<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">Check out Don Lancaster's "Pitch Generators for Electronic Music", Popular Electronics magazine, March 1974. It's basically the same thing.<div><br></div><div> https://www.worldradiohistory.com/Archive-Poptronics/70s/1974/Poptronics-1974-03.pdf</div><div><br></div><div>Of course the divider approach has been used in a number of electronic organs to produce a dozen pitches at once that don't need to be individually tuned. And Top Octave Generator chips are probably still available. But they famously suffer from pitch inaccuracies and an unnatural syncing between the pitches.</div><div><br></div><div>The Hammond Organ ("1935 consumer technology") mechanically bases its pitches on a common motor, but that involves a ratio of three gear values, so it's significantly more accurate.</div><div><br></div><div>I don't see any advantages to a divider approach. And there are a number of disadvantages, such as the lack of portamento that you mentioned in your writeup.</div><div><br></div><div>And I especially don't see any advantages over an accumulator approach.</div><div><br></div><div>HOWEVER... in electronic music design, the goal is not to be perfect, but rather that your imperfections are musical and charming.</div><div><br></div><div><div><div><div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div dir="auto" style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div style="color: rgb(0, 0, 0); font-family: Menlo; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"> -- Don<br>--<br>Donald Tillman, Palo Alto, California<br>https://till.com</div></div></div>
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<div><br><blockquote type="cite"><div>On Jul 11, 2025, at 12:19 PM, Phillip Harbison <alvitar@xavax.com> wrote:</div><br class="Apple-interchange-newline"><div><div>Hello, Synth-DIY people. I'm a long time listener but infrequent poster. The following has been on my mind and IO would appreciate your opinions.<br><br>I graduated from the University of Alabama in Huntsville (UAH) in 1981 with a degree in Electrical Engineering. For my senior design project I designed and implemented what I called a Digital Waveshape Generator (DWG). I intended this DWG to be the core of a single voice in a synthesizer. A block diagram and design document are attached.<br><br>I had a strong interest in music synthesizers as I was a trained classical pianist and a fan of progressive rock music. For most of high school I dreamed of being the next Rick Wakeman or Larry Fast, but I did not have the necessary gear. I intended to build my own, but after graduation I was to busy with Real Life to work on toys.<br><br>One reason I lost interest is at the time I thought the master clock frequency needed to be 256 times the least common multiple of the 12 notes of the top octave. I don't recall how I calculated it, but I thought I needed a clock in the hundreds of megahertz and in 1980 the only technology capable of handling such frequencies was ECL, That was not happening on a poor student's budget. I still got an A+ because my advisor did not give a damn if my DWG was musical. He saw it simply as a cool function generator.<br><br>Now that I am semi-retired I revisited my design and the first thing I did was realize that I was wrong about the master clock frequency. For one thing, there is no Least Common Multiple possible since 11 out of 12 notes are not integers. I also realized I don't need to find divisors that will produce the exact frequency of each note. Getting within a few cents would be close enough for rock & roll. After a lot of calculating I determined that a 1802240 clock and a 16-bit divisor would allow me to generate all notes of the top octave within 0.02% of perfect.<br><br>My prototype was wire-wrapped. Now I am wondering if I should create some circuit boards and realize my dream of a DIY digital synthesizer. Is this something anyone else would find interesting? Am I wasting my time? I would appreciate any comments.<br><br>-- <br>Phil Harbison</div></div></blockquote></div></div></div></body></html>