers...

Something that might come in handy for this or other small projects with a sub, this Reckhorn active crossover does the high pass (to relieve those little drivers of the bass) as well as the low pass if you use a plain amp for the sub. If not, it gives you additional rolloff for the plate amp (some low power ones are only 12db/octave) as well as level adjustment of the low end.

Been using it, like it a lot, did the mods, but you could live without them if you aren't so handy. Great value for $50.

Reckhorn F1 info and mods

For little drivers like this, a high pass at 100hz or so will make a big distortion improvement at high volume with bass...