random static while recording

[anevsky]

Not running any other major tasks, only Outlook and web browsers, maybe Word. Symantec is on but not scanning. The recording cursor moves smoothly during the bursts of static. Definitely not zoomed in, if anything zoomed out. I don't have a timer to dedicate to my LP, but I can try. My sense is that it continues to move smoothly though. It's odd, one second it will be recording fine, then all static. The timing seems entirely arbitrary. I have been running Seagate Dashboard for an external HD in the background, so I'll close that and try again. Other than that, no outstanding software but an ancient Russian-English dictionary that can't be causing any trouble. CPU Usage indicator is minimal. Also, last attempt I lowered the bits from 32-bit float to 24, no progress. Maybe I'll go down to 16 on the next try. It's always been at 44100 Hz.

[billw58]

Also, last attempt I lowered the bits from 32-bit float to 24, no progress. Maybe I'll go down to 16 on the next try. It's always been at 44100 Hz.

What is the default bit depth of the device? You should set Audacity to match it.

-- Bill

[Edgar]

At this point I am grasping at straws...

There is some tiny possibility that there is a device near by which is putting out enough "noise" (RF??) to interfere (might even be the external power supply--wiggle all the connections -- wall/AC plug, 120V into transformer, out of transformer, into laptop -- while recording; try recording on battery with AC unplugged or vice versa).

Are you always recording in the same location? Move the laptop out of the room, off-site etc. and record.

To exclude one possibility, unplug amp from USB & mic in, set Audacity to record from the built-in mic and let it record for an hour--any static?

Use another app to record the USB amp. Use another computer to record USB amp with Audacity.

[Gale Andrews]

Can you attach a sample of the noise (a few seconds of WAV will do). You can use "Upload attachment" underneath the message "Preview/Submit" buttons. I assumed there were no dropouts and the level was much increased when this happens.

I assume the mic (you're recording from) is built in, but a few laptops can switch the headphones out to an input. Have you looked in the laptop Manual? Have you checked Options > Properties in Sounds and Audio Devices ?

Have you tried winding the usb cable a few times through a ferrite ring or adding ferrite beads around the outside of the cable (both should be available from Maplin/Tandy/Radio Shack...)
http://en.wikipedia.org/wiki/Ferrite_bead ?

Try with and without battery as Ed suggested.


Gale

[anevsky]

Well, it appears that it happens at 16 bits as well. I'll attach a very brief example of that here. I will try again tomorrow with battery and without, etc. I can't really change location very easily. Recording from LP is hard with small children running around. The office is the safest place.

Anyway, the brief bit that I attach to this message exemplifies one of the changes that has occurred as I've tinkered with things. At first it was just normal music then straight static to the end (or at least until I saw it and hit the stop button). In the attached recording, you'll encounter a bit of static that is a split-second long, but I can tell by zooming in with Audacity that the wave pattern is the same. The difference that has started occurring is that the static breaks in for short periods then goes back to normal recording (sometimes). So here's a sample of that. I'll attach a longer sample tomorrow when I have one available. I tend to just delete them when it happens so I don't have any on my HD at the moment.

I have been looking but haven't been able to find anything about switching the headphone to an input. I've looked everywhere I can think to. I'll look into the ferrite options when I have the chance.

Thanks again!

[anevsky]

OK, here's a better bit, recorded on battery alone. This one just kept going until I cut it off.

[billw58]

That looks like low level random noise that has been amplified to full scale. At 1 s + 34030 samples if goes from +1 to -1. I'm not sure that this tells us anything that will help us solve the problem though.

Do you have any other computers you can try the interface with? It would not be necessary to have the turntable connected, just the ART. I'm trying to determine if the fault lies in the ART or the new laptop. It is possible that the sound from the analog outputs of the ART would be fine while the digitized signal on the USB cable would fail. Have you tried a different USB cable?

-- Bill

[anevsky]

I'll see if I can get my wife to give up her dell laptop tomorrow to see if it works better there. It's also running XP but it's the same type the school gave me a few years ago and the recording was fine. Anyway, I'll see if it makes a difference. That should tell us whether it's the laptop or the amp that's the problem. I have used this amp quite a bit for these purposes, I guess it could be shot. We'll see. I have tried a couple of different USB cables. By the way, I tried on the plug alone with the battery removed and also encountered the static. Now I'm trying with the amp gain set at -2 (previous static came from setting of 0). Obviously, I'm just grasping at straws. I figure I can use the amplify mechanism in audacity to get the volume up if the recording is at all successful.

[anevsky]

I don't know if this helps, but out of options, I tried something else. I plugged in a Logitech USB headset and positioned the boom right in front of one of the speakers. I then recorded an entire record that way without the slightest semblance of static. Obviously that's no good way to get a recording, but does it tell us anything about where the problem is? Maybe it does suggest the amp? However, I should also point out that the logitech headset installs its own drivers, so it bypassed the USB Audio Codec entirely and simply worked with its own drivers. That could still suggest that the problem is with the plug-n-play nature of this amp, using the generic audio codec instead of any particular drivers, right? So I guess my question is: Does this little experiment tell us anything at all?

[billw58]

I notice that the ART is powered from the USB bus. Is this what you are doing, or are you using the "optional" external power supply? If not, I'd recommend trying that. From the manual it appears they have been quite smart about the external power source: "150mA or more @ 7 Volts to 12 Volts DC (either polarity at the tip will work with our unit) or 9 Volts to 12 Volts AC".

-- Bill