Vintage Synth Explorer Forums

So I just fixed my X-911, but I feel it's not completely functional yet. On about half of the voices the trigger doesn't re-trigger quickly, i.e. if you play sixteenth notes the sound will just fade out, whereas if you play quarter notes it will retrig. The voices are 4"synthe, and the electric bass, tube, trumpet, and distortion guitar. The rest retrigger fine. Is this happening to others? Any ideas?

Also, what is the polarity switch supposed to actually do...it doesn't seem to do anything for me, and I can't find a copy of the manual. I assume it would invert the trigger...

Thanks for any future help...I'd love to find someone who knows the device pretty well, I've been studying the schematics hard enough to be at least the engineer's latte fetcher, haha.

These things are weird, and I never found a manual when I had it. as far as the fading out, that might be due to the sensitivity level not being low or high enough? so new notes aren't retriggering the env? Have you trying playing it via CV/gate? that should tell you if everything is at least triggering properly.

RE: polarity, I can't remember what effect this had.. couldn't figure it out myself!

Think I've figured it out, at least partially. All the voices have a little pot to adjust one of their sound parameters. The two 'synthe" voices that fade out have decay as their parameter. I noticed that when I retrigger the other voices, the respective parameter won't re-trigger unless the first trigger dies out, even though the voice itself will. So, these voices must have decay built into them, and that parameter isn't retriggering when a signal is sent again, though the voice may be retriggering. The only confusion now is that the parameters on the instrument voices that are behaving like this (three of them, bass, tuba, and guitar) are tone (which the service manual reveals in two of the cases is actually filter cutoff), while other instrument voices with that same parameter work fine...hmmm. I'm betting decay is somehow a part of the tone parameter for those instruments. Anybody have a reliable X911 at hand they would verify my theory with? Also, still curious about polarity.

Just gave it the rundown with my KR-55. The trigger and all other modulation / control sockets work, but each time it gets triggered like that, the old trigger has faded (its a square wave), so it's not quite the same situation. I'm pretty sure this is just a design flaw, the thing is weird enough.