MOTM

<<<I apologize for sending this to the master list! I of course wanted it
sent to the MOTM User's
group! now that I launched everyone's email address out there in the open,
please let's not
abuse that! Arrggghhhh!!!! I'm tired and need that upcoming Mexican vacation
*real badly*>>


> In some MOTM-420s, the initial cutoff freq, as set by the panel pot, is
too
> low for the ranges 0-3 ticks.
>
> What happens is the cutoff is less than 10Hz, so you get DC 'ticks' or as
> some user stated a sort of
> 'time delay' as you sweep the filter if the FREQ pot os between 0 and 3.
> This is because you can't
> hear anything out of it (in lowpass mode) until the cutoff is in the audio
> range.
>
> So, there needs to be a resistor adjustment so that 0 tick is not
something
> silly like 0.2Hz. Rather, it
> should be like 20 to 30Hz.
>
> R9 needs to be *increased* slightly. Currently, it is 221K. I'm going to
> start sending kits out
> with this resistor to be 255K 1%. Why 1%? just to reduce thermal drift.
Now,
> that's pretty anal for a VCF!
>
> The reason your particular '420 doesn't exhibit this is that the 2 2200pf
> caps are such that the low end is
> around 15Hz instead of like 2Hz.
>
> If you wish to use a 270K 5%, THAT'S OK BY ME. If you want to add a 22K or
> 27K 5% in series with the 221K,
> THAT'S OK BY ME, TOO. If you want me to send you free 255K, 1% please just
> mail me a SASE.
>
> You can actually replace this resistor from the top side of the board if
you
> are careful. I clip the leads as
> close to the body as possible, leaving the leads in the holes. I the use
> solder wick to remove the solder and
> use pliers to grasp the lead and pull it out *gently* while heating the
pad.
> I then clip the leads of the new
> resistor short after bending, and solder the top pads with all that extra
> no-clean solder you have lying around :)
>
> That's for bringing this to my attention. There is constructive bitching,
> then there is just palin bitching :)
>
> Paul S.
>
>