All measurements in 'db' ..really dB ... are comparisons ... to some
'standard'.
20 dB means NOTHING ... 20 dB above/below/gain/loss is meaningfull.
Now .. most SOUND measurements are in dBa .. that's a comparison to an
ACOUSTIC level of some measure.
20 dBa would mean 20 dB comparison above that level.
Don
N8DE
Jim Reid wrote:
>
> > Manufacturer states the noise level as 61...
> > Is this loud ?
>
> A some time ago, Bell Labs put out the following:
>
> Whisper at 5 feet..........20 db
>
> Average house.............45 dB
>
> Average conversation...65 dB
>
> Average factory...........75 dB
>
> Riveting machine at 35 feet...100 dB
>
> Loud rock music...........115 dB
>
> Threshold of ear pain....130 dB
>
> Other factors impacting the irritability of noise include
> the frequency components within, and of course, the
> separation from the noise source.
>
> There is a big Dayton blower(2C915A) in my Henry amp;
> it is pretty noisy. So the amp is in the next room, hi. In
> that room, and within 4 feet or so of the amp cabinet,
> the sound level is around 82 dB. Coming over here into
> the "shack" room, the sound level from the amp blower
> drops down to around 68 db. (Sound levels measured
> with the Realistic 33-1028 sound level meter, old but
> still operates just fine!) That 68 dB reads like it is a loud
> sound, but it is not to the ears; the frequency components
> are low and my ears are not as sensitive as the "flat"
> response curve of the sound meter. Similarly, the loudness
> sound of the blower near the Henry cabinet, seems more
> loud even than 82 dB; probably because there are more
> mid and high range components over there. Those are
> more muffled than the low components by the insulated wall
> between the two rooms.
>
> Not sure if all that helps, but is interesting anyway, hi.
>
> 73, Jim KH7M
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
|