OT: Any loudspeaker builders out there?

[Delaware Dave]

I've been building loudspeakers since my teens. Folded horn, bass reflex, full enclosure designs. Given that, I found the concept in this article interesting.

 

https://hackaday.com/2020/12/16/building-distributed-mode-loudspeakers-with-plywood/

[The Real MC]

Hardly a new concept. Fender "Tweed" guitar amps of the 1950s exploited the "floating baffle" concept where the speaker baffle was allowed to resonate. You definitely don't want to use plywood with any voids in the wood.

 

This concept was probably exploited in home stereo high fidelity speakers too.

[GRollins]

The idea goes in and out of vogue. Panasonic (if I recall correctly) had a version using a thin piece of styrofoam back twenty or thirty years ago. Others have used metal, even glass. The idea works, but it's a bear to get even frequency response because most materials tend to exhibit one or more very strong resonances. The low frequency response is plagued with harmonic distortion because the speaker tends to flex and the high frequencies roll off very quickly indeed (hence the whizzer cone in the example above). The Panasonic styrofoam version had fewer resonances because the styrofoam damped the standing waves internally, but was weaker mechanically so it flexed. One solution is to drive the speaker at multiple points, but that opens another can of worms in that the voice coils/magnets need to be matched so as to drive the panel evenly--else you're back to square one.

 

Note that if you take the multiple driver notion to extremes, you approach the planar speakers, especially if you start swapping in Mylar sheets in place of more rigid materials. What you lose in rigidity, you gain in lowering moving mass, so your transient response improves greatly. The problem then becomes how to drive the Mylar evenly. This leads to things like Magneplanars or electrostatic speakers. Depending on how you look at it, ribbon drivers might be seen as a related design concept.

 

All large diaphragm drivers tend to beam as frequencies increase, so that needs to be addressed, usually by employing crossovers and more specialized high frequency drivers (or ignoring the problem entirely..."That's not a bug, that's a feature!"). Quad developed an ingenious solution to beaming in their electrostats--they drove the center of their speaker separately from the rest, thus creating a small diameter "tweeter" in the middle.

 

Speakers are fascinating.

 

Grey

[Theo Verelst]

At primary school I was already fascinated with sound and would build my first speaker enclosures with parts I could afford.

 

More recently I built amoung others my large monitoring system I use every day for hours for synthesizers, TV, CDs/High Res audio etc. etc., it's a 5 way 3 x 100 liters closed system (no bass reflext, damped enclosures), with this as main speaker (there's a Dayton audio ribbon tweeter now, I think it's the PT2C-8)

 

The parts on top are the parts that are in as well:

 

http://www.theover.org/Diary/Ldi19/HPIM0782b1m.JPG

 

The enclosure is very damped:

 

http://www.theover.org/Diary/Ldi19/HPIM0774b1s.JPG

 

The sub is a 15 inch acoustic mainly foam based damped light enclosure experiment from the time (about 15 years ago) I added it to the setup, with it's own amplifier, which is part of a high quality 3 way electronic (not digital) active separation filter setup:

 

http://www.theover.org/Diary/Ldi36/hpim2736.jpg

 

It works under 40 Hz, with little harmonics being generated, so low test tones are extremely "boring" or strong without strange side effects, so good for monitoring and restful listening. The main 12 inchers (with relatively light foam suspension) are less strained because they only have to reproduce frequencies above 40 Hz.

[Docbop]

Floating baffle make me think of an archtop guitar in it resonates to create the sound. Archtop guitars well the good ones the tops are what they called tap-tuned. Where the top is done but not glued to the body. The luthier then taps the top to hear it and then chisels, scraps, and sands to get the different areas of the top to sound the way they want for bass side of the top and treble side. So do floating baffle makers get into working with thickness of the baffle for low end and high end areas? Seems like a floating baffle could start canceling out or enhancing frequencies based on wood and thickness.