[sdiy] Poly 800 (was DSP MIDI Synth (was Re: 566 Functional Replacement))

[Tom Wiltshire]

Checking the circuit diagram, there are eight filter envelopes that are demultiplexed, and eight DCO level envelopes fed to the sound chip. If I understand it right, in “double” mode you get four voices with two DCOs each, so you get two DCO envelopes per voice - hence three envelopes.

I hadn’t looked at it much before. It’s amazing that it’s a rectangular instrument. They cut so many corners on this thing it should be a circle ;)

Tom


> On 1 Apr 2018, at 07:16, rsdio at audiobanshee.com wrote:
> 
> When the Poly 800 was brand new, I was torn by the paraphonic aspect. I ended up passing on the product. It was one of the few keyboards I might have afforded in college, but I decided it was better to save up for a “real” poly.
> 
> However, I thought that only the VCF was monophonic. I got the impression that the digital envelopes were polyphonic. Weren’t there 8 of each of the 3 types of envelopes? I’d have to play one again to hear the answer.
> 
> Brian
> 
> 
> On Mar 19, 2018, at 9:13 AM, paula at synth.net wrote:
>> The Korg Poly 800 did alright with that :)
>> 
>> On 2018-03-19 13:43, Tom Wiltshire wrote:
>>> Yeah, yeah, I know…but one filter, one VCA, and one set of envelopes
>>> is monophonic to me, even if it has got five oscillators ;)
>>>> On 19 Mar 2018, at 11:53, paula at synth.net wrote:
>>>> 5 voice paraphonic, not monophonic..
>>>> it's just nuts, I'd love to hear some better quality demos (i.e. non-mobile phone microphone)
>>>> On 2018-03-19 11:30, Tom Wiltshire wrote:
>>>>> That’s an interesting read.
>>>>> There’s several things that strike me straight away:
>>>>> 1) Naive oscillator waveforms with no band limiting
>>>>> 2) Linear envelopes with 30ms steps, so no fine adjustment at the fast end
>>>>> 3) Very basic filter code
>>>>> I still think getting a entire DSP mono synth into an 8-pin DIP is
>>>>> quite impressive, especially in C, but a 32-bit ARM chip can produce
>>>>> better sound than this is going to.
>>>>> Tom
>>>>> ==================
>>>>>     Electric Druid
>>>>> Synth & Stompbox DIY
>>>>> ==================
>>>>>> On 19 Mar 2018, at 10:16, Vladimir Pantelic <vladoman at gmail.com> wrote:
>>>>>> On 18.03.2018 19:31, Roman wrote:
>>>>>>> And it sounds like crap and makes unpredictible things.
>>>>>> that's perfect for a Eurorack module then! ;)
>>>>>> btw, source code is here for the curiously inclined:
>>>>>> https://www.hackster.io/janost/the-dsp-gplug-midi-synth-80b2aa
> 
> 
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