Static / buzzing from speakers at low volumes

The111

Senior Member
Jul 4, 2010
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I just started playing a few games on this Nexus 7, and I turned the volume down to the lowest setting because it is late at night and other people in my house are sleeping. I immediately noticed a soft but very audible static buzz coming from the speakers... about the same volume as the audio itself. I held my ear up to the hardware and confirmed it is both top and bottom speakers.

Anybody else experience this?
 

smurfqq

Member
Jul 29, 2013
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copyists sorpeno

I didn't notice at first. Noticed this morning with audio low as well.

I'd like to know if anyone else has this too. Kinda wanna know if its hardware since I purchased at best buy and only have 2 weeks to return.
 
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Artood2s

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Jun 4, 2007
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Yup, I was going to report this too, but since it only occurs at minimal volume I didn't bother. I lost my good headphones so I can test the audio jack. Does it happen to you with them on too?

Btw- if this the trade off with the fantastic (for tablet speakers) surround sound I'll take it. Watch the test video on the Play Videos app.

Sent from my Nexus 7
 
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siraltus

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Jan 26, 2010
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It's because the Nexus 7 uses a crappy digital volume control that simply reduces the volume of the digital waveform before it hits the DAC, instead of having a real analog volume control -an op-amp that adjusts the volume of the signal before it hits the headphone/speaker amplifier.

What you're hearing is quantization noise as at the lowest volume the audio uses only 2-4 bits of dynamic range instead of the full 16 (or 24, dunno what DAC is in this thing). It's the same as the bit-crushing effect you hear in some dubstep and other electronic music that degrades the audio into a robotic crunchy mess, only here it's not on purpose, it's just cheap design.

There is nothing you can do about it.
 
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smurfqq

Member
Jul 29, 2013
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It's because the Nexus 7 uses a crappy digital volume control that simply reduces the volume of the digital waveform before it hits the DAC, instead of having a real analog volume control -an op-amp that adjusts the volume of the signal before it hits the headphone/speaker amplifier.

What you're hearing is quantization noise as at the lowest volume the audio uses only 2-4 bits of dynamic range instead of the full 16 (or 24, dunno what DAC is in this thing). It's the same as the bit-crushing effect you hear in some dubstep and other electronic music that degrades the audio into a robotic crunchy mess, only here it's not on purpose, it's just cheap design.

There is nothing you can do about it.
I'm not sure how you know that but if you're right I guess that means it would happen on all of them... which.. sucks.. Is there anyone that doesn't have this issue to disprove this?
 

siraltus

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Jan 26, 2010
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I'm not sure how you know that but if you're right I guess that means it would happen on all of them... which.. sucks.. Is there anyone that doesn't have this issue to disprove this?
I'm a professional audio engineer, I know exactly how these things work. Most cheap devices do volume controls that way, because adding a dedicated op-amp for analog volume control increases costs of the device, and the Nexus 7 is a budget device.

It does happen on mine, too, in every app that plays sound.
 

The111

Senior Member
Jul 4, 2010
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It's because the Nexus 7 uses a crappy digital volume control that simply reduces the volume of the digital waveform before it hits the DAC, instead of having a real analog volume control -an op-amp that adjusts the volume of the signal before it hits the headphone/speaker amplifier.
As the others have said, thanks for the explanation. Nice to hear from somebody who understands it, and if the problem is present in all units that actually makes me feel better since I don't have to worry about returning my otherwise perfect unit. :)

Question though, how come I don't hear the static when using headphones, even on the lowest volume settings where I hear the static from the built-in speakers? That makes me think it's related to the speakers and not the audio hardware... but you obviously know more than me on this.
 
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The111

Senior Member
Jul 4, 2010
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I've also noticed this (at first I was like, WTF? Is it raining in my game?). If what was said above is true, that makes me sad that nothing can be done about it.
Yeah, funny thing is the first game I played was Bad Piggies on some levels with an ocean tide moving back and forth at the bottom of the screen. I thought the static was the tide sounds... until I heard it in another game too.
 

The111

Senior Member
Jul 4, 2010
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I don't hear it. on mine. But My hearing is horked.
It only happens at the absolute lowest volume setting... i.e. one notch up from muted. It sort of happens at the next notch up too, but is most noticeable at the quietest setting, and you need to be in a quiet room. I only noticed because I was using the device in a small echoey mostly tile room (you can probably guess where) and because of the room having such acoustics I put the device on the lowest setting just above mute.
 
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Jan 6, 2013
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Had something like this on my original nexus 7

Except it happened regardless of the volume setting. Wasn't that audible- had to put my ear against the speaker to really hear it, but it did interfere with other devices, such as my radio, or keyboard with a head phone jack. It would make a sound like a quick DUH-DUH-DUH-DUH-DUH-DUH...DUH-DUH-DUH-DUH-DUH-DUH. My nexus 4 can sometimes cause static interference with other devices, too. Haven't gotten the new nexus 7 so I cannot say whether or not my new one has this issue
 

smurfqq

Member
Jul 29, 2013
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Well.. mine's not only happening at the lowest volume notch. If I put it to my ear (never actually going to do this for normal use) it's there at every volume level, just hard to hear once whatever I'm playing gets loud enough. The display unit at a local best buy does the same. I can hear it in a quiet room at the first couple notches (normal use), which is annoying. Also, since someone asked - No it doesn't happen through headphones.
 
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siraltus

Senior Member
Jan 26, 2010
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As the others have said, thanks for the explanation. Nice to hear from somebody who understands it, and if the problem is present in all units that actually makes me feel better since I don't have to worry about returning my otherwise perfect unit. :)

Question though, how come I don't hear the static when using headphones, even on the lowest volume settings where I hear the static from the built-in speakers? That makes me think it's related to the speakers and not the audio hardware... but you obviously know more than me on this.
My pleasure! There's tons of FUD on XDA about many things, so I try to contribute on stuff I know well to reduce that.

Without looking at the schematics of the thing I can only guess:

The speaker amplifier is probably just a simple design that outputs 100% power all the time, so you have to control the volume of the signal that enters it, whereas the headphone amp probably has an integrated analog volume control.

A volume control is much easier (read: cheaper) to do in an integrated chip with low power signals (headphone out) than higher power (speaker out), and again, cheaper was the way to go with the Nexus 7.

Hence, there are two separate outputs from the audio chip - one that feeds the speaker amplifier and uses the bit-crushing digital volume control, the other outputs full-scale audio to the headphone amplifier which controls the volume in analog.
 
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The111

Senior Member
Jul 4, 2010
284
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My pleasure! There's tons of FUD on XDA about many things, so I try to contribute on stuff I know well to reduce that.

Without looking at the schematics of the thing I can only guess:

The speaker amplifier is probably just a simple design that outputs 100% power all the time, so you have to control the volume of the signal that enters it, whereas the headphone amp probably has an integrated analog volume control.

A volume control is much easier (read: cheaper) to do in an integrated chip with low power signals (headphone out) than higher power (speaker out), and again, cheaper was the way to go with the Nexus 7.

Hence, there are two separate outputs from the audio chip - one that feeds the speaker amplifier and uses the bit-crushing digital volume control, the other outputs full-scale audio to the headphone amplifier which controls the volume in analog.
Makes sense. Thanks again.
 

paxunix

New member
Jan 13, 2012
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My pleasure! There's tons of FUD on XDA about many things, so I try to contribute on stuff I know well to reduce that.

Without looking at the schematics of the thing I can only guess:

The speaker amplifier is probably just a simple design that outputs 100% power all the time, so you have to control the volume of the signal that enters it, whereas the headphone amp probably has an integrated analog volume control.

A volume control is much easier (read: cheaper) to do in an integrated chip with low power signals (headphone out) than higher power (speaker out), and again, cheaper was the way to go with the Nexus 7.

Hence, there are two separate outputs from the audio chip - one that feeds the speaker amplifier and uses the bit-crushing digital volume control, the other outputs full-scale audio to the headphone amplifier which controls the volume in analog.
Is this something they can fix (or at least mitigate) in a software update?
 

Lawlbringer

Member
Dec 2, 2012
25
4
0
Noticed this too from the speakers regardless of volume, and regardless of what is playing audio. It's a high pitched squeal to my ears which I can't stand. I've thrown out computer power supplies and video cards that have made similar(obviously, louder) noises.

Was hoping it could be something improved in software, but I guess not. Time to sell this. :(
 
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