SR1- Spring Reverb Kit Instructions

The instructions for the spring reverb kit are divided into the 3 main sections of the circuit: PREAMP, MAKEUP GAIN, DRIVER. The sections should be individually built and tested one after the other, as opposed to building the entire unit all at once. This helps with avoiding potential mixups, and makes troubleshooting easier in case of a build error. These instructions use +-18vdc power supply, multimeter, and function generator for test procedures, and assume that the builder already possesses a basic understanding of soldering techniques. All AC test values are measured in RMS. We recommend printing out our “Parts Layout Sheet” before starting, and laying out your parts on top of the sheet to make identification easier.

If you have any questions while building your kit, feel free to reach out to us for support: mark@hamptone.com


PREAMP:

STEP 1: RESISTORS

Populate and solder resistors R19, R20, R21, R23, R24, R25.

STEP 2: TEST POINTS

Save 3 of the cut resistor leads [or use bus wire] to form hoops for test points: GND2, +18vdc, -18VDC. Solder them in place.

STEP 3: DUAL OPAMP

Populate and solder the dual opamp U3. Be sure that the opamp is inserted in the right direction. The “dot” on the top should align the direction of the notch printed on the circuit board. [Note that the opamps in the photo are socketed, this is not included/required.]

STEP 4: CAPACITORS

Populate and solder capacitors C10, C11, C12, C15, C8, C9. Be sure to follow the correct polarity for electrolytic capacitors.

STEP 5: POTENTIOMETER

Populate and solder potentiometer R22. We recommend breaking off the tabs on the side of the pot with pliers before populating them. This allows the pots to be flush to a front panel.

STEP 6: PREAMP TEST

  1. Measure between test points +18vdc and -18vdc. Turn on power [Bring up slowly if possible]. Meter should read +36VDC. Or you can measure each individually [+18 to ground] [-18 to ground].
  2. With function generator, input 0.1v 1khz signal to “instrument in.”
  3. On the “high” side of the preamp pot [R22], you should see 1.01v.
  4. Turn preamp pot [R22] all the way up.
  5. Measure output at “line in” on the pad titled TS, signal should be 10.2v.


MAKEUP GAIN:

STEP 7: RESISTORS

Populate and solder resistors R8, R9, R12, R13, R14, R15, R16, R27, R28.

STEP 8: DUAL OPAMP

Populate and solder dual opamp U2. Be sure to insert it in the proper direction, with the “dot” on top of the part facing the direction of the notch printed on the circuit board.

STEP 9: CAPACITORS

Populate capacitors C6, C7, C16. C20 is an optional filter cap for the makeup gain section. This capacitor can be used to high pass the signal after the tank return. Jumper these pads to bypass the filter. To experiment with this value,
reference the table in the C20 Table.

STEP 10: POTENTIOMETERS

Populate potentiometers R10 and R11.

STEP 11: MAKEUP GAIN TEST

  1. Input 0.1v 1khz signal into “tank return.”
  2. Turn reverb pot [R10] all the way up.
  3. “Line Out” pad should see a 9.16v signal.
  4. “Instrument Out” pad should see a 0.428v signal.


DRIVER:

STEP 12: RESISTORS

Populate and solder resistors R2, R3, R26.

STEP 13: CAPACITORS

Populate and solder capacitors C1, C2, C3, C5, C13, C14.

STEP 14: SWITCH

Solder the switch [SWT1] to the board. Be sure that the switch is straight, and fully pressed down to the board.

STEP 15: INDUCTORS

Populate and solder inductors L1 and L2. Be very careful to not bend or overheat, inductors are especially fragile.

STEP 16: HEATSINK

Populate and solder the heatsink to the board. Be sure that the heatsink is straight and pulled flush to the board.

STEP 17: DRIVER IC

Assemble the isolation hardware as shown in the picture to the left. Be sure that the black shoulder washer fits into the hole on the top of the driver IC for proper isolation. Install the hardware in proper order and screw the driver IC tight to the heatsink. To test whether your IC chip is properly isolated, use a meter to test connection between the silver top of the IC and the heatsink. They should NOT make connection.


Solder the IC chip into place from the bottom of the board. Be sure to never short the output of the IC driver to ground during operation or testing.

STEP 18: POWER RESISTORS

Bend power resistors R5, R6, R17, R18. Populate them suspended up off the board as high as possible. These parts must be up off the board for proper heat dissipation.

STEP 19: NON-POLARIZED CAPACITOR

Populate and solder the non-polarized capacitor C4. Pay no attention to the + sign on the board, the cap can go in either direction.

STEP 20: POTENTIOMETER

Populate and solder in potentiometer R1.

STEP 21: DRIVER TEST

  1. Input 0.1v 1khz signal to “line in” on the pad labeled “T.”
  2. Turn tank drive pot [R1] all the way up.
  3. Measure the output at the “tank drive” pad for each varying frequency given in the table on the downloadable test document. This measures the drive slope.