Doepfer

Ah, sorry, I didn't really read the details.  Sounds like he should be able
to fix it by soldering high value resistors to the inputs of the MFB EG... I
think.

On Sun, Nov 15, 2009 at 3:49 PM, Synthomaniac <tony.steventon@talk21.com>wrote:

>
>
> Hi Guys
>
> There seems to be some confusion about what's going on with loading, volts,
> current etc. The good news is that Ohm's Law isn't about to be disproved
> anytime soon. Volts and current are linked in Ohm's law by resistance, in
> this case the output resistance of the SH101 - this is about 22k and it
> connects to +15V in the SH101 gate out circuit.
>
> The MFB EG acts as a load and two in parallel act as a greater load, i.e.
> more current will flow. If for argument's sake the MFB has an input
> resistance of 10k then two EGs in parallel would then give a load of 5k.
> I'll ignore the A140 since that that has a very high input resistance (mine
> are around 5M to 7M).
>
> The arithmetic for this example is that 15V is loaded by 22k out plus a 5k
> load = 27k. This acts as a potential divider thus 15/27 x 5 = 2.8V. Not very
> big! So the more current out the more the voltage drop across the output
> resistance and hence a smaller gate voltage. So yes it needs a buffer to
> isolate the SH101 output's high output resistance; I use an A185-1. If you
> just had A140s then these have such a high resistance that it shouldn't make
> any difference.
>
> Hope that helps clear up the mystery.
> I'd be inteested if anyone can tell me what the MFB EG input resistance
> actually is.
>
> Cheers
> Tony
>
>
> --- In Doepfer_a100@yahoogroups.com <Doepfer_a100%40yahoogroups.com>,
> Monroe Eskew <monroe.eskew@...> wrote:
> >
> > Pardon if this is a dumb question, but are you sure you're measuring
> voltage
> > and not power? Is Ohm's law really that blatantly false? I've noticed
> VCOs
> > don't respond to voltage only; they are influenced by the amperage as
> well.
> >
> > On Sun, Nov 15, 2009 at 2:43 PM, Computer Controlled <acidted@...>wrote:
>
> >
> > >
> > >
> > > That's why there are Buffered Multiples, passive ones drop the voltage
> > > levels. So they need to be buffered to keep them at original levels.
> > >
> > > I just didn't think that the level would drop by so much!
> > >
> > >
> > > Monroe Eskew wrote:
> > > > It's strange because in theory the voltage should not drop since
> these
> > > are
> > > > parallel circuits-- only the current should change.
> > > >
> > > > On Sun, Nov 15, 2009 at 2:16 PM, Computer Controlled <acidted@
> ...<acidted%40gmail.com>
>
> > > >wrote:
> > > >
> > > >
> > > >> I've noticed recently that the A-180 Multiple really cuts the
> voltage
> > > >> signal down quite substantially. I just got an MFB Dual ADSR and
> noticed
> > > >> that when i mult the Gate Output of my SH-101 by 3x, it drops the
> gate
> > > >> voltage down to where the MFB won't trigger anymore. Basically, i
> had it
> > > >> set up where the gate out went into the A-180, then the first 2 outs
> > > >> went to the two Gate Ins on the MFB and the 3rd out went to my A-140
> EG.
> > > >> If i pulled the cable out that went to the A-140, the MFB would
> fire,
> > > >> but not with it inserted. However, it works if i use my 303, which
> has a
> > > >> hotter Gate signal. I checked the gate out voltages coming of the
> 101
> > > >> direct, then at each output of the A-180. I got the following:
> > > >>
> > > >> Direct Out from 101: 11.56v
> > > >> Into the A-180 w/no other cables inserted: same as above
> > > >> with 2 cables inserted: 7v
> > > >> with 3 cables inserted: 5.5v
> > > >>
> > > >> This is quite a bit of voltage drop if you ask me. Is there anyway
> to
> > > >> mod the A-180 so it doesn't eat up all my voltages?
> > > >>
> > > >> -Larry
> > > >>
> > > >>
> > > >>
> > > >
> > > >
> > > > [Non-text portions of this message have been removed]
> > > >
> > > >
> > > >
> > > > ------------------------------------
> > > >
> > > > Yahoo! Groups Links
> > > >
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>  
>


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