# Infrasonic frequencies causing high pitched pulses



## SinCron (Dec 20, 2010)

For the longest time, I have had a pulsing in my speakers and I couldn't quite figure it out but it seems to be related to infrasonic frequencies, regardless of any crossover in place. If I'm playing anything on the computer that has content 20hz or under, there is a high pitched pulsing which pulse speed is directly related to the frequency (7 pulses in a second for 7hz, ect..). Could it be this is due to most sound cards being rated from 20hz-20khz and not much else on either side of the spectrum? Is there a card that would work for me? I've tried different receivers as well and it's still present in my Pioneer VSX-1015.


----------



## EarlK (Jan 1, 2010)

- Do you hear this ( modulation ) with headphones plugged into the computer ( & with the computer sound-card not connected to anything else but the headphones) ?

- If the problem disappears ( with headphones ) then the problem is most likely severe inter-connect noise, being modulated by the FR content of the sound-card ( quite bizarre but can happen ) .

- If this seems to pin-point the problem, then one solution is a pair of audio isolation transformers placed in-between the computers sound-card & the receiver .

-  *Google = Audio Isolation Transformers* 

- OTOH, if the modulation persists ( within the headphones ), then ( yes ) you should get a new sound-card ( & there are many choices that I won't go into ).

:sn:


----------



## SinCron (Dec 20, 2010)

I forgot to mention that I'm using an optical cable.


----------

