Roland System 100m

On page 47 of Roland's "Practical Synthesis for Electronic Music" (which is basically the 
Roland System 100M 'manual') it states

"The multiple jacks cannot be used in place of a mixer.  If two outputs are connected to 
the same multiple jack set, the result will be what is effectively a short circuit to both 
outputs which could cause damage."

The first part I buy (obviously) -- it's not a mixer.

But I never thought that accidentally connecting two outputs to a multiple could cause 
damage.  It happens -- that one puts two outs into a multiple -- even if you try hard not 
to.  (In fact did it last night -- didn't get the result that I wanted, I tracked down problem 
and corrected).  I've never noticed any damage, never worried about it.   

In fact the manufacturer of my other modular (Blacet) says don't worry about that sort of 
thing -- his machine can take it.  Is the 100M a delicate beast?

Best

Robert

In general, most (if not all) op-amps do not like to have their 
outputs directly connected together. However, most op-amp based 
output circuits contain a protection resistor to guard against this 
happening. Otherwise, there would be far too many broken synths being 
returned for repair (most people will unintentionally patch two 
outputs together at some point in their life). As long as a 
protection resistor is present, then it's not a problem. I've had a 
quick look at the schematics for the 100m. Some of the outputs have 
protection resistors, some don't. But not all outputs are directly 
off an op-amp either. I think they are being a bit overcautious, I've 
not yet managed to fry anything in my 100m, but use a mixer if you 
have any doubts.

>On page 47 of Roland's "Practical Synthesis for Electronic Music" 
>(which is basically the
>Roland System 100M 'manual') it states
>
>"The multiple jacks cannot be used in place of a mixer.  If two 
>outputs are connected to
>the same multiple jack set, the result will be what is effectively a 
>short circuit to both
>outputs which could cause damage."
>
>The first part I buy (obviously) -- it's not a mixer.
>
>But I never thought that accidentally connecting two outputs to a 
>multiple could cause
>damage.  It happens -- that one puts two outs into a multiple -- 
>even if you try hard not
>to.  (In fact did it last night -- didn't get the result that I 
>wanted, I tracked down problem
>and corrected).  I've never noticed any damage, never worried about it.  
>
>In fact the manufacturer of my other modular (Blacet) says don't 
>worry about that sort of
>thing -- his machine can take it.  Is the 100M a delicate beast?

Thanks.  Has anyone else fried a Roland?  I have a friend who has one, never complained.

How has yours stacked up, reliability-wise -- "fryability"-wise -- versus modern modulars.  
I'm considering investing in another 100M, but also considering expanding my Blacet or 
getting a MOTM module or three.

I like Roland vintage -- but just took another piece of Roland vintage into the shop for 
repairs today (a Pro Mars whose power supply had died).  The fellow at the shop said "do 
you have _anything_ that works?".  And it got me to thinking...that I'm tired of stuff 
breaking down.  I do know that Blacet is pretty well protected agains the kind of thing 
Roland was warning against in their manual, but perhaps Roland was just being overly-
cautious, as you say.


--- In RolandSystem100m@yahoogroups.com, Scott Juskiw <scott@...> wrote:

>
> In general, most (if not all) op-amps do not like to have their 
> outputs directly connected together. However, most op-amp based 
> output circuits contain a protection resistor to guard against this 
> happening. Otherwise, there would be far too many broken synths being 
> returned for repair (most people will unintentionally patch two 
> outputs together at some point in their life). As long as a 
> protection resistor is present, then it's not a problem. I've had a 
> quick look at the schematics for the 100m. Some of the outputs have 
> protection resistors, some don't. But not all outputs are directly 
> off an op-amp either. I think they are being a bit overcautious, I've 
> not yet managed to fry anything in my 100m, but use a mixer if you 
> have any doubts.
> 
> >On page 47 of Roland's "Practical Synthesis for Electronic Music" 
> >(which is basically the
> >Roland System 100M 'manual') it states
> >
> >"The multiple jacks cannot be used in place of a mixer.  If two 
> >outputs are connected to
> >the same multiple jack set, the result will be what is effectively a 
> >short circuit to both
> >outputs which could cause damage."
> >
> >The first part I buy (obviously) -- it's not a mixer.
> >
> >But I never thought that accidentally connecting two outputs to a 
> >multiple could cause
> >damage.  It happens -- that one puts two outs into a multiple -- 
> >even if you try hard not
> >to.  (In fact did it last night -- didn't get the result that I 
> >wanted, I tracked down problem
> >and corrected).  I've never noticed any damage, never worried about it.  
> >
> >In fact the manufacturer of my other modular (Blacet) says don't 
> >worry about that sort of
> >thing -- his machine can take it.  Is the 100M a delicate beast?
>

My impression is that the manual isn't sure what sources you might be
trying to add together with the multiple jacks (audio or voltages) and
therefore issues a general warning not to do it...

I agree with Scott's comments.

Besides, this is the function that the Dual CV/Audio Mixer & Voltage
Processor module is suppose to fulfill...  it is a very useful module,
especially if you are interfacing with another make of synth.

Bill



--- In RolandSystem100m@yahoogroups.com, Scott Juskiw <scott@...> wrote:
>
> In general, most (if not all) op-amps do not like to have their 
> outputs directly connected together. However, most op-amp based 
> output circuits contain a protection resistor to guard against this 
> happening. Otherwise, there would be far too many broken synths being 
> returned for repair (most people will unintentionally patch two 
> outputs together at some point in their life). As long as a 
> protection resistor is present, then it's not a problem. I've had a 
> quick look at the schematics for the 100m. Some of the outputs have 
> protection resistors, some don't. But not all outputs are directly 
> off an op-amp either. I think they are being a bit overcautious, I've 
> not yet managed to fry anything in my 100m, but use a mixer if you 
> have any doubts.
> 
> >On page 47 of Roland's "Practical Synthesis for Electronic Music" 
> >(which is basically the
> >Roland System 100M 'manual') it states
> >
> >"The multiple jacks cannot be used in place of a mixer.  If two 
> >outputs are connected to
> >the same multiple jack set, the result will be what is effectively a 
> >short circuit to both
> >outputs which could cause damage."
> >
> >The first part I buy (obviously) -- it's not a mixer.
> >
> >But I never thought that accidentally connecting two outputs to a 
> >multiple could cause
> >damage.  It happens -- that one puts two outs into a multiple -- 
> >even if you try hard not
> >to.  (In fact did it last night -- didn't get the result that I 
> >wanted, I tracked down problem
> >and corrected).  I've never noticed any damage, never worried about
it.  

> >
> >In fact the manufacturer of my other modular (Blacet) says don't 
> >worry about that sort of
> >thing -- his machine can take it.  Is the 100M a delicate beast?
>