[Elecraft] (OT) Follow-up on CW Resonant Speaker

[David Anderson]

Stan,

Thanks for the video, most impressive.

I have one comment regarding the need for an amplifier with the KX1 /KX2 or KX3 radios, there is another YouTube video from a couple of years ago that appears to be almost what the more recent QST article is based upon and in it the constructor has it connected to a KX1 and it seems loud enough.

https://youtu.be/4iNELueaU6M

Then there is another video where another constructor dissects the original commercial design and makes one, this really shows how efficient the design is when at the end he compares the bare speaker on its own and how weak it sounds compared to when it resonates.

https://youtu.be/MF8bk6958Hg

The key seems to be that in both of the above cases the lower part of the resonant speaker is + not + sealed completely, air is allowed to enter and exit, though there is sound deadening material in the cavity. Perhaps that explains the greater sound efficiency?

This is something I plan to investigate myself with my KX3, once I get the parts here, of course being in the UK we are now metric and so some slight adjustments are necessary as our pipe is 50mm and so on. A friend has offered the services of his laser cutter and 3D printer which will come in handy too!

73 from David GM4JJJ

> On 14 Feb 2017, at 00:49, stan levandowski <sjl219 at optonline.net> wrote:
> 
> Folks, I posted about having built the CW Resonant Speaker in the February 2017 and having problems with low audio.  This is a follow-up report for those with interest in this subject.
> 
> It works!  It's fabulous!  It's unbelievable how great it sounds! CW pops out and background noise is significantly reduced.
> 
> 
> I built it EXACTLY as described in the article and ordered the EXACT parts listed.  My problem was not enough audio coming from either my KX1 or my KX2 headphone jacks.  
> 
> 
> I purchased a fully assembled 15 watt mono amplifier - Qianson TDA2030A 15W Mono Channel Audio Power Amplifier Board AC/DC 12V AMP Module - Amazon for $11.80.
> 
> 
> With the new amp, my speaker is acoustically resonant at 760 Hz and I have plenty of volume; enough to fill the room.  The author had claimed "around 700 Hz" so it's in the ballpark.  I can verify that the construction article was accurate.
> 
> 
> I wanted 600 Hz so I built a vinyl sleeve to insert into the street elbow and set my sidetone pitch for 600 Hz then slid the sleeve up and down until I got a very obvious peak in volume.
> 
> 
> I'm still a "can fan" for serious CW operating, but it's nice to be able to listen to sweet CW that pops right out now that the higher frequency sounds are substantially subdued.
> 
> 
> This was a really worthwhile little project.
> 
> 
> 73, Stan WB2LQF
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to gm4jjj at yahoo.co.uk