From CJones@sni.co.uk Mon Jan 15 07:37:37 1996 15 Jan 96 10:37:30 +0500 15 Jan 96 04:03:34 +0500 id <30FA1490@squidgy.sni.co.uk>; Mon, 15 Jan 96 08:47:12 UTC From: Clive Jones Subject: OBX-a / OB-8 answers Date: Sat, 13 Jan 96 08:36:00 UTC Encoding: 108 TEXT Hopefully this might help some of you guys with Oberheim problems ; > I am trying to figure out how the auto tune function works on my >OB-Xa. >There are two switches inside the unit near the voice kill dip switches. >I was told that the first switch turns auto tune on and off, the second >switch >does nothing, so I was told. My problem is I don't know if my OB-Xa is >tuning >itself, when I press the Auto tune button the keyboard voice selection LED's >strobe by from left to right and then they all begin to blink a few times >and return to the current patch..is this normal, the voices don't seem to >tune up. > Am I missing something? The 2 test switches located under the hood of the OBX-a are both related to the autotune circuit. Test switch 1 disables the autotune circuit when in the down position.Test switch 2 automatically removes voices that fail autotune on OBX-a's with serial numbers above 814202 ( another killer move by Oberheim engineers ) - 'up' removes the bad voices. My OBX-a has rev.G firmware - I can't tie down a software release to the autotune disable feature being introduced - sorry. The fact that the LED's strobe then blink would indicate the microprocessor / code side of the autotune cycle appears to be working - if you believe that the algorithm is bad try to compare ROM checksums with another OB owner. As far as I can remember the Autotune cycle is time dependant and the voices may actually be tuning but too slowly and may go outside the timing window ( JH?? ) - it's unlikely to be the DAC if you get a successfull pot-scan , but, check the comparator. >>match envelopes on all OB8's to the same standard - these parameters can >>( and should ) be saved by tape dump incase your OB8 fails ( although the >>Oberheim engineers thoughtfully provided a 'get-you-going-again' routine >>that re-aligns the EG's to a basic level via a special button sequence ). >How can you dump these to tape ? >I know how to save patches. >Also,, where is this "special button sequence" mentioned ? >I have the service manual, but don't remember reading this. Okay - here it is............................. **WARNING** You should not perform any of the following routines unless the memory in your OB-8 has been wiped by a bad battery etcetera - if you do - you will DE-CALIBRATE the EG's !!!!!!!!!!! - the same will occur if you use a tape from another OB-8 as the parameters are UNIQUE to each synth. The OB-8 calibrations are stored automatically everytime a patch dump to tape is made ( OB-8's with firmware rev A6 upwards ). To load the calibration parameters back from tape without reloading patches ; Enable the cassette interface and turn off mem-protect ( rear panel switches ), start the tape playback, hold down all the buttons in the Filter section - Osc1on, Osc2 half, Osc2 full, Noise, 4 pole and Track. When your hear that horrible leader tone press 'Play' - the group and play LED's will light during data transfer. * Reseting the OB-8 * This routine resets all the calibrations held within the OB-8's memory EXEPT THE EG PARAMETERS, namely arpeggio transpositions, bend amount and direction, split tanspositions etcetera. Make sure the memory protect switch is ON - hold down all 8 program number buttons and the SPLIT button - this was intentionally made difficult by the Oberheim engineers as not to be done accidently. * Reseting Including the EG's * If for some reason your OB-8 loses it's memory and you DIDN'T MAKE A TAPE BACK-UP - you can re-align the EG's to a basic get-you-going-again level by performing exactly the same reset proceedure as above, but, this time leave the MEMORY PROTECT switch OFF. The OB-8 calibrations CANNOT be saved via MIDI although single patch transfer is catered for ( unless the Oberheim engineers have placed a hidden routine in there somewhere - but I don't believe so ). You can obtain your OB-8's software rev by pressing the 'page 2' button twice and holding it down on the second press and pressing 'sync' - the software rev will appear accross the ABCD 1-8 programmer section LED's ( rev B5 would light 'B' and '5' - surprise, surprise! ). I hope this helps Clive ////////////////////// / / ...and on the 8th day /01344 850213 Work / God made Synthesizers /01344 850209/291 Fax/ ...and God was called /01628 602106 Home / ' Tom Oberheim ' //////////////////////