Piano World Home Page Forums Our Most Popular Forums Digital Pianos - Electronic Pianos - Synths & Keyboards Polyphony - how much is enough?

I have read various conflicting things about how much polyphony is enough. The message below I found on the Yamaha forum contrasts drastically with SteveY's comments earlier (SteveY basically said 128 polyphony was a bare minimum!).

I be interested to hear others thoughts in this, in particular a response from SteveY would be appreciated!

Message from Yamaha forum:
"I have watched the discussion about polyphony with interest. In
summary, I have to agree with those that state that polyphony is a non
issue.

I have a 105 (which I am totally delighted to own) that I have been
using for almost a year. Before I purchased it I had already learned
a bit about the truth regarding polyphony. I got a midi player
program off the net a couple of years ago that has an interesting
feature. It shows the maximum polyphony used in the midi file you are
playing.

I have collected hundreds of midi files of various styles, some with
simple instrumentation, some with full orchestration, some with
significant amounts of percussion. The highest polyphony I have seen
on any of them was 28 simultaneous notes.

Polyphony would only be a problem if the synthesizer used a type of
layering to build up a sound set. By this I mean, sandwiching many
patches as individual parts to form a sound. When this method is used
each individual instrument would take up one note of the polyphony.
This can use up polyphony fast if you have a sandwich of 5 or 6
individual patches "playing" when you strike a key.

If I understand it correctly, today's bigger memory processors don't
need to layer this way.

And so, a long note to simply say, you would have to be doing
something truly bizarre to come close to using up your polyphony. "

I would say this is only really an issue if you are sequencing with one unit.

I use as my primariy sound source an Emu E4 Ultra which is 128 voice polyphonic. I wouldn't say that it is a bare minimum for me personally, but 32 or 64 would definitely be too few.

David

"...sequencing with one unit... primariy sound source an Emu E4 Ultra..."

Sorry, I'm pretty ignorant about this and don't really know what that means!

I'm buying a Roland KR5 for quite a sum of money, and it is supposedly a top range digital piano. However, it only has 64 polyphony. I'm wondering whether I will find this limiting when playing, in particular say when I play along to an orchestra backing.

Does your post mean that 64 is definitely too few?

Definitely too few for what I do, but probably not for a digital piano.

Sequencing; arranging music within the context of electronic music, using a MIDI "sequencer" (such as Cubase or Logic).

Emu E4 Ultra; a digital sampler. It enables you to create "presets" from scratch by manipulating portions of sound loaded from a hard disk or recorded in directly. Controllable via MIDI from a sequencer or a keyboard.

HTH

David

I use GigaStudio (a disk-based sampler) for my piano sounds. It reports polyphony continuously. I often hit 100+ voices when playing pieces with moderate sustain. Remember that each stereo note typically uses 2 voices. YMMV.
jim

The Roland KR5 is pretty new (I believe it only came out a few months ago) so presumably has advanced processors, etc. I'm not sure how it all works, but is the amount of polyphony used related to other components of the digital piano? i.e. where a "lesser" keyboard may need 100 notes of polyphony, a more advanced one with better other components may be able to get the resources elsewhere, or maybe simply manage the polyphony it has better, so it does not need so much.

I guess an analogy would be PC computers - the performance of a computer depends not just on the processor speed, but on the whole set-up and how the components interact. Maybe polyphony works in this way - what do you think?

(I'm guess I'm just trying to justify why Roland would bring out a brand new "top of the range" digital rhythm piano (RRP $5000 or so), if the polyphony was so bad that note dropping was noticeable. I may be wrong with the above analogy but it seems the only explanation to me... what do you think?)

As Jim has already mentioned, 1 sound = 1 voice of polyphony; I don't know of any exceptions to this. There is no "managing" of polyphony with keyboards and modules - it is predetermined and finite. To have some sort of 'emergency polyphony' wouldn't make much sense... There is usually only one voice chip.

The only thing most manufacturers seek to implement is a dynamic use of the available polyphony, so that when note cut-off happens it is not so noticeable.

David

"As Jim has already mentioned, 1 sound = 1 voice of polyphony; I don't know of any exceptions to this."

Hmm...
I was under the impression that the number of voice files needed to replicate an instrument varies with different digital pianos. Surely this will have a huge impact on polyphony?

Eg. compare a piano that takes 4 voices to replicate a choir, say, compared to a more advanced one that can do it in one or two voices.

Do you not agree?

This is all confusing to me.

When you say dropping a note, is that like where I play 8 notes at once on my keyboard and when I add the 9th it wont sound? In which case I have something like 8 polyphony eeeeek

Seems to make more sense what Ender said - like the piano sound might be made up of a number of 'notes' or sounds - so the higher the polyphony, the richer the sound. Although I would have thought that you could have a continuous spectrum of sound making up one 'note'.

Could it be something to do with erm you no how a string vibrates and you have the primary wave, and you have the secondary wave with twice the frequency and so on and so on. Maybe something like 64 polyphony means the sounds made up of 64 frequencies in harmony?

I think Im thinking too much

>>I was under the impression that the number of >>voice files needed to replicate an instrument >>varies with different digital pianos. Surely >>this will have a huge impact on polyphony?

This is a very complex subject. Let me see if I can add to the confusion.

Your piano has a number of sampled sounds hard-wired into its memory. The sample was created by playing a note and recording it. Better samples record it at several velocities, let it ring longer, record more notes without interpolating sounds (up to 88 for a piano) etc. The note is the full sound spectrum.

The piano's software tweaks these samples in a variety of ways to create the instruments you get when you press the appropriate button. Some of the tweaking can use up more than one note of polyphony. Layering is an example of this. The only way I know to tell if an instrument is layered is to read the manual or look at the programming. Other tweaks don't consume polyphony - they add reverb or other effects, change the sound's envelope, etc.

For a basic piano sound, the usual relationship is one note = two voices of polyphony because the sounds are sampled in stereo. So if you play a 4-note chord you'll use up 8 voices. If you hold the sustain pedal down and then play another 4-note chord you're now using 16 voices because the first 8 are still sounding. Get the idea?

So does a choir use lots of voices? Not necessarily. If they sampled, say, a full choir singing in stereo, then each note might only take 2 voices. But if they sampled soprano, alto, tenor and bass voices and then layered them for a "full" choir you might use 4x2=8 stereo voices per note.

Most of this has very little to do with the "advanced" technology of the piano or lack of it. Better instruments typically have bigger and better samples so the sound is richer, lasts longer, whatever, but the basic polyphony issue remains 1 note = two voices. Usually.

Note-stealing happens when the piano runs out of polyphony. Different manufacturers handle this differently. The easiest algorithm is "first in, first off" - that is, the oldest sound is cut off first. There are other ways of doing it that are more complicated and may take more processing power, so I guess that's a place where faster computers help. Modern note-stealing techniques are pretty good.

Bottom line: more polyphony is better; 64 notes is probably good enough for solo piano; complex orchestrations want more than that; note stealing works OK for most things.

Whew!
jim

Nope - only if your keyboard is 8 voice polyphonic. Think of it like this:

Ignoring stereo sounds for the time being, let's say you have a keyboard that is 64 voice polyphonic. You press down 65 notes; one of them will not sound. Does that put things into better perspective?

David

>>I was under the impression that the number of >>voice files needed to replicate an instrument >>varies with different digital pianos. Surely >>this will have a huge impact on polyphony?

This is a very complex subject. Let me see if I can add to the confusion.

Your piano has a number of sampled sounds hard-wired into its memory. The sample was created by playing a note and recording it. Better samples record it at several velocities, let it ring longer, record more notes without interpolating sounds (up to 88 for a piano) etc. The note is the full sound spectrum.

The piano's software tweaks these samples in a variety of ways to create the instruments you get when you press the appropriate button. Some of the tweaking can use up more than one note of polyphony. Layering is an example of this. The only way I know to tell if an instrument is layered is to read the manual or look at the programming. Other tweaks don't consume polyphony - they add reverb or other effects, change the sound's envelope, etc.

For a basic piano sound, the usual relationship is one note = two voices of polyphony because the sounds are sampled in stereo. So if you play a 4-note chord you'll use up 8 voices. If you hold the sustain pedal down and then play another 4-note chord you're now using 16 voices because the first 8 are still sounding. Get the idea?

So does a choir use lots of voices? Not necessarily. If they sampled, say, a full choir singing in stereo, then each note might only take 2 voices. But if they sampled soprano, alto, tenor and bass voices and then layered them for a "full" choir you might use 4x2=8 stereo voices per note.

Most of this has very little to do with the "advanced" technology of the piano or lack of it. Better instruments typically have bigger and better samples so the sound is richer, lasts longer, whatever, but the basic polyphony issue remains 1 note = two voices. Usually.

Note-stealing happens when the piano runs out of polyphony. Different manufacturers handle this differently. The easiest algorithm is "first in, first off" - that is, the oldest sound is cut off first. There are other ways of doing it that are more complicated and may take more processing power, so I guess that's a place where faster computers help. Modern note-stealing techniques are pretty good.

Bottom line: more polyphony is better; 64 notes is probably good enough for solo piano; complex orchestrations want more than that; note stealing works OK for most things.

Whew!
jim

Thanks for your reply, Jim - that was very detailed and informative.

I still have not yet made my decision about which digital piano to buy...it doesn't help that I don't know exactly what I will be using it for, so don't know if the extra expense for 128 polyphony or higher is justified.

I think I'm through with reading about polyphony though!! It's a very complex issue, and starting to drive me mad!! Jim's post makes a great deal of sense, but there are also those who equally coherently and persuasively insist that polyphony is really not an issue on today's modern digital pianos.

I will re-visit the showrooms and play various models to death, because after all I guess it comes down to personal preference and whether I can personally notice it or not. Though that will be hard to tell in a showroom with a piano I'm unfamiliar with...

Ah, maybe I'll just go back to my saxophone!

Not really. Anyway, my shortlist has now been expanded to:

Roland KR5
Roland KR7
Yamaha CVP205
Yamaha CVP207
Yamaha higher CLP range, where I can get 128 polyphony and 40W or 60W speakers at the same price as the KR5.

The more I read about digital pianos, the more my shortlist grows!

Hmm... thanks again for everyone's input.

I think I'll start a new thread asking about speakers... is 2x 30W enough??

Want some more confusion?

Your new short list is a little apples and oranges because you've introduced the Yamaha CLP line. These pianos have fewer features than the CVP or KR lines - they are basically pianos with a few extra instruments, whereas the CVP/KR pianos have many more instruments, auto-arranging functions, score display and zillions of other features. The equivalent Roland line is the HP. If what you basically want is a piano, I'd go for the HP/CLP lines - cheaper. If you want to add the other functions later you can interface a computer running something like Band in a Box or other midi programs. It's less convenient than built-in but cheaper and more powerful. You can also add more sounds/polyphony later with outboard sound modules or computers - same tradeoff between quality and convenience apply.

Re speaker and amplifiers, I think 2x30 is acceptable, but more is better - pianos in particular can put out large transients when played fortissimo. My Roland has 240 watts and 12 speakers! Again, you can always run it through your home stereo if you want more power and better speakers. It sounds more convincing coming from inside the piano cabinet, though. Be sure to budget for a set of headphones - I play my piano probably 70% of the time through headphones. Best I've tried are Sennheiser's open-back models, by far the most comfortable.

At the end of the day, what matters most is how the keyboard feels to you and how the instrument sounds to your ears. All else is distinctly secondary.

BTW, have you considered a "stage piano?" Essentially the keyboard and electronics of the home pianos without the cabinet and speakers. Lots cheaper. Yamaha P80, P120, Roland RD700 are all good. They aren't furniture, however, if that matters.
jim

"If you want to add the other functions later you can interface a computer running something like Band in a Box or other midi programs."

Hmm...I had considered doing this, as I have a computer, but then the piano will probably live in the lounge and the computer upstairs...not that convenient! Plus, although maybe cheaper overall, I suspect it will be drastically more complicated and troublesome than just pressing a button on the piano to record, then playing away.

With regard to the CLP/CVP thing, it's hard to decide! Having never owned a digital piano, I'm not sure whether to sacrifice bells and whistles for polyphony and speakers...

Thanks again for your helpful comments.

>.I'm not sure whether to sacrifice bells and whistles for polyphony and speakers...

If you're already a pianist, I'd go this way. I practically never use the bells and whistles on my KR. The floppy-based sequencer is nice, though - I think it's available on some of the higher-end HP/CLP models.
jim

Yes, I already play the piano - have done for many years.

Excuse my ignorance, but what's a floppy based sequencer?

>>Excuse my ignorance, but what's a floppy based sequencer?

A sequencer is like a midi tape recorder. You can record your performances and play them back. You can also download midi files from the internet (there are tens of thousands of them out there) and play them through your piano. You can do "music minus one" where you turn off the piano track and play along with the accompaniment. That's a lot of fun for all kinds of music - jazz, classical, pop. There is software (some of it free) that will print a score from a midi file.

The floppy is where you store the midi files. Some pianos have an internal memory-based sequencer, which means you can record but not easily export or import files from your computer. Get one with a floppy if you can afford it. Midi files - which are digital instructions for the piano about how to play a song - are tiny compared to audio files. Complete concertos take up 100KB at most.

Note: The General Midi standard defines a set of 128 sounds (piano, strings, horns, percussion, etc.) and all GM-compliant instruments will play these sounds. The KR and CVP series pianos have complete GM impementations, plus special sounds of their own (XG for Yamaha, GS for Roland, don't worry about it.) Lower-end pianos may only have subsets of General Midi. That may or may not be enough for you. Again, more sounds can be added llater externally if the piano doesn't have them built in.

If you're getting into digital pianos you should read some general background material about midi. It's a powerful thing. Do a Google on midi and you'll get zillions of hits, some of which will provide information for beginners. For example, try:
http://www.midi.org/about-midi/resource.htm

And remember, buy what feels and sounds best to you!

jim

Thanks for that Jim.

And yes, I think that is exactly what I was after - the ability to play along with orchestra, etc. I've just been reading about the Yamaha CLP 150/170 and they both can do that.

Then what can the rhythym piano do then that the CLP 170 can't? If I want to play with rhythym on the CLP, can't I just download a midi file and play along with that?

And on the CLP, I can record songs as I play, over and over, multi-layering so I can do duets with myself or play along to a realistic sounding orchestra? I think that is all really I want to do - I can't really see myself jamming along randomly to a rhythym. Is that the main advantages of the CVP's over the top of the range CLP's?

I'm not that familiar with the CVP vs. CLP specs or HP vs. KR specs. In general, the "ensemble" pianos (CVP, KR) have a variety of auto-accompaniment features that you can jam to as well as single-finger melody with automatic accompaniment, more instrument sounds, score display and other features that you probably won't care about very much.

I think the CLP/HP lines are what you want, except that you probably won't get the full General Midi instrument set which means midi files that need them won't play everything. If you're interested in Yamaha pianos there's a good user group for the CVP series at www.cvpug.com. You might ask for help over there - lots of friendly users world-wide!