Forums - Music techology
Subject: Prophecy´s SubOscillator is a sampled wave?
Original Message 1/12 20-Mar-98 @ 09:03 PM - Prophecy´s SubOscillator is a sampled wave?
wave
To proove it, try to isolate the sub sound and play it at
a medium or high note:
1.Take an initialazed patch, go to the mixer section and
turn off Osc1, then let the Sub go to out 1 at max volume.
Go to the Filter section and select the "paralell"
configuration and turn filter 1 tu "THRU" mode. Then
go to the sub and select waveform=SAW, and tracking the
osc1=2 OCTAVES ABOVE.
Press the octave up button.
In this situation, if you play the kbd at a medium to high
note. What do you hear? under the SAW wave you can
notice a very loud alias wave..........mmmmmmmm
2.You don´t have PWM in this oscillator (impossible if it a
sample single cycle wave)
Try this and say me if I am wrong, please!
DAN
Message 2/12 20-Mar-98 @ 09:03 PM - Prophecy´s SubOscillator is a sampled wave?
wave
To proove it, try to isolate the sub sound and play it at
a medium or high note:
1.Take an initialazed patch, go to the mixer section and
turn off Osc1, then let the Sub go to out 1 at max volume.
Go to the Filter section and select the "paralell"
configuration and turn filter 1 tu "THRU" mode. Then
go to the sub and select waveform=SAW, and tracking the
osc1=2 OCTAVES ABOVE.
Press the octave up button.
In this situation, if you play the kbd at a medium to high
note. What do you hear? under the SAW wave you can
notice a very loud alias wave..........mmmmmmmm
2.You don´t have PWM in this oscillator (impossible if it a
sample single cycle wave)
Try this and say me if I am wrong, please!
DAN
Message 3/12 20-Mar-98 @ 09:08 PM - Prophecy´s SubOscillator is a sampled wave?
wave
To proove it, try to isolate the sub sound and play it at
a medium or high note:
1.Take an initialazed patch, go to the mixer section and
turn off Osc1, then let the Sub go to out 1 at max volume.
Go to the Filter section and select the "paralell"
configuration and turn filter 1 tu "THRU" mode. Then
go to the sub and select waveform=SAW, and tracking the
osc1=2 OCTAVES ABOVE.
Press the octave up button.
In this situation, if you play the kbd at a medium to high
note. What do you hear? under the SAW wave you can
notice a very loud alias wave..........mmmmmmmm
2.You don´t have PWM in this oscillator (impossible if it a
sample single cycle wave)
Try this and say me if I am wrong, please!
DAN
The others oscillator not reproduce this behavior
(and they have PWM) so I think they couldn´t be
samples.....anyway if you use the sub-osc like.....
.well like a SUBoscillator you don´t notice it, but
this limits the 3 notes fixed chords thats the Proph
is capable....
Message 4/12 23-Mar-98 @ 11:42 AM - RE: Prophecy´s SubOscillator is a sampled wave?
Message 5/12 23-Mar-98 @ 11:42 AM - RE: Prophecy´s SubOscillator is a sampled wave?
Message 6/12 02-Apr-98 @ 06:49 AM - RE: Prophecy´s SubOscillator is a sampled wave?
TOY YOU CALL A KEYBOARD AND BUY A REAL
PROFESSIONAL SOUND ENGINE, WITH GREASY
AND GRINDING ANALOG BASSES AND BEEFY
SAND-LIKE STRING : THE CASIO CZ-5000
( YEAH, THE COSMOSYNTHESIZER !! )
by the way YOU WANNA BUY ONE ?
Message 7/12 02-Apr-98 @ 07:48 AM - RE: Prophecy´s SubOscillator is a sampled wave?
a controler it rules. Any way the Nord Modular makes
every thing look like a toy! This is the Cosmotic synth!!
Message 8/12 11-Apr-98 @ 05:40 AM - RE: Prophecy´s SubOscillator is a sampled wave?
becuse i have one Korg and it have the same problem.
i buy here in thailand 3 years ago and the sound the
same is rude and crik.
my keybord is name Momopoly (with a /)and i going to sell
it becuse i dont like it sound.
Korg not good.
Buy other.
i see one here in Bangkok called Casio i thinq better buy.
Message 10/12 26-Apr-98 @ 04:36 PM - RE: Prophecy´s SubOscillator is a sampled wave?
All aliasing is is when the speed at which you process the sound data isn't fast enough .To avoid alising you need to process the sound at least twice as fast as the highest frequency in it. A sawtooth has lots of high frequencies bacause it's got a sudden jump in it's shape. The sound being processed inside the DSP chips is all digital numbers just like in a sampler, the difference being that they are made up mathematically rather than stored from an external input or memory file in a sampler.
When you ask a sampler for a sawtooth, it looks up numbers from a sampled sawtooth wave, just a list of numbers in a table. When you ask a Prophecy or other modelling synth for a sawtooth it doesn't have a table, it makes up the numbers on the fly, like 0,1,2,3,4,5,6...254,255,0,1,2,3 etc. If you want a higher frequency sawtooth it has to think up the numbers faster. If you want them faster than it can think them up, it will start missing some numbers out. You'll begin to hear these errors as aliasing.
What you hear is just a compromise by Korg. The DSP chips in any modelling synth are shared out to do lots of jobs like oscillators, filters, effects etc. They obviously had a cost target and had to compromise somewhere - they could have had the sub as a full blown 3rd oscillator with pwm and fast enough processing to take out this aliasing, but they'd have had to put up the cost or missed something else out.
Most of the time we use the sub at low enough frequencies that we don't meet the aliasing so I think it was a fair compromise. The Prophecy makes other compromises like the LFOs are also processed a bit too slowly so the waveforms aren't quite right at high speeds, but again most of the time it's hard to spot.
The Prophecy design is now a few years old and DSPs are a lot more powerful and cheaper now. Some manufacturers use this extra power to give us more voices and features like the Z1, others try to get the accuracy of the modelling better instead, like Nord, so you get higher quality and none of the aliasing at the extremes but do without the reverb and some features. Some claim to do it all (Supernova) and we'll continue to see more features and higher quality from all manufacturers as DSP chips get more powerful.
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