APC40 creating high pitched noise

[CerebralNektar]

Ok I admit that some units could be not affected by this buzz

[paq]

next to the ac/dc which often makes noise in cheap hardware (but normally its a bzzing) it might be the leds. some leds produce very high pitched tones (the ones of my mp3player do so).

so long that fuckin apc is expensive enough, i would definitely exchange it.

[necho]

glad I was too broke to get one from the first batch then...

[channelite]

I still get the noise when the APC is plugged into my Furman PL-8C power conditioner.

[Tone Deft]

some leds produce very high pitched tones

no they do not.

my guess. ALL switching power supplies hum but they're designed to hum well above our hearing range. if a component drifts out of spec, is inserted wrong etc then that sound can drift into the audible range. somehow this is being heard inside the APC and not the supply or people are putting their ears to the supply. or somehow the supply isn't matched to the APC correctly or some APCs are screwy, messing with the supply. maybe an inspection of the supplies might help, maybe they're undervoltage, maybe the APCs weren't AOT'ed corrected, lots to speculate about. LEDs do not 'ring.'

my power supply is rated at 12V 2A
model Sunny SYS1308-2412-W2
Part number SYS1308-2412

maybe try a different 12V supply with a higher current rating. it's OK to rate a supply at a higher current, just not at a higher voltage. some devices are OK with higher voltages, it depends on whether or not they have internal regulators.

I bet what's happening is that when you turn on more and more LEDs you're drawing more current, stressing out the supply until it hums. [speculation]which means mine is working now but in a few years time it could start humming. [/speculation]

[kenporter]

some leds produce very high pitched tones

no they do not.

my guess. ALL switching power supplies hum but they're designed to hum well above our hearing range. if a component drifts out of spec, is inserted wrong etc then that sound can drift into the audible range. somehow this is being heard inside the APC and not the supply or people are putting their ears to the supply. or somehow the supply isn't matched to the APC correctly or some APCs are screwy, messing with the supply. maybe an inspection of the supplies might help, maybe they're undervoltage, maybe the APCs weren't AOT'ed corrected, lots to speculate about. LEDs do not 'ring.'

there's not much to discuss, send them back. sucks.

Considering that the unit has a wallwart switch mode power supply and that the input to the APC is DC, your explanation can't be correct. Since the high pitch noise is only audible when Live is started and the USB connection is active (drawing current), I suspect that it has something to do with the USB circuitry. I can hear it but don't think it's really a big deal and wouldn't return it because of it.

Ken

[Tone Deft]

you can't dismiss my point, most anything's possible at this point. I edited my post, read it again.

a bad supply would introduce ripple current into the DC, causing internal parts to (forgetting the word now damnit, vibrate due to fluctuations in the supply current.)

maybe the power from the USB is being connected when it shouldn't because the box solely relies on the wall wart and noise from the computer is being coupled into the box.

I always keep an open mind to all possibilities when debugging.


the only real answer is to play loud or send them back.

[Android Bishop]

the thing is, the hum is far more noticeable when the unit first powers up in a blank set. As clips are added and lights go on, the hum gets quieter

[kenporter]

Wel, I think it's pretty obvious that it is a mechanical noise, since the "squeal" is coming from the APC itself and is not audible in the audio path. I still think it has something to do with the USB circuitry. The power supply (wallwart) does not make a sound, it's the APC unit itself. Maybe it's the voltage regulator that's converting the 12VDC to 5VDC for the USB (since the squeal starts once Live is started and USB is drawing current). Who knows? All I know is I am not going to return my unit because of such a small thing. My HD's are louder than the high pitch noise of the APC.

Ken

[Tone Deft]

Ken - the wrong move would be to dismiss theories in a brainstorming session, right? I dismissed the 'LEDs are known to buzz' theory because they don't, or at least no more than any other semiconductor device. of course it takes a mechanical vibration to produce sound waves, but what's the cause? you have to dig further.

idea - is it possible to turn off USB power to the APC via software? or hack a USB cable to lift the power connection? leave ground.

the thing is, the hum is far more noticeable when the unit first powers up in a blank set. As clips are added and lights go on, the hum gets quieter

I misread earlier info, thought it was the opposite. the Monday AM rule is in full effect.

[paq]

I dismissed the 'LEDs are known to buzz' theory because they don't

mine do!

[Tone Deft]

I dismissed the 'LEDs are known to buzz' theory because they don't

mine do!

mine don't, suck it.

I've spent half my life studying electronics. do you want help or do you want to be a smart ass?

it could just as easily be the trim resistors. it doesn't matter what's buzzing it's why.

/monday oh man...

[paq]

> I've spent half my life studying electronics. do you want help or do you want to be a smart ass?

i dont need no help, its just my mp3 player and i dont hear it because the music in my ears is much louder

> it could just as easily be the trim resistors. it doesn't matter what's buzzing it's why.

its no buzz, more like a very high contant bleep. and its coming out of every led (on that mp3). but its monday so i dont wanna anger u . so _technically_ u might be right. u must. u have to. spend half of your life with studying electronics.

> /monday oh man...[/quote]

relax man its leisure-time

[Hidden Driveways]

Damn you guys, now I hear it too. But only if I put my ear right next to it, evne then it's still really quiet.

Is this like when you read a word you that you don't know the definition of, so you look it up in the dictionary and you're like "Oh wow. I had no idea." Then the very next day you encounter the word 14 different times, one of which is when a 6 year old uses the word to describe the shapes clouds make in the sky?

Translation... now that you've heard the whine up close, do you hear it all the time?

[paq]

Is this like when you read a word you that you don't know the definition of, so you look it up in the dictionary and you're like "Oh wow. I had no idea." Then the very next day you encounter the word 14 different times, one of which is when a 6 year old uses the word to describe the shapes clouds make in the sky?

Translation... now that you've heard the whine up close, do you hear it all the time?

this one really is a thing ive got no explanation for. not even nearly. in 26 years of living this happened so often to me that i no longer believe in simple coincidences (as i ever id). of course some other things happened as well. but this one is so obvious and if happens to everyone... so long i think i know now, that simple materialism cant be the only truth, and human conciousness constructs a mental world as well, where things are interacting. sorry, ot...