[Elecraft] optimal headphones impedance for K2?

Sat Aug 9 08:25:01 2003

Jeff:
  I have used several pair of very inexpensive Sony earphones, the sort 
that come with Walkman items, with my K2 and found them very satisfactory. 
They are very light weight and can be worn for hours at a time with no 
problem.  They seem to match quite well, but, given the nature of my set 
up, I have them attached to the speaker output, not the phone jack.

best wishes,

dave belsley, w1euy

--On Friday, August 8, 2003 9:49 PM -0500 Jeff Burns 
<[email protected]> wrote:

> Before I installed the KDSP2 in my K2 I used my David Clark headphones
> most of the time. Their impedance is only 10 ohms so the audio was low but
> sufficient.  I found the David Clark's comfortable to wear despite being
> heavy.  The isolation form outside noise is also great.
>
> Now with the KDSP2 the David Clark headphones sound bad.  The output is
> weaker. To get good output I have tried using the speaker jack on the
> back. That gets the volume up but produces more hiss. Some CW sounds are
> fairly distorted.  I do not understated what the KDSP2 did. Maybe the
> signals are so much cleaner that I am noticing the shortcomings of the
> headphones?
>
> This has led me to try every pair of headphones in the house. My Pioneer
> SE-72 sound very good. Unfortunately, they are the supra-aural type and
> hurt my ears in short order.  They also do not block out sound as much as
> I would like. Their impedance is around 30 ohms.  I remember someone on
> this list stating that this was about the optimal impedance for
> headphones used with the K2.
>
> In looking at possible new headphone I have noticed that many of the best
> ones are very high impedance.  For instance the Koss Pro 4/aa impedance is
> 250 ohm, and the sensitivity is 95dB SPE/1mV. Just considering the power
> dividing between the resistors in the K2 and the headphones it seems that
> the higher the headphone impedance the better. I suppose that at some
> point the amplifier will not be able to put any current into circuit and
> audio output will decrease.   So what is the optimal impedance for
> headphones used with the K2?
>
> I have found one nice set of headphones with an impedance of 55 ohms -
> the AKG K271. They have a sensitivity of 91dB SPE/1mV. These look like
> great headphones, but their price is getting a little salty.
>
>
> Jeff Burns
> AD9T
>
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----------------------------------
David A. Belsley
Professor of Economics