MOTM

Hey fellas,

I have noticed in my two VCO system that when I use the transpose switch on 
my Roland M-181 keyboard or play higher up in scale thru my Kenton that the 
VCO's do start to sound flat or slightly off key. Especially one compared to 
the other. Could be my calibration (Unique problem to me) It is not a big 
difference, but in a live situation I would have to re-adjust the tuning of 
the 300's on the fly. Not very easy to do in an accurate fashion on stage 
right? Who out there plans to change these resistors and has anybody else 
had similar problems? Thanks loyal friends,

Thomas White

"MOTM 300", Still one thousand miles ahead of the competitors and a million 
miles ahead of the Moog VCO's! Has anybody ever thought about trying to get 
together some beautiful MOTM cheerleaders? JK


>From: "Paul Schreiber" <synth1@...>
>Reply-To: motm@egroups.com
>To: "MOTM listserv" <motm@egroups.com>
>Subject: [motm] MOTM-300 resistor change
>Date: Sun, 13 Aug 2000 21:23:21 -0500
>
>**NOTE**
>
>This is NOT a required change! Please read the following carefully!
>
>***************************************************************
>
>All new MOTM-300 kits will be shipped with R50 changed from 3M to 2M2 (also
>called 2.2M).
>
>Assembled MOTM-300s will have a 2M2 or a 1M8 depending on the particular
>performance
>of that circuit.
>
>This resistor adjusts the "High Frequency Track" of the VCO. Specifically,
>the tracking accuracy from 500Hz
>and up. No, I can't make it a pot because that causes more problems than it
>fixes.
>
>Newer batches of the MAT02EH NPN transistor used in the exponential
>converter show *improved* HFT
>when R50 is lowered.
>
>Now, should you immediated tear apart your MOTM-300 to replace this?
>NONONONONONONO!
>
>*ONLY IF* you think that in tracking multiple VCOs ABOVE 500Hz you have an
>issue, then you
>can change this resistor. You WILL HAVE TO RECALIBRATE THE VCO IF YOU DO
>THIS!!
>
>The following is the tracking of 1 VCO with R50 changed. Voltage source is
>Pro-2000. Errors in the Pro-2200
>are included in this (about 700uV over the range).
>
>Desired   Actual     With R50 = 3M
>25            24.97        24.91
>50            49.98        49.92
>100         100.01       100.2
>200         200.07        200.18
>400         400.06        399.97
>800         799.97        796.1
>1600        1599.5       1587.2
>3200        3197          3180
>6400        6386          6369
>
>This is an improved *average* error over 8 octaves of 0.065% Let's see
>anybody else top this!! :)
>
>You can see how the VCO "runs flat" in the upper octaves. Now, can you
>*hear* this? Probably NOT!
>But, if you are 'zero beating' VCOs without sync in lower octaves and want
>to maintain that in the upper
>ones, the lower value resistor will help.
>
>If you want a freebie 2M2 resistor(s), send me email.
>
>Paul S.
>
>
>
>
>
>
>

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--- In motm@egroups.com, "thomas white" <djthomaswhite@h...> wrote:
> Hey fellas,
> 
> I have noticed in my two VCO system that when I use the transpose 
switch on 
> my Roland M-181 keyboard or play higher up in scale thru my Kenton 
that the 
> VCO's do start to sound flat or slightly off key. Especially one 
compared to 
> the other. 

A little detective work is in order here before you blame your 300s. 

First, it's hard to please 2 masters, so to speak. Your Kenton and 
Roland may be calibrated slightly differently. If so, you will be 
able to calibrate your 300s to play in tune with one or the other, 
but not both.

Second, the Roland may track fairly accurately when you play the 
keyboard, only to introduce errors when you use the octave switches.

If the 2 vcos track differently than each other using the same 
source, you need to calibrate them as closely as possible.

If they stay in tune with each other in the low mid range, but get 
further out of tune in the higher range, you may have one that needs 
the high frequency tracking resistor change that Paul mentioned. The 
problem with only 2 vcos is that it may be hard to tell which one is 
tracking correctly, and which one is not linear.

My fave calibration technique is to beat a tracking vco against a 
nontracking drone vco. Hendry likes to feed the drone into the 120 to 
get exact suboctaves, so you can do close comparisons over many 
octaves.

Moe

...A lot of junk deleted...  It would be cool if MIDI-CV convertors let you
compensate for tuning problems in our VCOs.  A very clever method is
probably waiting out there to do this.  Unfortunately I don't think the
convertors out there currently are that advanced yet.

--Shemp (out there)

> First, it's hard to please 2 masters, so to speak. Your Kenton and
> Roland may be calibrated slightly differently. If so, you will be
> able to calibrate your 300s to play in tune with one or the other,
> but not both.

--- Tentochi <tentochi@...> wrote:
> ...A lot of junk deleted...  It would be cool if MIDI-CV convertors let you
> compensate for tuning problems in our VCOs.  A very clever method is
> probably waiting out there to do this.  Unfortunately I don't think the
> convertors out there currently are that advanced yet.

The Encore Expressionist has a scaling value for each output in each patch.  I've
used this to compensate for various scaling issues at times.  The most common need
for it is when I have a huge number of CV devices hanging off the same output.

Eric


__________________________________________________
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This is a single value?  Linear scaling?  I was looking for something with a
little more flexibility, although I don't know what a curve would look live
of played note versus what should be played.  Tuning could also be note for
note if you wanted to tune everyone of them.
--Shemp

> -----Original Message-----
> From: alt-mode [mailto:alt_mode@...]
> Sent: Monday, August 14, 2000 10:47 PM
> To: motm@egroups.com
> Subject: RE: [motm] Re: MOTM-300 and cheerleaders
>
>
>
> --- Tentochi <tentochi@...> wrote:
> > ...A lot of junk deleted...  It would be cool if MIDI-CV
> convertors let you
> > compensate for tuning problems in our VCOs.  A very clever method is
> > probably waiting out there to do this.  Unfortunately I don't think the
> > convertors out there currently are that advanced yet.
>
> The Encore Expressionist has a scaling value for each output in
> each patch.  I've
> used this to compensate for various scaling issues at times.  The
> most common need
> for it is when I have a huge number of CV devices hanging off the
> same output.
>
> Eric
>
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Mail \ufffd Free email you can access from anywhere!
> http://mail.yahoo.com/
>
> 
>
>
>
>

It is a single value that either stretches the range or shrinks it depending on
whether the value is positive or negative.  I believe it just changes the slope of
the voltage curve.  Certainly this is not intended to be a microtonal thing where
you could change every note but it is software controlled... Ask Tony nicely, he's
on the list ;)

Eric

--- Tentochi <tentochi@...> wrote:
> This is a single value?  Linear scaling?  I was looking for something with a
> little more flexibility, although I don't know what a curve would look live
> of played note versus what should be played.  Tuning could also be note for
> note if you wanted to tune everyone of them.
> --Shemp
> 
> > -----Original Message-----
> > From: alt-mode [mailto:alt_mode@...]
> > Sent: Monday, August 14, 2000 10:47 PM
> > To: motm@egroups.com
> > Subject: RE: [motm] Re: MOTM-300 and cheerleaders
> >
> >
> >
> > --- Tentochi <tentochi@...> wrote:
> > > ...A lot of junk deleted...  It would be cool if MIDI-CV
> > convertors let you
> > > compensate for tuning problems in our VCOs.  A very clever method is
> > > probably waiting out there to do this.  Unfortunately I don't think the
> > > convertors out there currently are that advanced yet.
> >
> > The Encore Expressionist has a scaling value for each output in
> > each patch.  I've
> > used this to compensate for various scaling issues at times.  The
> > most common need
> > for it is when I have a huge number of CV devices hanging off the
> > same output.
> >
> > Eric
> >
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Yahoo! Mail \ufffd Free email you can access from anywhere!
> > http://mail.yahoo.com/
> >
> > 
> >
> >
> >
> >
> 
> 


__________________________________________________
Do You Yahoo!?
Yahoo! Mail \ufffd Free email you can access from anywhere!
http://mail.yahoo.com/

--- In motm@egroups.com, "Tentochi" <tentochi@c...> wrote:
> ...A lot of junk deleted...  It would be cool if MIDI-CV convertors 
let you
> compensate for tuning problems in our VCOs.  A very clever method is
> probably waiting out there to do this.  Unfortunately I don't think 
the
> convertors out there currently are that advanced yet.
> 
> --Shemp (out there)

Well, the Encore Expressionist is advanced enough to allow storing 
the CV scaling PER OUTPUT (8 of them), PER PRESET.

Way to go Tony...

Moe