Roland System 100m

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?