Dac Calibration Procedure - Roland TR808-M Installation Manual

TR808 TR808 TR808- - - - M M M M TR808

4. DAC CALIBRATION PROCEDURE

Problem with multiple triggering of TR-808's sound generators can occur at some TR-808
drummachine – more instruments are sounding after just one instrument is launched via MIDI
command. It is given by variability of parameters of transistors used in launching circuits of TR-808's
sound generators. In that case, it is necessary to calibrate outputs of the interface.
Calibration procedure can be done via special MIDI System Exclusive messages transmitted to
the interface. Form of messages is :
F0 00 20 21 7F 62 30 03 dd xx F7 [hex]
where dd databyte is calibration constant and xx byte is checksum (please refer MIDI SYSTEM
EXCLUSIVE COMMUNICATION manual for details about checksum calculating).
Calibration constant is set to 127 during production. If problem described above occurs,
calibration constant must be decreased. Valid values of calibration constant are from 00h to 7Fh.
SysEx messages for some values shows table below.
Calibration Corresponding MIDI SysEx
constant
127 F0 00 20 21 7F 62 30 03 7F 6C F7
124 F0 00 20 21 7F 62 30 03 7C 6F F7
120 F0 00 20 21 7F 62 30 03 78 73 F7
116 F0 00 20 21 7F 62 30 03 74 77 F7
112 F0 00 20 21 7F 62 30 03 70 7B F7
108 F0 00 20 21 7F 62 30 03 6C 7F F7
104 F0 00 20 21 7F 62 30 03 68 03 F7
100 F0 00 20 21 7F 62 30 03 64 07 F7
96 F0 00 20 21 7F 62 30 03 60 0B F7
92 F0 00 20 21 7F 62 30 03 5C 0F F7
88 F0 00 20 21 7F 62 30 03 58 13 F7
84 F0 00 20 21 7F 62 30 03 54 17 F7
80 F0 00 20 21 7F 62 30 03 50 1B F7
76 F0 00 20 21 7F 62 30 03 4C 1F F7
72 F0 00 20 21 7F 62 30 03 48 23 F7
68 F0 00 20 21 7F 62 30 03 44 27 F7
If there are some problems with multiple triggering of TR-808's sound generators after the
interface installation (when calibration constant is set to 127), set lower calibration constant and then
try functionality of TR-808. If problem persists, decrease calibration constant repeatedly up until all
sound generators are launched correctly.
Calibration constant is stored in internal interface's memory so new value isn't lost after TR-808
is turned off and the interface will work with it during all next sessions.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
Table – SysEx messages for some calibration constants
message [hex]
Copyright © 2010 CHD Elektroservis. All rights reserved.
MIDI Interface For Roland TR- - - - 808 MIDI Interface For Roland TR MIDI Interface For Roland TR MIDI Interface For Roland TR
Calibration Corresponding MIDI SysEx
constant
64 F0 00 20 21 7F 62 30 03 40 2B F7
60 F0 00 20 21 7F 62 30 03 3C 2F F7
56 F0 00 20 21 7F 62 30 03 38 33 F7
52 F0 00 20 21 7F 62 30 03 34 37 F7
48 F0 00 20 21 7F 62 30 03 30 3B F7
44 F0 00 20 21 7F 62 30 03 2C 3F F7
40 F0 00 20 21 7F 62 30 03 28 43 F7
36 F0 00 20 21 7F 62 30 03 24 47 F7
32 F0 00 20 21 7F 62 30 03 20 4B F7
28 F0 00 20 21 7F 62 30 03 1C 4F F7
24 F0 00 20 21 7F 62 30 03 18 53 F7
20 F0 00 20 21 7F 62 30 03 14 57 F7
16 F0 00 20 21 7F 62 30 03 10 5B F7
12 F0 00 20 21 7F 62 30 03 0C 5F F7
8 F0 00 20 21 7F 62 30 03 08 63 F7
4 F0 00 20 21 7F 62 30 03 04 67 F7
15
Model 8- - - - 448 ver. 3.2 Model 8 448 ver. 3.2
Model 8 Model 8 448 ver. 3.2 448 ver. 3.2
message [hex]
808 808 808