[CW] Headphones or Loudspeaker?

[Richard Knoppow]

    You don't have to use resonant phones. In fact they are 
antiques now. Modern "hi-fi" phones are non resonant and can work 
at any frequency.
    With some research you can probably find how to make a fairly 
sharp filter. An active filter with a small amplifier for the 
phones or a passive one that just goes in the line between 
receiver and phones. In the tube days there was a gadget called 
the _Selectoject_. It was first described in QST, then made as a 
commercial product by National. I don't know if there was a solid 
state version but I suspect there was. It could be used as a 
tuneable rejection filter or a tunable peaking filter.
    A problem with any filter that is too sharp is that it rings 
on noise and can make CW harder to read rather than easier.
    How did you tune the speakers?

On 6/15/2018 8:18 AM, John Westerlage wrote:
> I would like to use headphones to keep from bothering the rest of 
> the household.
> 
> BUT - the frequency one prefers seems to have something to do 
> with the ear's
> physical structure as well as other factors.
> 
> For me, a tone of around 432 c.p.s seems to be MUCH louder than 
> any other freq
> either higher or lower.
> 
> So, I have built speakers tuned to that frequency, but I cannot 
> find any headphones
> that do the same thing.  I suppose some sort of R/C network as 
> pre-filter in the
> earphone line could do the job, but I haven't been able to come 
> up with the right
> combination.
> 
> Any suggestions on how I could do this ?
> *vy 73, John, N5DWI*


-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL