I love the DX7 but it's a shame that the maximum LFO frequency is so low. It really hampers the sound design possibilities
Yamaha DX7 Technical Analysis
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Re: Yamaha DX7 Technical Analysis
#22> In mathematical terms, FM synthesis is achieved by using the instantaneous amplitude of a sound wave (the modulator) to adjust the rate of change in the phase angle of another wave (the carrier). > As convoluted as this sounds, it makes more sense when visualised: [1] ...but does it?? [1] https://ajxs.me/static/img/articles/dx7_technical_analysis/f...
"rate of change of the phase angle" is just a convoluted way of saying 'frequency'
I'm not sure. Intuitively I would think "phase angle" means "offset into the sine wave lookup table".
If you step through the lookup table with constant size steps, you would get a sine wave. If the steps are not constant size then you get a distorted sine wave. The "rate of change of the phase angle" would then be the step size.
Re: Yamaha DX7 Technical Analysis
#23> In mathematical terms, FM synthesis is achieved by using the instantaneous amplitude of a sound wave (the modulator) to adjust the rate of change in the phase angle of another wave (the carrier). > As convoluted as this sounds, it makes more sense when visualised: [1] ...but does it?? [1] https://ajxs.me/static/img/articles/dx7_technical_analysis/f...
> ...but does it??
I think in this case the clearest explanation is the equations + graphs:
1. modulator(t) = sin(t)
2. carrier(t) = sin(t*4)
3. result(t) = sin(t*4 + d modulator(t)/dt) = sin(t*4 + cos(t))
EDIT: it's wrong, see below
Re: Yamaha DX7 Technical Analysis
#24The synth that made a new genre of music possible - 80's music would not have been the same without it.
Re: Yamaha DX7 Technical Analysis
#25Earlier quoted context omitted.
"rate of change of the phase angle" is just a convoluted way of saying 'frequency'
I'm not sure. Intuitively I would think "phase angle" means "offset into the sine wave lookup table". If you step through the lookup table with constant size steps, you would get a sine wave. If the steps are not constant size then you get a distorted sine wave. The "rate of change of the phase angle" would then be the step size.
"frequency" would mean the same thing in your weird practical analogy.
Re: Yamaha DX7 Technical Analysis
#26Awesome -- the DX7 had a huge musical impact.
I repair them to keep them in play, impossible to get some of the parts so I tend to use one that is too far gone to repair a number (usually three or so) of others and then I still end up with some more spares that might come in handy later. They are incredibly durable, one that I got had been in a fire but it still worked, even though more than half of the keyboard had been burned off. The mainboard went on to repa…
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Re: Yamaha DX7 Technical Analysis
#27Earlier quoted context omitted.
"rate of change of the phase angle" is just a convoluted way of saying 'frequency'
I'm not sure. Intuitively I would think "phase angle" means "offset into the sine wave lookup table". If you step through the lookup table with constant size steps, you would get a sine wave. If the steps are not constant size then you get a distorted sine wave. The "rate of change of the phase angle" would then be the step size.
This is exactly how direct digital synthesis works and the 'step size' is labelled 'frequency' (specifically, frequency in HZ = step size / size of table * update rate)
Re: Yamaha DX7 Technical Analysis
#28I love the DX7 but it's a shame that the maximum LFO frequency is so low. It really hampers the sound design possibilities
I think I saw somewhere that you can actually tell the LFO is done in software because it actually slows down if you move the sliders a lot while the CPU tries to pay attention to too much at once.
Re: Yamaha DX7 Technical Analysis
#29I love the DX7 but it's a shame that the maximum LFO frequency is so low. It really hampers the sound design possibilities
I think I saw somewhere that you can actually tell the LFO is done in software because it actually slows down if you move the sliders a lot while the CPU tries to pay attention to too much at once.
Yeah it's a shame, on the other chips you can get amazingly air-y textures by setting the LFO to noise and then putting the frequency all the way up. See this video for example: https://youtu.be/_xL3qr-9-ZE
Re: Yamaha DX7 Technical Analysis
#30Interestingly, the DX7's log drum patch is having a massive comeback in the South African genre Amapiano. I would draw a parallel here to the 808 bass, in that I wouldn't be surprised to see the Log Drum become a lasting element in South African electronic music.