I was wondering if when mixing drum samples and soft synth's I should be looking at phase issues.
If so, what do I need to be looking out for?
Also what's the best way to fix any problems?

Cheers
Steve.

The act of mixing multi tracks down to 2 tracks is a form of additive synthesis and so there will always be phase "issues"

What to look for?

One easy too recognize circumstance is that you may notice an occasion when you turn something up and it gets quieter. If that happens you'll want to look for something that is 180* out of phase. This is also known as reverse polarity and it can cause nulling or loss of amplitude.

Other small phase issues can cause a thinner sound than you expect... this can happen when very similar tones have slight timing differences. This type of phase issue causes nulling and peaking at frequencies specific to the circumstance.

Many times, phase issue occur because of bleed in microphones from a multi track take. The same symptom of thinning and perhaps fluttering is realized. You may observe this on tracks of a live drum kit. The sounds from each drum reaches all the microphone in varying degrees of amplitude. The sounds get to each mic at different times becasue they are different distances to the drums. Most people learn to place the mics to avoid the worst effects of phase cancellation.


With regard to drum samplers... it's hard to say. It really depends on the actual and specific sample library and how each and every sample is prepared. It also has a lot to do with the sample libraries mic set up... some feature "bleed" and most do not.

With regards to soft synths. A synth uses synthesis... and is almost always purposefully manipulating phase in an effort to sculpt a complex timbre out of a basic tone.


That's a start... there's plenty of other ways to looks at it... there are meters, analysis, stereo to mono issues, etc. etc.

I wouldn't worry to much if you aren't hearing something that bothers you.


best regards,
mike

Thanks for a very helpful reply, could I get issue's between a kick sample and a VST synth bass for example?

Cheers
Steve.

I wouldn't worry to much if you aren't hearing something that bothers you.

This is the key when using samples because of the fact they come from many disparate sources it's likely you will run into phase issues and likely reject certain comibinations of sounds when you are choosing them simply because the phase issues created make them sound bad in the first place.

In practice therefore it hardly becomes an issue.

I've used some multi-mic'd libraries that have manifested phase issues but normally a little time (mis)alignment between the different sources has helped but it's been very rarely I've done that to fix/improve phase issues.

What Mike is saying is pretty on the money. If you are using a soft synth and it is represented over a stereo or two channel signal then as long it is sounding great don't worry but at some point you may hear something that involves phase relationships and it might not sound good for whatever reason. Most samples and if they are stereo and usually pretty phase coherent.

It is important to get quite involved with the effects processor of any soft synth. They are usually present and often engaged in the total sound making process. Sometimes they might program a silly chorus effect that could be making a preset sound phasey or actually worse than it could be or drenched reverb sound. There might be stereo imaging effects being used. Often all it takes is to either alter the wet/dry setting of any given internal effect or something I like doing is to switch off that chorus or reverb effect say and re apply it later with something much cooler like Dimension D or a way better reverb.

The quality of internal effects processors inside many soft synths varies. Some of them are better than others. Often they are programmed too heavily on the wet side or inappropriate effects may be applied which does not help the original patch. In one Korg Wavestation patch I have they have polarity reversed on side of the stereo image. It is a wide patch and because of this it seems to get a bit wider and less focused. But it was a silly programming concept in some ways. I had to put the polarity back to normal on that side and then the patch sounded way better and also narrow down the stereo image somewhat before this sound sat much better in a mix.

If you hear a tight reverb over a snare or something check into it to see if they are not adding this stuff in later down the track. Many drum VST's feature complex mixing pages with lots of sends and returns for fx etc...Often you will not even know these pages are there. You have to navigate your way to them. FX processors are often not that noticeable on the main front page of a soft synth.

If you are hearing some sort of ambience on a drum hit it might also be in the sample and no effects are being applied. Often in those cases the phase relationships of the ambience are good. You can always use a gate as well to remove unwanted extended ambiences that might be present in a sample and new ambiences can be substituted.

steve@psbnoe.wanadoo


Thanks for a very helpful reply, could I get issue's between a kick sample and a VST synth bass for example?

Cheers
Steve.

There is a remote possibility that you might encounter a situation with reverse polarity.

A snare for example; If mic'd from the top usually starts with a downward movement in the waveform because the skin moves away from the mic for an instant before snapping back.

Some sample libraries may have flipped the polarity of the snare.

Some synthesized percussion tones may start upwards or positive because that is the norm for most other types of synth patches.


The kick usually has a upwards or positive pulse because we usually mic the front. So, the same ideas apply that I mentioned with the snare.

The bottom of the snare, the toms, etc. all have similar situations to consider if you are combining or layering two sources and think you may have some problem you need to track down.


best regards,
mike

steve@psbnoe.wanadoo


Thanks for a very helpful reply, could I get issue's between a kick sample and a VST synth bass for example?

Cheers
Steve.

In this scenario rather than a bona fide 'phase' issue you are more likely to run across conflicting harmonics causing similar comb filtering artifacts, again it's more of a case of choosing nice complementary sounds at the outset rather than getting into solving phase issues IMO

I was wondering if when mixing drum samples and soft synth's I should be looking at phase issues.

As a general rule, no. Phasing would not be a problem between kick drum and bass guitar samples, for example.


That doesn't mean it's impossible to get cancellations between two samples. But any scenario I can think of would be quite atypical. For example, if you used the same drum sample on two separate tracks and introduced an effect that would cause a phase shift in one but not the other. So don't do that.

But any scenario I can think of would be quite atypical.

LOL, now Bit's said pretty much the same thing I guess it's official.

Having said all that and not worry about 'issues' per se I do often like to make timing alignments and frequency domain phase adjustments just for the sake of maximum impact and sometimes for creative effect there is a great tool I use for that kind of thing.

Which is this!

It is free, works a treat and you can download it...

Here

Thanks for the help everyone.
If I'm layering kicks or snares should the waveforms be pointing up or down together and at the same time?
Watching this video got me started on this,


http://www.waves.com/content.aspx?id=11948#video

Cheers
Steve.