Spider building instructions

Introduction

Make sure you read our assembly tips.

The components marked with a + have a polarity.

To mount them the right way, look for hints either:

  • on the screenprinting on the PCB itself
  • in the Eagle file of the board
  • in the datasheet of the component linked from the parts list

PCB drill sizes

  • ø 0.8: all drills unless documented otherwise.
  • ø 1.0: leads of the potentiometers P1 and P2, battery connector X1, and diode D1.
  • ø 1.2: leads of the LM317 U1, and interruptors S1, S2, and S3.
  • ø 1.5: leads of the input jacks J2 and J3, central lead of the headphone plugs H1 to H14.
  • ø 2.0: plastic anchors of the input jacks J2 and J3.
  • ø 2.5: small leads of the power plug J1, anchors of the potentiometers P1 and P2, lateral leads of the headphone plugs H1 to H14, and leads of the extension plug J4.
  • ø 3.0: big lead of the power plug J1 and spacers.

Preparation

  1. Solder the 5 DIL8 sockets+. The socket pins which have to be soldered on top have a longer shape to ease soldering.

  2. Mount the spacers: the spacer itself goes on the bottom of the PCB, the washer, and then the bolt go on top of the PCB.

  3. Test for short-circuits between the pins of the sockets.

Power supply

  1. Solder J1 both on top and on the bottom of the PCB to make it stronger.

  2. Plug the heat sink on the LM317 U1: the flat part of the heat sink touches the metal plate of the LM317. Mount the LM317 on the bottom of the PCB, and bend the wider part of the LM317 leads to fit the heat sink in its correct position: the flat part of the heat sink touches the bottom of the PCB. Solder U1. Beware: it is all-right for the heat sink to touch the central lead of the LM317 but not the other ones. Then separate a bit the LM317 from the PCB to make sure it doesn't touch the other components.

  3. Solder J1, U1+, R5, R38, C19+, X1+, S1, and R16. C19+ must be well pressed onto the PCB.

    • Make sure that S1 is well pressed onto the PCB on all its sides.

  4. Solder LED1+ so its base is 11 mm above the PCB. The flat side of the LED must be on the side of the switch.

  5. Solder D1+. The white marker on the diode must be the side of the switch.

  6. Plug the DC transformer and measure 8 V between the lateral lead of J1 (GND) and the central lead of the LM317 (VCC).

  7. Unplug the DC transformer and connect a 9 V battery. Verify that the LED lights on with the battery only.

Virtual ground

  1. Solder R14, R15, C14+, and C15.

  2. Mount IC2+.

  3. Measure 8 V between pin 8 of IC2 (VCC) and GND.

  4. Measure 4 V between pin 5 of IC2 (VCC/2) and GND.

  5. Measure 4 V between pin 6 of IC2 (VCC/2) and GND.

Floor line amplification

  1. Solder J3, S3, R40, C20+, R37, R30, C21, and C23+.

  2. Mount IC4+.

  3. With an oscilloscope, visualize the signal of a line input on pin 1 of IC4.

  4. To feed a continuous sine signal into the line input you can run the following command in Linux:

    speaker-test -t sine

Floor power amplifier

  1. Solder P2, C9, C26, R36, C27+, R11, C11+, R31, R35, H13, and H14.

    • Make sure that P2, H12, and H14 are well pressed onto the PCB on all their sides.

  2. Mount IC5+.

R11 sets the gain of the LM386. As explained in the datasheet, without this resistor, the gain is set to 20, with a resistor of 1.2 kΩ to 50, and with a shunt to 200. Let's puts a 1.2 kΩ resistor by default.

  1. Listen to a line input in the 2 headphone plugs.

Floor microphone amplification

  1. Solder R29, R32, C22+, C24, R34, C25+, and R33.

  2. Listen to a microphone input in the headphone plugs.

Interpretation line amplification

  1. Solder J2, S2, R1, C1+, R3, R4, C2, and C16+.

    • Make sure that S2 is well pressed onto the PCB on all its sides.

  2. Mount IC1+.

  3. With an oscilloscope, visualize the signal of a line input on pin 1 of IC1.

Interpretation power amplifier

  1. Solder R12, P1, C8, C3, R10, C7+, C10+, R9, C5+, R28, H12, R27, H11, R26, and H10. C10 and P1 must be well pressed onto the PCB.

    • Make sure that P1, H10, H11, and H12 are well pressed onto the PCB on all their sides.

  2. Mount IC3+.

R9 sets the gain of the LM386. As explained in the datasheet, without this resistor, the gain is set to 20, with a resistor of 1.2 kΩ to 50, and with a shunt to 200. Let's puts a 1.2 kΩ resistor by default.

  1. Solder C10 on the bottom of the PCB.

  2. Listen to a line input in the 3 headphone plugs.

Interpretation microphone amplification

  1. Solder R2, C4+, R6, C6, R8, C12+, and R7.

  2. Listen to a microphone input in the headphone plugs.

Interpretation headphone plugs

  1. Solder R20, R21, R22, R23, R24, R25, R26, R27, R28, H4, H5, H6, H7, H8, and H9.

    • Make sure that H4, H5, H6, H7, H8, and H9 are well pressed onto the PCB on all their sides.

  2. Listen to a microphone input in the 12 headphone plugs.

Extension plug

  1. Cut out the three plastic knobs of the RCA plug J4 (the two square ones and the round one) so that the main package touches the PCB.

  2. Solder J4.

  3. Measure 8 V between the pin of the red RCA plug and GND.

  4. With an oscilloscope, visualize an audio signal on the pin of the black RCA plug.

Enclosure

Panel

  1. Print the layers "Document (48)" and "Screenprint (102)" of the board design on the side of the enclosure which has the battery lid.

  2. Drill all the holes first at ø 2 and then at ø 5.

  3. Drill the holes of the potentiometers and headphone plugs at ø 7.

Sides

  1. Close the enclosure with its screws. Drill first at ø 2 and then at ø 5 to be able to adjust the placement:

    • Power plug J1: ø 7. Center on the junction between the two parts of the enclosure.
    • Input jacks J2 and J3: ø 9. Center on the junction between the two parts of the enclosure.
    • Extension plug J4: ø 10. Center 1.0 mm above the junction of the two parts of the enclosure.

Battery lid

You will notice that the battery lid is sometimes hard to open when the enclosure is closed and screwed. To solve this problem, cut the upper right corner of H14 with a cutter, like shown on this picture: