Clear acrylic speakers - any ideas? (Also, how should I make B3s open baffles?) - diyAudio
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Old 20th October 2006, 11:03 PM   #1
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Default Clear acrylic speakers - any ideas? (Also, how should I make B3s open baffles?)

To make a long story short, I'm in an art metal and glass class. Most of the class does stained glass; I prefer constructed sculpture. (Read: I get credit for building amplifiers, or so far, trying to. No, really!)

Anyway, someone donated some REALLY nice clear acrylic. There's about 10-20 sheets of 24x36" roughly 1/8" acrylic sheet. I've also found a trick for covering right angles with 90-degree sections of copper tube to make them look better.

Can anyone reccomend speakers for this stuff? OB's have an obvious advantage of being simple and flat, but I'm limited by size. (Multiple panels can be joined in the middle if necessary, though.) Normal speakers or MLTL's might work better still, but they'd need stuffing, which would not look good at all. Horns may also be a possibility; if made of flat panels, they'd be easy to build, but it might be possible to heat-shape the acrylic.

There's also the issue of reinforcement. There's the good old-fashioned I-shaped joiner made of two pieces of flat metal with a rod inbetween them; although normally used for glass, some rivets and/or epoxy will let them work just fine.

Finally, can I get any better acoustic properties for using glass in certian areas?


So, what do I build? I'm within a short distance of Madisound, so I can get the B3S's for 10$ ea. (no shipping!), and I have the following:

2x 40-1041 RadioShack FR drivers. They look like 40-1354's, except less efficient.

2x RFT slightly oblong FR drivers. I've yet to test these.

2x Tesla drivers. These are weirdly long and narrow drivers, roughly 1' long by 3" wide. I've yet to test these, but they have an awesome vintage look.

1x Foster 10T3 driver from a Solo 103 speaker. This thing sounds like crap, and is nothing like a FE103. However, I feel bad not doing anything with it.

SI Soundpads. A friend of mine, after experiencing the excellence of the T-amp, bought a pair. However, he has no idea what to do with them. I was thinking some simple boxes, or perhps horns; these need'nt be truly hi-fi, as they're liable to just be rear-channel or workshop speakers anyway.

Hi-Vi B3S. I just ordered a pair. Obviously, some woofers are necessary.

I'd also like to use some of the following drivers if possible. (3$
each! WOOT!)

http://www.madisound.com/cgi-bin/ind...23023&pid=1902

Obviously, they're going to need a tweeter, but they might make nice OB speakers.

If I can get a good, working design based around the RadioShack, Foster, or Hi-vi drivers, that would be great. (I have a venue for sales).
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Old 20th October 2006, 11:44 PM   #2
Aengus is offline Aengus  Canada
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Hi Spasticteapot

There are others in this forum (actually, almost anyone in this forum) who can give you better advice than I about speaker design issues.

I just wanted to say that, since one of the advantages of acrylic sheet is that it's heat-formable, if you go to boxes (as opposed to OBs) you might consider a curved shape. A truncated cone would be almost as easy as a cylinder to bend, would have good acoustic properties, would be much stiffer than a flat panel of 1/8" acrylic, and could look very nice indeed.

Sounds like a great project - I look forward to the pictures.

Aengus
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Old 20th October 2006, 11:59 PM   #3
Gasho is offline Gasho  Croatia
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Clear speakers?
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Old 21st October 2006, 02:05 AM   #4
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Quote:
Originally posted by Gasho
Clear speakers?

Explain to me a simple way of making those and I will be a happy man indeed.
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Old 21st October 2006, 02:12 AM   #5
ronc is offline ronc  United States
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Its called a form mold The product is heated to a given temperature and either vacumme molded or press fit in which it tales a male mold and a female mold. Another method is a heat draw in which a center form is made the product is heated to a given temperature and the center is drawn into the shape thats required.

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Old 21st October 2006, 05:00 AM   #6
ScottG is offline ScottG  United States
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There was once a loudspeaker from I believe Acoustic Research that looked a little like a b@stard child of a Dahlquist DQ-10 and the main panel of the Infinity Beta (..without the sloped/tilted profile of either speaker). In fact it looked considerably better then either (taken alone).

Note my poor "drawing" below. The front is covered with "grill" cloth like the Quad electrostats:

http://www.quad-hifi.co.uk/

However, with the exception of the vertical column of drivers and the surrounding frame, the extension panels from the vertical column can be seen through - because they should be from acrylic. This is not dissimilar from the "void" space at the top of the Infinity Beta main panel as viewed here:

http://www.arduman.com/aa/Sayfalar/rob/speak.htm

The bass bin should contain a 12 inch driver.

The basics are:

4 of the Foster "woofers" (not the fullrange drivers) open baffle with a 4th order LR around 3 kHz.

1 HiVi K1 with a first order filter around 3 kHz.. (this will limit spl somewhat and increase distortion). Driver rotated to an inverted position for aiming the polar "tilt" up. This driver should be about 2 feet from the floor. Measured by member Zaph here:

http://www.zaphaudio.com/tweetermishmash/

1 12 inch Powered woofer/subwoofer "box/bin". DVC connected in parallel to an MCM sub plate amp. (prob. bass reflex - need to do some sim's though)
http://www.partsexpress.com/pe/showd...number=295-490
http://www.mcminone.com/product.asp?...5Fid=50%2D6272

In effect the top OB column is two way phase coherent design with a dipole midrange section. With the tweeter below the midbass line (and considerably lower than the listener) but with an upward veritical radiation angle of 15 degrees - gives a good stand-up/sit down even high freq. sp-level (..in other words when you stand-up from the listening position the treble won't dramatically reduced in level). The bottom section is a powered sub.

The top portion will need to be modeled for the crossover and baffle effects. The bottom "sub" will need box modeling to give the desired character.

Cost-wise the loudspeaker can be fairly in-expensive for such a *fullrange* design (particularly because its also powered in the bass).
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Old 21st October 2006, 01:34 PM   #7
Aengus is offline Aengus  Canada
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Gasho said (and illustrated):

Quote:
Clear speakers?
Gasho, those are extraordinarily lovely - can you tell us more about them?

Aengus
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Old 21st October 2006, 02:43 PM   #8
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Ferguson Hill FLHs. They also have a spherical, transparent subwoofer to go with them. Guess what's in carton number one, and you win a years free supply of Mr Sheen polish...
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Old 21st October 2006, 02:56 PM   #9
Aengus is offline Aengus  Canada
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Thank you, Scottmoose. I found them, and the thread on them.

ronc: Have you done such moulding of similarly large parts? I can see that one could make a form from, say, plaster of paris, but I doubt my ability to vacuum-mould something that size in the garage. Tempting idea, though.

Aengus
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Old 21st October 2006, 07:01 PM   #10
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Quote:
Originally posted by ScottG
There was once a loudspeaker from I believe Acoustic Research that looked a little like a b@stard child of a Dahlquist DQ-10 and the main panel of the Infinity Beta (..without the sloped/tilted profile of either speaker). In fact it looked considerably better then either (taken alone).

Note my poor "drawing" below. The front is covered with "grill" cloth like the Quad electrostats:

http://www.quad-hifi.co.uk/

However, with the exception of the vertical column of drivers and the surrounding frame, the extension panels from the vertical column can be seen through - because they should be from acrylic. This is not dissimilar from the "void" space at the top of the Infinity Beta main panel as viewed here:

http://www.arduman.com/aa/Sayfalar/rob/speak.htm

The bass bin should contain a 12 inch driver.

The basics are:

4 of the Foster "woofers" (not the fullrange drivers) open baffle with a 4th order LR around 3 kHz.

1 HiVi K1 with a first order filter around 3 kHz.. (this will limit spl somewhat and increase distortion). Driver rotated to an inverted position for aiming the polar "tilt" up. This driver should be about 2 feet from the floor. Measured by member Zaph here:

http://www.zaphaudio.com/tweetermishmash/

1 12 inch Powered woofer/subwoofer "box/bin". DVC connected in parallel to an MCM sub plate amp. (prob. bass reflex - need to do some sim's though)
http://www.partsexpress.com/pe/showd...number=295-490
http://www.mcminone.com/product.asp?...5Fid=50%2D6272

In effect the top OB column is two way phase coherent design with a dipole midrange section. With the tweeter below the midbass line (and considerably lower than the listener) but with an upward veritical radiation angle of 15 degrees - gives a good stand-up/sit down even high freq. sp-level (..in other words when you stand-up from the listening position the treble won't dramatically reduced in level). The bottom section is a powered sub.

The top portion will need to be modeled for the crossover and baffle effects. The bottom "sub" will need box modeling to give the desired character.

Cost-wise the loudspeaker can be fairly in-expensive for such a *fullrange* design (particularly because its also powered in the bass).
Woah...


Those look AWESOME!

Prices:

8x Fostex Unnamed Woofers: 24$
2x Hi-Vi tweeter: 18$

Total cost of drivers without subwoofer: 32$.

So, how much are you going to ransom the crossover specs for? I'm hardly opposed to bi-amping; would two LM3875 gainclone modules, one for the tweeter and one for the woofers (wired series-parallel) do the trick, or should I use one for each set of woofers wired in parallel?

Also, I now must find some cheap subwoofer drivers.
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