[Elecraft] optimal headphones impedance for K2?

Sat Aug 9 12:57:00 2003

Hi Jeff - I don't know the "optimal impedance for headphones" for the K2 -
but I'm pretty happy with an Optimus Multimedia Stereo Headset with electret
boom mic that I got at Radio Shack.  The model number is 33-1107 and they
are currently on sale for $9.97.  I think the regular price is only around
$20 - hardly "high end" !! - but at $9.97 the risk is small (you can always
take them back) and they may be something for you to try.  The headphone
side of the headset works very well.  I don't know the impedance but I'm
guessing that it is around 30 ohms or so.  Plenty of volume with a very
smooth sound.   I also have the DSP module in my K2 and have not noticed
that it degrades the audio either on the speaker or the headphones. The
headset is very light weight and the attached boom mic (a bonus since you
just mentioned looking for headphones) sounds great with the K2 (even works
quite well with the un-modified vox when compression is set to 2:1 and gain
to 2).  I power the mic through a 10K 1/4 watt resistor from the 5 volt line
available on the mic connector.  The 10K resistor is inside a small cable
adapter that I made up (no need to go inside the rig) so that I can just
plug the mic right in to a stereo 1/8 inch socket without trying to cut the
molded plug off, deal with the very tiny wires that are used on all these
molded plugs, etc. etc. To me, it makes a nice system for contesting or just
general operating.  I also use the D-104 and both the Heil HC-5 and HC-4.
They each have much tighter frequency response than the electret. They do
work very well and I get excellent audio reports with them too.    As usual,
YMMV and I have no financial interest in RS.

Have fun !  ' 73  --don  n4hh  K2/100 #2028

<snips>
----- Original Message ----- 
From: "Jeff Burns" <[email protected]>
To: "elecraft_list" <[email protected]>
Sent: Friday, August 08, 2003 10:49 PM
Subject: [Elecraft] optimal headphones impedance for K2?

> Now with the KDSP2 . . . .headphones sound bad.  The output is
> weaker.  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?

> So what is the optimal impedance for headphones used
> with the K2?
>
>....These look like great... headphones, but their price is getting a
little salty.
>
> Jeff Burns
> AD9T

----- Original Message ----- 
From: "Jeff Burns" <[email protected]>
To: "elecraft_list" <[email protected]>
Sent: Friday, August 08, 2003 10:49 PM
Subject: [Elecraft] optimal headphones impedance for K2?

> 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
>
> _______________________________________________
> Elecraft mailing list: [email protected]
> You must be subscribed to post to the list.
> To subscribe or unsubscribe see:
http://mailman.qth.net/mailman/listinfo/elecraft
> Postings must be plain text (no HTML or attachments).
> Elecraft Web Page: http://www.elecraft.com