My Crumar Bit One Information Page

Introduction

I've kept this page nice and simple, it's just for information specifically regarding the Bit One that other webpages don't cover.

Opening up the Bit One

The synthesiser has a lid on top which swings back when you undo all the screws.

First, there are 2 screws, 1 either side, closest towards the front. Then there are 3 screws just above the keys, at the front. Make sure the power cable is unplugged (the power supply is on the inside right of the box)! Undo the screws and open the lid.

I can't take any responsibility for any accidents caused by not unplugging the power first, or by any damage caused to the circuit boards when you open it.

Simple Repair Tip

When I played the Bit One in unison or doubled mode, some of the keys weren't making a noise, while others were. I figured this must be down to one of the oscillator chips being faulty, or the connections on the filter chips were oxidised (as I remember reading about on another webpage about a problem with Curtis filter chips, which the Bit One uses). I opened the lid and I saw some socketed chips (it is the sockets' connections that become oxidised).

Basically, I pushed in all the chips and then put the lid down, plugged the power lead back in, and tried a key in Unison mode. There were no quiet keys anymore.

I came to the conclusion that the chip had either come unseated, or the contacts were oxidised. So, if your Bit One has non-working oscillators/voices, try first pushing the 6 chips into their sockets, then if that doesn't work, you can take the chips out of the socket (carefully) and wipe the contacts with some kind of cloth. This is only advised if the synth really is faulty though, the problem being that the chips can be hard to re-seat without bending the pins. You have been warned; I take no responsibility for anyone attempting this.

Factory default tape (as a WAV file) for restoring patches

Once the batteries have gone, the Bit One reverts to wierd-mode, where it makes a Bladerunner-style noise, as the patch memory is full of garbage. So you load the factory default patches from cassette (this is an old synth!) OR the hi-tech modern equivalent: Download and play this WAV file out of a soundcard. After downloading and unzipping the file, you plug your soundcard's Line Out into the Bit One's Tape In, set the volume about 3/4 of the way, then play the WAV in a program like Windows Media Player. Then you have working patches to edit and play around with. Get the patches here or directly from my website here.

Note (4th December 2015): To load in tape patches, press the 'Tape' button, then the 'Split/Load' button. Then connect the output from your soundcard as above.

Also, likewise, 'Tape' and 'Double/Save' to save patches.

Memory Backup Battery Installation

Because the old battery was long dead (probably hadn't been replaced since 1985), I went out and bought a new lithium battery (CR2016) for my Bit One, then I got the top of the synth open (with the power off), and plugged the battery in. Then I loaded some patches from tape, then switched the synth off for a while to waste the memory (having the power still plugged in while off does *not* keep the memory). When I switched it back on, however, the patches were gone from memory, so the battery clearly wasn't working.

I decided I would have to rely on loading the synth from tape every day and saving to tape at the end of it. Then I saw a newsgroup posting where someone said, in effect, "The battery backup doesn't work on my Bit One anymore, even though the battery is fine". Obviously the chances of that happening to both of us were slim, so I decided to put the battery in the opposite way round. It worked as I left the synth off overnight and the patches are still there this morning.

The top of the battery, the side with the text "CR2016" on it, doesn't face towards you as you slide it into the hole (which has 2 metal bars behind to hold the battery in), but it goes face inwards, and the blank-faced side of the battery faces towards you.

The battery hole is 2/3rds the way along, at the very top of the circuit board. Be careful, as the battery can fall down the back of the circuit board if you're not careful, then you have to turn the synth upside down to get it out again (like I did!).

MIDI Omni Mode and Channels

This is very simple. In Omni Mode, the Bit One answers notes on all channels (which is a pain when using it from another synth via Midi Thru). So, use address 65 for the MIDI channel you want the Bit One to respond to (1-16), and set the flag in address 64 to 0 to indicate Omni Mode off. You have to change these settings every time you turn the synth on, even with a working lithium backup battery inside.

MIDI from the Computer to the Bit One

Cheap soundcards have a Gameport MIDI interface, but I think that the Gameport system lacks an opto-isolator, which means older synths (such as the Bit One) don't work with these soundcards.

There are 3 options:

  1. Get a better (professional) soundcard, like a Turtle Beach.
  2. If you have a Soundblaster Live like I do, then you can get a breakout daughterboard with digital in/out sockets (call the LiveDrive), and Mini-DIN sockets. If you get a MIDI Din adapter lead from Creative Labs, you get a little lead with a Mini-DIN on one end which goes into the daughterboard, and on the other end of the lead is a MIDI socket, into which you plug a MIDI lead which goes to the synth that won't normally receive MIDI data from your soundcard. This works great. The part number for these from Creative Labs' store is 0414620001, which you can find easily on Google (search for "Creative Labs 0414620001" on Google).
  3. The other option is to get a pro synthesiser like my Korg Z1 (even a cheap Yamaha will do) with a MIDI Thru. The cable goes from the Thru to the input on the Bit One, then you turn Omni off and set the channel as 2 so it doesn't interfere with its Master keyboard, and you can sequence the Bit One to your heart's content, by plugging the soundcard's Gameport MIDI into the Master keyboard's Midi In. This tip will work with any stubborn old synth or sampler.

Crumar Bit 1/99 Manual

Just as a final note, you can download the manual here.


Email me at jeremy@decompiler.org for any further questions 1