(OT) CW Resonant Speaker
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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 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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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 <[hidden email]> 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 > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by stan levandowski
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 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: (OT) CW Resonant Speaker
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Try Pipe organ design. Gives you the input to cut the tube to any audio frequency.
Mel, K6KBE From: P.J.Hicks <[hidden email]> To: ELECRAFT <[hidden email]> 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 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: (OT) CW Resonant Speaker
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In reply to this post by cheng076
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 <[hidden email]> To: ELECRAFT <[hidden email]> 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 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: (OT) CW Resonant Speaker
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In reply to this post by cheng076
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 > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by cheng076
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 <[hidden email]> 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 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: (OT) CW Resonant Speaker
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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 <[hidden email]> 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 <[hidden email]> 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 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: (OT) CW Resonant Speaker
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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 > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: (OT) CW Resonant Speaker
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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 ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] >> >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] >> >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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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 <[hidden email]> 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. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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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" <[hidden email]> 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 <[hidden email]> 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. > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: (OT) CW Resonant Speaker
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> 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" <[hidden email]> 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 <[hidden email]> 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. >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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