[Elecraft] Microphones (was electronic product standards)

[Alan Bloom]

I read years ago that speech processors like pre-emphasized audio
(louder highs, quieter lows).  And the heavier the processing the more
pre-emphasis is optimum.  Does anyone know if the K3 speech processor
does that automatically?

Al N1AL


On Thu, 2008-02-14 at 01:52, Brendan Minish wrote:
> On Wed, 2008-02-13 at 12:12 -0800, Ron D'Eau Claire wrote:
> 
> > There were some microphones produced for the "communications" market back
> > then such as the famous Astatic D-104 which had a microphone element with a
> > shaped response showing a distinct hump around 3 kHz, rolling off slowly at
> > lower frequencies and somewhat faster at higher frequencies. That hump
> > helped with "articulation" by emphasizing the mid-range speech frequencies.
> 
> This is a presence peak.
> 
> > I don't know if anyone is doing that today for mainstream communications
> > microphones.
> 
> Today Paging Microphones are still specifically designed to have this
> pronounced mid range presence peak and also usually include Quite a bit
> of low frequency Roll off 
> 
> Shure have a range of dynamic elements available for this market, that
> have response curves that look remarkably similar to the HC4 and HC5
> elements.
> take a look at the response curve of the Shure 450
> http://www.shure.com/ProAudio/Products/WiredMicrophones/us_pro_450SeriesII_content
> a direct link to just the curve 
> http://www.shure.com/groups/public/@gms_gmi_web_us/documents/web_resource/site_img_us_rc_450series2_larg.gif
> 
> the 522 has a broader presence peak
> http://www.shure.com/ProAudio/Products/WiredMicrophones/us_pro_522_content
> Direct to curve 
> http://www.shure.com/stellent/groups/public/@gms_gmi_web_us/documents/web_resource/site_img_us_rc_522_large.gif
> 
> elements for these mics (and many others) are available at low cost as
> replacement parts. 
> 
> Heil sound plot their curves on a different log scale but after
> accounting for that the similarities are remarkable. 
> http://www.heilsound.com/amateur/products/hc4/index.htm
> 
> 
> The needs of paging systems which include efficient use of limited power
> and maximum intelligibility in noisy environments are pretty much
> identical to our requirements for effective SSB modulation. Any well
> made paging/ Dispatch mic (or element..) is ideal for amateur radio use,
> most are far more durable and cost effective than 'the made for ham
> radio' stuff that is popular these days.  
> 
> >  Even the "high end" Ham mics only offer general and
> > uninformative comments about "shaping" and "clarity" that say much and
> > convey little.
> 
> These words (in ham radio use anyway) have become marketing speak and
> now mean nothing. As a former audio professional I cannot understand why
> all the hype about Audio in ham radio and to my ears there's a lot of
> money wasted on trying to make SSB into something it isn't.
>   
> >  Interestingly, one of the big exceptions is the inexpensive
> > little Radio Shack electret element. It comes with a frequency response
> > chart showing a very flat response across the audio spectrum.
> 
> If you are looking for flat then these are a great place to start,
> however the design of the housing may have quite an impact on how things
> sound, this can be used to your advantage to create a presence peak or
> LF roll off.
> 
> My own headset is based on a salvaged electret condenser mic with some
> audio tailoring done by means of a simple R/C filter, being lazy I
> copied the circuit of an Icom handmic. It works great and cost me almost
> nothing.   
> 
> 73's Brendan EI6IZ