Annoying high pitch sound

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clavguy
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Annoying high pitch sound

Post by clavguy » Sat May 30, 2015 8:03 pm

RIddle me this one... I wonder if it is a ground loop.
When I plug my hardware synth (yamaha motif rack-xs) directly into my studio monitors, everything is good and quiet.
When I plug the output of the synth into the inputs of my Presonus Audiobox and then the outputs to the monitors, I get a very high pitch scratchy sound. Is this a possible ground loop or is my Audiobox broken?
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Rolling Estonian
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Re: Annoying high pitch sound

Post by Rolling Estonian » Sun May 31, 2015 11:56 am

Have you tried plugging something else into the Presonus in? Try another cable? Try plugging power of anything into a different power strip and/or outlet....... I know, basic, but try to rule out and isolate as much as you can.

M

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outteh
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Re: Annoying high pitch sound

Post by outteh » Sun May 31, 2015 12:28 pm

Also, on the presonus you might be getting an impedance mismatch. The output from your synth I'm assuming is a line out? Might need a line transformer to keep things matched up?
Last edited by outteh on Sun May 31, 2015 1:03 pm, edited 1 time in total.

geobee
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Re: Annoying high pitch sound

Post by geobee » Sun May 31, 2015 12:56 pm

Hi there, shouldn't be an earth loop, as these are normally a low hum, not high pitched. To me, sounds like you may have a crook cable, or even, possibly, a faulty capacitor somewhere in the system.

clavguy
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Re: Annoying high pitch sound

Post by clavguy » Mon Jun 01, 2015 7:34 pm

So I did some more experimenting.
My son has the exact same Audiobox. I switched it for mine and no change. It definitely is a computer noise. The pitch changes as I open applications or scroll the mouse up and down.
I powered the Audiobox with a USB charger instead of my computer. That reduced the sound somewhat but it's still there.
I agree this is not ground loop. It isn't 60 cycle hum.

I am trying to figure out how to isolate this. I have a furnam power line conditioner. My powered monitors, synth and MIDI keyboard are plugged into that. The computer is in its own power outlet.

I feel this is radiated noise and not coupled in the wiring.

If I unplug the synth from the inputs of the Audiobox but leave the monitors plugged in to its output, the high pitch raspy squeal goes away but there is still a low pitch low volume rumble when I scroll the mouse.

When I disconnect the monitors everything is clean. Obviously I can't play music at this point
If I plug the monitors directly into the synth, everything is totally quiet and clean and the music plays fine.

These are M-Audio BX8a monitors that have both XLR ant TRS inputs.
http://medias.audiofanzine.com/images/n ... 721707.jpg
I am using the TRS input but feeding it with a TS cable. Could this be the problem?

I guess I can answer my own question here. When I bypass the Audiobox directly with TS cables, everything is quiet and clean

Thanks
Pierre
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Mark Bliss
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Re: Annoying high pitch sound

Post by Mark Bliss » Mon Jun 01, 2015 10:26 pm

I am not sure about what you mean in that last part Pierre, but I think you might be onto something. The shielding effect of the balanced cabling would be lost anyway, and "noise" could be induced. Though it is unlikely in short runs, its something to consider.
The high frequency nature of the described noise is also a puzzle. Not 50/60 Hz as you point out, but flourescent lighting perhaps? Or an internal electronic source maybe.
My laptop sound card has an odd low level "flutter" (only audible with headphones it seems) when idling, that goes away immediately when a sound source becomes active. Also oddly not near the typical 50/60 Hz. I have ignored it as it doesn't seem to show up in any recordings or anything.
Stay in tune, Mark

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Tiasdad
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Re: Annoying high pitch sound

Post by Tiasdad » Tue Jun 02, 2015 1:26 am

Is it a wireless mouse?
Gary
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clavguy
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Re: Annoying high pitch sound

Post by clavguy » Tue Jun 02, 2015 6:40 am

Tiasdad wrote:Is it a wireless mouse?
Yes it is... hmmmmmmmm. That might explain the low volume low frequency rumble I hear when I move the mouse..... ya think???

I'll try using a wired mouse tonight when I get home

Thanks Gary

Pierre
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clavguy
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Re: Annoying high pitch sound

Post by clavguy » Tue Jun 02, 2015 7:29 pm

Ok.... I swapped out my wireless mouse and keyboard for wired versions and that didn't help.
I recorded a few seconds of the annoying sound I hear and uploaded it
here it is

https://dl.dropboxusercontent.com/u/127 ... CREECH.mp3

Any ideas?
And it gets louder when I launch Mixcraft 7
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outteh
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Re: Annoying high pitch sound

Post by outteh » Wed Jun 03, 2015 6:14 am

That is electrical interference, low level. Try having everything plugged nto your line filter you talked about. Something like this

http://www.musiciansfriend.com/amplifie ... tor?pfm=sp
Last edited by outteh on Wed Jun 03, 2015 7:53 am, edited 1 time in total.

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fredfish
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Re: Annoying high pitch sound

Post by fredfish » Wed Jun 03, 2015 7:01 am

I know this sounds completly wacky - but I had a problem once with my Line 6 HD500 that was similar. Turned out for me to be a dodgy circuit on my fridge!

Cheers

John

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AHornsby
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Re: Annoying high pitch sound

Post by AHornsby » Wed Jun 03, 2015 8:28 am

Do you have a "smart" meter?

It doesn't sound like line noise to me, but it seems more like radio or magnetic (telephone/wifi) interference. It's reminiscent of a fax transmission, only monotonous.

If the computer you're using for Mixcaft is hooked up to the internet directly, you could try and disable the adapter temporarily and see if that doesn't make any difference.

I hope you can get it fixed.

clavguy
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Re: Annoying high pitch sound

Post by clavguy » Wed Jun 03, 2015 10:07 am

AHornsby wrote:Do you have a "smart" meter?
What's that?
AHornsby wrote:If the computer you're using for Mixcaft is hooked up to the internet directly, you could try and disable the adapter temporarily and see if that doesn't make any difference.
It's on WiFi

This is the power line conditioner that I am using:
http://www.furmansound.com/product.php?div=01&id=M-8x2

The items that I have plugged in to it are:
1) The two studio monitors
2) The Yamaha Motif Rack-XS synth
3) The M-Audio Keystation 88 MIDI keyboard the I use to send note data to the rack
4) A small wall wart used to power my MIDI velocity converter

The computer and, in turn, the Audiobox USB interface that is powered by the computer is NOT plugged in to it.
I also have a powered USB hub used for a couple MIDI control surfaces that is not plugged in to the power conditioner.
(note) the Audiobox inface is plugged directly into the computer and NOT the USB hub.

Here are some previously mentioned observations:
1) That noise is not there if I don't plug the rack's output into the inputs of the Audiobox. I can plug microphones in there and no noise. Only when I plug the rack into it does it manifest itself.
2) No noise if I plug the rack outputs directly into the studio monitors bypassing the interface.
3) Powering the Audiobox interface with a USB wall charger in order to take the computer "out of the picture" only lowers the noise a little
4) Replacing my wireless keyboard and mouse with wired versions did nothing to fix the problem.
5) The noise gets louder and rises in pitch a little when I launch some applications but not when I launch others. It gets the loudest when I start Mixcraft 7
6) I have never noticed this before because,until now, I have been using MIDI only and never had anything plugged in to the audio inputs of the interface.
7) I swapped out the interface with my son's identical interface with no change. Noise is still there.

Addendum to #6 above. A long long time ago, I plugged the autio outputs of my Alesis QS7 keyboard into the interface. If my old fart memory serves me right, the noise was there then also. I didn't pay much attention to it because it was just a quick experiment before going back to MIDI only as mentioned in #6 above.
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outteh
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Re: Annoying high pitch sound

Post by outteh » Wed Jun 03, 2015 10:29 am

How do you connect the Yamaha to the audibox? What cables, do you have options to use other cables, connectors(trs, ts, RCA, xlr)?

clavguy
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Re: Annoying high pitch sound

Post by clavguy » Wed Jun 03, 2015 2:06 pm

outteh wrote:How do you connect the Yamaha to the audibox? What cables, do you have options to use other cables, connectors(trs, ts, RCA, xlr)?
Top quality 5 foot TS cables. And, I connect my MIDI keyboard to it with standard 5pin MIDI cables.

Here is an excerpt from the Audiobox user manual
  • Front-Panel Connections
    Microphone/Instrument Inputs.
    Both channels of the AudioBox USB have Mic/
    Instrument combo jacks. This convenient connector accepts either a ¼-inch phone
    plug or an XLR plug.
    • Microphone Inputs.
    The XLR inputs on channels 1 and 2 are equipped with two
    custom PreSonus microphone preamplifiers. These preamps work great with all
    types of microphones including dynamic, ribbon, and condenser microphones.
    • Instrument Inputs.
    The ¼-inch TS connectors on channels 1 and 2
    are for use with instruments (guitar, bass, etc.). When an instrument
    is plugged into the instrument input, the mic preamp is bypassed,
    and the AudioBox USB becomes an instrument preamplifier.
    Power User Tip:
    Active instruments are those that have an internal preamp or a line-level output.
    Active instruments should be plugged into a line input rather than into an instrument input.
    Plugging a line-level source into the instrument inputs on the front of the AudioBox USB not only
    risks damage to these inputs but also results in a very loud and often distorted audio signal.


I am not getting a very loud and/or distorted audio signal. But do you think there might be a mismatch there from plugging a line level device into those inputs. I have never had this issue when plugin microphones in there or my son's guitar.

I was just looking at the Focusrite 2i2 interface...
http://us.focusrite.com/usb-audio-inter ... arlett-2i2
It has a switch to switch from Instrument to Line
Excerpt from their web site
  • Plug straight in
    Use the front panel high quality XLR/jack combination inputs to connect line and instrument level signals as well as microphones – perfect for recording a synth or stage piano, or at the flick of a switch, an electric or acoustic guitar.
Excerpt from 2i2 user manual
  • The Front Panel includes the input connectors for 1ic, Line and Instrument signals, as well as the input gain and
    monitoring controls.
    1. Inputs 1 & 2 – Combo XLR input sockets - connect microphones, instruments (e.g., guitar) or line level signals
    via XLR or ¼ ” (6.35 mm) jacks as appropriate
    2. Gain 01 and Gain 02 - adjust the input gain for input signals on inputs 1 and 2 respectively. The gain controls
    have concentric bi-colour LED ‘rings’ to confirm signal level: green indicates an input level of at least -24 dBFS
    (i.e., ‘signal present’), the ring then turns red when signal level reaches 0 dBFS
    3. 48V - phantom power switch for mic inputs - enables +48 V phantom power at the XLR contacts of both Combo
    connectors
    4. LINE/INST - Line / Instrument level switches for each input – switches gain to suit instrument or line level signal
Do you think this kind of interface might fix my problem???
Thanks
Pierre
Last edited by clavguy on Wed Jun 03, 2015 2:43 pm, edited 4 times in total.
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