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Permanent noise/hum from Speaker

ToKillTime

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Hello all,

I own a Rotel RA-1592 since recently. Generally, I am very satisfied with the device and compared to the predecessor (Denon X3500H) a huge leap in terms of listening quality.

What I noticed, however, is that I perceive a constant (volume) noise/hum from the speakers with any active source when I go with my ears to the speaker (from about 1m). With no/quiet music, the noise is audible from the distance and the louder the music, the less perceptible.

It makes no difference whether I choose an analog (record) or digital source (optical from TV, USB from RPI4, Bluetooth). The noise is permanently present from the speaker.

When I connect headphones to the amplifier, the noise is particularly noticeable.

With analog signals the noise/hum is normal but I thought that with digital signals there should be no noise/hum. Above all, the Denon did not have this phenomenon.

Is this a possible defect of the device?

Many thanks in advance!

Kind regards
ToKillTime
 
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AdamG247

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Unplug and disconnect the Cable/Sat box from system entirely. Hum should go away. First step to regaining sanity!
 

Jim Matthews

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The Rotel has a large toroidal transformer. If the noise you hear is persistent, even with the output muted, placing something compliant (such as a soft rubber mat) beneath the unit feet may help.

Be cautious to allow air circulation.
 

Vini darko

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It has an A weighted signal to noise ratio of 103db for line and 102db for digital claimed. A weighting can hide a lot of noise. It may be 15db worse than the claimed number. Wich will be audible easily , especially with efficient transducers. As @AdamG247 says try disconnecting each input to check for them introducing problems.
 
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ToKillTime

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Thank you all for your replies?

However, I already tried all mentioned suggestions without any success.

I have plugged the amplifier in a different grid with only one input source but the noise/hum was still present.
 

tonycollinet

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Are you talking noise/hum from the device itself, or from the speakers.

If from the device it is most likely from the transformer -and may be caused by a DC offset on your mains supply. You can test if that is the cause by putting an isolation transformer between the mains and the amp - if you have, or can borrow one.


EDIT : See also
 

AdamG247

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Thank you all for your replies?

However, I already tried all mentioned suggestions without any success.

I have plugged the amplifier in a different grid with only one input source but the noise/hum was still present.
Please take the time to find everything plugged into this single circuit. Did you disconnect the cable coax from the wall outlet?
Please list all equipment connected in your audio chain. Include how it is connected and if it has a separate power supply.
 
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ToKillTime

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It is coming from the speakers. Sorry for the misleading title.

Yes, I already disconnected the coax.

The amplifier is plugged in a Power strip with a TV, Ps5, and RPI4. The TV is connected to the amplifier with a toslink and the RPI4 with USB. Having just one source plugged in doesnt help.

I already moved the amplifier in another room and plugged in just the RPI 4 but the noise/hum was still audible through the headphones.

I also tries to isolate the amplifier from potential disturbances, even a DC Blocker install es but the noise is still coming from the speakers.
 

AdamG247

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It is coming from the speakers. Sorry for the misleading title.

Yes, I already disconnected the coax.

The amplifier is plugged in a Power strip with a TV, Ps5, and RPI4. The TV is connected to the amplifier with a toslink and the RPI4 with USB. Having just one source plugged in doesnt help.

I already moved the amplifier in another room and plugged in just the RPI 4 but the noise/hum was still audible through the headphones.

I also tries to isolate the amplifier from potential disturbances, even a DC Blocker install es but the noise is still coming from the speakers.
OK so plug the amp directly into outlet bypassing the power strip?
Ps5, tv rpi4, are all or any of these connected to internet by means of a Ethernet cable? Disconnect all of this ?
You can hear hum through headphones? What? I thought the speaker was humming?
 

tonycollinet

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Disconnect *everything* from the amp. Try it in a different room well away from the other kit. Select an optical toslink as the input.

Does the noise go away. If not the amp may be faulty.

If it does, plug one device in at a time (ideally in the other room) until the noise comes back.
 
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ToKillTime

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Yes, the humming is coming from the speaker but when I plug in the headphones I can hear the hum with them. So it must be something created from the amplifier.

And I already made an extensive testing with different Setups. For eyample, full disconnecting of all Devices but not the amplifier and one source. I moved in another room and connected only one source but the hum is still coming from the speakers or headphones, when plugged in.

Hence I guess, there is a defect present in the amplifier.
 

Vini darko

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Yes, the humming is coming from the speaker but when I plug in the headphones I can hear the hum with them. So it must be something created from the amplifier.

And I already made an extensive testing with different Setups. For eyample, full disconnecting of all Devices but not the amplifier and one source. I moved in another room and connected only one source but the hum is still coming from the speakers or headphones, when plugged in.

Hence I guess, there is a defect present in the amplifier.
Is it still under warranty? Or within the return window of the supplier?
 

tonycollinet

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Yes, the humming is coming from the speaker but when I plug in the headphones I can hear the hum with them. So it must be something created from the amplifier.

And I already made an extensive testing with different Setups. For eyample, full disconnecting of all Devices but not the amplifier and one source. I moved in another room and connected only one source but the hum is still coming from the speakers or headphones, when plugged in.

Hence I guess, there is a defect present in the amplifier.
Disconnect the one source. You need to eliminate ANY chance for a ground loop. If it does it with nothing connected, then a fault with the amp.

If it needs something connected to cause the noise, then more investigation is needed.

(is the noise low frequency (like mains frequency (50 or 60Hz depending on where you are)

Sounding a bit like this in tone:
 
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ToKillTime

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It is only audible at the output with a connected device. For example, when only something is connected in optical 1 and I switch to optical 2 or coax 1, I hear nothing.

And it is more likely a white/grey noise:

And Yes, the device is still under warranty. If the troubleshooting fails, I will contact the vendor.
 

MakeMineVinyl

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It sounds like you're not isolating the amplifier totally. As above, disconnect everything except for the speakers. If it still makes the noise, it is possible there's something inside which needs servicing. This could be a bad filter capacitor, a bad rectifier diode, or something else related to the power supply - at least if I were servicing it, that's the first place I would look.

Does it pass signal through all inputs? If the noise is like in the video, there are a lot of things it could be. Is the noise really loud? Is it on both channels or only one channel? Does it get louder as you turn the volume control up? Is the noise gone with the volume control all the way down?
 
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tonycollinet

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It is only audible at the output with a connected device. For example, when only something is connected in optical 1 and I switch to optical 2 or coax 1, I hear nothing.

And it is more likely a white/grey noise:

And Yes, the device is still under warranty. If the troubleshooting fails, I will contact the vendor.
Well that's interesting.

What happens if you select an analogue input with nothing connected to it?
 

AdamG247

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Bad connection cable possibly? Do you have different connectors to try, does it remain with different cable ?
 
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ToKillTime

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When only the speakers are connected, nothing is audible. But when I plug in an input, the sounds start at the connected source. Switching to another source (without input), nothing is audible.

When switching to an analgoue input with only speakers connected, the typical noise floor (I guess) is audible.

And Yes, different cables make no difference, since the noise is aleven audible when only headphones and a source are plugged in.
 

restorer-john

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It is only audible at the output with a connected device. For example, when only something is connected in optical 1 and I switch to optical 2 or coax 1, I hear nothing.

What happens if you select an analogue input with nothing connected to it?

We are zooming in on the problem. The D/A outputs are muted until a valid/active source is selected. Also, the preamp stage will mute its output to the power stage during switching transitions.

It sounds like the preamp stage is introducing the issue based on the OP's last comment.
 

MakeMineVinyl

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When only the speakers are connected, nothing is audible. But when I plug in an input, the sounds start at the connected source. Switching to another source (without input), nothing is audible.

When switching to an analgoue input with only speakers connected, the typical noise floor (I guess) is audible.

And Yes, different cables make no difference, since the noise is aleven audible when only headphones and a source are plugged in.
With any source connected, the noise is there? Does it make a difference if the source is analog or digital?
 
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