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Static sound with keyboard setup

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Static sound with keyboard setup

Postby pianodude » Mon Jan 21, 2019 5:21 pm

Hi All.

I’m currently having some issues with a static sound (not sure what the correct terminology is) with my keyboard setup, which is as follows;

Yamaha CP33 stage piano (connected via USB to)
Lenovo y510p (laptop) (working with program)
Spectrasonics Keyscape (connected to)
Yamaha Stage PA 300 (via 3.5mm to stereo XLR cable)

After attempting to remove each piece of kit to determin the cause of this static, I’ve concluded that the issue is the Yamaha Piano is causing this sound.

Does anyone have any idea what the possible cause of this noise would be? Is my instrument not grounded properly, or is it an issue with the laptop/PA? How would I solve this? I’m hoping to use this setup in an upcoming show early next month.

Many thanks,
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Re: Static sound with keyboard setup

Postby Dave B » Mon Jan 21, 2019 5:38 pm

Is it a hum? That's more what a ground loop will sound like.

In your position, I would use a 3.5mm to 1/4" jack Y cable and plug into a stereo DI box. If that doesn't cure it, try lifting the ground on the DI box.

Obvious question : the 2 power supplies are plugged into the same distribution board?
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Re: Static sound with keyboard setup

Postby Sam Spoons » Mon Jan 21, 2019 5:56 pm

I'd bet it is the piano PSU generating 'digital hash' noise. The Yamaha piano PSU looks to be ungrounded so if the laptop PSU is also ungrounded there are two possibilities. First thing to try is running the laptop of it's battery to see if that helps. Definitely try a DIbut a passive one might be better (or, it might make it worse too). Also try a jack cable connecting the piano to a spare input on the PA if you have one, the volume does not need to be up but it will add another earth.

As Dave says if it's hum then breaking the earth somewhere should help but if it's digital noise (usually from SMPSUs) it's often getting in because the earth scheme is not good enough. Be aware that both can come and go according to the room you're in.
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Re: Static sound with keyboard setup

Postby pianodude » Mon Jan 21, 2019 7:25 pm

Dave B wrote:Is it a hum? That's more what a ground loop will sound like.

In your position, I would use a 3.5mm to 1/4" jack Y cable and plug into a stereo DI box. If that doesn't cure it, try lifting the ground on the DI box.

Obvious question : the 2 power supplies are plugged into the same distribution board?

Hi, thanks for your response. I was going to buy a Y jack cable, but all of them seemed to be Mono? I couldn’t find any info saying each of the ‘L’ and ‘R’ were outputting the same sound, or in a stereo mix? If you could point me in the right direction I would be very greatful. I presume though that using an XLR input would be similar?

I only have one distribution board in our house, so both the power supplies are plugged into it. I have tried using different plugs, as opposed to the same extension lead.
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Re: Static sound with keyboard setup

Postby pianodude » Mon Jan 21, 2019 7:28 pm

Sam Spoons wrote:I'd bet it is the piano PSU generating 'digital hash' noise. The Yamaha piano PSU looks to be ungrounded so if the laptop PSU is also ungrounded there are two possibilities. First thing to try is running the laptop of it's battery to see if that helps. Definitely try a DIbut a passive one might be better (or, it might make it worse too). Also try a jack cable connecting the piano to a spare input on the PA if you have one, the volume does not need to be up but it will add another earth.

As Dave says if it's hum then breaking the earth somewhere should help but if it's digital noise (usually from SMPSUs) it's often getting in because the earth scheme is not good enough. Be aware that both can come and go according to the room you're in.

Hi, thanks for replying. I’ve tried running the laptop off battery alone, and that doesn’t change anything. There is also a jack cable coming from the keyboard into the PA that doesn’t help with the noise.

How would I go about better ‘earthing’ the keyboard? Do I need another power lead?

Many thanks
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Re: Static sound with keyboard setup

Postby Martin Walker » Mon Jan 21, 2019 9:23 pm

Hi pianodude, and welcome to the SOS Forums! 8-)

As your problem does sound like a ground loop issue, I suspect having a rad of this step-by-step Q&A I wrote for SOS some time ago may help you narrow down the cause of the problem.

https://www.soundonsound.com/sound-advi ... -my-studio

Hope it helps!


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Re: Static sound with keyboard setup

Postby Sam Spoons » Tue Jan 22, 2019 12:04 am

pianodude wrote:
Sam Spoons wrote:I'd bet it is the piano PSU generating 'digital hash' noise. The Yamaha piano PSU looks to be ungrounded so if the laptop PSU is also ungrounded there are two possibilities. First thing to try is running the laptop of it's battery to see if that helps. Definitely try a DIbut a passive one might be better (or, it might make it worse too). Also try a jack cable connecting the piano to a spare input on the PA if you have one, the volume does not need to be up but it will add another earth.

As Dave says if it's hum then breaking the earth somewhere should help but if it's digital noise (usually from SMPSUs) it's often getting in because the earth scheme is not good enough. Be aware that both can come and go according to the room you're in.

Hi, thanks for replying. I’ve tried running the laptop off battery alone, and that doesn’t change anything. There is also a jack cable coming from the keyboard into the PA that doesn’t help with the noise.

How would I go about better ‘earthing’ the keyboard? Do I need another power lead?

Many thanks

The jack cable from keyboard to PA should be a satisfactory earth.

Can you post an .mp3 of the noise on a file sharing site so we can hear it, that would help eliminate some possible causes?
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Re: Static sound with keyboard setup

Postby Guest » Tue Jan 22, 2019 1:24 am

A static stale sound is common place with just keyboard setups, try intruding some real instruments like Guitar and Bass, even a simple film canister shaker can do wonders to cure the blandness of a everything done on keyboards sound.
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Re: Static sound with keyboard setup

Postby blinddrew » Tue Jan 22, 2019 10:35 am

I think the OP meant 'static' as in 'a noisy hiss', rather than 'static' as in 'lack of dynamics'. :)
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Re: Static sound with keyboard setup

Postby Hugh Robjohns » Tue Jan 22, 2019 11:32 am

pianodude wrote:I’m currently having some issues with a static sound (not sure what the correct terminology is) with my keyboard setup, which is as follows;

Yamaha CP33 stage piano (connected via USB to)
Lenovo y510p (laptop) (working with program)
Spectrasonics Keyscape (connected to)
Yamaha Stage PA 300 (via 3.5mm to stereo XLR cable)

After attempting to remove each piece of kit to determin the cause of this static, I’ve concluded that the issue is the Yamaha Piano is causing this sound.

Does anyone have any idea what the possible cause of this noise would be? Is my instrument not grounded properly, or is it an issue with the laptop/PA? How would I solve this?

I'm not sure which part of the world you're in -- it might be helpful to know -- and I'm not sure exactly what you mean by a 'static noise' ... but in the mean time, unwanted noises tend to come from three main causes: ground-loops, absent grounding, or system-created noise.

Ground-loops occur when more than one piece of equipment has a safety ground connection via their mains supply connections, and so in some situations you get a circulating current running from one device, through the audio cable screens to the other device, down to the building's mains power earthing, and back into the first device... hence 'ground-loop'. If the audio circuitry is not designed very well, that circulating current can get merged into the audio signal resulting in an audible low-frequency hum or buzz.

The solution in such cases is to break one or more audio screen connections -- thus breaking the loop -- often done using audio transformer isolation boxes or DI boxes as mentioned in other posts.

If this was the issue in your situation, I'd recommend buying something like the ART DTI audio line isolation box, a couple of XLR-XLR cables, and a 3.5mm - quarter-inch TS plug Y-cable.

You would connect the 3.5mm output from your laptop to the DTI input using the Y-cable, and run the XLR cables from the DTI box to the Yamaha PA. That box will provide electrical isolation between the laptop and the PA, which should cure the problem if it is a ground-loop issue .

However, I suspect from your description of 'static sounds' that this may not be a ground-loop at all. Most people complain if hums or buzzes when describing ground-loops. So it might well be the other problem -- a lack of system grounding.

It has been suggested that the keyboard uses an ungrounded power supply, and most laptop are ungrounded too (even when running on the mains charger). Both items should pick up a ground from the PA system, but if that has lost its mains safety ground for some reason (which is why it might be helpful to know where you are, as not all mains wall sockets are grounded) you will have a system which has no ground reference at all.

In that situation, everything that should be grounded and serve as a screen to keep interference out of the audio electronics will actually be acting as an aerial to collect interference and add it to the audio signal! However, in such cases the users often complain of a 'tingling sensation' when they touch metal parts on the equipment... but again you have't mentioned that.

In such ground-less cases, though, the fix is to introduce an earth to the system. You can prove if this is the requirement by getting a standard guitar TS cable, touch the tip of one end to something you know is properly earthed, and the other tip to an earthing point on the keyboard or laptop, such as the sleeve of a headphone socket etc... If the nasty noises go away you've found the cure!

The third possibility is that the laptop itself and/or the soundcard in the laptop, are generating nasty noises all of their own. The solution there would probably be to invest in a decent external audio interface connected over USB, with balanced outputs to feed your PA.

Hope that helps.

H
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