low volume sputtering?

[dkane360]

If i put my head next to the sub when its on (even if nothing is playing lol) there is a very faint sputtering noise, almost like if there were a fan inside. Is there a fan on the amp? I would open it up, but i dont have the right screw driver on me. Other than the faint noise, it performs fine.

 

[KEW]

You can start out by turning off your sub and disconnecting all connections (except power). Now turn the sub back on and see if the noise is still there. This will determine whether the source of the noise is from the electronics of the sub or from the audio signal into the sub.
Another thing you can do is feel the subwoofer driver to see if it is vibrating to determine if the sound is being "played" by the speaker or coming directly from the electronics.
Honestly, if the HVAC is off, the fridge is not running, there is no traffic, and it is a still afternoon (no wind, birds, crickets, etc.), I'm not sure any of my electronics are absolutely silent when on (if I really listen). I think it is usually from the AC to DC transformer, but I'm not too savvy on that stuff. Some units are louder than others, however, a "sputtering" noise seems strange.
If it was me, I would probably find the right driver bit to open it up. If you can't tell where the sound is coming from, a simple ~1/2" hose to your ear can usually find it if you can get the far end close to and pointed at the source.
Feel the source to see how hot it seems (the threshold of pain is about 140°F as a reference point).
Keep us posted!

 

[j_garcia]

Probably just transformer noise. If you put your ear right up to them, probably your receiver and any other amp have a bit of sound coming from them. A "sputtering" sound would seem unusual, but if it performs fine, it likely isn't an issue.

 

[federgejzla]

Have the same problem

OK... I am waking up this thread after a long time. I have what appears to be the same issue, with the same receiver, but I also have much more info:

- Sputtering comes out from the speakers... and *NOT* all of them.

- Sputtering *ONLY* occurs when *DIGITAL* inputs are used. When I use ANALOG inputs there is no problem.

- Sputtering is of constant (very low volume). Even if input is absolute (digital) silence, there will be sputtering as long as AVR-3300 is not set to "---" volume. The moment you set it to -59 it appears and stays the same all the way up to the maximum volume.

- Years ago I had this problem and sent the reciever to the service centre. They asked me whether they can remove some ROM chip from the socket and solder it directly to the board. I let them do that and it appeared to solve the problem, but I was never sure because when the problem started it was intermittent anyway. Sputtering is back, though ... this time on more channels than before (used to be only one before).

If *ANYONE* has any idea what this might be *PLEASE* respond. I sent e-mail to Denon techs... asking what needs to be done (even sending it to the service centre) but got absolutely no responses.

 

[TLS Guy]

OK... I am waking up this thread after a long time. I have what appears to be the same issue, with the same receiver, but I also have much more info:

- Sputtering comes out from the speakers... and *NOT* all of them.

- Sputtering *ONLY* occurs when *DIGITAL* inputs are used. When I use ANALOG inputs there is no problem.

- Sputtering is of constant (very low volume). Even if input is absolute (digital) silence, there will be sputtering as long as AVR-3300 is not set to "---" volume. The moment you set it to -59 it appears and stays the same all the way up to the maximum volume.

- Years ago I had this problem and sent the reciever to the service centre. They asked me whether they can remove some ROM chip from the socket and solder it directly to the board. I let them do that and it appeared to solve the problem, but I was never sure because when the problem started it was intermittent anyway. Sputtering is back, though ... this time on more channels than before (used to be only one before).

If *ANYONE* has any idea what this might be *PLEASE* respond. I sent e-mail to Denon techs... asking what needs to be done (even sending it to the service centre) but got absolutely no responses.

Sounds like a design problem with insufficient dithering in the DAC. With low level signals you end up with a choice of 1 or 0 which is 100% decoding error. So white noise is added so this does not occur. This is the dither signal and sets the noise floor of a digital system. The noise should be a faint hiss.

 

[federgejzla]

Unfortunately it isn't just a digital noise...

Sounds like a design problem with insufficient dithering in the DAC. With low level signals you end up with a choice of 1 or 0 which is 100% decoding error. So white noise is added so this does not occur. This is the dither signal and sets the noise floor of a digital system. The noise should be a faint hiss.

Unfortunately it isn't that. I am quite an expert in digital electronics and audio. The best I can describe this is either as a firmware bug (unlikely as it worked well for a while) or a buffer address line or memory segment bug. The reason I am saying this is that this truly is sputtering - ear can distinguish each of many "sputs" (don't know how to describe this sound), even though I can't count them. Digital noise would be different and related to the sampling frequency. Furthermore, while it is low in volume, this is quite strong. In fact, you could hear it with master volume all the way from -59 to about +10 dB, although at those high volumes it gets masked. It truly does sound like a fan blade hitting say a piece of paper... but it does not come from a fan at all...

Finally, as I understand AVR, internal signal processing is all digital (hence a separate DIRECT drive mode). But even with digital processing I do NOT get sputtering as long as I use an ANALOG input. Some devices I have connected both optically (digital) and using analog connections and I would hear the sputter only with a digital input (from any device). If my assumption is correct, there is neither an ADC nor a DAC before it comes to digital processing... after which it goes to main DAC anyway (even for analog inputs).

Also, don't forget that this wasn't an issue always. It *did* work for a while without this problem.

I have a recording of that sputtering sound... just trying to figure out where to put it...

 

[TLS Guy]

Unfortunately it isn't that. I am quite an expert in digital electronics and audio. The best I can describe this is either as a firmware bug (unlikely as it worked well for a while) or a buffer address line or memory segment bug. The reason I am saying this is that this truly is sputtering - ear can distinguish each of many "sputs" (don't know how to describe this sound), even though I can't count them. Digital noise would be different and related to the sampling frequency. Furthermore, while it is low in volume, this is quite strong. In fact, you could hear it with master volume all the way from -59 to about +10 dB, although at those high volumes it gets masked. It truly does sound like a fan blade hitting say a piece of paper... but it does not come from a fan at all...

Finally, as I understand AVR, internal signal processing is all digital (hence a separate DIRECT drive mode). But even with digital processing I do NOT get sputtering as long as I use an ANALOG input. Some devices I have connected both optically (digital) and using analog connections and I would hear the sputter only with a digital input (from any device). If my assumption is correct, there is neither an ADC nor a DAC before it comes to digital processing... after which it goes to main DAC anyway (even for analog inputs).

Also, don't forget that this wasn't an issue always. It *did* work for a while without this problem.

I have a recording of that sputtering sound... just trying to figure out where to put it...

I doubt we will solve this long range, it sounds like an interface problem. Are you outputting bit stream from your peripheral digital devices?

Does the sputtering occur with a digital input selected and nothing plugged in?

Does it occur with a source muted but plugged in or only when a peripheral is outputting digital data?

I have to say your original post was sparse on data.

 

[federgejzla]

I doubt we will solve this long range, it sounds like an interface problem. Are you outputting bit stream from your peripheral digital devices?

Exact stream type does not matter - as long as I am using a digital input for a given device.

Does the sputtering occur with a digital input selected and nothing plugged in?

I haven't tried that yet, but read the next answer. I think there would be no sputter in that case.

Does it occur with a source muted but plugged in or only when a peripheral is outputting digital data?

Sputtering occurs only when the source device is outputting digital audio. However, it does not matter whether there is any 'sound' there really. For example, if I pause a DVD, the sound from it stops, but sputtering continues. My PS3 occassionally stops sending digital audio and for that moment the sputtering goes away too. Same/similar for my other digital sources.

I have to say your original post was sparse on data.

Yes, I agree. Sorry about that...

You can start out by turning off your sub and disconnecting all connections (except power). Now turn the sub back on and see if the noise is still there. This will determine whether the source of the noise is from the electronics of the sub or from the audio signal into the sub.

I did. Many times. It is not coming from the source device. It also does not matter whether digital input is optical or coaxial... only that it is digital.

Another thing you can do is feel the subwoofer driver to see if it is vibrating to determine if the sound is being "played" by the speaker or coming directly from the electronics.

It is coming from the speakers, not the electronics. My speakers are far away from the device and you can clearly hear it. I also measured and recorded it.

Honestly, if the HVAC is off, the fridge is not running, there is no traffic, and it is a still afternoon (no wind, birds, crickets, etc.), I'm not sure any of my electronics are absolutely silent when on (if I really listen). I think it is usually from the AC to DC transformer, but I'm not too savvy on that stuff. Some units are louder than others, however, a "sputtering" noise seems strange.

No HVAC, fridges, traffic, trains, winds, birds, crickets ... I can live with standard noise. This sputtering is literally as if a fan blade was hitting a piece of paper... but it is coming from all the speakers .

If i put my head next to the sub when its on (even if nothing is playing lol) there is a very faint sputtering noise, almost like if there were a fan inside. Is there a fan on the amp? I would open it up, but i dont have the right screw driver on me. Other than the faint noise, it performs fine.

It does have a variable speed / controlled fan. But that is not the issue. I can sometimes hear it but it is a standard, unobstructed, perfectly functioning fan that is not the source of *THIS* problem.

Thanks to all who replied!

 

[federgejzla]

Found the cause... sort of

I found the cause. It appears to be a contact or a bad solder problem - problem disappears for a while when I push down on the DSP board.

I cannot post the the link that encouraged me to try to find this problem - I am not alone... But Google "How to fix Denon AVR-3300 audio glitches" and you'll find it. It is the blog post, not the forum one.

Thanks again for all the effort!

 

[TLS Guy]

I found the cause. It appears to be a contact or a bad solder problem - problem disappears for a while when I push down on the DSP board.

I cannot post the the link that encouraged me to try to find this problem - I am not alone... But Google "How to fix Denon AVR-3300 audio glitches" and you'll find it. It is the blog post, not the forum one.

Thanks again for all the effort!

Most, if not all of receivers seem to be in the POS class now.

 

[mtrycrafts]

Unfortunately it isn't that. I am quite an expert in digital electronics and audio. The best I can describe this is either as a firmware bug (unlikely as it worked well for a while) or a buffer address line or memory segment bug...

Well, I am not such an expert but my question then would be where did this buffer address line or memory segment failure come from? And, why would a direct soldering in the past made it go away for a while?

 

[TLS Guy]

Well, I am not such an expert but my question then would be where did this buffer address line or memory segment failure come from? And, why would a direct soldering in the past made it go away for a while?

It seems this problem is quite common and related to a poor DSP board design