Sound issue in mix playback

[JRocker]

I have a pair of Alesis M1 active 520 monitor speakers and I'm currently getting a synth sounding track mixed. I listened to the mix of my track and whenever the synth part begins to plays there's this kind of 'breaking up/distorting' sound happening.

Strange thing is, I can listen to the mix on other systems, on MP3 player, on headphones on stereo and that issue does not exist! Yet on my speakers it does. The mixer thinks the synth is heavy around the 250kHZ area and my speakers mustn't be able to cope with it. I've had other similar tracks that were bass heavy play with no issues in the past and when I play anything else on the same speakers, everything is perfect. It's just this particular synth part.

I have recorded through my phone the sound coming out of the speaker when the synth plays so you can hear the issue. Listen here:

https://a.tmp.ninja/kBMswhbq.mp3

What could be causing this issue?

[The Elf]

There is definitely some heavy distortion on those bass notes, so I think the problem lies with whatever playback system is not revealing that.

[JRocker]

There is definitely some heavy distortion on those bass notes, so I think the problem lies with whatever playback system is not revealing that.

Do you mean that my Alesis speakers are revealing the fact and the other systems are not?

[Hugh Robjohns]

No, that track is revealing a major problem with your speakers or their mounting.

Something is rattling in resonance. It could easily be something inside the speaker which has come loose over time -- the screws holding the drivers into the baffle, or the amplifier chassis into the back panel. It could be a resonance of the amplifier itself, or even the connecting wires inside the speaker rattling against something.

Or it could be a resonance of the speaker stands or something nearby on the desktop nor shelf the speakers are placed on.

It possible that it is being triggered by some ultra-low frequency component in the signal that you're unaware of, so it would be worth checking on a spectrum analyser to see what's going on.

[The Elf]

There is definitely some heavy distortion on those bass notes, so I think the problem lies with whatever playback system is not revealing that.

Do you mean that my Alesis speakers are revealing the fact and the other systems are not?

I'm just saying that the distortion is definitely there, so your main monitors are telling you the truth. You'll need to get to the bottom of it.

[CS70]

What could be causing this issue?

I once chased a problem like that for a couple days (distortion in speakers, not in headphones, phone or the hifi) before realizing that a certain frequency was causing a cup standing on the heater nearby my desk to rattle.

You could try to move the speakers someplace else and verify if the issue is still there...

[Drew Stephenson]

Get the speakers rattling, then lift them up, one at a time. If the rattle stays then it's in the speaker, if it goes it's in the connection between the speaker and (via any stands, supports, desk etc) the floor.

[Tim Gillett]

The phone's recorded sound is heavy in the 200 - 300 Hz range, but normally modest speakers distort first on deeper bass than that but there's not much below about 200 Hz in that phone recording which seems a bit strange.

I'm trying to work out why the speakers rattle on this music but not normally. The mono phone recording will sum the two speaker sounds together. Is it possible the recording (not the phone recording) has a lot of out-of-phase deep bass in it? That could explain the lack of deep bass on the single mic recording even though the speakers may be separately struggling with too much deep bass.

Maybe your phone recording alsays reduces a lot of the deep bass as well.

[JRocker]

Thanks for all your responses so far, I will follow through all the suggestions and report back to you. It's strange that I've used these speakers for ten years and listened back to mixes that have been released commercially and sounded fantastic, (and double checked on o0ther systems as well to verify) and I can play anything else on these speakers and the breaking sound does not happen, yet on this particular track is has occurred...

[JRocker]

By the way, if this is indeed the case, why then can I pay the track unmixed in my DAW through the speakers (as I recorded them) without any issue of this breaking up sound, yet once the track is mixed and it's played through the same set of speakers, the issue arises?

[CS70]

By the way, if this is indeed the case, why then can I pay the track unmixed in my DAW through the speakers (as I recorded them) without any issue of this breaking up sound, yet once the track is mixed and it's played through the same set of speakers, the issue arises?

Hard to say. In my case, the cup had been forgotten on the heater just recently, the heat has made the water evaporate and suddenly I had an empty hand-made ceramic up over a ceramic little dish which was prone to vibration. And that had not been there before.

Not an expert at all of sympathetic vibrations, but out of physics I would guess they occur only when a specific narrow frequency band keeps having enough energy for enough time.

But of course it could be something else entirely, I mentioned it because it just hadn't occurred to me at all, back then, that the reason had nothing to do neither with the music nor the playback system itself.

[Guest]

Well, if it only happens on this track, and only on the mix, then somethin' ain't right. Try pulling things out one at a time until the noise stops, or as you allude to a specific synth, perhaps the instrument's gain structure is fubar?

[Tim Gillett]

By the way, if this is indeed the case, why then can I play the track unmixed in my DAW through the speakers (as I recorded them) without any issue of this breaking up sound,
yet once the track is mixed and it's played through the same set of speakers, the issue arises?

Then it has to be related to the mix.

A symptom and its cause are not the same thing. The phone recording contains the rattling sound but may have removed clues as to the underlying cause of the rattling. You know the speakers play all other stuff OK. So the speakers and the room are probably OK.

Apart from it being related to the mix is the fact that you've only given us the phone recording. Any chance of a sample file of the (I assume) stereo mix which the speakers were playing?

[JRocker]

Tim Gillett said ..
>Any chance of a sample file of the (I assume) stereo mix which the speakers were playing?<

Great idea Tim! Then you can tell me if its related to the mix.

Here's the link to listen to the synth section where the issue is:

https://a.tmp.ninja/lPGDYBdj.mp3

[Hugh Robjohns]

If you look at that clip on a spectrograph or spectrum analyser, there are transients at each chord change with frequency components that go right down to single-Hz. There's also quite a bit of stuff floating around all the time in the 45 - 55Hz area.

Both of those are the kind of elements that will upset some speakers.

Here's a screen grab from RX8 with the (vertical) frequency scale showing the range from 1 to 200Hz. You can see the strong horizontal line at 50Hz-ish, as well as the vertical transient spikes on chord changes that go all the way down...

For the record, though (and ignoring the odd noise-burst at the beginning), your clip plays without any nasty (unintended) noises on all of my systems here.

[JRocker]

Hi Hugh,

Thanks for your reply. So does that mean that the Alesis speakers can't handle the 45 - 55Hz area? Which I assume means, they're not best suited for anything 'too bassy' and I should get myself a different pair that have a better frequency range and that do handle that range comfortably?

[Hugh Robjohns]

Thanks for your reply.

I've just added a screen grab to that previous post so you can see what I'm talking about.

So does that mean that the Alesis speakers can't handle the 45 - 55Hz area?

Not necessarily. It may simply be that something in your room or the speaker is resonating or rattling because of the strong energy at those frequencies.

As I said, screws can work loose. Objects can start to rattle sympathetically. Pulsing air flow through ports can cause internal connecting wires to bounce against speaker chassis...

You'll need to work through your system carefully to find the culprit.

The earlier suggestion to feed one speaker at a time while lifting it off its support is a good place to start. If the noise goes away you'll know the noise is related to a mechanical vibration through the stand. If it doesn't then it's a speaker issue. Try leaning the speaker back so it's pointing at the ceiling. Does that change anything? Check all the screws are tight -- does that help? ...And so on.

I should get myself a different pair that have a better frequency range and that do handle that range comfortably?

Well, if everything points at the speaker having a problem then it might be worth considering something more capable.

But equally, it might be worth tweaking the mix to remove the problem energy -- so high pass filtering at 40Hz, say, would help with those transients, and it maybe that a modest notch around 50Hz will help tame those deep rumbles which probably aren't really adding anything useful to the mix.

[Tim Gillett]

Looking at Hugh's screenshot there seems some heavy, complex modulation going on there, patterns I've not noticed before on the RX screen, and I use it regularly. I can also hear what sounds like the rattly/clicking sound (maybe 5 to 10 Hz modulation frequency) but not nearly as prominent as in the mobile phone recording.
It makes me think of how a vinyl record struggles with reproducing certain complex waveforms and a good engineer makes sure those complex waves are dealt with to avoid reaching the cutting stylus.

I agree with Hugh that certain sounds are not too agreeable with speakers but I also wonder if many such sounds are actually pleasing to the human taste anyway, this sound being an example. The sound, however it was concocted, is just not pleasant to this pair of ears. When the guitar chord came in - and partly masked the previously exposed sound - I felt relieved.

[JRocker]

Just wanted to add to this that I found out the specs for my speakers and it does seem that they only handle Frequency Response between 56 Hz - 20 kHz, so this does seem to add weight to the poster that advised me on the 45 - 55Hz area needing fixing.

[Drew Stephenson]

Bear in mind that the lower frequency limit isn't a cut-off, it's a roll-off. Generally best to make low-end decisions on headphones unless you've got a seriously well-treated room as well as full-range monitors.

[Martin Walker]

Bear in mind that the lower frequency limit isn't a cut-off, it's a roll-off.

Spot on Drew - and depending on the design, that roll-off can be gradual (sealed cabinets for instance), more sudden (ported cabinets), or come with a big bass hump just before the start of the roll-off, to have a more 'impressive' low end, but at the same time sounding less natural.

My tiny loudspeakers start rolling off around 50Hz, but they still have a small output at 20Hz because the roll-off is so gentle. BY placing them very close to my front wall, this reinforces that low end and gives me more smooth-sounding bass than you would expect from such a small 10-litre cabinet.

Martin

[JRocker]

Thank you for the advice and reply. I have actually gone ahead and purchased these speakers based on SOS review and because they have a wider freq range, M‑Audio BX8 Carbon. At least it will give another pair of speakers that I can also check my mixes on instead of just the one pair.