Audio synthesis via vacuum tubes/Using sheet-beam tubes (view source)
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'''Using sheet-beam tubes''' has no parallel in the transistorized age. Between the mid 1930s until integrated circuits became commonplace in the 1960s, special electron tubes were designed to take advantage of specific effects of electron-beam ballistics. Essentially, these tubes were "integrated circuits" before the term even existed. And they did fairly complex things using very simple designs.<ref name="usbdt">[https://web.archive.org/web/20171020033858/http://www.cgs.synth.net/tube/beam.html Using special beam-deflection tubes]
== Background ==
[[File:
The sheet-beam tubes were modified pentodes. Between the suppressor grid and a pair of matching anodes, there were placed two beam-deflection plates. By putting a push-pull modulation AC signal across these two deflection plates, the electron beam could be "forced" to switch from one anode to the other; giving a very good ring modulator effect, with reasonable carrier suppression (provided the input and modulation signals were fairly high in peak voltage). So far, this sounds similar to the differential-amp balanced modulator seen in IC form.<ref name="usbdt"/>
However, the tube has something the IC doesn't.......... a screen grid. By varying the screen voltage between the plate supply voltage and the actual plate idle voltage, drift effects take over, and the peaks of the waveform start to fold over on themselves. Moreover, this folding is not sharp, as in the famed [[Ken Stone/1973 classic Serge/Serge tripple wave-shaper|Serge
== Circuits ==
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== Warning ==
This circuitry is intended for the more advanced builder. Because high voltages are used, a shock hazard exists. We do not recommend that the novice DIY musician try to construct this
All these projects and designs should be considered dangerous if not lethal if not used safely. When working on projects based on these designs, use extreme care to ensure that you do not come into contact with mains AC voltages or high voltage DC. If you are not confident about working with mains voltages, or high voltages, or you are not legally allowed to work with mains voltages, or high voltages, you are advised not to attempt work on them.
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== External links ==
* [http://metasonix.com/ Metasonix]
* [https://www.modwiggler.com/forum/viewforum.php?f=13 Metasonix] subforum at Mod Wiggler Forum
* [http://www.nj7p.org/Tubes/PDFs/Frank/093-GE/6BN6.pdf 6BN6 data sheet]
* Mouser [https://www.mouser.co.uk/ProductDetail/RECOM-Power/R12-100B?qs=%2Fha2pyFaduikktQIuFSUoAlyCfBOgsEWTQI0oSVVCeJHhELUNNCVHQ%3D%3D RECOM Power R12-100B 5W DC/DC converter] - Takes 12 VDC and outputs 135V at up to 50mA, or [https://www.mouser.co.uk/ProductDetail/RECOM-Power/R15-100B?qs=%2Fha2pyFadujT2%2F2uiGzLeAHh0JKwi3RAPisAPJgodY8%3D R15-100B] 15V input version."<ref>[https://www.modwiggler.com/forum/viewtopic.php?f=17&t=219618 Re: TS-23 Tube VCO help] by metasonix, Mod Wiggler Forum, 22 May 2020</ref>
[[Category:Vacuum tube synthesizers]]
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