[sdiy] Casio VL-TONE

[rburnett at richieburnett.co.uk]

The chip is apparently a TQFP marked D910G made by NEC.  I suspect it's 
a basic 4-bit microcontroller programmed to make the sounds.  As you 
might imagine the percussion instruments sound like what they are (gated 
bursts of squarewave or white noise.)  They're a long way from anything 
remotely realistic!

To Adam:  I'm just looking at the possibility of adding the Casio 
VL-Tone drum sounds to my DSP based analogue-modelling drum machine.  I 
knew their make-up must be very basic being from that early digital era, 
so figured it might not be too hard to include their models as optional 
sounds along with 606, 808 and 909 models.  If I include them I want to 
do the job properly though, otherwise I'll just leave them out.

Best regards,

-Richie,





On 2014-09-05 01:12, Paul Anderson wrote:
> I believe it is a custom casio chip. Though, oddly enough, there's a
> voice that has programmable parameters. By punching a six digit number
> you set the different parameters.
> 
> Sent from my iPhone
> 
>> On Sep 4, 2014, at 6:41 PM, Adam Inglis <21pointy at tpg.com.au> wrote:
>> 
>> And that was presumably the cheapest (and most compact?) way that 
>> Casio could make a snare sound in 1980. Was it done with a proprietary 
>> Casio chip?
>> 
>> 
>> BTW I'm waiting with breath abated to see what "designer" digital drum 
>> delight Richie is cooking up in his lab using these ingredients...
>> 
>> Adam
>> 
>>> On 05/09/2014, at 6:09 AM, Richie Burnett wrote:
>>> 
>>> Thanks to all those who emailed offering help with this.  I've now 
>>> got some pristine quality 192kHz 16-bit samples of the drum sounds in 
>>> question. These revealed precisely the information I was looking for.
>>> 
>>> For anyone interested, I can now clearly see that the snare sound is 
>>> made up of a Pseudo Random Bit Sequence from a 15-bit Linear Feedback 
>>> Shift Register clocked at about 82150 Hz and using the polynomial 
>>> x^15 + x^14 + 1   An amplitude envelope that decays in 15 discrete 
>>> steps is then applied to this noise.
>>> 
>>> It's amazing what you can see from a decent hi-res audio recording!
>>> 
>>> Many thanks,
>>> 
>>> -Richie,
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>> 
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