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Permanent noise/hum from Speaker

restorer-john

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Is the mains plug a parallel US two pin that you can rotate through 180 degrees?
 
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ToKillTime

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Yes, the noise is there but only on a connected source. There is a difference in tone in the noise when switching between analog and digital.

I can rotate the Main plug and already fine but with no success.
 

Chrispy

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If this noise bothers you, and seems you've done plenty to eliminate it in your situation, sounds like time to return/exchange it, hopefully not a problem with all of the 1592s....
 

tonycollinet

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Just looked - that is a $2500+ (I guess) amp. It shouldn't be doing this. Noise on an optical input eliminates any chance of it being a ground loop. It needs to be returned.
 
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ToKillTime

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I will try the Setup tomorrow at a friends house. If the same is audible, I will return the device.
 

Vini darko

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I've just noticed you already have another thread about this amplifier having reactive mechanical hum due to the tv being near it.
 

trl

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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.
Please disconnect all the input cables and check if the noise on the speakers is still there; test first with volume to the min., then you can increase the volume slowly and recheck for noise (no input cables connected!).

Is there a CD-Direct option to enable it? I'm looking for a pre-amp bypass option at least. If there is, then enable this option and see if the hiss noise gets lower.
 
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ToKillTime

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With the direct option, the noise is also present.

I have now tested the amplifier in another household and could observe the same phenomena.

What I noticed (I was probably always too fast before) is that as soon as the active source is no longer played (e.g., sound off), the relay switches and consequently no more noise is heard.

Hence, the noise is generated by the Rotel. Now the only question is whether this is "normal" or the pre amp is faulty?
 

tonycollinet

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It is either faulty by design, or faulty by manufacture. It shouldn't be making a noise you can hear across the room. Especially at that price.
 

AnalogSteph

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I suspect what's happening is that all the sources galvanically connected to this amp (itself IEC Class II / double insulated) are using floating switch-mode power supplies with funny ideas when it comes to ground potential. Try earthing the amplifier via the phono input ground terminal. Toslink input should definitely be clean then, and probably USB as well. If that still doesn't cut it, I would start blaming the amplifier itself.
 

bcurtin

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I have a Rotel RA-1572 that I also noticed has a slight buzz that is noticeable close to speakers but inaudible (for me at least) at my listening position. I spent some time tracking it down and could not find an input to blame, but my phono stage when grounded to the amp chassis was particularly noisy. At some point I was able to reduce phono stage noise by tying the tonearm via the phono cable to earth ground, so assumed that at least that problem was related to EMI or a poor ground connection. I haven't had much luck reducing amplifier noise but am interested in what you find.
 

MakeMineVinyl

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I have a Rotel RA-1572 that I also noticed has a slight buzz that is noticeable close to speakers but inaudible (for me at least) at my listening position. I spent some time tracking it down and could not find an input to blame, but my phono stage when grounded to the amp chassis was particularly noisy. At some point I was able to reduce phono stage noise by tying the tonearm via the phono cable to earth ground, so assumed that at least that problem was related to EMI or a poor ground connection. I haven't had much luck reducing amplifier noise but am interested in what you find.
The tonearm ground should always be connected to the GND on the phono preamp chassis.
 

bcurtin

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The tonearm ground should always be connected to the GND on the phono preamp chassis.
I should clarify what I said - the tonearm is always connected to the phono preamp GND, however the preamp is integrated into the RA-1572. What I noticed was that when the chassis is tied directly to earth GND the noise is reduced.
 

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hello. While looking for a solution for my own problem I saw this. I have the exact same problem with the same symptoms. I have identified that RF is picked up by quality RCA cables with good shielding (acting as the perfect antenna) and my buildings ground line is inadequate to drain the noise. If I use cheap non shielded RCA the hum gets less. Give it a try and good luck.
 

tonycollinet

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hello. While looking for a solution for my own problem I saw this. I have the exact same problem with the same symptoms. I have identified that RF is picked up by quality RCA cables with good shielding (acting as the perfect antenna) and my buildings ground line is inadequate to drain the noise. If I use cheap non shielded RCA the hum gets less. Give it a try and good luck.
More likely that you have a ground loop. What is your connection chain (eg source to dac to amp to speakers), what is the interconnect type, and which of the devices in the chain is earthed.
 

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More likely that you have a ground loop. What is your connection chain (eg source to dac to amp to speakers), what is the interconnect type, and which of the devices in the chain is earthed.
Hi, Streamer to Pre/Dac to Amp. The Amp is grounded but the ground wire is disconnected in the electrical box of my flat. I tried connecting the amp to phone directly, same humm. The amp humms even when RCA cables are connected free on the other end. The Humm changes pitch when I move the RCA’s around. Hence me guessing that it’s RF interference.
 

tonycollinet

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An unconnected RCA will just act as an aerial to pick up any old crap in your environment. It is not representative of the noise you are experiencing when properly connected.

Do you get hum with nothing connected to the amp? When you connect the phone - have you disconnected everything else? Do you still get hum?

When you say the earth is disconnected in the electrical box what do you mean? Which electrical box, where (this might be related to your problem) - and why is it disconnected? How is electrical safety ensured?
 

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An unconnected RCA will just act as an aerial to pick up any old crap in your environment. It is not representative of the noise you are experiencing when properly connected.

Do you get hum with nothing connected to the amp? When you connect the phone - have you disconnected everything else? Do you still get hum?

When you say the earth is disconnected in the electrical box what do you mean? Which electrical box, where (this might be related to your problem) - and why is it disconnected? How is electrical safety ensured?
When I use good quality, shielded RCA’s the amp switches off into safety mode. When I use cheap RCAs at certain random routings, the hum diminishes. Irrelevant to their proximity to power chords. Only the mid drivers and tweeters reproduce humm (Even some faint radio music buried in the hum) I tried with different speakers, the same. The amp in question is a Audio Analogue Donizetti. My previous Rega had no such issue, but than again it wasn’t as clear and open as the A.A.

I don’t get any hum when the amp is only connected to speakers. Yes, the amp is a dual mono without a preamp stage. The Phone was the sole connected device.

I live in a building made in the beginning of 1900’s and in Istanbul. We take our time:)
Thank you for your time and effort. Cenk
 

tonycollinet

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When I use good quality, shielded RCA’s the amp switches off into safety mode. When I use cheap RCAs at certain random routings, the hum diminishes. Irrelevant to their proximity to power chords. Only the mid drivers and tweeters reproduce humm (Even some faint radio music buried in the hum) I tried with different speakers, the same. The amp in question is a Audio Analogue Donizetti. My previous Rega had no such issue, but than again it wasn’t as clear and open as the A.A.

I don’t get any hum when the amp is only connected to speakers. Yes, the amp is a dual mono without a preamp stage. The Phone was the sole connected device.

I live in a building made in the beginning of 1900’s and in Istanbul. We take our time:)
Thank you for your time and effort. Cenk
Fair enough - i have seen some interesting wiring in Istanbul. Do you have any RCD or similar fault current detection breakers in your system for safety?

I am wondering if perhaps the lack of an earth might be related to your problem. Many device power supplies filter the incoming mains with capacitors (and other devices) to earth. If there is no earth, then perhaps this device is unable to suitably filter the mains, and noise is getting into the amp? It may even be that other equipment in the building is also filtering all their noise to the earth cable of the mains wiring - and that it then conducting back into other devices through those filtering components - instead of draining to earth.

This is pure speculation of course.

Failing that - you say the phone is the only device connected - is the phone running off battery? Or is it also connected to power at the time? What type of connection from the phone and how long? (I'm still looking for potential ground loops)
 

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The only safety I have are concrete stairs going down to the street. The yellow/green wire is the ground wires summed up at my electical box. connected to air:)
I don’t think the earth is connected to any other earth in the building.
At the used hifi store, the amp did not have this issue because I suspected the listening room is in their basement. Hence less RF I assumed. (also because unshielded rca makes much less humm)
I used iphone connected through AidiQuest Cobalt to the amp. The phone was not connected to the mains.
thank you
 

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