Lots of noise on USB power

[lmv]

I have a portable recorder that doubles as a microphone. It can run on batteries or off a USB port.

It's not USB audio. It's just USB power. The audio is captured through a cable that connects the recorder's output jack to the computer's mic input jack. It records very cleanly on batteries, but very noisily on USB.

Connecting to the USB hub is hopeless. It's very, very VERY noisy. I mean, ohmygod noisy. Absolutely horrible and my voice disappears so completely you could swear I never spoke a word. I wonder if the recorder even captured anything I said.

Connecting directly to the computer is not so bad. I can hear my voice very clearly, but there is a background buzz.

So do you wise people know why it happens and if there is anything I can do to make it stop? I basically just want to save on batteries, that is the truth.

[kidslow]

If the USB cable detaches and you can try one with ferrite beads, start with that upgrade. Assuming you are not already using one like that. https://en.wikipedia.org/wiki/Ferrite_bead

May not work for you, but it also might, depending on the nature of the noise. If it is EMI or RFI, you're in luck. I was experiencing noise with a USB-powered headphone DAC and bought some cheap snap on cores from China and worked a charm. Double looping seems to make a huge difference too. https://qrm.guru/the-truth-about-ferrites/

[lmv]

If the USB cable detaches and you can try one with ferrite beads, start with that upgrade. Assuming you are not already using one like that. https://en.wikipedia.org/wiki/Ferrite_bead

My cable does have a ferrite bead on one end, the one close to the recorder.

(...), depending on the nature of the noise. If it is EMI or RFI, you're in luck.

I have absolutely no idea. Would you like to listen?

noise-Running_on_Batteries.wav
https://0x0.st/HWlt.wav

noise-Connected_to_PC_USB_port.wav
https://0x0.st/HWlv.wav

noise-Connected_to_USB_hub.wav
https://0x0.st/HWlw.wav

[kidslow]

If you have ferrite on the end closest to the recorder, probably it's doing its job for the interference. I'm not sure listening will give away the problem, at least not to me it won't.

What model of DAC is it?

[lmv]

Tascam DR-05.

[Jafo]

Get a USB isolator. Well-known problem with USB audio devices; USB is noisy AF. I went with a cheap model, and it lowered my noise floor 10-20 dB, depending on the source (OK, various guitars).

[BertKoor]

So you power it over usb from the same computer that receives the audio?
That's a ground loop which needs to be broken, eg with mentioned isolator.

Also worth a shot: power it from a phone charger alike usb power source? These usually have no ground. Or use a usb power bank instead of batteries.

[DrGonzo]

Get a USB isolator. Well-known problem with USB audio devices; USB is noisy AF.

+1

More often than not usb powered devices creates lots of terrible noise. Even more expensive gear can do this as well, like the original OP1. Sounds fine on battery and audio output. Horrible when connected to usb.

[whyterabbyt]

I basically just want to save on batteries, that is the truth.

use rechargeables then.

[uOpt]

Might want to try this:
https://www.amazon.com/gp/product/B0849 ... VNNI&psc=1

[lmv]

Also worth a shot: power it from a phone charger alike usb power source? These usually have no ground.

Oh, I never thought of that. And it works!

I have four. One doesn't work (the recorder won't turn on), the second one does but is a little noisy, the other two work and are just as silent as on batteries.

Problem solved. Thank you!