USB to Audacity Hum

Thanks for the help on my previous question. I got the software downloaded, was able to record, but when I playback I get a constant, steady high pitch hum. The green output monitors (left and right) are pinned. I have tried adjusting the record and playback volume on input and output volume controls.
I have Mac OS 10.9.2

Do us a favor and post your equipment list again when you start a new message. I arrived in the middle of the movie and have no idea what you’re doing.

When you recorded your show, were the two red recording meters all the way up?

Restart Audacity and Generate > Noise: Pink, 0.5 level, any duration. Does that play without the green meters jamming all the way up?

Thank you for the suggestion. I am just using a usb cassette player. I am trying to convert sermons on cassettes to cd’s. Kind of out of my comfort zone :wink:

Still need how you connected the cassette machine to the Mac, which Mac and how old.


Macs do not normally allow you to adjust the input level of USB audio devices.

Hum is expected with cheap USB devices. Does the Ezcap have a headphones output and does your Mac have an audio input separate from the audio output?


I tried the Pink noise suggestion, but the green bars are still pinned with the high pitched hum.
I have a iMac about 2 years old. OSX 10.9.2
Pentium 2.7 GHz Intel Core i5
Memory 8Gig 1600 MHz DDR3

The ezcap usb cassette player has a volume control for the headphones. The iMac has input and output volume controls. Both are set at about 60%. Changing these does not seem to do anything. Only the volume controls on the cassette player and the audacity software works.

Admittedly it is a cheap USB device.

What do you mean by “pinned”? What playback device are you choosing in Device Toolbar ?

If for example you generate a sine tone at 0.5 amplitude, the playback meter should be on a steady -6 dB. That will be the case however loud you play the tone.

What I asked was, does the Mac have a separate line-in port that looks like here?

If so, buy an appropriate cable and connect from the headphones out of the USB device to line-in of the Mac and choose the line-in input in Device Toolbar. Perhaps that will cure the hum which I assume to be USB hum caused by a poor USB cable.

Or, try another USB cable and ensure it is connected tightly both ends.