crap Synth idea-DIY

J.D. McEachin jdm at synthcom.com
Thu Feb 29 06:36:33 CET 1996


On 27 Feb 96 at 12:38, Clive wrote:

> This list is entitled "Synth-DIY", not "I think it's a crap Synth   
> idea-DIY", "You need $$$$ to build a synth before you start DIY" or "I'll  
> approve your ideas synth-DIY". Give us a break.

By this logic, if someone were to write "I'm going to build an Arp Quadra
Phaser clone" two months from now, then it would be wrong for Juergen to say "I
wouldn't recommend it, because I built one, and I had problems w/ distortion
on anything but pure sawtooth waves".  If we can't get any useful criticism of 
our ideas on this maillist, then what's the point of having it?  Isn't it a good 
thing to be able to benefit from the experience of others?

My original post said:

> >Building the keyboard seems like a complete waste of time. 
                         ^^^^^
If you are at all familiar with the English language then you know that this 
denotes an opinion, not a fact.  Please treat it as such.

> I think you completely miss the point here - it's got nothing to do with  
> cost as most engineers/tech's build for building sake to satisfy themselves,
> because *you* think it's a crap or expensive idea doesn't   mean others can't
> obtain something from it.

I think you completely miss the point here - just because I have spent
approximately 800 hours in the past year dealing with keyboard scanning and
the programming of mono and polyphonic voice assignment algorithms, and chose
to voice my opinion on the usefulness of building your own keyboard decoding
circuitry, doesn't mean that *you* can't go ahead and build one if you think
you can obtain something from it.  Whether you can benefit from my experience
or not remains to be seen.

BTW, the only poly (more than 2 notes of polyphony, that is) keyboard I am 
aware of that doesn't use a CPU is in the CS-50/60/80, and that uses a 
custom Yamaha LSI chip to do the trick.

Detecting which keys are depressed are the easiest part of the problem.  
Then you have to decide how to assign notes to a (presumably) limited 
number of voices.  Unison, rotating, nonrotating assignments - how are 
you going to do this in hardware?  These are difficult enough to 
implement in software.

My point is this: you really, really need a CPU to implement a polyphonic 
keyboard.  If you have a CPU, why not slap a MIDI interface on it and 
just read the output of a MIDI keyboard, and chuck the whole keyboard 
decoding part of your project?


On Mon, 26 Feb 1996, Haible_Juergen#Tel2743 wrote:

> Just to "proove" that my MS-20 filter is a "waste of time" as well:
> 
> Total time invested into the module: 25.5 hours.

Juergen, you need to spend more time with Ian.  He could teach you how to 
build a module or two in just an evening.  Maybe you could teach him how 
to not blow up so many chips!


Gene wrote:

>      In the same way much of synthesizer technology is running away from 
>      us. So in order to keep up I think it may be good for hobbyists to 
>      pursue back-breaking digital implementations of fairly mundane 
>      functions. Knowledge is power.
 
Where do you draw the line w/ DIY?  My philosophy is to buy what I can, 
and build what I can't buy.  If someone wrote "I'm hand-wrapping my own 
power supply transformers", wouldn't you feel compelled to tell them they 
could buy a transformer for US$10?

JDM




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