On 25/02/2016 09:52, gareth G4SDW GQRP #3339 wrote:
Some years ago, came across an article that took mono audio and
created a false stereo with a low pass filter feeding the left ear, and a
high pass
filter feeding the right ear, which gave the effect of a rising audio
frequency
travelling from left to right, and also apparently aided the reception of CW
because you could "look" in the direction of the signal that you wished to
pick out.

Such an arrangement fits in very well with the headphones generally
available today from Currys and the like.

Also, with computer audio boxes, is ther eany need to actually put
audio amplifiers inside rigs, so just leaving a headphone socket?

No. It does make it neater but external audio is common. I occasionally
use a USB sound system that simply plugs into a usb port (on the end of
an extention cable) and handles all the sound. You very much get what
you pay for and you can pick up a tinny device for £2 or 3 on ebay or a
more advanced system with much higher quality sound. At the top end you
have professional sound engineering systems that interface with USB.

Bottom end https://www.google.co.uk/#q=usb+sound+card&safe=off&tbm=shop

Andy