PV20 USB Mixer: Persistent, High-pitched Buzzing

[nbaronz]

Hello.

I recently purchased a PV-20 USB Mixer. Upon setting up, installing the appropriate drivers, and arming a track in REAPER for recording, I immediately noticed some sort of feedback coming through, despite everything being in apparent working order. Upon playback, my suspicions were confirmed: there was definitely a buzz. Specifically, it’s a high-frequency, grating sort of buzzing that varies slightly in amplitude and renders serious attempts at recording completely out of the question.

I have researched this problem extensively, and am very disturbed to have found that none of the other threads documenting this issue have been conclusive. I have purchased many Peavey products in the past, including a Peavey Bandit 112 and two Peavey 215 cabinets, all of which have been great products; I trust that the PV line of mixers will follow suit and we can reach some sort of solution to this problem.

Here are some things I noted while trying to solve the buzzing issue:

- The buzz is constant, and is not affected at all by the presence/absence of my laptop’s power supply. (Note: I am using a Toshiba Satellite laptop, a computer which has served me perfectly in previous recording endeavors and has not had any issues until now.)
- Windows confirmed that my audio drivers were up-to-date and functional.
- The buzzing is present even when there is nothing plugged into it, i.e. I can simply plug its power supply in and run the USB cable to my laptop, and it will still generate the buzz. Note that I have ALL sliders and gain knobs turned completely down.
- I have tried plugging the mixer into several outlets in different rooms and even different houses – yes, with the computer plugged into the same outlet – to no avail.
- The buzzing was reduced greatly when I routed a red/white audio cable from the mixer’s Tape Out to my computer’s microphone input; despite the feedback being reduced, it was still noticeably present. Regardless, I did not purchase a USB mixer to record audio in this way.
- I am using the mixer as a USB recording input exclusively, not as an input and an output simultaneously.
- There are no extraneous USB devices plugged in that might generate interference, nor are there any programs running in the background that might disrupt the recording process.
- The buzz is not trivial and cannot simply be ignored. It hovers around the -24.00db mark, and is plainly audible in both recording and playback.
- The mixer was purchased new (I opened the package myself) and could not have been subject to any sort of damage from use.
- The buzzing only occurs when the track is armed for recording. It is possible to circumvent the buzz by disconnecting and then reconnecting the USB cable and simply playing audio through it via iTunes; however, all attempts to edit the mixer's recording settings in Device Manager or otherwise record audio with the mixer immediately result in the troublesome buzzing.
- I have used a smaller Yamaha mixer (non-USB) in identical settings without feedback or harmonic interference of any kind.

Hopefully the source of this problem lies in the setup rather than a faulty/noisy mixer. I'd hate to have to go to the trouble of selling this mixer for a different brand, but I will if necessary. My thanks to anyone with suggestions to solve this issue.

[Josjor]

Is the buzz present in the headphone output of the mixer?

If you plug the L/R outputs of the mixer into an amplifier/speakers is the buzz present there?

If the buzz isn't in the mixers headphone out or L/R outs then that suggests that something is up with the computer/software. This is further evidenced by your statement that it only happens when you arm a track.

There is always the possibility that you got a defective mixer. Can you do an exchange with the place you bought it from and try another PV20USB?

[nbaronz]

Thanks for your response.

I tested the headphone output and it's crystal-clear: no buzz. However, upon test-recording a small file in REAPER, once again I could hear the buzz in the mix. Yes, the buzz is audible through my PA/stereo speakers. However, it will only appear if I incite the recording process somehow, be it through REAPER or accessing its options via Device Manager. Other than that, it is capable of playing back audio from my computer buzz-free.

So, then, based on the fact that the mixer itself doesn't seem to yield the buzz, it seems there is a problem either in the transference of the mix to my computer or with the computer itself. The most puzzling thing about all this is that I used a Yamaha MG82CX under the same circumstances (minus USB) without any problems whatsoever.

I installed REAPER on an older Dell laptop and tested the mixer out; the buzz is still there. The buzz was also present when I used Audacity to record instead of REAPER. Although I find it unlikely, it's possible the USB cord itself may be causing the problem. I'll find another one and try it out when I can.

Unfortunately, I purchased the mixer on ebay (new) and am doubtful that I can exchange it. As it seems now, the mixer itself is not the problem -- thankfully!

[nbaronz]

Revelations.

I played around with it a little more and discovered that, while using the headphone output jack to listen to sound straight from the mixer, the buzzing noise will only occur if I activate the TAPE/USB TO CTRL/HP button or especially the TAPE/USB TO MIX button, but not the CONTOUR button. Regardless of any combination of these buttons being activated, the mix on my computer will always be buzzing if I record through the USB cable.

However... if I record using red/white audio cables through the L/R Tape Out jacks (fed into the mic input of my laptop), the buzz is completely gone! So, it seems that for some reason the problem only occurs through USB recording, not USB playback, and that both recording and playback are efficient if done through the Tape Out/In jacks. This explains why I never had problems with my little Yamaha mixer: it didn't have USB functionality.

Hopefully people with similar problems with USB mixers can read this topic for potential solutions. Does anyone have any idea why the buzzing problem happens only during USB recording? Is it some sort of grounding issue? Also, are there any inherent benefits to USB recording in contrast with using the Tape Out for recording?

[brillowmeister]

I had what sounds like exactly the same issue with my new PV8.

I managed to circumvent the issue by changing my mic input levels (directly through windows sound control) alllllllll the way down to '10'.


EDIT:

Hey, look. After some perusing I found this:
http://forums.peavey.com/viewtopic.php? ... v8#p206323

Which was incredibly helpful as well.

[Bassguitarist1985]

Nbaronz, exactly what is your computer setup? Is it a desktop or laptop? It could be a defective mixer, but you should be able to exchange it no problem. I ran into this awhile back, it sounds like the noise from the power supply? Chirping, static, harmonic buzzing etc?

If your setup is a desktop, then what fixed this problem for me was removing the audio connector from the sound card inside that goes to the front panel mounted audio connectors. If I'm correct with the source of your problem, you are hearing the ground potential voltage difference between the circuit board ground, and the CASE ground of your desktop. Some manufactures ground that front panel to the case even though it already has the BOARD ground. It greats a bad ground loop and causes all kinds of noise. USB inherently requires a ground, 5 volts, and D+ & D- (the 4 pins of a USB) so even if you lifed the ground on the USB cord the USB wouldnt work.

Let us know what your exact setup is, but I think this is what you are hearing.