This is great discussion.

Sharke, it occurs to me that if you switch your send to 'pre-fader' you could then slide the volume of the bus with the phase flipped amp sim or the original track's fader up and down to get varying amounts of cancellation vs Amp Sim effect.

Can we assume you are speaking about the Mark Bass Studio 1 VST? Or are you speaking of an actual piece of hardware?
 
If I was using a VST and noticed weird phase issues (rather than normal phase issues) I would ask myself if the VST is reporting it's latency properly to SONAR. The timing needs to be reported by the VST so the DAW can use it's PDC effectively.
 
It should be easy to run a few tests and see what is going on with the timing. Send a test tone through there (use something with an easy to spot transient) and see what happens to the timing.
 
One thing to look out for... does the timing change with different patches in the VST? In other words, are some patches problematic while others are fine?
 
One thing you may want to do; embrace the idea that flipping the "polarity" on the *phase* button is a very specific thing. It may or may not be routine to flip that switch... As Dean mentioned, if you are flipping polarity on two identical tracks you will get a full null.
 
If you mix two tracks together where one is an original and the other has been *distorted* than flipping polarity will provide some sort of effect. A lot of signal will be nulled and a lot of signal will  not be nulled. What you hear is what you get.
 
The phase issues you are hearing are probably from a slight shift in timing... not a polarity flip flop. So, you can fool around with the polarity switch... it will provide some "effect"... but it has little to do the the phase coherency of your signal.
 
If you are curious about the phase you can run a few tests and check the timing to see if something is slipping.
 
 
 
You mentioned loops but you didn't mention a context of what you are comparing it too (mixing it with) when you hear the phase occur. This may be unrelated, but I have seen phase issues appear while looping a "clip" that is not an exact MBT increment. In other words, I have seen loops that are slightly shorter than what the users thinks they are and when they drag out a loop the timing drifts forward. Make sure your loops are a exact match to your grid.
 
 
Good luck.
 
best regards,
mike
 
 
 

sharke
Let's say I have a dry bass signal on a track, and I want to send a little of it to a bus that has a bass amp on to mix a little grunge into it. Is it customary to flip the phase on the send track? I'm a little in the dark regarding issues of phase. 
 
The reason I ask is because if I do the above with Mark Studio on the amp bus, I get a drastically different sound if I flip the phase switch on the amp. Also, if I use the same technique but with the Aphex aural exciter, sometimes the results sound a little phasey. 
 
One weird thing I've noticed doing this technique, is that if I loop a section of the track in question when I first fire up the project, and play back that loop, the first iteration of the loop will sound normal. But when it returns to the start for the second iteration, the phased effect begins, and remains for the duration of that session (i.e. until I close the project and reload it). Not sure how significant this is or if it's just another one of those oddities that happens when looping in Sonar. 

Hi Sharke,
Incidentally, if you're curious why Mike is using quotes, it's because phase and polarity are two different things. The phase button in Sonar is probably more accurately described as a polarity button (since phase deals with timing). If you're curious a good place to start might be here: http://www.prosoundweb.com/article/polarity_and_phase_explained/
 
Dean

Thanks Razorwit. I had been using phase and polarity as synonyms.

Hi gswitz, happy to help out. FWIW, while the difference is non-trivial, most places that I've been use phase and polarity roughly interchangeably. In situations where the differences matter the correct meaning can usually be derived from context.
 
Shorter version: calling the button on a pre-amp or board a "phase" button instead of a "polarity" button will generally not raise anyone's eyebrows that I've seen.
 
Dean

Thanks for the interesting replies everyone, I'm learning a lot about phase and polarity and I guess I have some experimentation to do. The difference in the sound in the bass track I'm working on is very dramatic. It's a fast moving bass line with alternating octaves, and I have found that with the polarity switch in one position, the lower octave notes sound boomy and much louder than the higher octave notes, wheres with the switch flipped they sound more balanced. 
 
Mike: with regards to the looping thing, I did wonder if it was something to do with timing. I'm tempted to blame Sonar here because its loop functionality is anything but watertight...take the widely reported issue of MIDI drift when loops have been playing a while, for example. FWIW the loop in question is an exact MBT increment. It's just weird that the sound changes permanently after one iteration of the loop (until I close and reopen the project), whereas if I don't set any loops at all, the sound won't change. 

To get back to the original question...you might need to flip the polarity when combining direct and miked versions of the same signal. It depends on whether the speaker is in phase with the amplifier's line output or DI box, which it usually is, but isn't guaranteed. 
 
What's more likely is that you have to adjust the phase relationship between the two signals because the amplified signal is slightly delayed compared to the direct signal. There is a little latency within the amplifier itself, but most of the delay depends on how far away the microphone was from the speaker. If it was close-miked, e.g. within an inch of the cone, the phase difference won't be noticeable on a bass.  It's only if you set the mic back a foot or more from the speaker that phase will become an issue.
 
You've got a lot more room for sloppiness with bass than other instruments, due to the longer wavelengths, but sometimes even a 0.5 ms shift can make an audible difference even on bass. That's equivalent to having the microphone 6 inches from the speaker.
 
If you are combining two separate bass tracks, e.g. two synths/samplers or a synth + real bass guitar, then you'll definitely want to fiddle with the phase (probably not the polarity button though). When I'm experimenting with layering sounds I find it convenient to insert a delay plugin with millisecond resolution (the Sonitus Delay will do this) so I can sweep the delay while listening for the best combination.
 
 
 

bitflipper
To get back to the original question...you might need to flip the polarity when combining direct and miked versions of the same signal. It depends on whether the speaker is in phase with the amplifier's line output or DI box, which it usually is, but isn't guaranteed. 
 
What's more likely is that you have to adjust the phase relationship between the two signals because the amplified signal is slightly delayed compared to the direct signal. There is a little latency within the amplifier itself, but most of the delay depends on how far away the microphone was from the speaker. If it was close-miked, e.g. within an inch of the cone, the phase difference won't be noticeable on a bass.  It's only if you set the mic back a foot or more from the speaker that phase will become an issue.
 
You've got a lot more room for sloppiness with bass than other instruments, due to the longer wavelengths, but sometimes even a 0.5 ms shift can make an audible difference even on bass. That's equivalent to having the microphone 6 inches from the speaker.
 
If you are combining two separate bass tracks, e.g. two synths/samplers or a synth + real bass guitar, then you'll definitely want to fiddle with the phase (probably not the polarity button though). When I'm experimenting with layering sounds I find it convenient to insert a delay plugin with millisecond resolution (the Sonitus Delay will do this) so I can sweep the delay while listening for the best combination.
 
 

 
Interesting! Can I presume that this talk of mic distances and amp latency applies to an amp/mic sim like Mark Studio too? 
 

sharke
 
Interesting! Can I presume that this talk of mic distances and amp latency applies to an amp/mic sim like Mark Studio too? 
 

Hi Sharke
No, not generally. Plugins shouldn't affect the phase relationship of tracks unless PDC isn't working properly. The scenario that Bitflipper is talking about with DI bass and a bass amp follows the same rules as a multi mic setup. 
 
That said, some plugs may not play well with Sonar's Plugin Delay Compensation (PDC) and you may need to adjust, but that should be rare and generally indicates that something is broken.
 
Dean