eHam Forums => QRP => Topic started by: ND6P on February 01, 2012, 05:41:54 PM

Title: QRP Speaker Enclosure Suggestions Wanted
Post by: ND6P on February 01, 2012, 05:41:54 PM
I have these 4 mini speakers taken from old headphones.  They are each 32 ohms at .1 watts.  If I put them in parallel, that will give me 8 ohms and match the audio output impedance of my QRP rig.  But I'm wondering how to go about building an enclosure to get a good sound.  Anyone have any suggestions?



Title: RE: QRP Speaker Enclosure Suggestions Wanted
Post by: KE7WAV on February 01, 2012, 08:00:33 PM
Why not four resonante cw speaker tubes setup in surround sound? Tune each tube to the fundamental resonate frequency you like to hear your code at, mount the speaker to the back end of each tube, and then line them up on the desk or mount them from the ceiling.  The possibilities are endless!
Have fun!

Title: RE: QRP Speaker Enclosure Suggestions Wanted
Post by: W1JKA on February 02, 2012, 02:27:02 AM
  I have made several QRP speakers from head phone size to 4 inch and all my enclosures are square plastic seedling pots.For the small pots  without recessed lips I super glue cut down plastic 45 degree angled wall mirror clips just inside the lip on all four sides an use hot melt glue to attach the head phone to,then left over screen door screening spray painted black for the grill.The 4 by 4 square pots have recessed lips to which I super glue strips of of popsicle stick thickness wood across each corner for a place to screw my speaker to then cut down the grills from junk transistor radios for the grill.Lay the pots on their sides with speaker wire out the back and they look like a store bought unit.These seedling pots are usually green or black,cheap or free from home gardeners.

Title: RE: QRP Speaker Enclosure Suggestions Wanted
Post by: W5FYI on February 02, 2012, 06:48:23 AM
Assuming you are wanting a CW speaker, I recommend mounting them in resonant enclosures. I've had good results using PVC tubing, but I've also seen them in Dixie cups and other specialized enclosures. Take a look at the following:

Your 0.1 watt won't sound like much, but in a 0.4W parallel resonant enclosure, you'll have enough volume that you can save your battery for longer operating time. GL

Title: RE: QRP Speaker Enclosure Suggestions Wanted
Post by: ND6P on February 02, 2012, 07:25:50 PM
Well, after seeing these replies, I decided to mount my mini-speakers into a 2.4 Ghz Cantenna.  I take the Cantenna with me when I camp in case there is Wi-Fi in the area, so I thought it would be handy to also use it as a QRP speaker. 

I drilled 4 equally spaced 1-inch holes in the back of the Cantenna and used silicon glue to attach the speakers.  Then I used the Cantenna's cover to hide the speakers, using black electrical tape to hold the cover in place.

The new speaker seems to work pretty well, both on SSB and CW.  I'm not exactly sure where it is resonant, but it does seem to peak CW signals at about 900 Hz.  And I'm thinking that the Cantenna will continue to work on 2.4 Ghz as well.

I'm listening to a SSB QSO on 40 meters as I write this, with the speaker connected to my Elecraft KX1, and the audio level is good.  And the background noise is much lower than what I am used to hearing on my base station transceiver, a pleasant surprise.

Thanks too all who replied.