Linux: Weird, Location-Dependent Playback Issues (Crackles)

ok, just throwing this out there hoping somebody has some good ideas…

i made some audio here at home with Renoise on my Linux laptop, all was fine. then i moved the laptop to some other place where we will be using that audio, and all of a sudden the audio crackles and does weird stuff. the most noticable and recurring weird thing it does is it will drop out at a certain low volume. it will then either come up again once the sample i’m playing reaches a certain volume, or i ‘boost’ it up by turning up my volume, which kicks it back into gear.
the place i am playing my audio has its own array of mixers, amps and whatnot, that i’m playing it through. at home i simply connect directly to an amp.

btw, this is not a Renoise-specific problem, but it does happen more with Renoise than it does with just playing a random MP3 or something. also, some of my Renoise tracks do not have the problem, while others do. it seems very much connected to the volume of the audio.

i am kinda at a loss here. the ideas i’ve had so far that might be causing this are:

  • gate settings at the amp (someone there told me they had this but he couldn’t find it)
  • a problem with the power supply, ie. ‘bad power’ (is that even possible)?

can’t think of anything else. any ideas?

Dodgy cables? Sounds like a bad connection somewhere. Ones going into the computer are probably more likely to be moved and disturbed when you are writing something on Renoise rather than just listening from the computer doing something else…

Does it happen with other sources? CD player? Friend’s laptop? On different cables/amp channels?

it doesn’t happen playing music from a phone. didn’t have another laptop to try that out. also, my laptop’s battery is broken so can’t try to see if its the power-supply messing this up. the cable i’m using to connect to the mixer is the same cable i use at home. plus, i had the same problem when listening through my headphones.
so i think it might be the power-supply here. but i don’t know enough about this stuff to really know whether it can make that big a difference?

I would say more likely your headphone socket is dieing.

well, i considered that too. but explain to me why it works perfectly fine at home, using the same headphone socket, the same OS, the same Renoise, the same audio cable? it has to be something else…

ok, i did some more experimentation. here’s what i found out:

  1. the sound dropping out is definitely something that is local to the place i’m connecting to the soundsystem. so not a problem in my computer (luckily). so last time i was diagnosing 2 issues at the same time, which sucks. so the only real computer-problem i’m having are the glitches/crackles.
  2. i attempted to find out whether the power source could be the problem. so i connected my laptop at my parent’s house, and still had crackles in Renoise (and xruns with Jack). same happens at the venue i’m connecting. the strangest of all is: it does not happen when i am at home.
  3. the glitches/crackles are only happening inside Renoise. i can play audiofiles (wav and mp3) through MOC and everything is just fine.

so… again, hoping somebody has any idea what is going on here. everybody i know from my friends etc who knows anything about audio and electronics i have asked, and nobody has the faintest idea. so that’s why i’m turning to you guys…

Would be weird if it would be a problem with the network current. A very wild guess: Is there some kind of internet connection passed through the electrical system? (either the electricity company suppling internet through the wire or neighbours using some Ethernet across electricity net adapters)
Or simply measure the voltage of the electric network and see if the readout swings or is simply underpowered.
The latter may have noticable impact on low voltage devices like laptops. What does your laptop do when it solely runs on batteries?

This. You keep on saying laptop and you think it’s the mains supply. What’s the easiest way to rule this out?

Although from your description I would still lean towards cables or connectors. I seem to remember you saying you had a fairly convoluted path. Simplify it. Laptop -> Amp -> Speakers. Get that sounding clean, slowly reintroduce the components that usually exist in your chain until you can hopefully narrow it down to either a troublesome cable or piece of equipment/connection.

@vV: the only type of internet connection would be the wifi on my laptop, which cannot connect to a wireless network because there isn’t any in that venue. aside from that, just my phone on 3G…

@kazakore: yes, i’d want desperately to test the laptop on batteries. however, the battery is fucked, so i can’t. not even a second. as soon as i unplug the power, the laptop dies. so i got a portable desktop, in essence :)

the audio-setup in that place is indeed convoluted. i’ll try and see if i can get it a bit simpler for testing purposes. am also still wondering if it might make a difference running Renoise on Win7…

thanks to both of you for replying and trying to help out!

For the network over mains, or any high frequencies (rf) superimposed on the supply, you can put a choke on the mains cable. I would be surprised if it’s this though.

eg:

Or if you can get your hands on a surge protector it may be worth trying, although I think even less likely to be the case.

Both can be picked up pretty cheaply from any electrical supplier.

Or the mains grounding might not be proper.

well i have no idea about whether power could actually influence stuff like that. when i try it with Jack so i can see some messages, i get xruns all the time (again, which does not happen when i’m at home). there is some amount of logic to the fact that power goes into the laptop and thus passes through to the soundcard in some way or form, and it could therefore influence this stuff… however, i have no solid basis for thinking this, it is simply the only thing i can think of.