Re: [Elecraft] (OT) CW Resonant Speaker

[Joe Subich, W4TV]

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 diameter tube will have lower losses and thus higher
"Q".


73,

   ... Joe, W4TV


On 2/20/2017 9:51 PM, Dean L wrote:

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 on my to do list, back in 89'... nearly 28 years later I FINALLY
sent Rick an email asking if he still had any of these little speakers
left, after so many years... A few days later I had a package from Rick
with a couple of the little speakers!
The generosity of old school hams never ceases to amaze me.

I have a question for those in the "know"--

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 " ?
How would on increase the Q of the device ( if that's even possible)?

I'd appreciate any input. TIA

72
Dean/K2WW

On Feb 18, 2017 8:09 AM, "jrquark"  wrote:


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
displacement antinode, where the particle displacement is maximum.

Jim - K7BIE



On Feb 17, 2017, at 9:43 PM, Joe Subich, W4TV  wrote:

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
formula uses 2f instead of f.


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Re: [Elecraft] (OT) CW Resonant Speaker

[Dean L]

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 on my to do list, back in 89'... nearly 28 years later I FINALLY
sent Rick an email asking if he still had any of these little speakers
left, after so many years... A few days later I had a package from Rick
with a couple of the little speakers!
The generosity of old school hams never ceases to amaze me.

I have a question for those in the "know"--

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 " ?
How would on increase the Q of the device ( if that's even possible)?

I'd appreciate any input. TIA

72
Dean/K2WW

On Feb 18, 2017 8:09 AM, "jrquark"  wrote:

> 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
> displacement antinode, where the particle displacement is maximum.
>
> Jim - K7BIE
>
>
> > On Feb 17, 2017, at 9:43 PM, Joe Subich, W4TV  wrote:
> >
> > 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
> > formula uses 2f instead of f.
>
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Re: [Elecraft] (OT) CW Resonant Speaker

[jrquark]

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 
displacement antinode, where the particle displacement is maximum.

Jim - K7BIE


> On Feb 17, 2017, at 9:43 PM, Joe Subich, W4TV  wrote:
> 
> 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
> formula uses 2f instead of f.

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Re: [Elecraft] (OT) CW Resonant Speaker

[Joe Subich, W4TV]

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
formula uses 2f instead of f.

A "closed cylinder" is excited on one end and the other end is closed
(plugged).  A closed cylinder is a *quarter wave* in air - its formula
would use 4f instead of f.


73,

   ... Joe, W4TV


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.


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 fractions of a foot) equals the speed
of sound in air (in feet per second which is approximately 1100) divided
by either f (for an open end cylinder) or 2f (for a closed end cylinder)
where f is the desired frequency of resonance you want.  Much like
making a simple dipole, you can start with the formula but it takes
trimming to get it optimized.


Example:  You want a speaker resonant at 600 Hz.  It is closed at one
end ( the end in which you mount the speaker).  The tube is *about* two
inches in diameter.  L=1100/2f  -- L=1100/1200  --  L=..916 ft.  --
 .916 inches x 12 inches = 10.9 inches.


The preceding is not perfect but, like a dipole, it needs final
trimming.  That's where an adjustable design (like the PVC versions with
a sleeve) make it easier to trim vs. building a wooden box (like the
KD1JV box design).


73, Stan WB2LQF


On Fri, Feb 17, 2017 at 06:07 PM, Mark Petiford via Elecraft wrote:


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.edu/hbase/Waves/opecol.html#c1

Good educational website from Georgia State University.


Mark,
KE6BB


On Friday, February 17, 2017 2:14 PM, Mike Furrey  wrote:

 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 of the bottle the lower the pitch. I like this
project and I am going to build one and it will be with a straight
tube mounted on a little stand so it aims towards me.
73, Mike WA5POK

On Friday, February 17, 2017 12:58 PM, P.J.Hicks  wrote:

 Has anyone built the resonator with a straight length of tube?
Perhaps terminated with a 45 deg. cut? Might be an interesting
experiment.
The 45 deg long radius street elbow in 2" is an order only item in my
area so thought I'd substitute a straight length.
PJH, N7PXY __
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[Elecraft] (OT) CW RESONANT SPEAKER

[John AE5X]

Here's a video of the Sky Tec and a few tips for building a copy:
https://www.youtube.com/watch?v=MF8bk6958Hg

John AE5X
http://ae5x.blogspot.com/
__


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 
of PVC pipe) so I could use two of them to take advantage the KX3's audio 
special effects.  So many projects, so little time. 


Mark,
KE6BB 

Losing Weight Is Easier Than Ever With This Magic Formula
Capitalizing Calories
http://thirdpartyoffers.juno.com/TGL3131/58a7a8d319fea28d266b8st02vuc
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Re: [Elecraft] (OT) CW Resonant Speaker

[stan levandowski]

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 fractions of a foot) equals the speed 
of sound in air (in feet per second which is approximately 1100) divided 
by either f (for an open end cylinder) or 2f (for a closed end cylinder) 
where f is the desired frequency of resonance you want.  Much like 
making a simple dipole, you can start with the formula but it takes 
trimming to get it optimized.



Example:  You want a speaker resonant at 600 Hz.  It is closed at one 
end ( the end in which you mount the speaker).  The tube is *about* two 
inches in diameter.  L=1100/2f  -- L=1100/1200  --  L=..916 ft.  -- 
 .916 inches x 12 inches = 10.9 inches.  



The preceding is not perfect but, like a dipole, it needs final 
trimming.  That's where an adjustable design (like the PVC versions with 
a sleeve) make it easier to trim vs. building a wooden box (like the 
KD1JV box design).



73, Stan WB2LQF


On Fri, Feb 17, 2017 at 06:07 PM, Mark Petiford via Elecraft wrote:

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.edu/hbase/Waves/opecol.html#c1

Good educational website from Georgia State University.


Mark,
KE6BB


On Friday, February 17, 2017 2:14 PM, Mike Furrey  wrote:

 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 of the bottle the lower the pitch. I like this 
project and I am going to build one and it will be with a straight 
tube mounted on a little stand so it aims towards me.

73, Mike WA5POK

    On Friday, February 17, 2017 12:58 PM, P.J.Hicks  wrote:

 Has anyone built the resonator with a straight length of tube? 
Perhaps terminated with a 45 deg. cut? Might be an interesting 
experiment.
The 45 deg long radius street elbow in 2" is an order only item in my 
area so thought I'd substitute a straight length.
PJH, N7PXY 
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Re: [Elecraft] (OT) CW Resonant Speaker

[Mark Petiford via Elecraft]

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.edu/hbase/Waves/opecol.html#c1

Good educational website from Georgia State University.


Mark,
KE6BB


On Friday, February 17, 2017 2:14 PM, Mike Furrey  
wrote:
 

 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 of the bottle the lower the pitch. 
I like this project and I am going to build one and it will be with a straight 
tube mounted on a little stand so it aims towards me.
73, Mike WA5POK
 

    On Friday, February 17, 2017 12:58 PM, P.J.Hicks  
wrote:
 

 Has anyone built the resonator with a straight length of tube? Perhaps 
terminated with a 45 deg. cut? 
Might be an interesting experiment. 

The 45 deg long radius street elbow in 2" is an order only item in my area so 
thought I'd substitute a straight length. 

PJH, N7PXY 
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Re: [Elecraft] (OT) CW RESONANT SPEAKER

[Mark Petiford via Elecraft]

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 
of PVC pipe) so I could use two of them to take advantage the KX3's audio 
special effects.  So many projects, so little time. 


Mark,
KE6BB 

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Re: [Elecraft] (OT) CW Resonant Speaker

[Mike Furrey]

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 of the bottle the lower the pitch. 
I like this project and I am going to build one and it will be with a straight 
tube mounted on a little stand so it aims towards me.
73, Mike WA5POK
 

On Friday, February 17, 2017 12:58 PM, P.J.Hicks  
wrote:
 

 Has anyone built the resonator with a straight length of tube? Perhaps 
terminated with a 45 deg. cut? 
Might be an interesting experiment. 

The 45 deg long radius street elbow in 2" is an order only item in my area so 
thought I'd substitute a straight length. 

PJH, N7PXY 
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Re: [Elecraft] (OT) CW Resonant Speaker

[Joe Subich, W4TV]

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 end of the pipe - which means the pipe will need
to be somewhat shorter than the true half wave.  End effect is
generally about 20% of the pipe diameter (from reading up on pipe
design).  I don't know what the effect of a 45 degree "end" would be
but I suspect you would want to make the mid-point of the cut about
where a square end would normally fall.

One could also experiment with *closed end* pipes ... pipes with the
far end plugged and a notch or hole near the speaker.  Closed end
pipes are a quarter wave long which would significantly reduce the
size for those using low frequency tones.  An open 700 Hz pipe is
49.5 cm (without end correction) - an open 440 Hz pipe would be 78.5 cm
and a open 300 Hz pipe would be about 115 cm (nearly four feet!) long.
Unfortunately, I have not seen any information on the sound port
(notch) design for closed end pipes - or whether they can be driven
by a speaker.

73,

   ... Joe, W4TV


On 2/17/2017 1:56 PM, P.J.Hicks wrote:

Has anyone built the resonator with a straight length of tube? Perhaps 
terminated with a 45 deg. cut?
Might be an interesting experiment.

The 45 deg long radius street elbow in 2" is an order only item in my area so 
thought I'd substitute a straight length.

PJH, N7PXY
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Re: [Elecraft] (OT) CW RESONANT SPEAKER

[Michael Goins]

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 'RC' Conley 
wrote:

> KD1JV has this version on his web page.
> I built one several years ago from fibre board and cement.
> Works very good and still using it,
> 
> RC KC5WA
>
> --
> May You Live Long and Prosper
> what's life without a few dragons
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Re: [Elecraft] (OT) CW Resonant Speaker

[Mel Farrer via Elecraft]

Try Pipe organ design.  Gives  you the input to cut the tube to any audio 
frequency.
Mel, K6KBE 

  From: P.J.Hicks <hickspj...@comcast.net>
 To: ELECRAFT <elecraft@mailman.qth.net> 
 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? Perhaps 
terminated with a 45 deg. cut? 
Might be an interesting experiment. 

The 45 deg long radius street elbow in 2" is an order only item in my area so 
thought I'd substitute a straight length. 

PJH, N7PXY 
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Re: [Elecraft] (OT) CW Resonant Speaker

[Ron D'Eau Claire]

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 want
to make out of harder material. 

73, Ron AC7AC


-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of
P.J.Hicks
Sent: Friday, February 17, 2017 10:57 AM
To: ELECRAFT
Subject: [Elecraft] (OT) CW Resonant Speaker

Has anyone built the resonator with a straight length of tube? Perhaps
terminated with a 45 deg. cut? 
Might be an interesting experiment. 

The 45 deg long radius street elbow in 2" is an order only item in my area
so thought I'd substitute a straight length. 

PJH, N7PXY
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[Elecraft] (OT) CW RESONANT SPEAKER

[Robert 'RC' Conley]

KD1JV has this version on his web page.
I built one several years ago from fibre board and cement.
Works very good and still using it,

RC KC5WA

-- 
May You Live Long and Prosper
what's life without a few dragons
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Re: [Elecraft] (OT) CW Resonant Speaker

[Mel Farrer via Elecraft]

Try this site.
Homemade Pipe Organ

  
|  
|   |  
Homemade Pipe Organ
 The story of how I designed and built an all wood pipe organ for my house.  |  
|

  |

 

Mel, K6KBE

  From: P.J.Hicks <hickspj...@comcast.net>
 To: ELECRAFT <elecraft@mailman.qth.net> 
 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? Perhaps 
terminated with a 45 deg. cut? 
Might be an interesting experiment. 

The 45 deg long radius street elbow in 2" is an order only item in my area so 
thought I'd substitute a straight length. 

PJH, N7PXY 
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Message delivered to farrerfo...@yahoo.com


   
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[Elecraft] (OT) CW Resonant Speaker

[P.J.Hicks]

Has anyone built the resonator with a straight length of tube? Perhaps 
terminated with a 45 deg. cut? 
Might be an interesting experiment. 

The 45 deg long radius street elbow in 2" is an order only item in my area so 
thought I'd substitute a straight length. 

PJH, N7PXY 
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Re: [Elecraft] (OT) CW Resonant Speaker

[Gary Watson]

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" vs. the "CW Resonant Speaker" detailed in the
> article of the same name in the February 2017 QST, page 43.
>
> Included for Elecraft KX product owners is the amp necessary to use the
> headphone jack output.
>
>
> Click on:  https://www.youtube.com/watch?v=htjgeHEf3-g
>
>
> 73, Stan WB2LQF
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[Elecraft] (OT) CW Resonant Speaker

[stan levandowski]

For those with interest I just put up a video comparison of a standard 
"communications speaker" vs. the "CW Resonant Speaker" detailed in the 
article of the same name in the February 2017 QST, page 43.


Included for Elecraft KX product owners is the amp necessary to use the 
headphone jack output.



Click on:  https://www.youtube.com/watch?v=htjgeHEf3-g


73, Stan WB2LQF
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