Not sure what you are reading, but that is not how the E-II works. The E-II uses DPCM mu-255. That's a technology borrowed from American Telecom Companies. That's an algorithm that gets similar results to 12 bit sampling with 8 bits of storage and ramI am pretty certain, as I have read it on multiple sources, that the original Microwave does what PPG Wave does, which is, similarly to the Emu II, it uses "pitch dictated EPROM scanning" (it would obviously be RAM on the Emulator) into an analog filter.
Simplified, it's a pulse corresponding to the pitch going into an increment input of an encoder, which goes into lesser significance address bits (higher significance ones selected the table), which effectively scans the ROM in such speed that a full cycle corresponds to the pitch fundamental. The value from the ROM is converted into a voltage in a fairly primitive DAC.
The E-II has no pitch fundamental, much like the telephone technology it uses wasn't concerned with pitch, the E-II isn't either. The E-II takes incoming audio and records it using the Telecom technology, then it stores that on a disk as a DPCM file at a 27.7khz sample rate.
On playback the DPCM file is loaded into system RAM from disk and assigned a root note. That is just there for math purposes, upon playback the CPU inside of the E-II changes the sample playback rate to alter pitch. Play it down an octave? It will drop from 27.7khz to 13.85kh, Play up an octave it and it will be 55.4khz. When you do this the pitch and the playback length of the samples changes. That data stream then goes through a DAC borrowed again from American Telecom
In Telecom use it uses an ADC to digitize your voice send it down the pipe in real time where it uses a basic DAC on the other end to convert it back to analog audio. E-mu recreated that only they also inserted a data recorder and playback system that plays back at variable speeds which also changes the pitch
The system because it uses off the shelf Telecom parts and designs on the digital parts made the E-II sound amazing and did so at an incredibly inexpensive cost compared to the Fairlight CMI or Synclavier II.
Essentially what E-mu did was take a basic analog subtractive synth design with 8 voices only instead of analog oscillators it plays back phone conversations at various speeds just like you were manipulating the speed of a tape deck, or record player
You wouldn't do that on a Wavetable synth, it would be to expensive to produce and not be needed for single cycle waveforms
Also should note that the Arturia plugin version of the E-II nails the digital side perfectly as the 8 Bit DPCM mu-255 is super well documented and they just needed to insert that into an analog synth model
Statistics: Posted by IvyBirds — Sat Aug 03, 2024 3:36 pm