Hey, I'm filtering some noise to get very low-pitched sounds. I want the high-pitched hum that comes with DC-offset (it gets better when I deliberately add a [+~ 0.5]), but I've read that DC-offset can be harmful to equipment. Does this hold true when done in Pure Data as well? If so, any tips on getting the DC-offset "sound" without actually having a DC? Adding a [hip~ 1] right before the output to get rid of the offset, I still hear some of the high-pitched sound, but not as much. I guess it's not exactly a bi-product of DC-offset?

@s.elliot.perez said:

Hey, I'm distorting and filtering some noise to get very low-pitched sounds. I want the high-pitched hum that comes with DC-offset (it gets better when I deliberately add a [+~ 0.5]), but I've read that DC-offset can be harmful to equipment. Does this hold true when done in Pure Data as well? If so, any tips on getting the DC-offset "sound" without actually having a DC? Adding a [hip~ 1] right before the output to get rid of the offset, I still hear some of the high-pitched sound, but not as much. I guess it's not exactly a bi-product of DC-offset?

edit: I guess I could just manually add a super-high-pitched [osc~]. Hard to get it to sound the same as the apparently non-existent high-pitch I hear at DC-offset though...

@s.elliot.perez DC offset "can" damage speakers. Low levels will probably be fine, especially if there is some AC component.
In the olden days when amplifiers were less reliable, and had no processor to shut them down when there were problems, we used to always put capacitors in-line with the speakers to filter any DC.
But the "DC problem" was output transistor failure dumping one power rail directly through the speaker.... so massively surpassing it's RMS capability with no cooling from movement....
That was very quickly catastrophic..... and smelly.

A hum from DC offset might be caused by the DC current being dumped to ground somewhere in the soundcard or amplifier, and might not be repeatable on other systems.
Is it at 50/60 Hz?

Any added noise could be clipping at the soundcard as the Pd output surpasses "1".
If you add Dc [+~ 0.5) to a low frequency sine that is what you will hear..... a click at that frequency.
So a buzz added to the hum at the same frequency.
David.

@whale-av Thanks for that tip. I tested it and it only made that sound with my Bluetooth headset. With the headphones plugged into my laptop or routed through my PreSonus, it didn't. I recorded the sound by putting a microphone up to the headphones and by looking at it in Sonic Visualizer found it to be around 5530Hz with a wobbly waveform, so I can simulate it fairly well with [noise~]->[lop~ 1]->[*~ 25]->[+~5530]->[osc~].