Ugly waveforms

[kozikowski]

Can you try a recording with the laptop on batteries -- not connected to the wall? The sound adapter uses the power from the USB connection, right? It does not use a wall power adapter?

If the buzz goes away, you might have a power supply problem or it's remotely possible it's plugged in backwards? Can you do that in Holland? And it could be a grounding problem. Are you plugged into two different wall sockets? Did you recently run out of sockets and put an extension cord in to another place in the room. I have sockets in one room that are connected to different power wires outside the house. That kind of thing can cause hum problems.

There is another character thing. You can't really hear power hum. It's too low (low organ pedal). But as the power distortion goes up from electric motors and other powerful devices, you start to hear it because the distortion in the 50 (or 60) goes up. If you have a bad switching power supply for your computer, it's possible the only thing left after filtering and processing the computer power is very high, intense, harsh, buzz. This might leak into all your USB equipment and cause all sorts of problems. I had a USB audio device I stopped using because I could tell exactly when my hard drive spun up because of the high-pitched whine in the sound.

You must have spoken to Kozikowski. He was the only person in the world that calls it that. Now there's two of you, perhaps the term will catch on.

I'm going to start a meme. All we need now is a banner with a kitten on it and it's a lock.

Koz

[NickGrouwen]

One of the difficulties for us is that we don't know what it sounded like before the problem.
In isolation (with nothing to compare with) the recording does not sound bad at all (I've heard very much worse ).
For you it is different because you are comparing with how it sounded before, how you want it to sound. All that we can do is to try and pick out any technical faults in the recording, such as that slight 50 Hz buzz. Interesting it is a "buzz" rather than a "hum", which suggests that the mains interference has mostly been rejected, other than a small amount of higher frequency harmonics.

Do you use any pedals with your guitar or are you straight into the USB-1G?
What sort of computer are you using? If it's a laptop, have you tried running on batteries?
Avoid fluorescent lights, in fact, try making a recording with no electric lights on.

This is the only clean signal I still have left from that period. Notice how smooth and dynamic and round it looks, right?

Waveform images are not a very reliable way of analysing sound quality. It's possible to have waveforms that look very different but sound identical, or waveforms that look virtually identical but sound very different.

This is the last note from the right channel of your "clean" sample (made mono for ease of comparison), and below it the "perfect" image that you posted:





Going just on the waveform, the most obvious difference is the the "perfect" note has a noticeably stronger sustain. I'm not a guitarist - what would cause that? Strings? Plectrum? Humidity? Compression?

Hey steve I actually have a few recordings from before the problem. This is an AC/DC song from their 1992 Live album, in which I basically extracted the center of the track using this "kn0ck0ut" plugin (great little thing), and then I just really quickly and sloppily recorded some messy guitar tracks to test the basic sound. Unfortunately I don't have the clean waveforms anymore.
http://soundcloud.com/roberta-hellfort/ ... wanna-rock
Soundcloud kinda has a little bit of compression going but it'll do =D
But anyways notice how loud you can turn up the guitars without having to turn them down because of any harshness. And it wasn't just like they only sounded good in a mix, they also sounded great on their own.
Now since I'm getting these ugly waveforms I can't realy turn up the guitar tracks like that anymore, and especially when I play certain chords or chord progressions, it starts to distort really badly.

I don't use any pedals or effects or whatever, it's just Guitar > t.bone USB > laptop.
I've been running my laptop on AC power since the battery died about a year ago. I don't think running my laptop without battery has anything to with this since I used to get good waveforms regardless.
As for lights, there is no difference, whether I have em on or off.

By the way, I also tried recording on my desktop PC in the living room, same result. Ugly spiky waveforms =(

You're absolutely right about the difference in how a waveform looks and how it actually sounds.
But I can tell you for sure that the sudden change in waveforms really affected how well the guitar signals distort. They used to distort soooooo much better when I had good clean waveforms. Now that they're spiky and flat, they still sound reasonable, but they just don't distort that well, especially when I'm playing certain chords or chord progessions =(

And about that difference in sustain, that's just the way the chords are played, generally, the harder you strike a chord the more sustain it'll have.

[NickGrouwen]

Can you try a recording with the laptop on batteries -- not connected to the wall? The sound adapter uses the power from the USB connection, right? It does not use a wall power adapter?

If the buzz goes away, you might have a power supply problem or it's remotely possible it's plugged in backwards? Can you do that in Holland? And it could be a grounding problem. Are you plugged into two different wall sockets? Did you recently run out of sockets and put an extension cord in to another place in the room. I have sockets in one room that are connected to different power wires outside the house. That kind of thing can cause hum problems.

There is another character thing. You can't really hear power hum. It's too low (low organ pedal). But as the power distortion goes up from electric motors and other powerful devices, you start to hear it because the distortion in the 50 (or 60) goes up. If you have a bad switching power supply for your computer, it's possible the only thing left after filtering and processing the computer power is very high, intense, harsh, buzz. This might leak into all your USB equipment and cause all sorts of problems. I had a USB audio device I stopped using because I could tell exactly when my hard drive spun up because of the high-pitched whine in the sound.

You must have spoken to Kozikowski. He was the only person in the world that calls it that. Now there's two of you, perhaps the term will catch on.

I'm going to start a meme. All we need now is a banner with a kitten on it and it's a lock.

Koz

Hi Koz, thanks for helping me. I tried recording on my own laptop, my sister's (without battery), my desktop PC in the living room, same result everytime =(

The sound adapter indeed uses USB power, nothing else.

I have changed nothing at all, I still have same setup in my room as always, and I barely have any electronic devices running, only my laptop is on, other than that, nothing =(

I'm still looking into this though! So...

I was actually Googling, looking for a solution, and I started going through countless of threads on this forum, and in one of threads it gave a link to a webpage with some information about that stuff, and it mention "Windows Conferencing" lol!

[steve]

Do you notice any difference playing the guitar through an amp?

[NickGrouwen]

Do you notice any difference playing the guitar through an amp?

Actually I don't have an amp I gave it to a buddy of mine, since I never had any need for it (and I live an apartment right now)

[steve]

I don't think that there's anything "broken". Audacity is recording correctly and you're getting a good signal level and a full sound spectrum so there is nothing drastically wrong. There is a bit of interference, but considering that the t.bone USB 1G costs less than an average instrument jack to jack cable it's still doing a surprisingly good job.
As to why there is a tonal difference now compared to some weeks ago, it could be just about anything, perhaps even something as simple as needing new strings. As the t.bone USB 1G is designed for guitar, you may find the tonality improves if you drive it a little harder - push a bigger signal into it (or perhaps a little less hard - either way it would be worth playing with the levels both from the guitar and into Audacity.

I don't think there's much more that I can suggest - perhaps others will have some ideas.

[PGA]

I don't think there's much more that I can suggest - perhaps others will have some ideas.

Were the clean recordings achieved on EXACTLY the same hardware/software as the problem recordings? This question doesn't seem to have been asked (unless I missed it)

Were any Windows updates installed at about the time the problem first became apparent? (The focus of the investigation seems not to have established what changed at the time the problem first occured).

When something suddenly fails, having worked OK until that point - and "nothing has changed", the truth of the matter is that "something HAS changed", but it isn't obvious what!

[kozikowski]

Yeah. Once you went through that whole multi-computer dance, we're going to jump on it right away. What was common? What did you take with you through all the recordings?

It's a very serious problem that you can't hear the guitar through an amplifier. If you have a bad guitar cord and the shield is going wrong, or a cracked connection even inside the guitar, you may pick up wall power buzz even before the first piece of electronics.

If you have that many computers available, surely one of them has a Stereo Line-In (blue in this illustration) in addition to Mic-In.

http://www.kozco.com/tech/audacity/pix/ ... Final2.jpg

You can do something like this, subbing the guitar for the tape player.

http://kozco.com/tech/audacity/pix/DesktopLine-In.jpg

That does work. The show will be a little low in volume, but one of our graphic artists does this regularly and boosts it up a little for presentation. If the distortion is gone, then the USB device is faulty.

Koz

[NickGrouwen]

I don't think there's much more that I can suggest - perhaps others will have some ideas.

Were the clean recordings achieved on EXACTLY the same hardware/software as the problem recordings? This question doesn't seem to have been asked (unless I missed it)

Were any Windows updates installed at about the time the problem first became apparent? (The focus of the investigation seems not to have established what changed at the time the problem first occured).

When something suddenly fails, having worked OK until that point - and "nothing has changed", the truth of the matter is that "something HAS changed", but it isn't obvious what!

Well actually I wrote in my opening post (don't worry if you missed it, it is kind of a long read lol)

Now this might not have anything to do with Audacity itself, but the thing is, this has been happening with another guitar as well. After my first guitar started giving me these ugly waveforms, I switched to my other one and that one gave me smooth waveforms again!! I was soooo happy!

BUT, after 2 weeks, I started getting the same ugly waveforms again like with my first guitar!

So yeah...I could try a third guitar but I don't really have one right now
I honestly don't know what it is...could be the guitars (pickups), could be the USB device, could be Windows, could be anything!
I'm installing a new pickup this week (probably tomorrow) and if that doesn't fix it I can at least cross it off the list =P

[NickGrouwen]

Yeah. Once you went through that whole multi-computer dance, we're going to jump on it right away. What was common? What did you take with you through all the recordings?

It's a very serious problem that you can't hear the guitar through an amplifier. If you have a bad guitar cord and the shield is going wrong, or a cracked connection even inside the guitar, you may pick up wall power buzz even before the first piece of electronics.

If you have that many computers available, surely one of them has a Stereo Line-In (blue in this illustration) in addition to Mic-In.

http://www.kozco.com/tech/audacity/pix/ ... Final2.jpg

You can do something like this, subbing the guitar for the tape player.

http://kozco.com/tech/audacity/pix/DesktopLine-In.jpg

That does work. The show will be a little low in volume, but one of our graphic artists does this regularly and boosts it up a little for presentation. If the distortion is gone, then the USB device is faulty.

Koz

Hey that's a great idea!!! I'm gonna do this first thing tomorrow morning, it's kinda late right now =P

And for my multi-computer dance lol, I just took my guitar and USB cable with me, nothing else.