Piano World Home Page Forums Our Most Popular Forums Digital Pianos - Electronic Pianos - Synths & Keyboards How many notes polyphony for a beginner

The reason I mentioned Pianoteq is the fact that it could help zxczxc12345 work around the polyphony issue on a digital piano, once it comes to that.

Kevin, there may be some sort of salesmanship going on, but 32 notes polyphony is not enough to comfortably play a digital piano without a computer. And if someone uses instrument as a MIDI controller, instrument’s polyphony becomes quite dispensable. Asa a controller, piano only has to send proper MIDI messages (key on, key off, velocities, etc.) and let computer do the rest. I guess you knew that, but I wanted to make it clear for anyone observing this thread.

Mezzo-poor, I am wondering how Pianoteq handles damper pedal in terms of polyphony. Would you please let us know does maximum polyphony differ in these two cases:
- two chords with damper pressed
- two chords with damper released

Yes. That's why I said

``I think this particular piece of music would struggle on an instrument with fewer than 32 conventional voices (that's assuming two per note for stereo).''



The issue of salesmanship I was referring to was whether manufacturers really need to sell a keyboard/DP with only 32-voice polyphony, given how cheap electronic technology now is. A long time ago when I worked in the electronics industry, my company used to make and sell products which they never expected to sell, just so customers could be encouraged to buy more expensive ones. The sales pitch generally ran like this: ``That one won't be enough for you, but this one has twice as many whotsits and it only costs an extra £100'' or whatever.

I do wonder if something similar goes on in the DP world, but maybe that's just my natural cynicism.

I've said on other threads that, in my view, a good way to get a decent piano sound without spending a fortune is to rig up a MIDI master keyboard (with no sound generator) to a computer and thence to a home-theatre amp setup. This is particularly cost-effective if you've already got everything except the keyboard. But it's not very convenient if you just want to be able to sit down and play.

I had this in mind...



But, yes, this particular piece.

Makes a lot of sense. There is the other direction of this salesmanship. Imagine, for instance, plain MIDI controller with AWA Grand Pro II or PHA III.

I'm afraid this post become long. I hope this post will be helpful for understanding how Pianoteq (or other software pianos, DP's) handles polyphony.

I am also wondering because I am not a developer of Pianoteq. Just I can do are experiments on my Pianoteq and guessing.

Before experiments, I should explain some basic things.

For a computer, a voice is a task which consumes some resources (memory, time). A voice is invoked when it is required and terminated when it becomes useless (for example, after sufficient decay).

There are two types of resonance, one is global resonance and another is sympathetic resonance. Global resonance represents the resonances of all chords while the damper is on (pressed). For example, press the damper pedal, and next press C4 (center C) key, then you will hear the global resonance. Recently even inexpensive DP's (for example, Privia's) handle this global resonance. Sympathetic resonance represents the resonance among all pressed keys while the damper is off (released). For example, without using the damper pedal, press G5 key with ppp and keep it pressed, and next press C4 key with staccato and with strong accent, then you will hear the sound of G5 (let me call it sympathetic resonance on G5 by C4). Only some high-end DP's handle this sympathetic resonance. Pianoteq handles both types of resonances.

Pianoteq has an indicator which shows the number of polyphony currently used. Let me call it polyphony counter. A pair of stereo voices is counted as ONE voice in the polyphony counter.

Now let me show some experiments and comments (prefixed with #).

Experiment 1) Playing arpeggio with damper off
I used the midi sequence "note-on C4 | note-on E4 | note-on G4 | all-notes-off". Note that each key was kept pressed until all-notes-off came.
Then I got

(0) | note-on C4 (1) | note-on E4(3) | note-on G4(6) | all-notes-off(0).

Each number in ( ) represents the number that the polyphony counter showed immediately after each event.

# note-on G4 invokes three voices.

• voice of G4. Let me call it direct voice
• sympathetic resonance on C4 by G4.
• sympathetic resonance on E4 by G4.

I also tried an arpeggio consists of 10 notes and I saw the polyphony counter exactly showed 55=1+2+...+10 when the last key pressed.

# I also found that no sympathetic resonance was invoked in the case that the interval of two note-on events is small(say less than 100ms). This is a reasonable saving because a sympathetic resonance is easily masked by a laud direct voice.

Experiment 2) Playing arpeggio with damper on
I used the same midi sequence as used in Ex.1. I got

(0) | note-on C4 (1) | note-on E4(2) | note-on G4(3) | all-notes-off(0).

# In Pianoteq, the global resonance seems to be implemented as a special task other than voices. So it does not affect the polyphony counter.

# Since sympathetic resonances are masked by global resonance, no sympathetic resonance is invoked while the damper is on. In other words, the number of sympathetic resonances can increase only while the damper is off. Therefore, as far as you use 10 fingers, the number of sympathetic resonances does not surpass 45=1+2+...+9. On the other hand, the number of direct voice has no limit while the damper is on.

Experiment 3) Same as Ex.1 but the maximum polyphony limited to 2
I got

(0) | note on C4 (1) | note on E4(2) | note on G4(2) | all notes off(0).

When G4 was pressed, one of two sound C4/E4 disappeared. In this case, less laud voice seemed to disappear.

# In this case, just direct voices are invoked. When Pianoteq meats the shortage of the number of voices, it reduces even direct voices.

Experiment 4) Same as Ex.2 but the maximum polyphony limited to 2
I got the same result about the polyphony counter. Disappearance of C4/E4 was same as in Ex.3. The difference from Ex.3 was that I heard the global resonance.

# Global resonance does not consume any voice.

End of experiments--------------------------------

I didn't mention half-damper or quarter-damper because I could not guess what happened. And I didn't mention the sostenute pedal because my silent upright does not have it.

As Kevinb mentioned, any software pianos or DP's should have the policy "Least significant voice should be reduced first." The meaning of "Least significant" depends on the developers. I believe every developer keeps this policy.

Through the experiments I found that in discussion of the number of polyphony, we should pay attention to

• How do they count the number of polyphony, in other words, what does ONE voice means?
• How many voices are invoked when a key pressed?
• When a voice is terminated?.

Let’s have a round of applause for Mezzo-poor!

Refreshingly thorough. Thank you very much.

I assume DP manufacturers count each note we hear as two voices (stereo samples), which means the second experiment would produce significant increase on the counter of any DP, as you go from C4 to G4. Of course, it would be nice to know, not to assume. My assumption is based on common results of competition and power of computers put in these pianos.

I agree with Geoffk on upgrading to YDP160 and now have to direct attention to another difference between these two instruments. The sound system of YDP160 is a bit more powerful - 2x20W compared to YDP140’s 2x6W.

Well, it's certainly worth checking with the manufacturer or vendor how they're measuring polytphony, since it isn't as simple as it might appear. The practice of counting two stereo channels as as two polyphonic voices is widespread and, I can't help thinking, a bit deceptive. It seems to me to be similar to the way that mid-priced hifi manufacturers find ways to express the power output of their amplifiers to allow them quote really huge numbers (e.g., only meausuring with one channel driven). It's not actually wrong, but it's unhelpful.

I noticed some mistakes.

In Experiment 2

is wrong. So please forget it. The number of sympathetic resonances has no limit too. If you keep pressing C4,E4,G4 with your left hand and repeatedly press C5,E5,G5 with your right hand then the number of sympathetic resonances increases 9=3*3 everytime you press C5,E5,G5.

In Experiment 3

Of course "laud" is a typo. "loud" is correct.

Last week, I posted two demos for testing polyphony with Pianoteq. Now let me show the answers.

Note

• A pair of stereo voices is counted as ONE voice in Pianoteq.
• In some cases(I wonder in what cases this happens), Pianoteq uses a few surplus voices. For example, even if you set the maximum polyphony setting 8, Pianoteq might uses 9 or 10 voices. In the answers, the maximum polyphony actually used during a performance is shown in (). However, I'm afraid the least significant digit in () is not accurate, because the polyphony counter was changing very quickly.

Please DO NOT evaluate the sounds after you know the answers.
The answers are here:

http://cid-902c819bc390f6ee.skydrive.live.com/self.aspx/pub/ans.txt

And let me show some extreme examples. In each example, the maximum polyphony setting is 2 and maximum polyphony actually used is 5.

http://cid-902c819bc390f6ee.skydrive.live.com/self.aspx/polyphonyTest/E.mp3
http://cid-902c819bc390f6ee.skydrive.live.com/self.aspx/polyphonyTest2/E.wav

(Hmm... I like this lightsome Chopin. I might use this minimal-polyphony setting as an effect.)