Pi causes pitch problem?!?

Hi all, I had a problem with Pi yesterday. It created audible pitch shifting effects. I mixed a simple jazz trio: 2 C12 in MS configuration for the main pair, plus spot mics for double bass, acoustic guitar, percussions and vocals. The pitching effect was particularly audible on guitar and bass, especially on long notes. It sounded to me as if I heard the GTR nicely blended through the MS pair and the spot mic, then one of the two was the shifted over time, therefore rubbing against the other signal’s pitch.
Has anyone come across this before? Any tips on how to avoid this?
I wasn’t able to use Pi, the pitching was just too audible unfortunately.

Thanks for your help!

Sunny greetings from ByronBay, Australia

Jan “Yarn” Muths

As no one replied yet -this was the main issue when I first started using Pi. A lot strange pitch and other problems. I am no expert but I only use the ‘Int’ mode on Groups and rarely include other Instruments in the Group (!) except individual Drums or Percussion.
This appears stable. The silence on this issue is worrying .
Anyway Pi must ALWAYS be used in Realtime including any track Bounces and especially Mix Bounce (I use Logic). The effects are remarkable when used this way.
That’s my contribution :slight_smile:

1 Like

Hi guys,

Thanks for your feedback. Pitch artifacts could happen if low end-heavy instruments are too significant in the levels Pi “sees” which in turn impact softer or lighter instruments by pulling their phase towards the heavier instruments.
That’s the reason gain staging is important and why we recommend to use Pi on post-fader inserts when available.
If post-inserts are not available in your DAW, the tracks average gain should be set in Pi, keeping the DAW’s faders around unity gain (There’s no need to mix with Pi’s gain, though). This will ensure that Pi’s sees the level of a track close to its real level in the mix.
If artifacts persists, increase the Weight parameter on the affected channels while listening to the mix (i.e. not in solo) until the artifacts are gone.

@janmuths, if your C12’s were recorded to two separate mono tracks, group then in Pi and set their group mode to PL (phase-locked). This will ensure that their phase relationship will remain intact while being optimized to the other tracks in the mix.

And if the vocal track was recorded in isolation from the instruments, try removing Pi from the vocal track. It will help it come forward in a cool 3D kind of way. That’s because by its nature, an all-pass filter tends to slightly soften the transients and therefore push the tracks ‘back’ into the stage (That could be one of the reasons folks like to use analog consoles which exhibit a somewhat similar effect due their slower slew rate when compared with mixing in the box…).

Cheers,

Nir