look what other Sonar X1 user has to say regarding this: http://www.voxengo.com/forum/ar/2779/

So this is the conclusion: 

Fast Bounce has no effect on the quality of the exported audio unless there is a plug-in which is incompatible with Fast Bounce.

When using any Voxengo plug-in and its Oversampling feature (set to AUTO or any value) use "Non-Fast Bounce" option when exporting audio, unless you are using the latest version of Voxengo plug-ins and have in the settings set "Oversampling: Lin-Phase".

Otherwise, the exported audio will not be the same as the original that you can hear while playing back in Sonar.

I assume this rule may apply to any plug-in with Oversampling feature, but this is only my guess.

Interesting thread. I would not have guessed that oversampling would have a deleterious effect. 

However, because I have more than one frequently-used plugin that performs badly with a fast bounce, I've long been in the habit of using the slow bounce option for both exporting and bouncing. A slow export is still faster than having to re-do a fast export, especially if you don't notice the degradation right away. (Or the worst-case scenario: the client points it out to you after you've burned them a test CD.) 
 
Most of the time it's a soft synth that's the problem. Omnisphere is the worst offender, and it may be related to memory allocation and/or disk streaming. On my RAM-constrained system Omni will often produce unrecognizable garbage when bounced fast. Kontakt, however, never does this despite being equally resource-intensive.

rainmaker, your post has inspired me to do some tests of my own. It would be great if others would do the same, perhaps resulting in a helpful list of plugins known to not do fast bounces well. Hopefully, someone will compare SONAR to another DAW and see if that makes a difference.

Unfortunately, there are plugins that cannot be tested reliably with a null test. Anything that has random modulation cannot be tested this way. For example, a tape echo emulator will likely produce different results each time it's used. 

Equalizers, however, I would expect to be consistent, even ones with dynamic action such as GlissEQ. I'll test that one with and without oversampling, as well as the previous version of the same plugin. I'll also compare it to other equalizers that support oversampling.

Sorry, I was unable to duplicate your results using GlissEQ. I used some fairly extreme filter settings and 8x oversampling. The tracks nulled.

This is probably not relevant, but I am running SONAR 8.5.3, not X1.

OK, I read the Voxengo thread and it makes sense now. GlissEQ only oversamples during a render operation. It's up to the host to signal a plugin that it's in render mode, and SONAR does not do that when doing a slow bounce. GlissEQ therefore does not know it's in render mode and does not turn on oversampling.

Oversampling does cause a slight phase shift, which is normally not a problem because it's no more audible than if you nudged a track. However, if you combine the phase-shifted version with a non-phase-shifted copy, there will be comb filtering and the two tracks will not null.

So what you're seeing is entirely normal and predictable behavior and not an indication of signal degradation as a result of a fast bounce.

Bitflipper your grasp of this is humbling. Thanks for sharing!

Peace,

Tunes

Bit is amazing, and a cool hang in person too!

Lance

Bitflipper, thanks for chiming in.

I understand your point about phase shift and comb-filtering and indeed yes, it is what I hear when I play the original and "flipped" track together.

However, my first post in this thread was inspired by audible difference in sound of the original mi and the exported audio.

In the project, there are around 12 instances of Gliss EQ (on tracks, on sub-groups - cuts and boosts), a few Crunchesors and tube amps, all by Voxengo.

While I was using the older versions of those plugins and Fast bounced the mix (Oversampling set to AUTO), the sound degradation was clearly audible. The high end went away. 

With new versions, where in all instances I set Lin-Phase, now the Fast bounced track sounds the same as the original mix, although it does not null completely when played along with the original mix. But the sonic quality is, at least to my hearing, the same as the original.

So, on a single track, the sound quality of a Fast Bounced track is the same as the original but phase-shifted. However, in a larger mix, it makes a difference to the sound.

Since null tests are not applicable, you'll have to compare the spectral signature of a track that's been bounced slow versus one that's been bounced fast. You'll need a spectral display that does averaging over the length of the clip. In the images below, I used Ozone because it has this feature.

The first image is the original file with GlissEQ. The 8x oversampling is not engaged because the spectrum was taken during normal playback.






The second image is a copy of the first track that was bounced using fast bounce. I verified that the "Render" indicator came on during the bounce, indicating that oversampling was enabled. Note that there is no discernible difference between the two, nor was there any difference in the correlation or phase meters. 


This does not mean that they are identical, however. A null test would show a drastic difference, because they are not in phase with one another. In the image below, I have zoomed in very tight on the two tracks so that the shift is obvious:






You would not, however, hear this difference unless you mixed the two tracks together.

This was done with the current version of GlissEQ. You said you heard a distinct loss of high end when you did a fast bounce using an older version of GlissEQ. I haven't tried this yet with the older version. Did you hear the effect with all other plugins removed (not just bypassed) from the project?

[Update: I tried the same test with GlissEQ version 2.9 and got the same results. rainmaker, were you using an older version than that? I have 1.1 around here somewhere... ]

I've misplaced my old help files for GlissEQ. Does anybody know if versions 1 and 2 work the same way as the current version? Is it the Quality button that turns on oversampling, and does it only oversample during Render mode?