Knowing very little about the physics of sound, does using a thinner
tube as opposed to a larger diameter one, make the tube have a
narrower " bandwidth " ?
See: http://www.fonema.se/qpipe/qpipe.htm
Since the primary loss component of an "organ pipe" is friction along
the wall, a larger diame
This whole topic is very interesting to me. Very ironically, just before
this topic got started, I was thinking about qrp hall of famer, Rick
Littlefield's, Ham Radio magazine article Mar 89', featuring a resonant cw
speaker.
It was built using a solo 16 cup and a small 700hz transducer.
I put it
The confusion here is a common one, closed vs open ended resonators, especially
if one looks at the poorly explained graphs in most physics texts.
The speaker, attached to one end of the pipe, is not the closed end, it is
open, since it drives the air particles at that end, and that makes it a
On 2/17/2017 6:56 PM, stan levandowski wrote:
> A cylinder with a closed end is a "closed cylinder" and requires the
> formula that uses 2f instead of f.
A cylinder with a speaker in one end and open in the other is an "open"
cylinder (open pipe). It is a *half wave* in air which means the
form
A cylinder with a closed end is a "closed cylinder" and requires the
formula that uses 2f instead of f.
The "real" formula accounts for lots of variables, including diameter of
the sphere. But a ballpark formula that works just fine for less complex
designs is just Length (in feet or fraction
I think a pipe with a speaker in the end is considered a closed end cylinder,
but I am not completely sure. If so, resonant lengths are shorter. Here is
the page from one of my favorite websites if you are interested in
experimenting with resonant speakers:
http://hyperphysics.phy-astr.gsu.ed
In the late 70's, I used a Sky Tec CW-1 resonant speaker. $9.95 USD in 1977.
It worked very well and had a very sweet sound. A sleeve in the top allowed
pitch adjustment. I still have it, somewhere around here...
When I first got my KX3, I considered duplicating it (it is made primarily out
I have not but you certainly can do it. The length of the tube will determine
the peak resonant frequency and you would have to experiment with the length to
tune it to the pitch you like best to listen to.
Remember the days you would blow across a bottle to make a tone? The more you
drank out
The wavelength and frequency of musical notes can be found here:
http://www.phy.mtu.edu/~suits/notefreqs.html
A closed end pipe as used in the resonant speaker is a half-wave
(half the given dimension).
Note also there will be some "end effect" because the sound continues
to vibrate past the
There was a commercial version available about 20 years ago and I used it
for quite some time. really made CW signals pop out of the background. May
build a new one of here.
Mike, k5wmg
Bella-Green Bed & Breakfast and Tiny Houses
www.bella-green.com
On Fri, Feb 17, 2017 at 1:25 PM, Robert
Try Pipe organ design. Gives you the input to cut the tube to any audio
frequency.
Mel, K6KBE
From: P.J.Hicks
To: ELECRAFT
Sent: Friday, February 17, 2017 10:56 AM
Subject: [Elecraft] (OT) CW Resonant Speaker
Has anyone built the resonator with a straight length of tube? Perhap
Yes. A number of the early designs in QST (decades ago) were straight
sections.
If you want to play around with the tube, pick up a couple of long "mailing
tubes". They are cardboard, so not quite as acoustically efficient I
suspect, but easy to trim and fiddle with to determine what length you w
Try this site.
Homemade Pipe Organ
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Homemade Pipe Organ
The story of how I designed and built an all wood pipe organ for my house. |
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Mel, K6KBE
From: P.J.Hicks
To: ELECRAFT
Sent: Friday, February 17, 2017 10:56 AM
Subject: [Elecraft] (OT) CW Resonant Speak
That is really an excellent video Stan. That's a pretty effective speaker,
I will be digging thru my plumbing supplies tomorrow!
Gary N7DXT
On Thu, Feb 16, 2017 at 6:14 PM, stan levandowski
wrote:
> For those with interest I just put up a video comparison of a standard
> "communications speaker
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