# Background noise in CD recordings



## jhorvat

I have been trying to find if anyone reported a background low-frequency noise in CD recordings-no one seems to be reporting this, yet many of my CD's have this annoying feature. 

I just got a CD with Bruckner's 9. Symphony (Bruno Walter and Columbia Symphony Orchestra, ADD). Great recording, however.... quite obvious "hum" can be heard in quieter sections (second movement, the very beginning of the third movement, for example). At first I thought this was due to speakers not being able to reproduce properly the very deep playing of an organ or something. It sounds like a very deep sound of an instrument mumbling in the background. However, this assumption somehow does not make sense with the rest of the music, so I guess this must be something else. Would it be possible the traffic noise penetrated into the recording venue? On some other recordings this sometimes indeed does sound like a traffic noise (even though they are studio recordings). One would think the recording studio would be well insulated acoustically...

I also suspected this might be the CD player (Audiolab 8200CD), however the same can be heard on my old Hi-Fi system, just not as clearly. With headphones, I cannot hear it (probably, they cannot reproduce these low frequencies). Streaming on YouTube, I cannot hear it.

I can hear similar with ADD and DDD recordings. It is often really distracting, especially in quieter passages.

I wonder if anyone else has this problem and is there a solution? 

Joseph


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## bigshot

If it's only in specific CDs, it probably isn't your equipment- it's in the original recording. Air conditioning in the recording venue perhaps. Or traffic noise outside. Walter's Bruckner 9 is 58 years old and was originally intended for LP release. It's likely low level noise like that would never have shown up on vinyl, so they didn't worry about it.


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## Triplets

bigshot said:


> If it's only in specific CDs, it probably isn't your equipment- it's in the original recording. Air conditioning in the recording venue perhaps. Or traffic noise outside. Walter's Bruckner 9 is 58 years old and was originally intended for LP release. It's likely low level noise like that would never have shown up on vinyl, so they didn't worry about it.


Walters recording of Mahler2 with the NY Phil has all kinds of noise on CD that I had never detected on lp. On can hear the HVAC system turning on and off, sounds of sheet music falling from stands and hitting the floor, chairs creaking, etc


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## Oakey

I more and more often listen to classical music through my noise cancelling headphones and also started to notice all sorts of background noises, especially on older recordings. It does not bother me, it adds to the authenticity and is rarely really disturbing. Although I recall having read a review of one recording (can't remember where, maybe even here?) that sounded like someone was folding chairs in the background


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## Oldhoosierdude

I have some older recordings with the noises already mentioned. Along with humming or other such things I assume by orchestra members. Can't remember which recording, but it sounds like a bow being dropped. More direct to the op, yes I have heard that low background noise a few times.


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## jhorvat

I was under impression that such artifacts get "photoshoped out" in the digital remastering process. Otherwise what is the point in having a top quality recording medium, expensive Hi-Fi system if the external noise is fused into the music? This is much more disturbing than the "live" external noise, as it always appears at the same places in the music, whereas "live" noise is random. This is like adding a score to the music


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## Nate Miller

jhorvat said:


> I was under impression that such artifacts get "photoshoped out" in the digital remastering process. Otherwise what is the point in having a top quality recording medium, expensive Hi-Fi system if the external noise is fused into the music? This is much more disturbing than the "live" external noise, as it always appears at the same places in the music, whereas "live" noise is random. This is like adding a score to the music


what happens is that white noise, like the hiss in cables and stuff like that disappears when you sample the analog sound. the sample rate is too slow to reproduce those transient spikes that make "hiss"

the way you get rid of low freq hum is when you master the track, you make a sharp drop-off at the threashold of hearing so those really low freqs get dropped out. You can't hear them, but they take a lot of energy for the speakers to render, so its best to leave them out.

there can be a hum at around 60hz due to the AC power, but that is also really easy to filter that small freq range with your EQ settings when you master the track

but there are re-releases of music on CD where they didn't really have a great master audio track to start with. there's only so much you can do in post-production


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## Oakey

jhorvat said:


> I was under impression that such artifacts get "photoshoped out" in the digital remastering process. Otherwise what is the point in having a top quality recording medium, expensive Hi-Fi system if the external noise is fused into the music? This is much more disturbing than the "live" external noise, as it always appears at the same places in the music, whereas "live" noise is random. This is like adding a score to the music


Don't agree. Almost by definition, classical music is an acoustic affair, produced by humans playing live and in concert and recorded through microphones in its entirity. So there is no direct digital feed into a mixing desk like in pop music where only the singers and (not even always) the drums are recorded acoustically, and every instrument or even parts of instruments are recorded separately in quiet rooms and mixed together at a later point in time.

Obviously the background noises should not be distracting, but the occasional huff and puff, bow drop etc does not bother me at all. There is also a limit to what you can do with tweaking with these recordings to remove background noise. I find the tape hiss on older recordings more annoying, but this can be removed digitally without affecting the music. I very much like the 63 Karajan Beethoven cycle on bluray where most of the tape hiss has been removed.


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## Larkenfield

I would be more inclined to believe it’s a system problem. It might be helpful to mention more CD titles you notice this problem on. Comparisons could be made by others. Personally, I cannot take hum on playbacks and it’s exceedingly rare to find on commercial disks. The only thing I’ve never noticed on any of the Columbia recordings Walter did was minor tape hiss, and that was a normal part of the recording process at the time, unrelated to annoying hum.


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## KenOC

I get this effect sometimes when my subwoofer is turned up too high. Sounds like some almost-subsonic artefacts on the CD. I don't hear it on the FNM, probably because the very low frequencies are filtered out before broadcast.


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## Radames

jhorvat said:


> I have been trying to find if anyone reported a background low-frequency noise in CD recordings-no one seems to be reporting this, yet many of my CD's have this annoying feature.
> 
> I just got a CD with Bruckner's 9. Symphony (Bruno Walter and Columbia Symphony Orchestra, ADD). Great recording, however.... quite obvious "hum" can be heard in quieter sections (second movement, the very beginning of the third movement, for example). At first I thought this was due to speakers not being able to reproduce properly the very deep playing of an organ or something. It sounds like a very deep sound of an instrument mumbling in the background. However, this assumption somehow does not make sense with the rest of the music, so I guess this must be something else. Would it be possible the traffic noise penetrated into the recording venue? On some other recordings this sometimes indeed does sound like a traffic noise (even though they are studio recordings). One would think the recording studio would be well insulated acoustically...
> 
> I also suspected this might be the CD player (Audiolab 8200CD), however the same can be heard on my old Hi-Fi system, just not as clearly. With headphones, I cannot hear it (probably, they cannot reproduce these low frequencies). Streaming on YouTube, I cannot hear it.
> 
> I can hear similar with ADD and DDD recordings. It is often really distracting, especially in quieter passages.
> 
> I wonder if anyone else has this problem and is there a solution?
> 
> Joseph


I have that recording on CD and I do believe I recall hearing that if I played it loudly. It doesn't bother me - it's still much better that what we had to put up with in the old days. Click - pop -POP*POP*!! I always figured it was the air conditioning.

I have a Dvorak's 8th with Maazel conducting. At the end of the first movement it sounds like Maazel is stomping his foot!


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## bigshot

I would rather have normal small noises made by the orchestra members than the weird dynamic noise gate pumping or pink noise blots you get with over zealous editing.


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## Larkenfield

I hear no 'hum' or low-frequency noise through my high-end headphones at the beginning of the 3rd movement of Walter's Bruckner 9th. It's quiet. I have no idea what artifacts others are hearing. This performance, along with Walter's other Columbia recordings, was remastered during the early 1990s by Sony for their box set Bruno Walter Edition:

https://www.amazon.com/Bruno-Walter/dp/B00BNZN27E


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## Joe B

I have heard low frequency artifacts on some of my CD's emanate from my subwoofer. I thought for sure there was something wrong with my system when I set it up, but after careful analysis (eliminating cables, subwoofer, amp, and CD player from the equation), it turns out it is on the CD's themselves. This occurs on a few harpsichord and clavichord discs I have (go figure?). It sounds as if the subwoofer is playing a mirror image of the program material at a much, much lower frequency. Because I started to think that the problem was my system, I started hearing other noises on a few other CD's as well (paranoia taking over). Upon very, very careful listening, I believe I determined they were HVAC sounds at the recording location. On another, I could hear a low frequency rumble, which turned out to be a truck that I could actually hear pull away and shift gears.

I have never heard these sounds on recorded material that has low frequency sounds. What I mean is, I have never had a problem with a symphony with double basses, an organ disc, rock and roll recordings, etc. The mirrored "noise" was only on recordings that had no low frequency material. And these are all older recordings (1980's) My fix was to set another playback option using only the main speakers. These few discs I listen to in 2.0 instead of 2.1, and there is no problem what so ever. It makes me wonder if a recording engineer forgot to activate some kind of low frequency filter when the master was made. Thankfully it is only a handful of discs in my collection (5 or 6).


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## Dan Ante

Some of my old CDs recorded in London have traffic noise I cant remember which ones but guess they were live rec in a Church or a poorly sound proofed studio to be honest it does not worry me at all.


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## Pugg

The Decca recording fro La Traviata / Sutherland/ Pavarotti from 1983 has a nasty sound in the prelude 1, seems to be the underground train beneath Kingswayhall London.
With a good sound system you hear it clearly.


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## jhorvat

I don't use subwoofer in my "new" system, just the Concept 40 speakers (Q-Acoustics), coupled with Cambridge Audio Azur amp and Audiolab 8200Cd player. This gives me very detailed, clean sound, but without the lowest bass notes. As I said, the noise is also heard on another, older HiFi system (using a blu-ray player, Audiolab 8000A amp and a pair of old Mission floorstanders ). Therefore, it must be coming form the CD recording itself. It is the same noise on both the HiFI systems, but is more obvious on the new one (probably because the new one can better reproduce low-volume audio).

The same as mentioned here, the low-frequency hum is most obvious when there is quiet music playing, especially with higher frequencies. On some CD's it sounds just like the city traffic. 
I wasn't listening to my CD's regularly for a while now (am just re-starting this activity :lol and it is best not to list which recordings were most affected, because I will have to talk form memory. I may keep you updated, though, as I start listening again over weekend. Perhaps, a new thread could be started on this .


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## Dan Ante

jhorvat said:


> I don't use subwoofer in my "new" system, just the Concept 40 speakers (Q-Acoustics), coupled with Cambridge Audio Azur amp and Audiolab 8200Cd player.


I don't use a sub woofer either, the mid range is the one to concentrate on, good speakers and amp etc should do all you want in classical.


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## bigshot

...with the exception of Wagner!


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## Dan Ante

bigshot said:


> ...with the exception of Wagner!


Who dat......................................


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## bigshot

If you listen exclusively to harpsichord music, you probably don't need more than a boom box!


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## JSBach85

What about birds? I have some recordings with bird sounds as background, seems to be popular in harpsichord and lute works recordings as well as plainchants.


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## Another Howard

Newbie here, from England. Yes - the dreaded lows. I've built a large pair of subs that make 18 Hz audible, though not at big volume, and yes the cones tremble on some CDs.
Fitting a safety optical limiter to both channels I noticed the sub-20s on some organ CDs, not all. It is present on DDD as well as other varieties. The high-pass filter on my analogue EQ box can be set to 20 Hz and this really clears the issue, with only slight reduction of those very low, gorgeous, organ tones. To address Fletcher-Munson, small room, etc etc, I rise to a 20dB boost at 20Hz - and that's why a safety limiter is comforting!

I also noticed, as has been said on this thread, that these lows can appear when there's lots of higher frequency content and no bass at all. It's only on some discs, and not necessarily during high recorded levels. So, yes, must be distortion preserved on the disc. Again, the filter clears it.
Worth attending to because these inaudible lows can really waste watts heating up the amplifier, as well as distress speakers in the long term.

Great to join a community that's already well ahead on these matters!


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## Guest

The world has pink noise, 1/f noise that covers the entire frequency spectrum. The amplitude gets larger as the frequency gets lower so configuring your audio system to reproduce below the limit of human hearing is particularly absurd, since the low frequency noise can be very large amplitude although you can't hear it. Demanding your system reproduce it can only induce distortion in the frequencies you do hear.

If you have a well set up system which reproduces the entire audible range and beyond, then you should hear the natural ambient noise of the recording venue. If you hear rumble, then you probably have a system setup to give artificial boost to low frequencies (to make you stereo sound even more awesome). If you have a subwoofer it is turned up too high.

I have noticed that even a harpsichord recording can benefit from good low-end reproduction, those plucked note transients have a broadband spectrum and the low frequency component helps give the a bit of "air." But if you hear weird ghosting in the low frequencies there is either some serious distortion in the recording/playback chain or you low frequencies are boosted out of proportion.


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## SixFootScowl

I guess an advantage of poor hearing is that you don't hear a lot of these noises.


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