Xpantastic!

Hi All,
I am thinking about trying this, but can anyone really tell the 
difference in one thousandth of a second. It seems like only a scope  
could tell the difference. And looking at the schematics changing 
Rx51 will only affect the VCA in the filter chip. No other 
destinations, sorry. The second mod looks more promising as this is a 
whole string of 1M resistors in the Sample and Hold Circuit. One for 
each Voltage Controlled Input In the Circuit VCO1,PW1,VCO-VOL1,VCO2
etc... This would affect any modulation source used. ENV, LFO and so 
on. As Mr Doidic points out "you may get more discontinuity in the 
shape of the modulation". Maybe some experementation would be in 
order here. My guess is, if this value was too small the S/H cap will 
discharge too rapidly. Causing a bumpy shape to an otherwise smooth
envelope. 
If I do try this I will let yal know.
Karl


--- In xpantastic@yahoogroups.com, William Cason <randycason102@...> 
wrote:
>
> Wow, that's very interesting.  I would love to see faster envelopes 
on my M12; I'm wondering if that mod works for all destinations of 
that env?
>  
> I'm trying to figure out if I have the guts to try it... anyone 
else?
>  
> Randy
> 
> --- On Tue, 9/9/08, analogholic <publik@...> wrote:
> 
> From: analogholic <publik@...>
> Subject: [xpantastic] Faster envelopes on Matrix 12/Xpander - 
Conversation with one of the designers
> To: xpantastic@yahoogroups.com
> Date: Tuesday, September 9, 2008, 4:52 AM
> 
> 
> 
> 
> 
> 
> Hi everyone,
> 
> When I read the "percussive like patches"-thread, I was reminded 
that 
> I while ago (when the Matrix 12 was my only analog synth) that I 
(as 
> many others) was a bit frustrated with the M12´s slow enevelopes.
> 
> SoI wrote an email to one of the creators of this beast(Michel 
Doidic)
> and asked what could be done. Here is our conversation:
> 
> "Mr Ryle, Mr Doidic, first off I want to thank you for being part 
of 
> designing (among other things) the fantastic Oberheim Matrix 12.
> I have the incredible luck to have found one (Matrix 12) for sale 
in 
> Sweden. Although this is very "off topic", I would be incredibly 
> grateful and happy if you guys could try (who else could?) answer 
the 
> following question: Do you think it would be possible in some way 
to 
> modify the envelopes of the Matrix 12 to be faster ?
> I know they are software envelopes, but today there are a lot of 
> softEnvs that are snappy, also on at least two analog synths which 
> have softwareEnvs (one is Studio Electronics Se-1/x) where if you 
> changed a resistor on the motherboard, the software envelopes 
became 
> dramatically faster and snappier, almost at Minimoog speed. 
> Could it be enough to change resistors in the right place, or would 
> it be necesarry to recode/reprogram the whole software for the 
Matrix 
> 12? I know this a hard question, but a solution,if possible, would 
> mean that a fantastic synth would become the greatest of them all 
> IMHO.
> I thank you once again and send you my best
> regards Attila" 
> 
> His answer:
> 
> "Hi Attila, To do the job right would be very difficult because, as 
> you noticed, the envelopes are generated by the code of the 6809 
> microprocessor. Short of using a faster 6809 (assuming that you 
could 
> get one) and modifying the code there is not much which can be done.
> The Matrix 6 and 12 were designed about 25 years ago, and 
> microprocessors where a lot slower back then. There is still a bit 
of 
> hope however. The fastest time for the envelopes is about 2 
> milliseconds.
> This could be reduce to 1 ms by changing RX51 for the VCA (where X 
> will be 3, 4, 5, 6 or 7 according to which of the six voice it 
> controls on each of the two voice boards) from 18K to 9.1K.
> The next fastest time is set by the microprocessor and an analog 
> smoothing filter on the voltage control circuit (= Sample and 
Hold). 
> This time is set not only by the software but also by a resistor 
RX14 
> on each of the main voice PCB for the VCA control and by RX10 for 
the 
> VCF frequency control.
> You may want to try reducing these resistors from their original 1 
M 
> Ohm value to let say 500K Ohm. This will reduce that time from 
about 
> 7 ms to about 3.5 ms. The draw back however is that you may get 
more 
> discontinuity in the shape of the modulation.
> The next fastest times however will still be determined by the 6809 
> software and that will not change. Give it a try on one of the 
voice 
> and see if that goes toward what you want. 
> Hope that this helps a bit. Michel Doidic Line 6 CTO"
> 
> OK guys, what do you think?
> 
> I changed a resistor in my SE-1, and it become snappier (not 
> fantastic, but better)
> Also, the Chroma has a reputaion of very slow envelopes, but same 
> thing there, if you remove a resistor or change it to a lower 
value, 
> envelopes supposedly become faster.
> 
> I would even go so far to check out the possibilities of putting in 
a 
> faster processor and find someone to recode the software. 
> 
> Brainstorming please begin :)
>