[Elecraft] KPA1500 Fan Noise - Not An Issue

[Mel Farrer]

While I appreciate all of the sound proofing suggestions, the old rule keeps coming back.: " Stop the source as much possible FIRST."  I hate patches......
Mel, K6KBE

      From: Bob McGraw K4TAX <rmcgraw at blomand.net>
 To: elecraft at mailman.qth.net 
 Sent: Monday, June 4, 2018 2:20 PM
 Subject: Re: [Elecraft] KPA1500 Fan Noise - Not An Issue
   
One of my favorite methods of sound treatment is the products in the 
link following: http://www.sonex-online.com/Pro%20Audio.htm

There are many other products, and many individuals use their own 
creative means to be effective in sound absorption.

73

Bob, K4TAX


On 6/4/2018 1:00 PM, Jim Brown wrote:
> On 6/4/2018 8:34 AM, Bob McGraw K4TAX wrote:
>> Room acoustics play a big part of the "how loud" factor. Absorptive 
>> materials applied to the walls an ceiling of a room, specially small 
>> rooms,  do reduce the build up of sound / noise emitted from fans and 
>> blowers.
>
> YES! This is excellent advice. Indeed, the first place to put 
> absorptive material is on wall surfaces around the amp, treating other 
> wall surfaces can also help a lot. Hard surfaces contain the sound, 
> causing it to bounce around the room. Soft surfaces absorb the sound, 
> causing it to die out more quickly.
>
> Mechanical coupling of vibration to the desk increases the audibility 
> of noise, so it can also help to isolate the amp from the shelf it is 
> sitting on.
>
> Fan noise on the transmitted signal can be minimized in several ways, 
> all of which are pretty simple.
>
> First, keep the mic close to your mouth -- sound falls off by 6dB per 
> doubling of distance. Boom mics, like the CM500, are great for this. 
> For best sound quality, I try to keep the mic an inch or two above and 
> to the side of my mouth. The principle is to maximize speech and 
> minimize noise -- a simple signal to noise problem.
>
> Second, don't turn mic gain up higher than needed, and don't overdo 
> compression. This is the primary cause of excessive noise on 
> transmitted signals.
>
> Third, set TXEQ to emphasize the speech range and de-emphasize other 
> sound. My guideline EQ settings do this -- max cut of the three lower 
> bands, 6 dB cut of the fourth band (400 Hz), and then get reports from 
> a careful listener.
>
> 73, Jim K9YC
>


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