Doepfer

Enough already Peter.  I submit.  Okay... when can I buy a couple?  Seriously, I'm sold.

Regards,
Kevin


--- In Doepfer_a100@yahoogroups.com, "(i think you can figure that out)" <peter@b...> 
wrote:
> Oddly enough, the saw waveshaper in this cicuit is my design 
> and about the only part that I'm really proud of as it uses only two 
> componets, tracks wonderfully across the whole frequency 
> range and sounds great (this is what you're hearing with the high 
> end fizziness you mentioned). 
> 
> As far as the improvements, most of what I did was replace all of 
> the 258's wacky discrete components with ICs and modern day 
> equivelents.  Buchla used an FET for the initial amplification, I 
> used a TLO Op amp.  He had a discrete comparator made from 
> a series of NPNs, I used an LM311.  Most significant however is 
> that ALL of the semiconductors in the core circuit in the original 
> 258 are obsolete now and it will cost you about $125 for these 
> parts alone if you set off to make one in the 21st century.  I 
> replaced all of these with modern day equivelents and in so 
> doing, dropped the cost significantly and decreased the 
> matching from 5 mv to .3mv (this is a good thing btw as it effects 
> the drift).
> 
> Luckily, these subs did not change the sound at all.  You see, I 
> was building a 258 kit for somebody when I designed this circuit 
> and had one here for a sonic reference.
> 
> As far as the other additions, I just looked the circuit over added 
> things that Buchla omitted originally.  For instance, he didn't have 
> a sync input (VERY easy to add).  While he had square out, he 
> didn't have PWM.  Without going into details, the way Don made 
> the square waves would not allow for PWM. I used the traditional 
> method off the triangle core and was amazed at the sound.  Don 
> also didn't elect to bring the triangle waveform to the faceplate.  
> Given that this is a triangle core VCO, it's VERY easy to do that, 
> so I did. 
> 
> Another thing - in that all of my waveshapers are first generation 
> (all using the triangle as a source), I was able to include a 
> waveshape crossfader (which I call morphing) because all of the 
> waveshapes are in phase with one another.  Now, I'll admit this 
> part doesn't sound like the Buchla method, which sort of 'grew' 
> either a ramp of square out of the sine waveshaper circuit, but I 
> am happy with my results.  As a point of ference, I used vactrols 
> in my crossfader which really smoothes the cross fading out, 
> much more so if it was done soley with op amps.
> 
> What I tried to do was make a VCO that behaved like a 258 in it's 
> reaction to FM (AC) and frequency response to linear VC (DC).  
> That part I was able to nail down accurately.  I wasn't concerned 
> if the other parts sounded different, because both being triangle 
> core I knew they wouldn't be THAT different and they aren't
> 
> - Peter