[Elecraft] My K3's hissy and noisy audio

[Joe Subich, W4TV]

> Now upgrade the series caps to 330 uF and re-run the 
> calculation.  With 32-ohm phones (ref 100 Hz), the frequency 
> response improves to 15 Hz.  Now that's t real Hi-Fi on par 
> with what Icom delivers and the difference is immediately 
> noticeable to anyone -- not just the folks with "golden ears."

On the other hand, plug a Heil ProSet with its 200 Ohm elements 
into an unmodified K3 and the -3dB point is 80 Hz ... low enough
for communications use without being overly sensitive to hum and 
other low frequency noise,   Similarly, with 8 Ohm speakers, the 
-3 dB point is 40 Hz with the 470 uF coupling capacitors in the 
speaker amp. 

73, 

   ... Joe, W4TV 
 


> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Paul 
> Christensen
> Sent: Monday, April 06, 2009 6:54 AM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] My K3's hissy and noisy audio
> 
> 
> > Perhaps the band noise is more obvious in the K3 because the low 
> > frequency audio is restricted causing the noise to be 
> distributed over 
> > a more narrow range. This lack of bass tends to induce for ear 
> > fatigue. Steve Ellington
> 
> I agree with Steve on this one.  Once more low-end was rolled 
> into my audio 
> hardware changes, I noticed a significant reduction in my own 
> listener 
> fatigue.
> 
> Others have noted the K3's audio frequency response variance across 
> different headphone models, most notably the Heil product.  The K3's 
> headphone circuit uses 10 uF of series capacitance from the 
> headphone amp to 
> each of the headphone coils.
> 
> For the moment, assume that your headphones are 32-ohms (ref 
> 100Hz).  What 
> is the best possible low-end response from the K3?  The 
> answer is 500 Hz 
> @ -3dB.  That part of the circuit needs some help.  With a 
> headphone Z even 
> lower toward 8-ohms, the attenuation of bass response is worse.
> 
> Now upgrade the series caps to 330 uF and re-run the 
> calculation.  With 
> 32-ohm phones (ref 100 Hz), the frequency response improves 
> to 15 Hz.  Now 
> that's t real Hi-Fi on par with what Icom delivers and the 
> difference is 
> immediately noticeable to anyone -- not just the folks with 
> "golden ears."
> 
> Finally, compare the result of the modified K3 with the Icom 
> '7700 or '7800.
> 
> Paul, W9AC 
> 
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