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Phase relationship between bass guitar and kick drum

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Re: Phase relationship between bass guitar and kick drum

Postby Wonks » Mon Dec 07, 2020 11:06 am

armans wrote:Ok thank you. What exactly do you mean by "similar times" and how similar is "similar"?

Assume you were quantising the track to say 16ths. If the notes on the other instruments are basically on the same 16th beat (allowing for human timing errors), or at least are meant to be, then that would be a ‘similar time’.
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Re: Phase relationship between bass guitar and kick drum

Postby armans » Mon Dec 07, 2020 11:33 am

Wonks wrote:
armans wrote:Ok thank you. What exactly do you mean by "similar times" and how similar is "similar"?

Assume you were quantising the track to say 16ths. If the notes on the other instruments are basically on the same 16th beat (allowing for human timing errors), or at least are meant to be, then that would be a ‘similar time’.

So only if you are quantizing to 16 notes does having the same polarity become necessary? In other words polarity does not matter when the performance is natural and not quantized to a grid in a DAW?
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Re: Phase relationship between bass guitar and kick drum

Postby Wonks » Mon Dec 07, 2020 11:53 am

Use some common sense. I'm simply trying to indicate what 'similar' means.

[I've removed the exasperation... Christmas goodwill everyone! ;-) -- HR]

If you wrote the music down on a score, then the notes that are supposed to be played at the same time are 'similar'. If a note is supposed to be played 1/32 note after another, then it isn't.

And whether you bother to mess about with time shifting to align transients and flipping polarities almost all depends on the type of music being made and the sounds you want. If you are close micing the top and bottom of a snare, then you'd almost certainty want to flip the polarity of tone of the channels. But whether you decide to time align bass and kick drum sounds all depends on the musical effect you want. It is a creative process with no rules that must be obeyed, and as mixer/producer, you decide what you want the end result to be. Time alignment and polarity reversal are simply tools, and like all tools they can be useful but don't always have to be used.

No one can tell you 'do this' and you'll have a great sound or a huge hit. It's just stuff to try and it may sound better or it may sound worse or may take away some of the feel of the playing or improve the feel. Context is everything. Know the tools/tricks exist and if you feel there beat isn't coming through as strongly as you want, then try applying them. It may sound better, it may not. You decide.
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Re: Phase relationship between bass guitar and kick drum

Postby blinddrew » Mon Dec 07, 2020 11:58 am

Bit impolite there Wonks. We're all learning from different starting points.
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Re: Phase relationship between bass guitar and kick drum

Postby Hugh Robjohns » Mon Dec 07, 2020 12:06 pm

This is beginning to feel like a college correspondence course... I'm very happy to help, of course, but I can't help thinking that some background reading might make the learning process a lot easier on both of us. Can I suggest these two books as excellent starters (the links are to the UK Amazon site, but I'm sure you'll find them at all good book retailers):

Recording Secrets and Mixing Secrets -- both by former SOS section editor Mike Senior -- would explain all of this well improve your understanding dramatically?

armans wrote:What exactly do you mean by "similar times" and how similar is "similar"?

Similar in that they influence each other in a significant way. Low frequency signals change slowly, so the timescale over which they remain similar is very much longer than the timescale for mid or high frequency signals.

Lets say I record my bass without editing, the notes will be very inconsistent in relation to the kick drum so what difference does it make if the polarity is one way or another since every note relative to the bass drum will be different?

If they are very inconsistent you've got a much bigger problem than phase and polarity! If they are trying and mostly succeeding to play on the same beat then they are 'at a similar time!'

Try it and see! It may make no difference at all, or it might all the difference in the world. And with experience you'll hear straight off if there's a polarity issue or not.
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Re: Phase relationship between bass guitar and kick drum

Postby Wonks » Mon Dec 07, 2020 12:07 pm

I'd already heavily toned it down.
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Re: Phase relationship between bass guitar and kick drum

Postby Luke W » Mon Dec 07, 2020 12:21 pm

I think an important thing to remember, is that it's usually only worth diving so deeply into this sort of thing if there's something that needs fixing. Being aware of phase and polarity and how they will affect your recording is great, and applying that knowledge correctly whilst tracking will almost certainly lead to technically better recordings with less problems to solve when it comes to editing and mixing.

However, it's very easy to get tied up in the details and the "rules" to the extent that you lose sight of what is really important. Early on in the process that's capturing a good peformance, and later on it's mixing it in a way that makes it sounds good, that's really all it boils down to. As a few people have already said, in the majority of cases then a quick polarity flip on a track to see which option sounds best is all that is needed. A lot of the things you're getting into here sound to me like a solution looking for a problem.
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Re: Phase relationship between bass guitar and kick drum

Postby Mike Stranks » Mon Dec 07, 2020 1:30 pm

I'm going to pitch in with similar comments in tenor to what Wonks has said...

... this for the O/P...

Nearly all of your posts have a common theme... you're analysing the way sounds are recorded and interact in minute technical detail. If seems that you're looking more at waveforms and other measurement devices in preference to listening to sounds.

Of course an understanding of the physics of why things sound as they do is helpful, but it's by no means a prerequisite to mixing a song. Your ears - not your eyes - are the best judge of whether the way sounds are presented and interacting is working. If not, perhaps then have a look at waves and other analyses or come here to ask for some advice.

What I'm reading - which of course is but a small window on your working practices - reminds me somewhat of when I used to train people with a scientific frame of mind to mix live-sound. I'd often be asked 'What EQ settings do I use for voice, or piano, or guitar... or whatever?" I tried to give them general pointers, about how to use the controls to get a good sound, but some found that inadequate and struggled with it. Indeed, on a subsequent 'refresh/washup' visit one of them had a notebook with lists of numbers as to how to set controls.

In one sense 'numbers' are a good starting point, but as I always said to my 'pupils', "Mix with your ears; it's not painting-by-numbers." :)

And, of course, no offence is intended with this post.
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Re: Phase relationship between bass guitar and kick drum

Postby The Elf » Mon Dec 07, 2020 1:57 pm

I think fair points are being made above. When things aren't sounding the way we like, then any of us can get down into the minute techical details, but it's not the place we start from.

The technicalities of phase obviously fascinate you, and there's nothing wrong with that, but while you're looking at the brush strokes you're not seeing the picture!
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Re: Phase relationship between bass guitar and kick drum

Postby Tomás Mulcahy » Mon Dec 07, 2020 2:54 pm

Hugh Robjohns wrote:This is beginning to feel like a college correspondence course... I'm very happy to help, of course, but I can't help thinking that some background reading might make the learning process a lot easier on both of us.
Agreed! OP is interested in the physics of sound, asking the right questions, but is unsure of where to find the answers. Paying for a college course would answer all of his questions :)

That Jacquire King Youtube video sounds like a nightmare of over-simplification. Un-referenced, didactic and appealing to authority.
armans wrote: I record acoustic guitar with a spaced pair and I also record cajon with 2 mikes. Would flipping polarity or phase shifting the tracks be more appropriate in these cases?
You don't "fix it" afterwards- you set the mics up correctly. The spaced pair recording SHOULD have "phase issues" because the stereo image is created by the differences in arrival times between the two mics. There are tried and tested techniques to get the best results:
https://www.dpamicrophones.com/mic-univ ... and-setups

This is like the other thread on drum tuning. Phase and polarity are as different as pitch and timbre... the waveform display in the DAW only shows amplitude against time. It doesn't show the individual harmonics in the sound. It doesn't show that each of them has a different wavelength, so would require a different time delay to "line up"... which you would realise is wrong-headed if you understood Fourier transforms. There are other tools to use, such as a spectrograph.

@Mike Stranks I fully agree, he needs to use his ears. But that needs a grounding in physics and training of the ear. This is a great resource I think:
https://sites.google.com/a/umich.edu/ja ... r-training
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Re: Phase relationship between bass guitar and kick drum

Postby Mike Stranks » Mon Dec 07, 2020 3:40 pm

Tomás Mulcahy wrote:
@Mike Stranks I fully agree, he needs to use his ears. But that needs a grounding in physics and training of the ear. This is a great resource I think:
https://sites.google.com/a/umich.edu/ja ... r-training

I think it was Harman who had a really good ear-training tool available online... can't find it now though... :thumbdown: I used to give it as 'homework' on my training sessions! :)
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Re: Phase relationship between bass guitar and kick drum

Postby Tomás Mulcahy » Mon Dec 07, 2020 4:44 pm

I don't remember the Harmann one. Was it just for eq? The Corey book is excellent. Goes beyond eq to reverb, compression, editing and stereo image. Very cleverly put together. Very nice helpful guy too :) The book is a great handbook for the instructor. You would have to develop your own lessons/ notes around it as it would be heavy going for most students.

You'll notice he's not covered phase issues. Those are hard to train for! For example IME it takes quite a lot of time to deliberately set up audibly obvious violations of 3:1 rule in the studio. Needs a bit of grounding of theory and computer based demoing first. The Reaper delay is a great tool for demonstrating phasing in a simple, audibly obvious way.

The difficulty of phase audibility is why we have people using shotgun mics indoors, or as recently revealed on this very forum, two close mounted lavs in the mix at the same time on a major national TV show :(
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Re: Phase relationship between bass guitar and kick drum

Postby CS70 » Mon Dec 07, 2020 4:51 pm

Mike Stranks wrote:reminds me somewhat of when I used to train people with a scientific frame of mind to mix live-sound. I'd often be asked 'What EQ settings do I use for voice, or piano, or guitar... or whatever?"

Pardon me, "engineering" frame of mind. Nobody who ever did a little bit of science would ask a question like that. Whereas people who actually build stuff and are payed to make things work like nice, packaged recipes.

You spot a scientist because he/she always says "it depends".
And you spot physicists because they're always humming when they say it.

:lol:
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Re: Phase relationship between bass guitar and kick drum

Postby CS70 » Mon Dec 07, 2020 4:55 pm

The Elf wrote:I think fair points are being made above. When things aren't sounding the way we like, then any of us can get down into the minute techical details, but it's not the place we start from.

The technicalities of phase obviously fascinate you, and there's nothing wrong with that, but while you're looking at the brush strokes you're not seeing the picture!

I agree but in fairness: the OP has questions. Nobody's obliged to answer them if they don't want to? It can be a little bit patronizing to assume that he doesn't know how to listen.

We know nothing of his situation, whether or not he needs to do it for a job, for music or because he simply enjoys tinkering. Or maybe he does a lot of listening by ear already and he's interested in understanding more about the mechanisms that do things. Where else should he go if not this forum?

Just my $.10.

(not to you in particular Elf, but a general comment).
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Re: Phase relationship between bass guitar and kick drum

Postby Hugh Robjohns » Mon Dec 07, 2020 5:04 pm

Quite so... and I suspect that English is not the OP's first language, either, so some additional consideration is in order I think.... The OP is obviously keen to learn and that's to be applauded, but I wonder if perhaps it might be better to focus on the foundations before worrying about the decorations.

Taking an amusing tangent since Tomás (kind of) mentioned stereo imaging anomalies...

I was just listening to a Johnny Dankworth Album of film and TV themes from the 60s and 70s. There's a track on it called Willie's Flat which starts off noticeably left-heavy and very narrow with jazz piano, drums and bass all panned well left amidst 60s stereo plate reverb.

After eight bars a muted trumpet comes in with a wind section backing it, and immediately pans very audibly right across the sound stage towards the right hand side, taking the piano, drums and bass with it!

After a verse and chorus everybody in the band then goes wandering back to the left again ready for a sax solo... and when the blower has run out of puff they all go back across to the right for another trumpet section again. As the piece comes to an end everyone finally creeps nervously back to the middle for the closing chords!

It's quite hilarious... I've put a copy on Soundcloud as a private link for educational purposes: https://soundcloud.com/hugh-robjohns-443206878/1-16-willies-flat/s-lUlAAENDpd6

I presume it was originally mixed in mono, and then someone in a suit decided they needed a stereo version. So a frustrated remix engineer, probably wearing a brown dust coat and with a ciggy hanging from his lips, decided to run it through a stereo reverb and mess about with the pan-pot.

Sadly, he mistimed his opening pan for the first trumpet entry, but couldn't be bothered to do a corrective retake! :lol:
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