MOTM

>it would be a custom job to get a pot that reacted in log fashion for
half its travel, and in reverse log fashion for the other half, no?

You can do this with a load on the pot wiper, say a 10K resistor on a
100K pot. But I think a linear pot is better for most uses.

Regards,

Tony Allgood  Penrith, Cumbria, England

My music: www.mp3.com/taklamakan

You can make a case for reversing attenuators in the audio side as 
well - for instance I want to mix waveforms from a single VCO, and 
want to do so both out of phase and in phase.

I think I understand where you are coming from, however - it would be 
a custom job to get a pot that reacted in log fashion for half its 
travel, and in reverse log fashion for the other half, no?

Moe

--- In motm@y..., "Paul Schreiber" <synth1@a...> wrote:
> Then on the left column, these are 100K Bourns panel
> pots and A is normal and
> B & C are reversing attenuators. You want reversing atenuators to 
be linear,
> anyway!
>

Thanks for all the Mixer suggestions. Here is the "final" decision:

a) Mixer model is 830, as in MOTM-830

b) Moe inage #1 is the design: a bias switch, and a switched jack. The
reason I like the
jack is that it minimizes wiring, and is sort of slick, imho. I don't see a
need for switches/LEDs
as certainly you know if a patchcord is plugged into OUT 1 or not.

And if you want to play reconfiguration games 'on-the-fly-, look at the
MOTM-700. That's what it's for :)

c) Now, since I am *assuming* that 95% of the time, this is an audio mixer,
then I propose that
the D/E/F inputs (the right column) all 3 be log pots. The reason they have
to be over there is that
the are pcb mounted. Then on the left column, these are 100K Bourns panel
pots and A is normal and
B & C are reversing attenuators. You want reversing atenuators to be linear,
anyway!

Well?

Paul S.

Fearless Leader has spoken! New image up at:

http://motm.retrosynth.com/moe_stuff/future_motm/m-830.jpg

Moe

--- In motm@y..., "Paul Schreiber" <synth1@a...> wrote:
> Thanks for all the Mixer suggestions. Here is the "final" decision:
> 
> a) Mixer model is 830, as in MOTM-830
> 
> b) Moe inage #1 is the design: a bias switch, and a switched jack. 
The
> reason I like the
> jack is that it minimizes wiring, and is sort of slick, imho. I 
don't see a
> need for switches/LEDs
> as certainly you know if a patchcord is plugged into OUT 1 or not.

> I think I understand where you are coming from, however - it would be
> a custom job to get a pot that reacted in log fashion for half its
> travel, and in reverse log fashion for the other half, no?

Unity gain buffer amp drives cw end of pot. Inverting amp drives
ccw end. Middle connection of pot is output, and loaded to GND
by a smaller resistor. For 100k pot, 30k load. Not truely exponential,
but better than linear.
You can also load the pot with two identical resistors to both ends.
This works in that other Reversible Attenuator configuration (with
the pot at the input of a differential amp).

JH.

In a message dated 3/4/2001 12:22:24 PM, oakley@... 
writes:

>>it would be a custom job to get a pot that reacted in log fashion for
>half its travel, and in reverse log fashion for the other half, no?
>
>You can do this with a load on the pot wiper, say a 10K resistor on a
>100K pot. But I think a linear pot is better for most uses.

I'm not sure if this is what Tony meant, but it might be a better choice to 
go linear on all pots (or Juergen's idea on all the pots -- nice to see you 
back JH!) if only for the uniformity of operation. Correct me if I'm wrong 
here guys, but this module seems to be more of a "pre-mixer" (since there's 
no output level controls) in that levels wouldn't typically be adjusted on 
the fly. The inputs might have a "touchy" quality to them, but I'd think that 
would be less strange than "pot 1 operates this way, pot 2 operates a little 
differently, and pot 3 operates differently still!"

In fact, it might be nice to have reversing attenuators on all the inputs (I 
can hear Paul groan from here) -- hey Moe, great idea about mixing waves from 
the same VCO!
JB

I just thought I'd throw in my two cents...

--- In motm@y..., "Paul Schreiber" <synth1@a...> wrote:
> ... 
> b) Moe inage #1 is the design: a bias switch, and a switched jack. 
The
> reason I like the
> jack is that it minimizes wiring, and is sort of slick, imho. I 
don't see a
> need for switches/LEDs
> as certainly you know if a patchcord is plugged into OUT 1 or not.
> ...

I agree with the switched jack concept. No need for a switch or LED 
as you can simply tell by looking. I don't have an issue with either 
OUT1 or OUT2 for "splitting" the mixer, a case could be made for 
either one. Overall, simple and intuitive. That said, switches/LEDs 
are always nice (but more parts = $$).

> ...
> c) Now, since I am *assuming* that 95% of the time, this is an 
audio mixer,
> then I propose that
> the D/E/F inputs (the right column) all 3 be log pots. The reason 
they have
> to be over there is that
> the are pcb mounted. Then on the left column, these are 100K Bourns 
panel
> pots and A is normal and
> B & C are reversing attenuators. You want reversing atenuators to 
be linear,
> anyway!

Reversing attenuators for E & F would be nice! <ugh>

GeorgeK

Well, not to be nitpicky, but I would want the bias pot to be on the left
column and mixer, since that side is more likely to be used with control
voltages (linear pots and reversing attenuator).

I would definitely like to have log pots on the right side mixer.

John Loffink
microtonal@...

----- Original Message -----
From: "Paul Schreiber" <synth1@...>
To: <motm@yahoogroups.com>
Sent: Sunday, March 04, 2001 2:13 PM
Subject: [motm] Battle over


> Thanks for all the Mixer suggestions. Here is the "final" decision:
>
> a) Mixer model is 830, as in MOTM-830
>
> b) Moe inage #1 is the design: a bias switch, and a switched jack. The
> reason I like the
> jack is that it minimizes wiring, and is sort of slick, imho. I don't see
a
> need for switches/LEDs
> as certainly you know if a patchcord is plugged into OUT 1 or not.
>
> And if you want to play reconfiguration games 'on-the-fly-, look at the
> MOTM-700. That's what it's for :)
>
> c) Now, since I am *assuming* that 95% of the time, this is an audio
mixer,
> then I propose that
> the D/E/F inputs (the right column) all 3 be log pots. The reason they
have
> to be over there is that
> the are pcb mounted. Then on the left column, these are 100K Bourns panel
> pots and A is normal and
> B & C are reversing attenuators. You want reversing atenuators to be
linear,

> anyway!
>
> Well?
>
> Paul S.
>
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>

John has a point. Since the BIAS pot must be on the right side due to 
physical constraints, how about if the LEFT side had 3 log pots with 
range 0 - 10, and the RIGHT side had 3 linear pots, two of them 
reversing.

Then mixer 1 is optimized for audio, pot taper wise, and mixer 2 is 
optimized for cvs with reversing attenuators and the bias knob.

Paul, is there any practical reason that the log pots can't go 
offboard?

Moe

--- In motm@y..., "Microtonal" <microtonal@w...> wrote:
> Well, not to be nitpicky, but I would want the bias pot to be on 
the left
> column and mixer, since that side is more likely to be used with 
control

> voltages (linear pots and reversing attenuator).
> 
> I would definitely like to have log pots on the right side mixer.
> 
> John Loffink
> microtonal@w...
>

I'll see if it fits mechanically. And, in it's current position the BIAS pot
is pcb mounted. Less wire, less labor.

Paul S.

----- Original Message -----
From: "Microtonal" <microtonal@...>
To: <motm@yahoogroups.com>
Sent: Sunday, March 04, 2001 4:13 PM
Subject: Re: [motm] Battle over


> Well, not to be nitpicky, but I would want the bias pot to be on the left
> column and mixer, since that side is more likely to be used with control
> voltages (linear pots and reversing attenuator).
>
> I would definitely like to have log pots on the right side mixer.
>
> John Loffink
> microtonal@...
>
> ----- Original Message -----
> From: "Paul Schreiber" <synth1@...>
> To: <motm@yahoogroups.com>
> Sent: Sunday, March 04, 2001 2:13 PM
> Subject: [motm] Battle over
>
>
> > Thanks for all the Mixer suggestions. Here is the "final" decision:
> >
> > a) Mixer model is 830, as in MOTM-830
> >
> > b) Moe inage #1 is the design: a bias switch, and a switched jack. The
> > reason I like the
> > jack is that it minimizes wiring, and is sort of slick, imho. I don't
see
> a
> > need for switches/LEDs
> > as certainly you know if a patchcord is plugged into OUT 1 or not.
> >
> > And if you want to play reconfiguration games 'on-the-fly-, look at the
> > MOTM-700. That's what it's for :)
> >
> > c) Now, since I am *assuming* that 95% of the time, this is an audio
> mixer,
> > then I propose that
> > the D/E/F inputs (the right column) all 3 be log pots. The reason they
> have
> > to be over there is that
> > the are pcb mounted. Then on the left column, these are 100K Bourns
panel
> > pots and A is normal and
> > B & C are reversing attenuators. You want reversing atenuators to be
> linear,
> > anyway!
> >
> > Well?
> >
> > Paul S.
> >
> >
> >
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/

> >
> >
> >
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

>
>

On Sun, 4 Mar 2001, Microtonal wrote:

> Well, not to be nitpicky, but I would want the bias pot to be on the left
> column and mixer, since that side is more likely to be used with control
> voltages (linear pots and reversing attenuator).

  The majority of pots, when possible, go on the right side for
circuit-board reasons.

Crow

/**/

In a message dated 3/4/2001 2:33:31 PM, mate_stubb@... writes:

>is there any practical reason that the log pots can't go 
>offboard?

Will the switch clear the PCB? I bet Paul already has the pots and they are 
board mounted which I find to be a hassle mounting offboard.

JB

New image, with audio mix on left, cv mix on right:

http://motm.retrosynth.com/moe_stuff/future_motm/m-830r2.jpg

Moe

--- In motm@y..., mate_stubb@y... wrote:
> John has a point. Since the BIAS pot must be on the right side due 
to 
> physical constraints, how about if the LEFT side had 3 log pots 
with 

> range 0 - 10, and the RIGHT side had 3 linear pots, two of them 
> reversing.
> 
> Then mixer 1 is optimized for audio, pot taper wise, and mixer 2 is 
> optimized for cvs with reversing attenuators and the bias knob.
> 
> Paul, is there any practical reason that the log pots can't go 
> offboard?
> 
> Moe

I like the version with the 3X2 and 6X1 switch.  Excellent for live
performance IMHO.  It looks cool on Moe's mock-up too!

--Shemp

> -----Original Message-----
> From: Paul Schreiber [mailto:synth1@...]
> Sent: Sunday, March 04, 2001 3:14 PM
> To: motm@yahoogroups.com
> Subject: [motm] Battle over
>
>
> Thanks for all the Mixer suggestions. Here is the "final" decision:
>
> a) Mixer model is 830, as in MOTM-830
>
> b) Moe inage #1 is the design: a bias switch, and a switched jack. The
> reason I like the
> jack is that it minimizes wiring, and is sort of slick, imho. I
> don't see a
> need for switches/LEDs
> as certainly you know if a patchcord is plugged into OUT 1 or not.
>
> And if you want to play reconfiguration games 'on-the-fly-, look at the
> MOTM-700. That's what it's for :)
>
> c) Now, since I am *assuming* that 95% of the time, this is an
> audio mixer,
> then I propose that
> the D/E/F inputs (the right column) all 3 be log pots. The reason
> they have
> to be over there is that
> the are pcb mounted. Then on the left column, these are 100K Bourns panel
> pots and A is normal and
> B & C are reversing attenuators. You want reversing atenuators to
> be linear,
> anyway!
>
> Well?
>
> Paul S.
>
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>