Sequential prophet 5 - Sd313 Tun Mux.s;Hs. Audout; Sd411-15 Voices

eous 5-V changes in UNI CV. Q309 is a matched transistor pair. One transistor is a diode-connected
current source, which biases the other's emitter 0.6V above ground. If GLIDE CV is 0, the current
through both emitters is equal. Control current through R3125 is maximum. Increased CLIDE CV
pulls U379-5 more negative, reducing charging current to C348.
2-22 SD313 TUN MUX, S/Hs, AUD OUT
VDAC is distributed on PCB3 by the COMMON CV DMUX and on PCB4 by the INDIVIDUAL VOICE
DMUX. U353-1 OSC A INIT, U354-1 OSC B INIT. U370-7 UNI. and U370-1 SEQ CV have a range of 5-V.
The remaining CVs have about twice this range.
U358 SEQ CV DRVR buffers SEQ CV IN and allows for offset trimming by R303.
U416 TUN MUX LEVEL COMPARATOR output goes negative for the period the 10-V oscillator saw¬
tooth is below the 1.5-V threshold (see Figure 2-10).
R4134 in series with U496 AUD DRVR minimizes effects of capacative loads. R4137 reduces hum
resulting when the Prophet is switched off but left connected to an energized amplifier.
2-23 SD411-415 VOICES 1-5
The following refers primarily to SD411. VOICE 1. However passive components (resistors, capacitors,
diodes) designators are the same for all voices.
OSC A and B and the LFO are based on the SSM 2030 VCO (see Figure 2-11). The 1C consists of two
matched "logging" transistors, a precision current mirror, a low-leakage buffer, waveshaping circuits
for pulse and psuedo-triangle outputs, a comparator and a discharge circuit including a capacitorless
one-shot.
Figure 2-11
2030 VCO Block Diagram Courtesy SSM
2-27