I’ve had a little time to troubleshoot this in sound checks etc and hope to have some time in a few days to set it up at home… but in the meantime I thought I’d post here and see if anyone had any thoughts.
In the middle of my show Friday my laptop came up with low battery warning…though it was plugged in and then didn’t respond to replugging everything, different power source etc. Before I was able to shut down the laptop properly, it shut down on its own because of the low battery. So I had to finish the gig without it.
Later I tried a back up AC adapter and the laptop powered up and started charging and I thought problem solved. But the next night when I set my gear up I was getting digital grunge noise (the audio goes from my laptop into Yamaha YC88 USB… and just touching the cable to the Yamaha’s USB port housing before even plugging it in causes the noise). But if I unplug the laptop and run on battery the noise does not happen.
I had the opportunity to plug the laptop into my other YC88 at home and did not get any noise, so I guess ruling out a problem with backup AC adapter. Thinking with fingers crossed maybe it was just some weird electrical issue at last venue…but again last night still had the same issue of this digital noise and got through just running on battery.
Sure appreciate any thoughts if any of this makes sense to anyone.
The initial battery problem does sound like a bad power adapter. Your noise with the other adapter sounds like a ground loop. Whenever I use a power adapter with my Windows laptop I have to use a ground loop eleminator such as this:
Typically, in the simplest terms possible, a ground loop occurs when two electrical devices are plugged into (and grounded intro) different outlets and then are connected together somehow, such as through an audio or data cable, and then you create a voltage differential between their respective grounds which causes 50 or 60 cycle hum through the connecting cable.
It makes sense that the hum is not there if you are running on battery since there is only one device plugged in at that point and not two differently grounded devices.
Did the main power supply for your laptop stop working? Does this only happen with your backup AC adapter? Is your laptop and Yamaha plugged into the same power outlet or different ones?
I recently had a similar issue with a bass guitar multi FX pedal where I needed to plug it in via USB so it could accept MIDI PC messages, but then it started to make a lot of noise when hooked up via USB just for MIDI while also hooked up to it’s normal power supply. I didn’t realize ground loops could happen through data cables until then.
Another thing to check is the integrity of your USB cable. If it has a short in it it could wreck havoc with your system (either from an AC adapter failing, or maybe cause an AC adapter to short out and fail). A long time ago (2008?) I bought a new laptop because I was afraid my current laptop was failing when it was a USB cable that had exposed shielding that was shorting out and the laptop shut down to protect itself. The exposure happened over time from wrapping up the cable and throwing it into my laptop bag many times.
You also might want to look into getting a power conditioner such as from Furman or Radial and make sure all of your gear is powered from that, but that would be a last resort as it seems you have a very straightforward setup and that would be the most expensive.
Appreciate the responses. This is definitely not a 60 cycle hum. It is a digital type of squawking and squealing. I’ve never had this issue in the three years or so I’ve had this set up… until now with the power adapter crappy out, though possibly it’s not related. I need to double check this again, hopefully tomorrow, but it all works fine plugged into my back up YC88
This sounds similar to when guitarists mix digital pedals with analogue pedals on their pedalboard and daisy chain the power for them. I once got my wife a nice digital tuner pedal for her pedalboard from Walrus Audio, and even when the tuner was not engaged we’d get screeching and whining coming through the signal chain. It was only resolved with getting a power filter/isolator from Truetone.
From what you’ve told us, and based on what has happened, my best guess is that the culprit is the backup power adapter. Is it identical to the one that failed or is it a generic one that meets your laptops specs? Does the backup have a three prong adapter with a ground? Does the original?
