I had been aware of this problem for a while, but I thought it is coming from my guitar pedals. Then I started experimenting to investigate the source, and I found a confusing but interesting result. However the cause is still unknown to me.
The problems: when I pick note pairs or chords below about the 20th fret on my guitar (20-24), a buzz-like high pitched distortion appears.
I narrowed down the list of possible causes to my guitar and my Alesis iO4 USB audio interface. But even so, based on my findings, you cannot say for sure that they are the problem indeed.
Here is the list what results I got. These are the connection and playback orders that I tested:
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Guitar → Zoom G1 Multieffect → JBL headphone: no buzz. Signal is clean.
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Guitar → Alesis iO4 Interface (proper Input levels) → JBL headphone: buzz audible. Distortion.
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Guitar → Alesis iO4 Interface (proper Input levels) → Oneodio headphone: no buzz audible
So at this point you lost the logical clues for causes. Because depending on combinations the buzz may appear and disappear. You may say: the JBL headpone has problems, but that does not distort when plugged into the multieffect.
Checking further:
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Guitar → Alesis iO4 Interface (proper Input levels) → Sound recorded in Goldwave → Played back in Spectralayers though Asio4all → Alesis iO4 Headphone OUT → JBL headphone: buzz audible.
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Guitar → Alesis iO4 Interface (proper Input levels) → Sound recorded in Goldwave → Played back in Spectralayers though Windows drivers → Laptop Headphone OUT → JBL headphone: NO buzz audible.
At this point you may notice the combination that did not work was the Alesis iO4 and the JBL headphone. That two together seems to trigger the problem when connected together. Then check this:
- Guitar → Alesis iO4 Interface(proper Input levels) → Sound recorded in Goldwave → Played back in Windows Media Player through Windows drivers → Alesis iO4 Headphone OUT → JBL headphone: NO buzz audible.
When you plug the guitar into the Zoom G1, and plug any of the headphones in it, there is no buzz. The problem starts to appear once the signal enters the Alesis iO4. But even after that, depending on the situation, it may appear or disappear.
I have no idea what’s going on here, but I noticed in the past that when you record guitars either from the AMPs with mic, or through line-in, on certain devices the playback tends to distort easily. On others not. I wonder if a similar phenomenon is going on here? There is something that is not okay with the signal, and depending on hardware or software circumstance, the problem may be triggered.
Another clue can be that apart from the guitar signal, just any track and song I listened to through the Alesis interface with the JBL headphone had no distortion problems. This points to the guitar signal again as a cause.
I also checked, and I have no EQ switched on for Windows Media Player, so that cannot be the cause.
There is 1 thing that differs very much until the multieffect and after the multieffect: the multieffect have stereo out. If I route the signal further to the USB interface, I use mono cable. Maybe that change from stereo to mono is responsible for messing up the signal?
To complicate all this further, some of you may think the drivers cause an issue in the Alesis iO4. That may not be the main cause. Because if I unplug the Interface from the computer, play the guitar, with JBL headphone the buzz is audible through the Interface OUT, with the Oneodio headphones it is not.
Anyhow, I tried to check the recorded sample that can trigger the problem ins Spectralayers, but I see nothing in the high frequency ranges that might be problematic. But when opening the sample in normal editor I can see that the signal is asymmetric. The top half seems to be clipped, but it is not normal clipping, because as you see long portions seems to be clipped, and there are shorter portions where the amplitude goes over that clipping limit on the top half, too, and there the signal seems to be symmetric.
Here is the wav sample:
Can you load the sample in Spectralayers to check if you can see anything that might be a clue to what’s going on here? This situation totally messes up my recording processes and monitoring. I checked but I see nothing.