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Nancy -- some polyphony tests

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mnailor

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Nancy -- some polyphony tests

PostMon Sep 06, 2021 9:33 am

My computer is a Dell Precision 3431 with Windows 10 Pro, i9-9900 8 core 16 threads 3.1 GHz base speed, 64 GB RAM.

Its static polyphony is 10,000 voices at 48k sample rate, 1024 samples, higher definition pitch shifting on in HW 6. That's 20 notes held at 500 pipes per note on the 4+ GB polyphony test organ, hitting the top yellow bar on the CPU meter, just short of red. 7,500 voices (15 notes) stays in the green.

To test Nancy's polyphony demands, I used a 12" ruler covering 14 notes, some free fingers, and both feet to put as many long releases into play as possible using 18 note chords. This gave me about 50% more concurrent voices than I can do with both hands and feet but no ruler, so this is a bit of a stress test. Registration was all stops, all couplers. Amplifiers turned off! About 2 chords per second semi-legato to get long releases into play.

1. Nancy all 4 perspectives, all samples, no higher def pitch shifting, 48k sample rate, 16 bit samples to fit in 64 GB

Polyphony limit - polyphony meter bars - CPU meter bars (highest)
9000 - 2 yellow - 2 yellow
8000 - 2 yellow - 1 yellow
7000 - 2 yellow - in green
6000 - 2 yellow - in green

2. Nancy all 4 perspectives, all samples, with higher def pitch shifting, 48k sample rate, 16 bit samples to fit in 64 GB

Polyphony limit - polyphony meter bars - CPU meter bars (highest)
8000 - 1 yellow - 2 red
7000 - 2 yellow - 3 red
6000 - 2 yellow - 1 red
5000 - 3 yellow - 2 yellow
4000 - 3 yellow - in green

3. Nancy 2 perspectives (Front and Middle), all samples, with higher def pitch shifting, 48k sample rate, 24 bit samples

Polyphony limit - polyphony meter bars - CPU meter bars (highest)
8000 - 1 yellow - 1 red
7000 - 1 yellow - 3 yellow
6000 - 2 yellow - 2 yellow

Note: This is the configuration I play, with polyphony limit at 12512. Without the ruler abuse, the polyphony and CPU meters both stay in the green no matter how dense the music gets.
Last edited by mnailor on Fri Sep 24, 2021 12:10 pm, edited 1 time in total.
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vpo-organist

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Re: Nancy -- some polyphony tests

PostMon Sep 06, 2021 1:31 pm

The required polyphony can be calculated approximately as follows:

Number of registers used * Reverberation time * Number of voices played simultaneously * Tone changes per second and voice

Example:
Number of stops used (40) * Reverberation time (6 s) * Number of voices played simultaneously (4) * Tone changes per second and voice (8)

= 40 x 6 x 4 x 8 = 7680 voices = required polyphony
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B777Captain

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Re: Nancy -- some polyphony tests

PostMon Sep 13, 2021 5:50 pm

Not knowing your formula to figure out the best polyphony with the Nancy sample, as it turns out after tweaking it for a few weeks, I am coming up with almost exactly the same setting you have…. I’m within 100 of your figure!

Thanks

Pat
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Las Vegas, Nevada
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B777Captain

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Re: Nancy -- some polyphony tests

PostSun Sep 19, 2021 3:40 pm

Mark…

May I ask how many Stops you had engaged at the time of this test?

Pat
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mnailor

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Re: Nancy -- some polyphony tests

PostSun Sep 19, 2021 5:45 pm

All 65 stops, all coupled and GO suboctave coupler. Amps off, so who cares if character reeds and celestes are in there?

However, the pedal stops were only played with 4 notes, while manual stops were played with 18 - 20 notes (14 note ruler, feet, spare fingers).

By the way, when trying to throw as many concurrent releases as possible, you have to hold each big chord long enough for long releases before restriking the keys. Fast playing uses less polyphony because you get short releases.

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