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Musical Technology

A Spotterʼs Guide to HIPs and Strings

Posted under Musical Technology at . Last updated 2022-05-05 17:11.
Tags:artwork, ELEX, ELKA, Hohner, Logan, piano, reference, string machine

A summary of investigations into Hohner analogue electronic pianos and string machines. (To date. Not planning any updates at this point, but you never know.)

Not long after the technology became reasonably affordable, Matth. Hohner AG sold several electronic piano and string machine models under their Hohner International brand, apparently aiming at cheapness and portability compared with their acoustic and electromechanical keyboards. Most of these were either rebadged ELEX (Excelsior) products or perhaps Hohner-inspired modifications of them. Some were rebadged ELKA and Logan instruments, and they produced a couple of their own designs. [1] (Hohner did also produce organs, bass keyboards and pedalboards, acoustic and electromechanical piano-like instruments amongst others, but thatʼs not todayʼs topic.)

The plethora of these instruments from different manufacturers, some sold as Hohner, some not, some easily distinguished, some not, some modified either inside or out over their production span, has led to a certain amount of confusion in the years since, and poses a puzzle for people interested in obtaining and/or repairing them. But perhaps itʼs possible to construct a comprehensive overview which will allow them to be identified and distinguished?


HIPs and Strings

Ephemeral photos of most of these instruments turn up occasionally in online sales; longer-term linkable references are given below. Different branding seems to have been used by Hohner in different national markets, however, so even if this list is comprehensive technically (which I canʼt guarantee), there may be alternative names in some parts.

Drawings below are sketches intended to highlight the distinguishing characteristics of the instruments, rather than be exhaustively accurate. Or get the perspective right or anything. Slider caps in particular may vary even in the same model; so Iʼm not trying too hard to represent the exact types found — where they havenʼt all vanished or been replaced.

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Korg SD pictures

Posted under Musical Technology at .
Tags:BBD, Korg, musical equipment, photographs, SD‑200, SD‑400

Side by side shots of the Korg SD delays, the -200 opened for comparison while I convert the -400 for 240V.

Korg SD-400 and SD-200 front panels

The SD-400 (brown) has the bypass, short/long delay option, swell, and ADT settings, but no tone control. I havenʼt quite worked out which I prefer; the -400 seems to have a fixed filter; itʼs smoother than the SD-200 (silver) on simple delays, unless you turn the -200 tone down. Maybe the -200 is better for harsher delays. The only online technical information Iʼve found for them suggests they have roughly the same range of 30–400ms for the -200 and 25–400ms for the -400. Presumably the -400 should go lower on its Short setting, but itʼs the same as the -200 on its Long setting. In practice, comparing these two, the -400 gets up to around 10% longer delay, but that could just be a calibration thing on one of them.

Korg SD 200 and 400 open

Vermona Synth Question

Posted under Musical Technology at .
Tags:hardware, instrument, KHW, questions & answers, synthesiser, Vermona, Synthesizer

Message Received

Flavio, 2016-06-06

Hi there!

Thanks for your articles on the Vermona Synthesizer - I read entirely through the first part, went a bit too techy in the second article but still very interesting.

I got my Vermona Synthesizer a couple of days ago and Iʼm now facing two issue, which I hope you can help/suggest how to solve them.

First of all: for VCO 2 the register buttons donʼt remain pressed (none of them). I opened up the synth and I found out that the mechanism is somehow stuck in the open position (the position in which nothing gets blocked).


Second issue is the keyboard: as some keys were having double triggers or didnʼt trigger immediately, I took an eraser and tried to clean up what was accessible without removing any keys at all. I also moved the plated bars slightly a bit more left and then back right . . . now I got the lower 4-5 keys which play the same note (???) and all the others play ok but some of them are still not clean enough. What is your suggestion for this issue?

Thanks in advance and kind regards,



Well, sometimes I am a bit too techy. Until itʼs the too techy bit you want. Ignore the rest and let the search engines read it. (happy emoticon)

(Iʼm writing these articles because I find it useful to record all the information I discover — less or more techy; and the interesting or entertaining thoughts that happen while looking; Iʼm publishing them specifically because I usually canʼt find the exact techy bit I want online, or anywhere else . . . )


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Vermona Synth Boards

Posted under Musical Technology at . Last updated 2019-09-10 00:00.
Tags:artwork, hardware, instrument, KHW, synthesiser, Vermona, Synthesizer

In spite of the apparent quietness of the last few months, Iʼve been working on synths in between other things; in particular on the Vermona. After the initial post, in the absence of any written technical information, I was planning to draw my own circuit diagrams. Actually I did some board drawings, because thatʼs easier when all you have are last yearʼs photos and enough space to sit. (happy emoticon)[1] A couple of weeks ago, this was complicated by my discovery of a new (I think) and rather great old manuals page at, which includes circuit schematics [2] for both versions of the Synth. The full update I was slowly working on will be rewritten in the light of the new information . . . but it will be better. For now, here are my drawings — with the component numbering brought into line with the schematics, as far as possible. (My earlier numbering was entirely arbitrary as there is no screening on the boards.)

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Korg MS-10 Notes

Posted under Musical Technology at .
Tags:instrument, Korg, MS-10, synthesiser

MS-10s need no introduction, so — hereʼs one. Probably from about 1980 but I havenʼt got it far enough apart to look for component dates.

front (on arrival)

This arrived in a purportedly Pro-Serviced state. In contrast to my many other gripes on the topic, I must note that it was well-packed, and arrived faster than the estimated earliest date. Also in near-perfect physical condition, which for me is a first, for a synth without a case. So would buy again? Maybe. It doesnʼt even smell bad. No rotting food or wildlife, no decaying components, no decades of garage-storage and no undead tobacco. [1]

But Iʼd like to know what Pro-Serviced means. Perhaps that this time Iʼm paying someone to do the things I would normally do myself? This clearly doesnʼt include cleaning, past a cursory wipe; thereʼs a lot of dust ingrained on the modwheel and at the back of the keys.

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Some Pipe and Register Measurements

Posted under Musical Technology at .
Tags:history, organ, prime, typography

(Actually an update to a tangential note.)

I mused:

Are feet and Prime an English-language convention? Since this convention stems from pipe organs, were pipe organs all over Europe described in feet, in the past? . . . Have there ever been organs (or synths) described in cm? Or, were the Prime (′″) marks used with other pre-metric measurements?

From a survey of the web, it seems that different languages do use versions of the foot measurement to describe organ registers, but the Prime mark was not always used. e.g.:

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