[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" <jamesforsman at me.com> 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 <lists at subich.com> 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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