Doepfer A-188-2 Tapped BBD Module - Manual (Page 3)

DOEPFER System A-100 BBD Module A-188-2
3
The following table shows the relation between clock frequency, used output stage (tap) and delay time for the BBD circuit
used in the A-188-2 (MN3011).
Table 1: Relation between clock frequency [kHz], used output (tap) and delay time [ms]
clock frequency
(clock input socket)
BBD clock frequency
(= 1/2 clock input)
MN3011
tap/stage output
[kHz] [kHz] 396 662 1194 1726 2790 3328
1 0,5 396,00 662,00 1194,00 1726,00 2790,00 3328,00
2 1 198,00 331,00 597,00 863,00 1395,00 1664,00
5 2,5 79,20 132,40 238,80 345,20 558,00 665,60
10 5 39,60 66,20 119,40 172,60 279,00 332,80
20 10 19,80 33,10 59,70 86,30 139,50 166,40
50 25 7,92 13,24 23,88 34,52 55,80 66,56
100 50 3,96 6,62 11,94 17,26 27,90 33,28
200 100 1,98 3,31 5,97 8,63 13,95 16,64
300 150 1,32 2,21 3,98 5,75 9,30 11,09
400 200 0,99 1,66 2,99 4,32 6,98 8,32
500 250 0,79 1,32 2,39 3,45 5,58 6,66
Remarks:
The
grey italic characters indicate parameters out of the data sheet specifications as the MN3011 circuit is specified only for
clock frequencies between 10kHz and 100kHz. But the A-188-2 is able to generate even clock frequencies below 10kHz
and above 100kHz. From our experience the MN3011 cannot be damaged if it is operated with frequencies out of spec. This
is why we decided to include out-of-spec frequencies to obtain special audio effects – especially for clock frequencies below
10kHz. But the regular circuit behaviour is no longer guaranteed (especially increasing voltage losses at lower frequencies).
As the clock frequency falls below ~ 15 khz the clock signal itself will become audible. This clock noise can be used as
unusual audio source or it can be filtered out with an external low pass filter.