4600/5600 synth: any know more?

[David Halliday (Volt Computer)]

A minor comment about the digital noise source - it is generated by a
pseudo-random shift generator. The problem is that the period repeats
every few seconds - this is 99% of the time not a problem but in cases
where you have long periods of nothing but noise, the repetative nature
is very obvoius.  It is possible to build longer length PSR-SG's but the
chip count gets a bit much compared to the traditional back-biased
analog transistor unit.



> -----Original Message-----
> From:	Prof. Antonio Guerrieri [SMTP:ga026sci at pzuniv.unibas.it]
> Sent:	Monday, September 15, 1997 2:27 PM
> To:	synth-diy at horus.sara.nl
> Subject:	4600/5600 synth: any know more?
> 
> 	Hi All,
> 
> 	Someone wrote:
> 
> >I'm amused at all the excitement about the 5600.  I downloaded the
> 4600
> >docs yesterday and saw how strange some of the circuits are in this
> synth.
> >(7 and 14 volt rails? Huh?)
> >
> >The idea behind the transient generator is really good, combining an
> EG
> >with a VCA to provide different types of responses.  Maybe there's a
> way to
> >update this design to work with a more standard +/-15V.
> >
> >R>
> 
> 	Incidentally, I'm trying to build up a 4600/5600 synthesizer
> and,
> sorry, I do not think that an electronic device can be just judged by
> the
> power supply rails!!
> 
> 	At the moment, I have just done some little modules so I am not
> able to give you a critical rewiew of such a synth. However,
> discussing
> about with other  related mailing list people, the following appears:
> 
> - VCO/EG/Mixer/Transient (i.e. ADSR): good;
> - Noise generator: interesting, it is digital !!;
> - VCF: probably, the more interesting from the circuital point of view
> but
> also probably a not nice filter (just 12 dB, no CV control of
> resonance,
> etc.);
> - Keyboard module: the analog one (4600) requires a further little
> module
> which corrects some faults/ the digital one (5600) SEEMS ok.
> 
> 	If any know more, I would like to read more critical issues
> about
> this synth.
> 
> 	Best regards,
> 
> 	Antonio
> 
>