Your choice of a speaker for your BITX40 can really make a difference to the receive audio quality. I had been using a small 2-1/4 inch speaker (you can see it to the right of the circuit board in the picture) and struggling with the poor audio quality with lots of hiss. Picked up a small 8 ohm mobile communications speaker in a 3 x 3 x 2-1/4 inch deep black metal case and hooked it up to my Bitx40. Wow! what a difference, much of the hiss is gone and since the speaker is optimized for human voice frequencies, the SSB signals I tune in really stand out. It even improves listening to CW signals. 73, AL VE3RRD
