0    The Apple IIgs uses an Ensoniq    085
1     synthesizer to produce sound.    085
2                                      034
3  Pin 1 of J25 on the motherboard is  034
4  the input to the A to D converter.  034
5  This input requires a 2.5 volt max  034
6  input signal to produce a digital   034
7  sample of the input sound.          034
8                                      034
9  The pre-amp outlined here and either034
0  a high impedance mike or a low im-  034
1  pedance output from an amplifier    034
2  will give quite good results at a   034
3  modest cost in time and parts.      034
4                                      034
5  Click PICTURE for a schematic and   034
6  wiring diagram.                     034
7                                      034
NEWLINE 
0                                      034
1                                      034
2  CONSTRUCTION*                       051
3                                      034
4  Use a 2 by 3 inch perfboard for     034
5  constructing this circuit.  All the 034
6  parts with the exception of P1 are  034
7  available from RADIO SHACK.  P1 can 034
8  be anything that will fit...shop    034
9  around.  Parts placement and con-   034
0  struction are not critical& but best034
1  results require a metal box for     034
2  shielding.  If you aren't handy with034
3  electronics& ask a friend who is to 034
4  help you.                           034
5                                      034
6                                      034
7                                      034
NEWLINE 
0          PREAMP PARTS LIST           051
1  ----------------------------------  051
2  R1     RESISTOR 100 1/8W            034
3  R2&4   RESISTOR 10K 1/8W            034
4  R5&8   RESISTOR 10K 1/8W            034 
5  R3     RESISTOR 680 OHM 1/8W        034
6  R9     RESISTOR 3.9K 1/8W           034
7  R10&11 RESISTOR 39K 1/8W            034
8  R6     POTENTIOMETER 15K            034
9  R7     POTENTIOMETER 25K            034
0  C1&2   CAPACITOR (MYLAR) .1uf 10v   034
1  C3     CAPACITOR (LYTIC) 1uf 10V    034
2  C4     CAPACITOR (LYTIC) 470uf 10v  034
3  J1     PHONO JACK                   034
4  P1     CONNECTOR .100 PIN SPACING   034
5  U1     OP-AMP (TL071 - LOW NOISE)   034
6  S1     SWITCH& D.P.D.T.             034
NEWLINE 
0  ALIGNMENT* (Center at 1.28 volts)   051
1                                      034
2  Connect P1 to J25 on the mother     034
3  board. Unplug the microphone or low 034
4  impedance (line) input source.      034
5                                      034
6  Switch your circuit on and bring    034
7  up the SONIX Waveform Editor.       034
8                                      034
9  Select CAPTURE and then SAMPLE.     034
0                                      034
1  Set the CENTER ADJUST control to    034
2  produce a horizontal white line     034
3  across the center of the screen.    034
4                                      034
5  You must RE-SAMPLE to see what      034
6  has changed after each adjustment.  034
7                                      034
NEWLINE 
0  ALIGNMENT* (Set preamp output)      051
1                                      034
2  Connect a sound signal source to    034
3  the circuit's input connector& J1.  034
4  Set SW 1 for high impedance if you  034
5  are using a mike& or for low imped- 034
6  ance if you are using a line-level  034
7  input (such as an amplifier output).034
8                                      034
9  Sample the input and adjust the GAIN034
0  CONTROL to produce a waveform that  034
1  just touches the top and bottom of  034
2  the Waveform Window.                034
3                                      034
4  This completes all adjustments....  034
5                                      034
6  YOU ARE NOW READY TO SAMPLE SOUND   085
ENDLINE