Doepfer

Peter,
 
In the event that Dieter is not compelled to develop a 258, I would ask
you to consider a short run of your design.
 
Also any chance of some sound bites of your VCO?
 
Many thanks
 
David
 
 

David Salter 
Reuters Ltd 
UKI Project Management 
Tel. +44 207 542 2402 
Fax. +44 207 542 2699 
Email. david.salter@reuters.com 
Reuters Messaging. david.salter.reuters.com@reuters.net 

	-----Original Message-----
	From: (i think you can figure that out)
[mailto:peter@buzzclick-music.com] 
	Sent: 18 June 2004 19:52
	To: Doepfer_a100@yahoogroups.com
	Subject: [Doepfer_a100] Re: Complex oscillator
	
	
	Doefperions -
	
	258/259 - whaddya want to know?
	
	I've built a Buchla 258 kit and passed on a 259 kit once seeing 
	the how much work envolved, but I am intimately familiar with 
	both of them.
	
	There's a few things about these guys which make them unique 
	- they have triangle wave cores.  This means the basic engine of

	the circuit creates a triangle wave, as opposed to a saw wave 
	that most VCOs out there work from, including the Doepfers.  
	Other VCOs which incorporate a triangle core are Wiard and 
	Aries.
	
	What a trui core affords you is a completely different reaction
to 
	AC FM (and PWM if you care to doo that, which Buchla didn't) 
	than almost anything out there, which is one of the personality 
	traits ofthe Buchla VCOs.  The FM is really really warm.
	
	The 258 and 259 have basically the same engine, although 
	Buchla replaced many of the discrete parts in the 258 with ICs
in 
	the 259. Not to worry,  most of these parts are not 'sounding' -

	(not in the audio path), but functions such as the internal
reset, 
	which on the 258 is done with a bunch of matched transistors 
	(begs the question of 'why'), were rightly done with a LM311 
	comparator in the 259.
	
	Another difference (actually, a big one) was the selection of 
	what's called an expodential converter in the 259.  In the 258, 
	Don used the infamous UA726 IC, an absolete part also used in 
	the rev 2 Minimoog VCOs which would set you back upwards to 
	$150 A PIECE if you needed to replace one today.  Don used 
	another part for the 259, also obsolete now but easily sub'd
(not 
	so with e UA726) but because of this difference, the 259 FM 
	does not sound the same in the 259 - and it's my opinion that
the 
	258 sounded better. Let it be known, from personal experience 
	the Buchla 258 expo circuit conventions can be duplicated with 
	modern day components - but it's a trade secret (mine) and I'm 
	not tellin!!!
	
	Another unique quality of the Buchla VCOs is the sine 
	waveshaper.  Not a Buchla design (although he did some major 
	hacking with it), but one borrowed from an article published in 
	Electronics Magazine in the mid 60's which also later appeared 
	in the first edition of electronotes.  It intentionally
overdrives two 
	diodes to bring them into nonlinearity and produces one of the 
	sweetest sines out there.  Dieter, if your listening - this too
would 
	be an absolute requirement if your intention was to make a VCO 
	which behaved like Buchla's.  For my buck,  this is arguably 
	better than the Thomas Henry tri to sine converter circuit,
largely 
	held as the best out there.
	
	This is where the simularities of the 258 and 259 end.  The 259 
	had with it a very complex waveshaper and a modulation VCO.
	
	They are GREAT VCOs - both of them.  They don't track worth 
	shite, but remember, the Buchla was not considered a 
	performance instrument as much as a studio instrument, so 
	periodic tuning was not as much as an issue.
	
	Let it also be known that there's a way to fix this, too...but I

	reserve this also as my trade secret!
	
	OK OK OK - I've done a VCO which while not a clone of the 258 
	by any means, sounds pretty much identical on all counts and 
	does things it didn't  (both hard and soft sync, PWM, a triangle

	output and selectable wavemorphing among other things) and 
	it's much more stable.  I am contimplating bringing it to
market. 
	although the jury is still hung on this one.  I have two made
now, 
	both in Doepfer size configuration to fit my system, with a
couple 
	more to come in the next few months (i'm having PCBs designed 
	now).
	
	hope this helps,
	
	Peter
	
	
	
	
	
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