MOTM

thanks, Barry S.

Hello Barry,

I think Al's answer covers most of the details on Del's axe.  I got to
check it out (and play it a bit!) at soundcheck in San Jose on the first
('94) SR tour.  Just a pickup -> Pitch/CV converter -> EMS Synthi.  Del
said that he'd owned that Synthi since '73 or '74, when they toured Europe
and his original VCS3 was blown out by the different power supply there.
I've greatly enjoyed using the pitch/CV converter on my MS-20, both for
melodic/pitched and "weird" stuff.  Definitely a good way of adding human
unpredictability to synth work.

And, in the interest of on-topicality, I'll point out that I played MOTM
(as well as Prophet 600, MS-20 and Triwave Picogenerator) in the Hawkwind
cover band (Ad Hawk) I had (and would still have, if the guitarist hadn't
moved to LA last month with the drummer to follow in early 2001).  Yes,
Hawkwind are (one of, if not THE) main reason(s) I love analog synths ...

	-Doug
	 ceres@...

>Hello Barry,
>
>I think Al's answer covers most of the details on Del's axe.  I got to
>check it out (and play it a bit!) at soundcheck in San Jose on the first
>('94) SR tour.  Just a pickup -> Pitch/CV converter -> EMS Synthi.  Del
>said that he'd owned that Synthi since '73 or '74, when they toured Europe
>and his original VCS3 was blown out by the different power supply there.
>I've greatly enjoyed using the pitch/CV converter on my MS-20, both for
>melodic/pitched and "weird" stuff.  Definitely a good way of adding human
>unpredictability to synth work.

Cool! So whe are we going to see a MOTM Pitch->CV? Is it possible to get a
Pitch->CV out of existing modules (I've converted bass to an ugly square
wave via the octave divider, but it's not exactly the same thing.
>
>And, in the interest of on-topicality, I'll point out that I played MOTM
>(as well as Prophet 600, MS-20 and Triwave Picogenerator) in the Hawkwind
>cover band (Ad Hawk)

Great band name!



 Yes,
>Hawkwind are (one of, if not THE) main reason(s) I love analog synths ...
>
Yeah, I spent my fair share of early college smoking pot and listening to
Hawkwind and Gong. Ahh, the daze.///

____________________________________________
Dave Trenkel : improv@...
Minus Web Site: http://listen.to/minusmusic
Minus MP3's: http://www.mp3.com/-minus-
____________________________________________

If you are using an EMS, just set up the guitar or keyboard stock patch
and plug right in (or bump it with an eq or compressor) and off you go.

Almost thirty years later the Hawks are still turning people on to synths

G. Wong

baron swodeck wrote:

> 
> So does that mean that if I had a pitch/CV converter I could play my
> guitar the same way? If so where can I get one?
> 
> >From: improv@...
> >Reply-To: motm@egroups.com
> >To: motm@egroups.com
> >Subject: Re: [motm] Re: Del Dettmar's double headed synth wood-axe
> >Date: Wed, 6 Dec 2000 15:09:52 -0800
> >
> > >Hello Barry,
> > >
> > >I think Al's answer covers most of the details on Del's axe. I got
> to
> > >check it out (and play it a bit!) at soundcheck in San Jose on the
> first
> > >('94) SR tour. Just a pickup -> Pitch/CV converter -> EMS Synthi.
> Del
> > >said that he'd owned that Synthi since '73 or '74, when they toured
> Europe
> > >and his original VCS3 was blown out by the different power supply
> there.
> > >I've greatly enjoyed using the pitch/CV converter on my MS-20, both
> for
> > >melodic/pitched and "weird" stuff. Definitely a good way of adding
> human
> > >unpredictability to synth work.
> >
> >Cool! So whe are we going to see a MOTM Pitch->CV? Is it possible to
> get a
> >Pitch->CV out of existing modules (I've converted bass to an ugly
> square
> >wave via the octave divider, but it's not exactly the same thing.
> > >
> > >And, in the interest of on-topicality, I'll point out that I played
> MOTM
> > >(as well as Prophet 600, MS-20 and Triwave Picogenerator) in the
> Hawkwind
> > >cover band (Ad Hawk)
> >
> >Great band name!
> >
> >
> >
> > Yes,
> > >Hawkwind are (one of, if not THE) main reason(s) I love analog
> synths ...
> > >
> >Yeah, I spent my fair share of early college smoking pot and
> listening to
> >Hawkwind and Gong. Ahh, the daze.///
> >
> >____________________________________________
> >Dave Trenkel : improv@...
> >Minus Web Site: http://listen.to/minusmusic
> >Minus MP3's: http://www.mp3.com/-minus-
> >____________________________________________
> >
> >
> 
> ----------------------------------------------------------------------
> Get more from the Web. FREE MSN Explorer download :
> http://explorer.msn.com
> 
>                       eGroups Sponsor
> [Click Here!]

On Wed Dec 6, 2000 3:09pm, Dave Trenkel wrote:
>Cool! So whe are we going to see a MOTM Pitch->CV? Is it possible to get a
>Pitch->CV out of existing modules (I've converted bass to an ugly square
>wave via the octave divider, but it's not exactly the same thing.

I would love to see one, too.  I have a set of MS-20 schematics and have
been tempted to build a clone of the pitch->CV section (if I had better DIY
skills), but that would yield a V/Hz CV, unfortunately.  I actually find
the MS-20 external signal processor to be quite usable, and sufficiently
accurate if you play the source instrument with the correct touch.

>>And, in the interest of on-topicality, I'll point out that I played MOTM
>>(as well as Prophet 600, MS-20 and Triwave Picogenerator) in the Hawkwind
>>cover band (Ad Hawk)
>
>Great band name!

Thanks!  The name comes from the fact that I put the band together less
than a week before the show, with only one rehearsal.  Good thing the
guitarist and drummer were so good (and were already very familiar with the
tunes) ...

	-Doug
	 ceres@...

I have the schematics for a Korg device that was a stand-alone instrument
interface that came out around the same time as the MS series (I want to say
that it was called the "MS-09" but I'm sure that's not right). I *think* it
had both linear and exp control outputs on the pitch/CV converter. As well
as envelope follower, pre-amp, etc.

I don't know if a pitch-cv converter is the kind of thing you want to return
to a 25-year-old schematic for, though, is it? It's not like a filter that
might have a vintage sound; in this case you have a very specific result in
mind, and accuracy is everything. I would think (could be wrong) that after
a quarter century of electronic advances, we (not meaning 'me') should be
able to come up with a better design, no?

 -----Original Message-----
From: 	Doug Pearson [mailto:ceres@...] 
Sent:	Thursday, 07 December, 2000 4:25 PM
To:	motm@egroups.com
Subject:	[motm] Re: Del Dettmar's double headed synth wood-axe

...

I would love to see one, too.  I have a set of MS-20 schematics and have
been tempted to build a clone of the pitch->CV section (if I had better DIY
skills), but that would yield a V/Hz CV, unfortunately

...

Seems simple enough conceptually. Square up the input signal with a 
comparator, feed it to a counter and timer that determine the time 
between 2 cycles, use that number to index into a memory lookup table 
representing the output voltage transfer function that you want, use 
a DAC to bring it back into the analog realm. Add an envelope 
follower cause you'll need a gate extracter, a latch to hold the 
lookup table address at the last valid value whenever the input 
signal disappears, and bingo!

The fun would be in designing some data compression tricks so that 
you would have good resolution, but could avoid a giant table.

It would still have the limitation that all P-V converters have, in 
that you have to wait a full cycle before you know what the pitch is -
 the source of notorious lag problems on bass frequencies.

Moe

--- In motm@egroups.com, "Tkacs, Ken" <ken.tkacs@j...> wrote:
> I don't know if a pitch-cv converter is the kind of thing you want 
to return
> to a 25-year-old schematic for, though, is it? It's not like a 
filter that
> might have a vintage sound; in this case you have a very specific 
result in
> mind, and accuracy is everything. I would think (could be wrong) 
that after
> a quarter century of electronic advances, we (not meaning 'me') 
should be
> able to come up with a better design, no?

the only problem with that design is that it only works well with pure
waveforms one note at a time. sounds rich in harmonics like guitar or
other natural instruments confuse counters and give very unpredictable
results. try playing a guitar chord through a MOTM-700 and listen to
what comes out. the pitch to cv from tomg has this problem, it's only
accurate over a small frequency range, plus it only responds well to
clean waveforms (i believe it was based on dr. bob's theremin to cv
circuit) -Nate

Dave Bradley wrote:

> Seems simple enough conceptually. Square up the input signal with a
> comparator, feed it to a counter and timer that determine the time
> between 2 cycles, use that number to index into a memory lookup table
> representing the output voltage transfer function that you want, use
> a DAC to bring it back into the analog realm. Add an envelope
> follower cause you'll need a gate extracter, a latch to hold the
> lookup table address at the last valid value whenever the input
> signal disappears, and bingo!
>
> The fun would be in designing some data compression tricks so that
> you would have good resolution, but could avoid a giant table.
>
> It would still have the limitation that all P-V converters have, in
> that you have to wait a full cycle before you know what the pitch is -
>
> the source of notorious lag problems on bass frequencies.
>
> Moe
>
> --- In motm@egroups.com, "Tkacs, Ken" <ken.tkacs@j...> wrote:
> > I don't know if a pitch-cv converter is the kind of thing you want
> to return
> > to a 25-year-old schematic for, though, is it? It's not like a
> filter that
> > might have a vintage sound; in this case you have a very specific
> result in
> > mind, and accuracy is everything. I would think (could be wrong)
> that after
> > a quarter century of electronic advances, we (not meaning 'me')
> should be
> > able to come up with a better design, no?
>
>
>
>                       eGroups Sponsor
  [Click Here!]
>

--- In motm@egroups.com, Nathan Alan Hunsicker <nate@e...> wrote:
> the only problem with that design is that it only works well with 
pure
> waveforms one note at a time. sounds rich in harmonics like guitar 
or
> other natural instruments confuse counters and give very 
unpredictable
> results. try playing a guitar chord through a MOTM-700 and listen to
> what comes out

Well, sure! If you're asking for a circuit to pick apart a guitar 
chord and analyze it, you're dreaming. The point of the comparator 
circuit I spoke of is precisely to get rid of the harmonics of a 
single note and just create a fundamental. Sorry, but monophonic is 
still the best you can do without hex pickups, six separate analysis 
circuits and all that crap. A wired fretboard would give you better 
results, but then that's not pitch to CV anymore...

Moe

Even without talking about polyphony, it's still a trick to pull a pure
waveform out of an acoustic source with a comparator in order to extract the
pitch information. If you look at a single pure guitar note on a scope, you
will see that, unlike with a pure geometric synth waveform that crosses the
zero-threshold only twice per period, the acoustic wave may cross many more
times than that, and as the note continues and decays, and harmonic phases
change, the number of crossings per period may change.

Generally you want to do some gentle lowpass filtering before you get to the
comparator. You aren't using the input for sound---just for data---so you
can beat it up any way you need to in order to get that period info out of
it! So if you whack off as many of the upper harmonics as you can, THEN
square it up, you're better off.

The next issue with Pitch->CV converters is response time. The human ear can
hear some pretty low frequencies. As you start getting down there, the
amount of time it takes for a P/CV to figure out what the pitch is can be
noticeable, since typically a few cycles need to go by before the circuitry
can "lock on."

I would really love to see someone come out with a good, economical synth
module to do this. It's long been a dream of mine to own one.

In a message dated 00-12-08 08:53:58 EST, you write:

<< 
 I would really love to see someone come out with a good, economical synth
 module to do this. It's long been a dream of mine to own one. 
 
  >>


ken,
sadly, i don`t think this pvc device / module is available any more but a 
company called "gentle electric" ( a gentleman named carl fravel ) used to 
make a very good unit. at one time, he sold the circuit boards o.e.m. and 
there were serge and aries versions available ( in fact, way, way back, he 
used to work for aries ) in addition to free standing units. i had one built 
into a custom panel ala serge ( prior to their availability in that format ). 
it worked very well with about any monophonic signal i threw at it and the 
response time was good, too.
maybe we can do a search and see if carl is still around.....perhaps if there 
is enough interest, he`d do another run of the boards ( or maybe some are 
still packed away in his closet or something) or license the design to an 
enterprising current synth maker who might be interested in producing it - ?
just an idea.......
best,
dave