What's wrong with this song? Phase problem?

G

gravehill

New member
Hi all,

I heard yesterday one of my songs played through a big PA system in a club. I was shocked and horrified how it sounded: The overall sound was shrill and some parts were not audible at all. I have heard the song through various systems before and this was the first time I noticed there's a problem.

The PA system shouldn't pose a problem as everything else sounded good. Also I have heard another songs of mine, made with the same equipment and under all the same conditions through the same PA and they were also fine so that would rule out the possibility that I would have a problem with my monitoring set up.

I made a (another) mono compatibility test with the problematic song. Everything was audible, except most of the reverb. There's a big reverb throughout the song, on purpose.

I posted the song to SoundClick so you can hear what I'm talking about. The URL for mp3 download is http://www.soundclick.com/util/downloadSong.cfm?ID=2475745

You can also access the song through my artist page http://www.soundclick.com/bands/9/chaosresearch_music.htm

I figure the problem has something to do with phase. I would appreciate it very much if you could check the song out with your system and tell me what you think the problem is exactly. Any suggestions on what I should do to correct it would be most welcome!
 
Small update:

Firstly, if you go the artist page, the problematic song in question is "Eternal Passion".

I was able to reproduce the horrible effect I heard at the club by inverting the phase on one channel and listening to it in mono mode. That would suggest that one of the cabinets at the club was wired in inverse phase. But the question is why then didn't all the other songs sound equally horrible?

I suspect it has something to do with stereo expander interacting with the reverb. Any suggestions?
 
without hearing it in the club it's hard to say, but from what you described it sounds like you're right about one of the speakers being wired wrong. there might also have been a panning issue with the board where it was summing it to mono...but that would have been easier to detect and fixed. Doing a quick invert of phase on one channel I can hear a loss in a lot of content which is probably what you heard...no kick drum for example which is probably a prominent part of this song.

it's hard to say what track actually gave you the phasing problem...but probably anything panned center. next time you hear this...check to see if the house board has phase buttons that you can quickly check the channels with...or check the wirings of the speakers. but depending on the placement of the speakers this may prove difficult/impossible to do the night of the gig. you may also consider packing cables that are wired with opposite-polarity wires. That way you can just replace the cable feeding that channel.
 
It could be even simpler than a wiring problem; lot's of PA systems are, in fact, mono systems and they automatically just mix stereo sources into a mono amp.

One of the bands I do live work for has their own PA system that's mono. Between sets they play standard mix CDs of everything from Aerosmith or Norah Jones through their PA, and honestly, half the songs sound pretty bad because of the mono mix.

G.
 
SouthSIDE Glen said:
It could be even simpler than a wiring problem; lot's of PA systems are, in fact, mono systems and they automatically just mix stereo sources into a mono amp.

One of the bands I do live work for has their own PA system that's mono. Between sets they play standard mix CDs of everything from Aerosmith or Norah Jones through their PA, and honestly, half the songs sound pretty bad because of the mono mix.

G.
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which systems are these? i don't do any live audio work...but this seems ridiculous that you would spend money on a mono system. is this most PA systems, or just the lower end ones?

however, i doubt this would have been a mono problem. if you check his mix in mono it sounds alright...just louder and centered. reversing the polarity on one channel produces an annoying mix which I think might have been what he heard. And of course...if he amplified it in a big club combined with the reflections around the room it might have made it sound worse in spots.

I don't know, I wasn't there to hear...just speculating :cool:
 
Thanks for the replies so far. When reversing the polarity on one channel and listening in mono you get exactly the effect I heard in the club. It was not a live situation but a DJ playing songs from laptop computer to the FOH PA system. The cabinets themselves were hanging from the roof so I couldn't check the cabling. Also the mixer the DJ was using was one of those small DJ mixers. I don't think it had any button for reversing the polarity...

What do you think, is the problem in my mix? I guess that is the only logical possibility since the other songs were fine... But still. The more I think about it the more confused I get :confused:
 
My bad

First, let me retract my suggestion about a mono signal maybe being the problem. I just re-read grave's original posts and realized I completly mis-read it to say that it did not sound good in mono. I plead temporary dyslexic insanity. :o

But to answer your question anyway, Benny: Most of the bands I deal with live play the local lounge and club circuit. Most of these places provide the stage and (sometimes) the lighting, but the bands need to carry their own PA and stage monitor systems. Most (but not all) of those bands use either mono PA amps or mono powered mixers for their sound reenforcement. Not only is it easier on their budget, but frankly in the types of sonic spaces in which they set up, a stereo PA is really kind of an academic exercise.

In the places I have worked where there is a house system, yes you are right; many, if not most, of those place do have stereo PA systems. But even then, the band can't always count on the FOH engineer going through the paces to set them up with a decent - or sometimes any - stereo mix. The larger or better the venue, the more likely that the FOH will take the pains to do it "right", but it's often a crapshoot, at least in my (admittedly somewhat limited) experience with the live arena.

G.
 
hmm, i see what you're saying Glen.

sounds like the problem is both a combination of gravehill's problem and the clubs. if it were me, I'd tell the club to take sometime and run some test tones through their system. but at the same time, an engineer should always check their mixes in mono. however, you're probably get most problems with your mixes phase issues than it being summed to mono. do what you can to get the club to fix their system....but all that you may be able to do is try and fix it on your end.
 
.......this all sounds to me like an exercise in the importance of checking your stereo mixes in mono before you print em.......


cheers,
wade
 
bennychico11 said:
if it were me, I'd tell the club to take sometime and run some test tones through their system.
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Ahhh, if only... ;) That's something to be *very* careful and diplomatic about, unless you already have a good relationship with either the engineer or the management. With some places - around here, anyway - that's a good way to not get invited back, unfortunately.

It's kind of like sex... waiting until the third date to make such an advance will usually not only get better results but will help ensure there will be a fourth date. :D

Also, you guys are all absolutely right that checking one's mixes in mono is not only an excellent idea for trapping potential phase problems, but it can also be a nice trick for improving the stereo mix a it sounds in stereo. Sometimes if you listen to an OK mix in mono, and you play with the channel pans a little while in mono, you might find one of the channels suddenly jumping out at you *in mono*. This can sometimes be a great way for finding an optimal pan location for a track in the stereo soundscape. It can expecially work well when dealing with dual electric guitars, but it can work as well for any instrument.

G.
 
SouthSIDE Glen said:
Ahhh, if only... ;) That's something to be *very* careful and diplomatic about, unless you already have a good relationship with either the engineer or the management. With some places - around here, anyway - that's a good way to not get invited back, unfortunately.
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that's true i guess...especially if you're just the DJ at the club. if you were a house engineer then you might be able to bring it up easier to the management. i think most people might listen to an audio engineer about audio things especially if they don't know anything about the audio system. you could even offer to do it for them for free. nobody can turn down free especially if it improves their sound system.

checking your mix in mono should be a must...but that won't fix all problems that may occurr with polarity issues within the speakers. and if you have polarity and mono summing issues....things can get even worse!
 
Like Yoda I read

bennychico11 said:
that's true i guess...especially if you're just the DJ at the club. if you were a house engineer then you might be able to bring it up easier to the management. i think most people might listen to an audio engineer about audio things especially if they don't know anything about the audio system. you could even offer to do it for them for free. nobody can turn down free especially if it improves their sound system.
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Oh, absolutely. In fact, I'd even go so far as to say that if I were the house engineer, I wouldn't even bother the management with it (other than to bring it up the next time I wanted a raise :D), I'd just go ahead and take care of it myself. Unless they got a different guy (or union) for taking care of the actual physical wiring stuff; but (again, around here anyway) that's typically only the larger venues.

I also again apologize in that I think we're talking about two slightly different situations. The DJ playing stereo tracks is, in the context of what I was explaining, an entirely different animal than a band playing live music. In the case of a DJ playing a DJ-centric club, most of what I was explaining in my answer to you (Benny) has little relevance.

Like I say, I got a bit dyslexic at the beginning of this thread. Too much BBQ in my blood today, it's making my eyes and brain misfire. Sorry. :o

G.
 
SouthSIDE Glen said:
Oh, absolutely. In fact, I'd even go so far as to say that if I were the house engineer, I wouldn't even bother the management with it (other than to bring it up the next time I wanted a raise :D), I'd just go ahead and take care of it myself. Unless they got a different guy (or union) for taking care of the actual physical wiring stuff; but (again, around here anyway) that's typically only the larger venues.

I also again apologize in that I think we're talking about two slightly different situations. The DJ playing stereo tracks is, in the context of what I was explaining, an entirely different animal than a band playing live music. In the case of a DJ playing a DJ-centric club, most of what I was explaining in my answer to you (Benny) has little relevance.

Like I say, I got a bit dyslexic at the beginning of this thread. Too much BBQ in my blood today, it's making my eyes and brain misfire. Sorry. :o

G.
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lol...all good. my last reply was more in response to mrface's post :cool:
 
benny, i hear ya--i must be suffering from some "glen-BBQ-disease" as well....b/c i too misread part of the original post. :D

the symptoms to me DO sound like something that translated poorly when summed to mono. but when you're talking about a DJ, a laptop, a nightclub, and a PA.....all bets are off. :D

still, i'd check the "stereo expander" that he mentioned in the 2nd post--maybe pull it off the mix and give that a run through the same system. lord only knows what something like that is doing to the phase in the mix.


cheers,
wade
 
Wow! I'm really pleased to see so many answers to the thread. Thank you all.

I think something in my mix is what is causing the problem as all the other songs at the club sounded fine. I'll try to make another mix of the song and see what kind of difference it would make. I guess the problem is multiple stereoreverbs interacting with the stereo expander somehow.

So when I'm checking my mix in mono should the balances between tracks sound exactly like in stereo? Should I tweak it until the mono signal is good enough to listen to in itself?

Do you guys normally use stereo expanders? Is there some kind of preferred method, should it be applied to the whole mix or just some individual tracks? In the song in question it was applied to the whole mix.
 
Ok, I asked the DJ from the club about the equipment. He said that there's "some problem" with the PA there. He described it the way that one channel is louder than the other and also the bass seems to appear on one channel only. To me it would sound that one cabinet is out of phase as previously suggested. If I can still get a confirmation that the sound was summed to mono at some point then the problem is solved!
 
Grave,

I just gave a listen to your "passion" ;) I also imported it into Sound Forge and played around with the channels and phasing a bit myself, just to see what was going on. There's probably only so much I can reproduce precisely because I'm working with a 128K MP3 as a source, and a lot of the original WAV information is lost, but it's better than a sharp stick in the eye ;).

I did comparisons between the "unretouched" MP3 (as converted to WAV by SF), a version of it summed to mono, a version of it summed to mono with the left channel inverted, and a stereo version with one channel inverted. The results were not entirely suprising. To my ears, here were the results, from best to worst:

- The unretouched stereo was of course ovbiously the best sounding overall.

- The stereo with phase inversion did suffer some loss of verb; that's to be expected.

- The summed mono without w/o inversion was dramatically worse than the stereo with inversion when it came to reverb loss. This was rather suprising to me; I would have thought the effects to be of similar degree. On the other hand, the higher freq stuff like the bells, piano and attack on the percussion stood out brighter than any of the other mixes, including the original.

- Inverting one channel and then summing to mono was by far the worst; even more so than the summed mono alone. The bass keyboard line definitely had a "pump" to it as if there was almost no decay set on a dry keyboard sound.

How all this actually compares to what you heard in the club, there's no way for me to say. However, maybe the BBQ talking yesterday was not all that stupid :p in that the mono mix did have a definite adverse effect on the sound, even more so than just the phase inversion did...at least in my quick 10-minute tests on a compressed MP3 source, for whatever that's worth.

I'm with benny and face in principle. In specifics, I'd try something like this and see what happens...

1.) Make the mix first dry to best effect. Then listen in mono and tweak the panning, if necessary, to bring out anything that you might think is to veiled in the mono mix.

2.) Apply the verb to the stereo mix as desired. See how that flys in mono as well. With stereo verb there is always going to be some cancellation when summing to mono, that's physics. If you can't get the sound you want in mono, you might either have to just accept that in the way one has to learn that red and blue both look gray in monochrome, or try a mix using layered mono reverbs with discrete panning.

3.) Repeat #2, with the expander. Same caveats. Remember that expanders usually do their job specifically by playing games with phase polarities. Combining expanders with verbs is going to give your sounds more phases than the moon has in a month ;). Don't expect too much out of the mono sound there, it's going to suffer by definition.

To relate all this back to your original posts, I'd conclude that there was most likely a "problem" of some type with the playback system. Whether it was that they were mono-ing the signal, or flipping polarity in the signal path somewhere, or both, I can't say. What I can say is that any mix with heavy layers of stereo verb and track phase expansion applied to it - while it may sound great in stereo - will be sure to bring out "problems" in the playback system more than just about any other mix could.

G.

P.S. The owner should thank you for running such an excellent test signal through his stystem ;)
 
Thank you a million to taking the trouble! I ran similiar tests myself and with the same results you did. So the mp3 conversion didn't make any critical difference in representing the problem.

SouthSIDE Glen said:
- Inverting one channel and then summing to mono was by far the worst; even more so than the summed mono alone. The bass keyboard line definitely had a "pump" to it as if there was almost no decay set on a dry keyboard sound.
Click to expand...

This is exactly what I heard from the PA. I still haven't been able to get confirmation on if the music was converted to mono but all signs definitely point that way.

SouthSIDE Glen said:
1.) Make the mix first dry to best effect. Then listen in mono and tweak the panning, if necessary, to bring out anything that you might think is to veiled in the mono mix.

2.) Apply the verb to the stereo mix as desired. See how that flys in mono as well. With stereo verb there is always going to be some cancellation when summing to mono, that's physics. If you can't get the sound you want in mono, you might either have to just accept that in the way one has to learn that red and blue both look gray in monochrome, or try a mix using layered mono reverbs with discrete panning.

3.) Repeat #2, with the expander. Same caveats. Remember that expanders usually do their job specifically by playing games with phase polarities. Combining expanders with verbs is going to give your sounds more phases than the moon has in a month ;). Don't expect too much out of the mono sound there, it's going to suffer by definition.
Click to expand...

Thanks for the tips. This has definitely been a learning experience for me.

SouthSIDE Glen said:
P.S. The owner should thank you for running such an excellent test signal through his stystem ;)
Click to expand...

I'll have to remind them :p
 
i just thought of something...you said the speakers were up in the ceiling so you can't reach them....are they active or passive? if they're passive the amps should be down on the ground level somewhere and you could try switching + and - there on one of speakers.

your statement about one speaker being louder and the bass being only in one channel makes me assume you have a stereo system and not a mono one.
 
bennychico11 said:
i just thought of something...you said the speakers were up in the ceiling so you can't reach them....are they active or passive? if they're passive the amps should be down on the ground level somewhere and you could try switching + and - there on one of speakers.

your statement about one speaker being louder and the bass being only in one channel makes me assume you have a stereo system and not a mono one.
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If the louder speaker is not the one with bass loss, it could simply be a bad bass speaker in one of the cabinets, too.

But you idea of accessing the wiring on the amp end is not only a good idea, but by getting a visual on the amp(s) he can tell whether their amping two discrete channels for stereo or whether everything is going through a mono amp channel.

G.
 
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