Here are three short videos showing my old Prophet-5 revision 2 which I have now exchanged (it was in need of repair for the past 10 years). The pictures were taken days before I let it go and the music is from years ago in 1999, on old tape recordings, played on my hi-fi using a lovely Denon cassette deck that I bought from the local BHF charity shop a year ago for 10 GBP. The video shows the P5's front panel and rear panels, including MIDI connections and cassette interface (both retrofits on such an early instrument, one of the first 400 made). It shows the ultra mellow sound that could be got from the SSM sound generation microcircuits that made the early Prophets happily sound to good and also be so hard to repair, sadly. The Prophet-VS is also broken now after 18 years of fun playing.
Prophet-5 Revision 2 front panel & gratuitous filter sweeps jam.
https://www.youtube.com/watch?v=FKSMWd4U7AU
Prophet-5 Revision 2.0 strummed acoustic instrument sound with purring cat.
https://www.youtube.com/watch?v=TbXibOyxgKw
Prophet-5 Revision 2 acoustic instrument type sound Jam from 1999. Revision 2.
https://www.youtube.com/watch?v=22F-nVNtWXA&t=56s
Description for the videos:
Prophet-5 Revision 2 front panel & gratuitous filter sweeps and other jams from tapes recorded around 1999.
Front panel sections: modulation, oscillators, mixer, filter, amplifier.
Thanks to Dave Smith for developing such an amazing instrument. I had always wanted to own one; now I have let it go. I enjoyed making sounds on this more than on anything else, even when they were rough and even when it went out of tune. It was the instrument where you would just play the same note gratuitously again and again just to hear it again and wait for it to fade away.
Other synths arpeggiated in the background are the Roland JP-8000 (Arctic E-knows sound on cat video) and Korg Prophecy (guitar sound on cat video). Prophet-5 is the jamming instrument that sounds alive with the presence. Rough jam recorded to cassette tape in 1999, so playing is rough, totally live, just tinkering with the sound.
This was the day I let go of the P-5 (now broken, hopefully going to be restored by someone else) - and while clearing up, I found the old tape recording the previous day in a box.
Video file P1300052.
All music and videos copyright David Bellamy 2017 (as if anybody is gonna steal it!)
Demonstrating the "stepping" in the P-6 filter resonance, which in my view is probably always related to harmonics / overtones of the notes being accentuated by the filter resonance at the cutoff frequency and not to quantization of the cutoff knob.
When I say quantizaion, I mean apparent quantization becausue I actually think now that it is all overtones sounding. THE FILTER IS JUST TOO GOOD!! It's most apparent when resonance is at 9-10, which is when the resonance is at its narrowest bandwidth (highest quality factor), which is where you would expect it.
This was a jam not a demo at first but I posted it because I had a lot fun making the thing and trying to get a handle on this Prophet-6 filter. So no complaints about camera work please - it's difficult to hold the camera, play the synth notes and tweak the controls with only two hands!
Features filter sweeps using cutoff knob, filter envelope amount know and low frequency oscillator, alone or in combination. No particular order.
To me, the question might become - why don't you hear this "stepping" effect so much on other synths?
I'm getting to like the sound of the Prophet-6 more and more.
At high frequencies, any overtones are so close together that I guess they merge and they are indistinguishable.
At mid frequencies (around 2-4 octaves above the note played), the harmonics are close together but are still distinguishable as notes. They almost follow the chromatic scale but some will be missing depending on how many notes you are playing and which notes they are. This is where the apparent stepping occurs. Careful listening reveals that there are gaps and the stepping is not quite chromatic.
At lower frequencies, 1-2 octaves above the note, you can clearly hear the 2nd, 3rd and 4th harmonics (1st, 2nd and 3rd overtones) separately.
2:54 With filter keyboard tracking OFF, HALF and FULL.
The effect is greater with filter keyboard tracking ON because each note will have a different filter cutoff frequency, lighting up more overtones.
So with keyboard tracking OFF, you get fewer harmonics because of this. I stopped mid-sentence when I was talking.
On any kind of high resonance filter sweep, as the cutoff frequency comes down on the down-sweep, the harmonics become more sparse and you get a deceleration effect as you get to the bottom of the cycle. This gives the effect of a sine wave type LFO wave, even though it's a triangle (apparently).
Also, since it is a polyphonic synth you can get more overtones than with a monosynth because you can play more notes at once. This is probably why people are noting this on effect polysynth like the P6 (they did on the P5 too).
To make the sweeps as smooth as possible, you probably need to do one or more of these things:
*play only one note at a time
*Have filter keyboard tracking OFF
*Use square waves on the oscillators (that don't have even harmonics, only odd) instead of saws (that have odd and even)
*avoid setting the cutoff in the region where the harmonics are almost chromatic
*set the resonance not above 9 or
*sweep really quickly
The overtones will probably also depend on which wave shape you use of course! Square waves don't have even harmonics, only odd ones but saw waves have odd and even (you can tell intuitively because of the skewed look or asymmetry of the saw shape).
I don't remember hearing that region of the harmonics so clearly on my old Revision 2.0 Prophet-5 with SSM filters. Instead, there was a kinf engine like pushing up sound as the resonance passed through the close spaced overtones and it was a little more vague and less obvious.
5:05+ growly harmonics and near 5:30 you can clearly hear the nearly chromatic part of the harmonic series.
At 6:28-6:50, I said there is some quantising sound on a filter sweep WITHOUT THE... I meant "without the cutoff knob being used" - only the LFO - but again it is just harmonics. You can hear that it is nearly chromatic but not quite. So I conclude that it is just overtones being lit by the resonant filter.
At 7:30-8:30 not a lot happens because I forgot what controls I had moved.
8:22+ and 9:20+ I get the run of almost chromatic notes followed by an arpeggio of the lower harmonics coming out.
At 9:20 you get several chords with arpeggios of harmonics - and again at 10:25+.
9:54 I particularly like this sound! Slow harmonics - leading to almost chromatic ones.
10:23+ I speed it up a bit and get better apreggios of harmonics.
11:45+ Slowing it down again, I get a favourite sound at the end.
Video file MVI 7410.
Keywords:
Sequential, Prophet-6, Prophet, filter, cutoff, harmonics, overtones, resonance, quality, quality factor, Q, keyboard, tracking, sweep, knob, low frequency oscillator, LFO, tone colour, tone color, Prophet-5, Dave Smith Instruments, Dave Smith, DSI,"
Pushing the filter on the Prophet-6. Not meant to be musical particularly! The steps in the filter cutoff frequency when the filter cutoff knob is turned on the Prophet-6 are an idiosyncrasy that a musician could use. Now I actually have a P-6, sometimes I can hear it, sometimes I can't. Sometimes I can just hear the harmonics picked out by the filter sweep and the filter seems to light them up audibly a lot, even to quite high frequencies. These can be clearly heard when using the low frequency oscillator (LFO) to sweep the filter slowly as you would expect. I love the harmonics generated by the P-6 filter and you can hear those speed and slow down as the cutoff goes up and down on a slow sweep. Sometimes they sound like stepping as they get closer together at higher frequencies.
I'm now convinced that there is no quantization of the filter cutoff knob that you can hear. It is just the harmonic series and it rises in to an area densely packed with overtones. If you sweep the filter slowly and carefully through this region, you can hear the harmonic series as the overtones get closer and closer together until they are almost chromatic (but not quite). The eventually the overtones are separated by microtones and are not resolved by the filter, then you get a "smooth" rise and fall in resonant frequency. Basically the Prophet-6 filter is so good that it is resolving the overtones even as they are separated only by about 1/2 tone. The whole point of a filter is to emphasize overtones anyway. In Playing around with this, I have been able easily to hear overtones on a C fundamental note up to the 7th or 8th harmonic at least. Series goes C, C, G, C, E, G, Bflat, C, D, E, etc then going into into microtones. Note that is not chromatic but it might sound like it as the harmonic series gets densely packed. I've heard the B flat clearly and the C (7th and 8th harmonics) and then it goes into what sounds like a chromatic run followed by a smooth rise ad the reverse is true on a down-sweep. This filter should be a musician's paradise and that's just the low pass one! If you play chords, you are gonna hear far more overtones especially if the filter cutoff key follow is on FULL (or weird ones if it is on HALF) because each voice's filter will have its own different resonant frequency. You can hear chords of overtones stepping up, which in my view is mega cool.
However, with the resonance a bit lower, at 8 for instance, the bandwidth of the resonance is a bit wider and the sweep effect is smoother and I would say this is to be expected. It gives the player the opportunity to use the filter at high resonance (high Q) to pick out overtones individually and get some fascinating sounds. Great tuned percussion for instance and all sorts of amazing blips and bloops are dead easy to get on the Prophet-6, with just the filter, even using no velocity, no aftertouch, no wheel, no polymod, just this kickass filter. One might ask what is wrong with the synths that don't show this "quantization" (that isn't)...?
Arpeggios:
I think you can hear filter cutoff "quantization" at
0:53(?), 1:03 onwards, 1:44 (cutoff knob) (but it is just closely placed overtones being resolved)
Seemingly smoother adjustment of filter cutoff at 3:30+, 4:18+.
2:18 onward, heavy resonance with faster LFO and cutoff knob too. Spot the "quantization" and the bubbling effect at 2:58. Mean.
Single notes: 2:58 with - harmonics filters swept 3:43+. Octaves and fifths around 5:00+.
Chords with LFO and cutoff knob adjustments: 5:40+
At 6:06, 6:11(?) it starts to get confusing as to whether it is a quick run of harmonics.
Chords with LFO filter sweep:
You can hear harmonics super clearly around:
2:11, 3:39+, 5:16+, 5:30?,
5:37 (high harmonics or quantization? - You tell me)
More harmonics 5:47, 6:00+, 6:27 run of close harmonics,
6:35+, 6:50, C major/F 7:02+, 7:18+, 7:28+, 7:44 (resonance to 9+) - this was too much fun!
8:10 and beyond.
High pass filter starts to come in after 9:00 somewhere and then at 11:08+.
The great thing about the Prophet-6 is that the filter and amplifier envelopes are right next to each other, one above the other making it a breeze to change them so quickly and in subtle ways.
The video after 8:55 is 2 short lots of messing about with the filter and amp ADSR envelopes and tweaking the filters low pass and high pass including resonance for some ear splitting treble - notes generated by the arpeggiator of course.
Totally gratuitous but this is why owning a synthesizer is fun, to experiment with the sound of music. Real time control abounds on the P-6. It's an abundance of riches as far as I can see.
The stepping seems to depend on whether the filter is in self oscillation. but I don't really care. You can get real smooth filter sweeps lots of other ways. Maybe there is a deliberate stepping of the self oscillation to enable the player to tune the self oscillation easily, as with the ordinary oscillators?
You can hear it plainly in this video in a couple of places and it gives a bubbly effect, really insane if used as an asset instead of a problem.
Filter sweeps and adjustment of controls in real time to give an idea of the range of sounds from the filters of the Prophet-6.
Real time jam, recorded to tape, played on a car stereo and recorded using a digital SLR camera, so some bass will be lost.
Slight on board digital delay effect. I as just messing about with the controls so I didn't take this effect off. It doesn't make much difference. All the same, you can still hear most of it! The treble is quite severe because I was pushing the resonance high. I didn't notice any quantization on using the high pass filter cutoff knob. Maybe that is because the high pass filter doesn't go into self oscillation.
Scene is of a cat in an untidy garden. Something catches the cat's attention at 3:02. I can't imagine what.
I have posted a couple of videos on YouTube about the wonderful filter on the Prophet-6 (six). Here they are:
DSI Sequential Prophet-6 great filters cutoff stepping? quantization? Nope! Harmonics!! Sweeps jam. The start reminds me of sounds from the albums Hawkwind Live '79 and Depeche Mode Ultra and also sounds a bit like the start of the original Prophet-5 demo record from the 1970s:
https://www.youtube.com/watch?v=IrH2dlvDaeA Here is the harmonic series / overtones series diagram that I drew showing overtones of a C major chord (or just a C note if you prefer). This shows that the overtones get dense about 3-4 octaves above the played note and could be mistaken for a chromatic scale in that region:
Description for first video:
Pushing the filter on the Prophet-6. Not meant to be musical particularly! The steps in the filter cutoff frequency when the filter cutoff knob is turned on the Prophet-6 are an idiosyncrasy that a musician could use. Now I actually have a P-6, sometimes I can hear it, sometimes I can't. Sometimes I can just hear the harmonics picked out by the filter sweep and the filter seems to light them up audibly a lot, even to quite high frequencies. These can be clearly heard when using the low frequency oscillator (LFO) to sweep the filter slowly as you would expect. I love the harmonics generated by the P-6 filter and you can hear those speed and slow down as the cutoff goes up and down on a slow sweep. Sometimes they sound like stepping as they get closer together at higher frequencies.
I'm now convinced that there is no quantization of the filter cutoff knob that you can hear. It is just the harmonic series and it rises in to an area densely packed with overtones. If you sweep the filter slowly and carefully through this region, you can hear the harmonic series as the overtones get closer and closer together until they are almost chromatic (but not quite). The eventually the overtones are separated by microtones and are not resolved by the filter, then you get a "smooth" rise and fall in resonant frequency. Basically the Prophet-6 filter is so good that it is resolving the overtones even as they are separated only by about 1/2 tone. The whole point of a filter is to emphasize overtones anyway. In Playing around with this, I have been able easily to hear overtones on a C fundamental note up to the 7th or 8th harmonic at least. Series goes C, C, G, C, E, G, Bflat, C, D, E, etc then going into into microtones. Note that is not chromatic but it might sound like it as the harmonic series gets densely packed. I've heard the B flat clearly and the C (7th and 8th harmonics) and then it goes into what sounds like a chromatic run followed by a smooth rise ad the reverse is true on a down-sweep. This filter should be a musician's paradise and that's just the low pass one! If you play chords, you are gonna hear far more overtones especially if the filter cutoff key follow is on FULL (or weird ones if it is on HALF) because each voice's filter will have its own different resonant frequency. You can hear chords of overtones stepping up, which in my view is mega cool.
However, with the resonance a bit lower, at 8 for instance, the bandwidth of the resonance is a bit wider and the sweep effect is smoother and I would say this is to be expected. It gives the player the opportunity to use the filter at high resonance (high Q) to pick out overtones individually and get some fascinating sounds. Great tuned percussion for instance and all sorts of amazing blips and bloops are dead easy to get on the Prophet-6, with just the filter, even using no velocity, no aftertouch, no wheel, no polymod, just this kickass filter. One might ask what is wrong with the synths that don't show this "quantization" (that isn't)...?
Arpeggios:
I think you can hear filter cutoff "quantization" at
0:53(?), 1:03 onwards, 1:44 (cutoff knob) (but it is just closely placed overtones being resolved)
Seemingly smoother adjustment of filter cutoff at 3:30+, 4:18+.
2:18 onward, heavy resonance with faster LFO and cutoff knob too. Spot the "quantization" and the bubbling effect at 2:58. Mean.
Single notes: 2:58 with - harmonics filters swept 3:43+. Octaves and fifths around 5:00+.
Chords with LFO and cutoff knob adjustments: 5:40+
At 6:06, 6:11(?) it starts to get confusing as to whether it is a quick run of harmonics.
Chords with LFO filter sweep:
You can hear harmonics super clearly around:
2:11, 3:39+, 5:16+, 5:30?,
5:37 (high harmonics or quantization? - You tell me)
More harmonics 5:47, 6:00+, 6:27 run of close harmonics,
6:35+, 6:50, C major/F 7:02+, 7:18+, 7:28+, 7:44 (resonance to 9+) - this was too much fun!
8:10 and beyond.
High pass filter starts to come in after 9:00 somewhere and then at 11:08+.
The great thing about the Prophet-6 is that the filter and amplifier envelopes are right next to each other, one above the other making it a breeze to change them so quickly and in subtle ways.
The video after 8:55 is 2 short lots of messing about with the filter and amp ADSR envelopes and tweaking the filters low pass and high pass including resonance for some ear splitting treble - notes generated by the arpeggiator of course.
Totally gratuitous but this is why owning a synthesizer is fun, to experiment with the sound of music. Real time control abounds on the P-6. It's an abundance of riches as far as I can see.
The stepping seems to depend on whether the filter is in self oscillation. but I don't really care. You can get real smooth filter sweeps lots of other ways. Maybe there is a deliberate stepping of the self oscillation to enable the player to tune the self oscillation easily, as with the ordinary oscillators?
You can hear it plainly in this video in a couple of places and it gives a bubbly effect, really insane if used as an asset instead of a problem.
Filter sweeps and adjustment of controls in real time to give an idea of the range of sounds from the filters of the Prophet-6.
Real time jam, recorded to tape, played on a car stereo and recorded using a digital SLR camera, so some bass will be lost.
Slight on board digital delay effect. I as just messing about with the controls so I didn't take this effect off. It doesn't make much difference. All the same, you can still hear most of it! The treble is quite severe because I was pushing the resonance high. I didn't notice any quantization on using the high pass filter cutoff knob. Maybe that is because the high pass filter doesn't go into self oscillation.
Scene is of a cat in an untidy garden. Something catches the cat's attention at 3:02. I can't imagine what.
Demonstrating the "stepping" in the P-6 filter resonance, which in my view is probably always related to harmonics / overtones of the notes being accentuated by the filter resonance at the cutoff frequency and not to quantization of the cutoff knob.
When I say quantizaion, I mean apparent quantization becausue I actually think now that it is all overtones sounding. THE FILTER IS JUST TOO GOOD!! It's most apparent when resonance is at 9-10, which is when the resonance is at its narrowest bandwidth (highest quality factor), which is where you would expect it.
This was a jam not a demo at first but I posted it because I had a lot fun making the thing and trying to get a handle on this Prophet-6 filter. So no complaints about camera work please - it's difficult to hold the camera, play the synth notes and tweak the controls with only two hands!
Features filter sweeps using cutoff knob, filter envelope amount know and low frequency oscillator, alone or in combination. No particular order.
To me, the question might become - why don't you hear this "stepping" effect so much on other synths?
I'm getting to like the sound of the Prophet-6 more and more.
At high frequencies, any overtones are so close together that I guess they merge and they are indistinguishable.
At mid frequencies (around 2-4 octaves above the note played), the harmonics are close together but are still distinguishable as notes. They almost follow the chromatic scale but some will be missing depending on how many notes you are playing and which notes they are. This is where the apparent stepping occurs. Careful listening reveals that there are gaps and the stepping is not quite chromatic.
At lower frequencies, 1-2 octaves above the note, you can clearly hear the 2nd, 3rd and 4th harmonics (1st, 2nd and 3rd overtones) separately.
2:54 With filter keyboard tracking OFF, HALF and FULL.
The effect is greater with filter keyboard tracking ON because each note will have a different filter cutoff frequency, lighting up more overtones.
So with keyboard tracking OFF, you get fewer harmonics because of this. I stopped mid-sentence when I was talking.
On any kind of high resonance filter sweep, as the cutoff frequency comes down on the down-sweep, the harmonics become more sparse and you get a deceleration effect as you get to the bottom of the cycle. This gives the effect of a sine wave type LFO wave, even though it's a triangle (apparently).
Also, since it is a polyphonic synth you can get more overtones than with a monosynth because you can play more notes at once. This is probably why people are noting this on effect polysynth like the P6 (they did on the P5 too).
To make the sweeps as smooth as possible, you probably need to do one or more of these things:
*play only one note at a time
*Have filter keyboard tracking OFF
*Use square waves on the oscillators (that don't have even harmonics, only odd) instead of saws (that have odd and even)
*avoid setting the cutoff in the region where the harmonics are almost chromatic
*set the resonance not above 9 or
*sweep really quickly
The overtones will probably also depend on which wave shape you use of course! Square waves don't have even harmonics, only odd ones but saw waves have odd and even (you can tell intuitively because of the skewed look or asymmetry of the saw shape).
I don't remember hearing that region of the harmonics so clearly on my old Revision 2.0 Prophet-5 with SSM filters. Instead, there was a kinf engine like pushing up sound as the resonance passed through the close spaced overtones and it was a little more vague and less obvious.
5:05+ growly harmonics and near 5:30 you can clearly hear the nearly chromatic part of the harmonic series.
At 6:28-6:50, I said there is some quantising sound on a filter sweep WITHOUT THE... I meant "without the cutoff knob being used" - only the LFO - but again it is just harmonics. You can hear that it is nearly chromatic but not quite. So I conclude that it is just overtones being lit by the resonant filter.
At 7:30-8:30 not a lot happens because I forgot what controls I had moved.
8:22+ and 9:20+ I get the run of almost chromatic notes followed by an arpeggio of the lower harmonics coming out.
At 9:20 you get several chords with arpeggios of harmonics - and again at 10:25+.
9:54 I particularly like this sound! Slow harmonics - leading to almost chromatic ones.
10:23+ I speed it up a bit and get better apreggios of harmonics.
11:45+ Slowing it down again, I get a favourite sound at the end.
Video file MVI 7410.
Keywords:
Sequential, Prophet-6, Prophet, filter, cutoff, harmonics, overtones, resonance, quality, quality factor, Q, keyboard, tracking, sweep, knob, low frequency oscillator, LFO, tone colour, tone color, Prophet-5, Dave Smith Instruments, Dave Smith, DSI,"
