Crumar Bit One -1984    Weight = 26.4 Lbs. Number manufactured = ? MSR = $1395


User Manual: fdiskc archive or Bit resources
Reset Proceedures: N/A
Operating System code: bitonea1.bin and bitoneb1.bin
MIDI or other control protocol:
Software related Links:N/A
Patches or knob settings: listing and MP3's or .wav file
Circuit Overview: below
Scematics/Service Manual: Bit resource page or soundprogramming.net
Common Service Issues/Tips: below
Parts Sources: Keys semiconductors misc
Uncommon chips/modules used: SSM2044 or CEM3328 on later versions. 8253 for DCO's.
Modifications:
General Info Links: Vintage Synth Explorer or Synth Museum





Circuit Overview:
     Digital controlled analog subtractive synth. I should add that the DCO's in this synth have two oscillators with baseline/span trims plus another interactive tune pot on the analog board and some offsets or something. A real pain to tune without instructions but sounds nice when it's all set up right. 6 voice 2 dco/voice with 2 lfo's, dynamic sensetivity, and MIDI in always onmi on. 63 patch memory. Split/layer. The sound qualities can be nice but turn up the resonance and sweep and you'll hear some of the nastiest...you can't even call it 'zipper effect'. More like "ratchet effect" if you ask me :-). Strong sounds...synth brass, analog pianos and maybe some analog pads. But the MIDI spec..eh.. get a filter if you are using it in a setup. I'm going to program a pic one of these days and put it in a box I have here with 8 midi outs and have each one selectable between like 1 and 9, 2 and 10, etc. So that you can send in from a 16 channel midi port in a complex setup and have easy full selection but never have two outs overlapping.


Service Tips:
     Button caps can be pulled directly up to remove and make it easier to spray contact cleaner in there. It would be a lot of work to actually replace the switches and I cleaned mine up from 5 of them not working to perfect in 15 minutes or so.
     The CEM3328 chips may not be the most reliable. Two of them went down in mine; one shortly after I had it all up and running right. Pin 9 has noise or goes offset if you check with a scope. That's your output. Since the 8253 is used for DCO's there probably aren't a lot of other problems with them. They socketed the filters on my CEM3328 version at least. Also when you plug midi in, there is a switch. IT KILLS THE AUDIO OUTS on mine! Drove me nuts there...like it works on the bench, but never in my setup! I assume this was a way to implement..local off? I found an old message in the crumar group confirming this. Apparently the had some problem data merging? Otherwise they'd have put it on the midi out, right? Since you use the OUT if you are using the bit one as a controller. But if it's just a slave in a midi chain you obviously want the ability to play the keys. Grrr. Dumb 'feature'. PS another thing. Once MIDI switch has been hit and stuff has happened you have to shut down and reboot it to get sound. Lovely.

It might also be helpful to post the codes for Tape dumping and procedure there. We want to set recording for -5 to 0db on tape machines and something below 0 if you try digital recording obviously. Noise reductions off. Hit the tape button and then Split/Double become Load/Save. Nothing atypical. Just roll the tape, say what you are saving if you want and hit 'save' and the data will be saved with 30 second leader and 2 minutes of data they say. Wow. Must be integrable compared to the..polysix which is like what 5 seconds or something? :-)

Then to load one of course just reverses the procedure assuming the deck is already hooked to both tape in and out properly. Ok some people probably need to be told that you hook the tape out to the input of the recorder...and tape in to output of tape recorder or whatever you are recording with. ahem. Now when you try to load the pathces by reverse process described above, you might get a '0' in the display afterward which means everything went ok. You might get a 1 which means you probably have bad connections. 2 means there is something possibly filtering or garbling the signal like dolby or dbx or the like. Then 3 means you might have damaged tape or too low or high output. Hope that helps someone in a fix.

Parts:
There are many discrete parts in these units. Ask if you need something specific. I have both VCF's.
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