Polyphony?

[bloodsample]

I bet when you clicked this topic you said to yourself: "Ah crap! Not another newbie question! "

 

Ok so I'm sure some shape or form of the question I'm about to ask has been asked before, but I searched through the first 3 pages of the search results and found nothing. Anything beyond that I consider outdated information .

 

On with the question..

What is polyphony exactly? Is it the amount of physical keys that can be pressed on a keyboard which will generate a sound? Or is it the amount of sounds that can be generated by the sound generator simultaneously?

 

When a keyboard has 64 note polyphony for example, does that mean 64 simultaneous notes can be played per midi channel? Or that 64 physical keys can be pressed at the same time while still hearing each note? Or is it 64 notes in total for all 16 midi channels?

 

As an example, lets say I have 16 midi channels recorded in a software sequencer. Lets say that each channel has 10 chord voicings in which each note is played at the same time in each channel (for a total of 160 simultaneous notes). Now say I play this back with a motif es rack for example. Does the 64 note polyphony limit prevent this from happening? Or does polyphony only affect the physical input of the notes (ie playing keys on a keyboard)?

 

I thought I knew this stuff pretty well until I actually started thinking about it...

 

Hope you were able to understand what the hell I just said, cause I sure didn't .

 

Aight thats all for now folks,

BS.

[Finale]

Originally posted by bloodsample:

What is polyphony exactly?

 

--> I'll use your text for the answers.

 

The amount of sounds that can be generated by the sound generator simultaneously.

 

When a keyboard has 64 note polyphony for example...

 

It means 64 simultaneous sounds (not necessarily notes, because certain synths can use more than one "sound or wave" per note, for example) total for all 16 MIDI channels.

 

As an example, lets say I have 16 midi channels recorded in a software sequencer. Lets say that each channel has 10 chord voicings in which each note is played at the same time in each channel (for a total of 160 simultaneous notes). Now say I play this back with a motif es rack for example. Does the 64 note polyphony limit prevent this from happening?

 

Yes. And then the way the synth responds to too many notes will depend on its particular current "note stealing" algorhythm. Certain synths have several choices for this and/or do a better job at this than others.

 

If the unit allows it, you could also limit the amount of polyphony for each MIDI channel so to keep the more important one(s) for the tracks you prefer.

 

[Mr. Nightime]

Remember also that some sounds use more than one voice to generate each note. So if you're playing a string pad, for example, that uses two sounds per note, then you will only get 32 notes out of the 64 voices possible.

 

If you have a combination of say piano and strings, and each uses 2 voices, then your total number of simultaneous notes drops to 16.

[RABid]

This is one reason that the ability to record a track to memory or to the sampler is popular in workstations. I think is most cases, if you record a track and use the sampler to play it back then you reduce the number of voices used for that track to 2, one for each channel of the stereo sample. If your workstation happens to manage audio directly without passing it through the sampler then you don't use any voices to play the recorded track. Most new workstations SHOULD work this way.

 

Robert

[Phred]

What is the best note stealing out there? I think note stealing algorithms should have a bias toward certain sounds - I don't know if any do. Never stop a cymbal for example. Never stop a pad. Things like that...

[ITGITC]

Originally posted by Phred:

What is the best note stealing out there?

Kurzweil equipment has a long-standing reputation as having a great note-stealing algorithm.

 

With stereo samples for the Piano patches and others, I decided to purchase the polyphony option for the PC2X. Now I've got the ability to play 128 notes at one time. Of course, with the stereo piano, that's 64 notes. I think that's enough for playing Brubeck.

 

In the past, while playing the K2000 with only 24 note polyphony, I didn't have too much of a problem with notes dropping out when performing live. However, I didn't want to chance it with the PC2X.

 

GEM is talking about their sustain pedal that is more than just an on/off switch. I'll have to try this, because they say it adds to the realism; although I haven't been bothered too much by this in the past. On the other hand, what could be more unrealistic than note-dropping? ...not that GEM has a problem with this. I'm just making a point.

 

A hundred years ago when I was using Cakewalk (DOS) with MIDI recordings playing back in real time, polyphony was an issue. So, we used quite a few synths and drum machines for their sounds. It was a mess. Today, it's not as much of an issue.

 

Is There Gas In The Car?

[zeronyne]

I think highest and lowest note priority are the worst voice stealing algorithms. Last note is OK...a little more effective that first note.

 

I think the Roland "voice reserve" method is great, as is the "lowest volume steal" algorithm.

[Dan Phillips]

Originally posted by Is There Gas in the Car?:

GEM is talking about their sustain pedal that is more than just an on/off switch. I'll have to try this, because they say it adds to the realism; although I haven't been bothered too much by this in the past.

Sounds like a "half-damper" implementation, which is also used by Korg, Roland, and Yamaha (and perhaps others). These sustain pedals are actually continuous controllers. When connected to an instrument which supports them, they can modulate Program parameters (such as release time, in Korg's case) as well as simply holding notes. This can be useful in some cases, though not all...

 

- Dan

[StillFightingIt]

My understanding is that the GEM sustain pedal has 16 levels, no?

[Dan Phillips]

Korg's implementation of half-damper has 128 levels (full MIDI CC depth). I don't know about GEM's.

 

- Dan

[ITGITC]

Yes.

 

I was playing my acoustic piano this evening and I thought about this post.

 

I'd like to try this newfangled damper pedal.

[StillFightingIt]

Dan my understanding of Korgs half damper is that it has three points, Off, Half-Way, and On.

 

Here's the spiel of the GEM:

PRP SERIES PEDAL UNIT

This professional triple-pedal unit is the perfect choice for PRP700/PRP800 user who want the most realistic pedal action. Thanks to the 'Damper Physical Model' -Generalmusic patent, the damper pedal of the PRP Pedal Unit (right pedal) allows to recognize 16 different positions during its travel, making it possible to play partially damped and 'half pedal' effects, just like the acoustic piano models.

[Dan Phillips]

Originally posted by StillFightingIt:

[QB] Dan my understanding of Korgs half damper is that it has three points, Off, Half-Way, and On.

I can assure you that it's a continuous controller. I recently wrote the manual for the half-damper implementation in OASYS, as below:

 

* * *

A half-damper pedal is a special type of continuous foot pedal, such as the Korg DS-1H. In comparison to a standard footswitch, half-damper pedals offer more subtle control of sustain, which can be especially useful for piano sounds.

 

The OASYS will automatically sense when a half-damper is connected to the rear-panel DAMPER input. For proper operation, you will also need to calibrate the pedal, using the Calibrate Half-Damper command in the Global page menu.

The off and full-on positions of the half-damper work just like a standard footswitch. In conjunction with the Enable Half-Damper parameter, below, intermediate positions allow a graduated control of sustain, similar to the damper pedal of an acoustic piano.

 

Enable Half-Damper [On, Off]

 

When this is On (checked), Half-Damper pedals, normal sustain pedals, and MIDI CC# 64 will all modulate the Amp EG, as described below.

When this is Off (un-checked), the pedals and MIDI CC#64 will still hold notes as usual, but will not modulate the Amp EG.

 

Half-Damper Pedal and Release Time

 

The amount of modulation depends on whether the Amp EG Sustain Level is set to 0 (as is the case with most acoustic piano sounds), or set to 1 or more. The modulation is continuous, from 1x (no change) to 55 times longer; the table below shows a selection of representative points.

 

* * *

 

My guess, though I am not certain, is that Yamaha and Roland's implementations are something along those lines, as well.

 

Best regards,

 

Dan