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Am I understanding correctly?

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Am I understanding correctly?

Postby Watchmaker » Wed Jan 08, 2020 12:59 am

I've always had the following problem and now that I seem to have a pretty sweet little room available, I aim to do so something about it and hope those like Luke W and Blinddrew et al will opine on my assessment and cruelly slay its flaws.

The number one symptom is when I mix in my space, I get pretty ok mixes. Nothing gonna win a grammy but not wince inducing... yet anyway...when I bounce them out to mp3, and play them back, they mostly sound mono, really losing crispness and definition. When I an mp3 in mono, the sound stage completely collapses.

My surmise is a hefty amount of comb filtering is occurring and this is due to an untreated room and huge desk reflections. I've run REW though have to put some effort into learning how to interpret the data. I'm no where near up to speed on a significant amount of that functionality. (I will be giving generously to the dev for it though)

I've been using Sonarworks but I think I'll stop using that until I get the room under control. Seems a bit cheating and it obviously hasn't cured the deficiencies in my listening skills.

I'm comfortable with my monitors in an equilateral triangle 60" o.c. The odd bit is my room is shaped a bit like a cross, very similar to the one in this thread https://www.soundonsound.com/forum/viewtopic.php?f=24&t=67269.

Its an upstairs space with dormer windows on one side and a higher single sloped ceiling on the other. so there are rooflines at about a 40% slope just over half way up the interior walls which form a cathedral over my listening spot.

I come to a complete loss when trying to understand the implications for bass response. Which is correct: to calculate the room's dimensions as the largest box that can be built around the space, or will the response be sufficiently different according the the type of wall and corner being formed? If the latter, my understanding leads me to think that trapping is better on the interior perpendicular faces. yes?

Thanks all for your wisdom!

Dave
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Re: Am I understanding correctly?

Postby Watchmaker » Wed Jan 08, 2020 1:04 am

Oh, I think another possibility might be related to phase issues, but I know how to read the impossible to say meter and really try to keep my phase together. It's entirely possible I'm not succeeding.
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Re: Am I understanding correctly?

Postby Tim Gillett » Wed Jan 08, 2020 1:33 am

Watchmaker wrote:...The number one symptom is when I mix in my space, I get pretty ok mixes. Nothing gonna win a grammy but not wince inducing... yet anyway...when I bounce them out to mp3, and play them back, they mostly sound mono, really losing crispness and definition. When I an mp3 in mono, the sound stage completely collapses...

Perhaps in your settings you are converting them to mono mp3s? Stereo mp3's of reasonable bitrate should sound fine.

Summed to mono, stereo sound does collapse into the centre.

In days gone by, mono compatibility of stereo recordings was a big deal. Perhaps you need to work on the mono compatibility of your tracks? It's probably not just the room. Stereo "widening" effects can collapse to mono badly.
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Re: Am I understanding correctly?

Postby blinddrew » Wed Jan 08, 2020 9:52 am

I found it very difficult to judge reverb effectively in my old room, and it's not something I can do easily on headphones. One of the symptoms of that was that when bouncing stuff to mono, everything went awry. I postulate that part of the reason was that i was listening to the reverb of the untreated room (comb filtering and other interference included for free!) rather than the actual mix.
I hope to find out soon. :)
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Re: Am I understanding correctly?

Postby CS70 » Wed Jan 08, 2020 9:54 am

Yeah it sounds odd. I mean, converting to mp3 by itself shouldn't cause a collapse to mono (listening to a mono system of course will, regardless of the source format).

Also a valid point about the bitrate, mp3 works partially removing "less important" content, i.e. bass and high frequency, and if the bitrate is low, that loss can be big - especially if your mix relies a lot on high freqs for spatial positioning and detailing.

Sure if you test your mix in mono from the DAW and it doesn't really work, you have a filtering problem that you may want to fix, but by itself it's should have nothing to do with mp3 conversion, it's just a mix issue. Sometimes using mono reverbs can give the same sense of spaciousness without compromising the mono feel too much. Since people listens to their phones a lot, or on single earbuds or mp3s on USB sticks can be used on mono PAs in breaks, it's always good to me to have a reasonable mono compatibility.

As of phase issues, that's usually something that happens irremediably only during recording, with different mics capturing the same sound at different times.. Sure, you can mess it up at mixing as well if you mix a signal and a similar loudness delayed version of itself.. easy to do if your delays have a "mix" knob. But then fixing is easy - you need to work the knobs. :)
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Re: Am I understanding correctly?

Postby Hugh Robjohns » Wed Jan 08, 2020 11:13 am

Watchmaker wrote:The number one symptom is when I mix in my space, I get pretty ok mixes. Nothing gonna win a grammy but not wince inducing... yet anyway...when I bounce them out to mp3, and play them back, they mostly sound mono, really losing crispness and definition.

I would suggest you need to check your MP3 encoder settings and/or find a new encoder.

The MP3 spec only defines the decoder, specifically to allow the encoder to be improved over time with better models of the human hearing system. Consequently, MP3 codecs do vary quite considerably in quality, and especially so at the lower bit rates.

It's also worth experimenting with the codec settings as you will get quite different results with different source material. Most MP3 codecs lop-off everything above 15kHz anyway (lower at lower bitrates), so that might account for the reduced 'crispness and definition'. The coding format (stereo or joint-stereo) can affect the stereo imaging quite significantly depending on the nature of the source material.

My surmise is a hefty amount of comb filtering is occurring and this is due to an untreated room and huge desk reflections.

This makes no sense. If the tracks sound okay in the raw, but sound mono-ish when converted to MP3, surely it's the MP3 conversion that's knackering the tracks? If it was the room you'd have the same problem with your raw tracks, no?

I come to a complete loss when trying to understand the implications for bass response. Which is correct: to calculate the room's dimensions as the largest box that can be built around the space, or will the response be sufficiently different according the the type of wall and corner being formed?

Trying to calculate the bass response is complicated at the best of times, as it depends so much on the constructions of the walls, floor and ceiling, but it is even more so when the room is an odd shape and with varying dimensions in each plane. On the upside, varying dimensions on each plane does reduce the chance of common standing wave frequencies, and thus provide a more even spread of resonances...

H
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Re: Am I understanding correctly?

Postby Tim Gillett » Wed Jan 08, 2020 1:16 pm

Any chance of a stereo sample?
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Re: Am I understanding correctly?

Postby Watchmaker » Wed Jan 08, 2020 2:03 pm

Thanks all for the replies, I only have time for a quick glance at the mo' and will cogitate.

Briefly, the mp3 codec is the native studio one v4.6 set to 256k 44.1 at 16 bits. I regularly monitor across several speakers/phones and check mono compatibility compulsively.

I thought it may be the codec, but I've heard no complaints relating to S1, hence my confusion. I'll try bouncing it to other codecs and see what happens.

cheers!

I'll try to get samples up to my sound cloud tomorrow. Wicked busy today!
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Re: Am I understanding correctly?

Postby Rich Hanson » Wed Jan 08, 2020 2:08 pm

I remember being distinctly unimpressed with the Studio One MP3 encoder, but that was back at version 2 and I haven't used it since. Is it possible that they haven't updated over two major revisions?

I have 4.6 so I'll see what sort of output it gives (when I've got a working music laptop again, that is!!)
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Re: Am I understanding correctly?

Postby Watchmaker » Sat Jan 11, 2020 12:23 am

Sorry to be absent, started a new job...

Anyway, I figured I put up new info and ask a new question...

A previously unmentioned variable is (was) my monitor controller. I've been using a Mackie Big Knob for years and it's been pretty good to me but at some point it started humming and, based on some research, I suspected the power supply was failing. So, I happily bought an Audient Nero which I plugged in oh...about ten minutes ago.

Two great things happened, one, my hum went away, and two, the horrible mp3 translation issue is now a minor difference which is acceptably within my tolerance for a converted lossy output.

So yay! Now, on to the new material...one of the reasons I bought the Nero was so I could invert polarity on one side (I know I can do that in software yet I never have). What happened surprised me and I'm hoping one of you kind folks can enlighten me.

My brain is telling me that something analogous to M-S processing is happening but I can't parse it clearly. I recall the inestimable Dr. Hugh Robjohns briefly touching on the topic not long ago but I can't find it.

This specific mix is pretty simple, centered without extravagant stereo nuttiness going on, just a little spread on the guitars. When listening in stereo, the mix is well centered and I like it for the most part. When I click the Pol button on the Nero, the stereo image widens. Quite a bit.

So, I experimented with other mixes, mostly Tidal Master quality streams, but also AIFF and wave files and it's pretty consistent. Older mono recording aren't as exaggerated, but there's still some widening of the stereo image and more high end clarity. It also sounds like a lot more comb filtering is happening.

What's going on here?

Kind thanks for the insight and generous help!

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Re: Am I understanding correctly?

Postby Hugh Robjohns » Sat Jan 11, 2020 1:12 am

The polarity button inverts the polarity of just one channel (the left in this case). This function effectively boosts the Sides component of the signal substantially, so material with a normal stereo spread will sound much wider than normal, and the sound stage will spread well beyond and outside the speakers, instead of spreading only between them.

In a good sounding room, with good monitors, and material with relatively strong central components, the effect of flipping the polarity of one channel should normally feel like your ears are being sucked out and most consider it to be an unpleasant effect!

With very spacious recordings, the effect is obviously much more subtle and may be almost imperceptible in some cases. I have some choral recordings made with a wide spaced pair where it is virtually impossible to tell the difference between normal stereo and with one side inverted!

But from your descriptions, I'd hazard a guess that either your monitoring environment suffers from strong local reflections, reducing the imaging accuracy and weakening the impact of one channel being polarity inverted, or your monitors have mismatched drivers leading to poor imaging accuracy and precision.

Basically, if you press the mono button on the Nero you should hear a central phantom image which is solidly located and paper thin, not a blurred spread. It should feel like you can reach out and almost touch the sound source at a specific point in space in front of you. If that's not the case, the monitoring acoustics and/or the monitors needs some serious attention. Strong reflections from a desk, computer screens, side walls and so on will quickly destroy imagine precision.
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Re: Am I understanding correctly?

Postby Watchmaker » Sat Jan 11, 2020 3:59 am

Thanks Hugh,

It's a new room I haven't had a chance to treat yet and my desk is definitely a problem. deep and flat 1" wood surface... the experience is as you describe...my ears getting sucked out. I hesitated to characterize it in the extreme as I felt a bit foolish...it's an odd sound for sure, but I wouldn't call it unpleasant. Intriguing perhaps, nothing I'd aim for in a mix :-)

You've answered my questions and filled in a gap in my understanding once again. Thanks ever so much!

* fwiw, my monitoring isn't atrocious really. I get the expected center image in mono and all. I have centered everything symmetrically and calibrated SPL for the monitors etc. Next year I hope to properly treat the room and will share that experience here.
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Re: Am I understanding correctly?

Postby Hugh Robjohns » Sat Jan 11, 2020 11:06 am

Fair enough!

The polarity button is rarely used on its own, altough it can be a handy 'sanity check' when working with very 'spacious' marterial just to see if it's is better focused with one channel inverted or not. If it does become more solid with the button pressed, there's something wrong somewhere!

More usually, though, the polarity button is used in conjunction with the mono button. With just the mono button pressed the output through the speakers is effectively the Mid channel, while pressing both the polarity and mono buttons together plays the Sides channel -- the 'stereo difference' information.

This is particularly useful when aligning and balancing the channels gains for stereo sources (adjust for minimum signal) , but is also very revealing and informative when analysing stereo mixes and the output of stereo codecs like MP3.
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Re: Am I understanding correctly?

Postby Watchmaker » Sat Jan 11, 2020 2:30 pm

You have such a gift for clarity!

I'm not entirely sure I understand what's going on to be honest. I can see in my minds eye the two different channel's content and I can intellectually model the interactions for mono, stereo, mid-sides concepts to the level of intuition.

For this, I will have to experiment, play and cogitate to grok the concept in it's full meaning.

Cheers!
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