Guitar Amp Reverb Tray (Spring Reverb)
Here's some information on reverb trays. The pictures below are from an old Carlsbro Stingray Lead.
TIP - If you ever disconnect the reverb from your guitar amp, make sure you connect the input and output back up the same way when reinstalling. The input coil is usually a lower impedance than the output. If you were to measure the DC resistance of the coils with an ohm meter (Note - this is not the same as impedance, but it will give you an indication which is Input and which is Output) the input coil might measure about 25 ohms and the output coil might read about 190 ohms.
If your reverb stops working, it's worth checking the wires which run from the phono sockets to the coils - sometimes they break as they're flexing all the time. You can see what they look like in the close up picture below.
Top view of a Reverb Tray
Underside of a Reverb Tray. You can see the springs running along the length of the tray.
Closeup of a Reverb Tray showing the springs and pick up coil.
If the spring reverb is manufactured by 'Accutronics' you will be able to gain more information about the reverb tray by looking for a series of seven numbers/letters printed on the case, which you will usually on the top.
This code gives you information as follows:
PART NUMBERING SYSTEM
Reverb part numbers consist of a seven digit code.
EXAMPLE: 4EB2C1B
Each digit in the part number represents a specification. The parameters are as follows:
1ST DIGIT = REVERB TYPE
TYPE 1 has simple 2 spring reverb
TYPE 4 Four counter wound and coupled springs
TYPE 8 is a three spring reverb
TYPE 9 has six springs, counter wound, coupled and placed in parallel
2ND DIGIT = INPUT IMPEDANCE (Note - Impedance is not the same as DC resistance)
3RD DIGIT = OUTPUT IMPEDANCE (Note - Impedance is not the same as DC resistance)
4TH DIGIT = DECAY
5TH DIGIT = CONNECTORS
6TH DIGIT = LOCKING DEVICES
7TH DIGIT = MOUNTING PLANE
PART NUMBERING SPECIFICATIONS FOR TYPE 1 & TYPE 4
EXAMPLE: 4EB2C1B
DIGIT #1 - REVERB TYPE
1 for Type 1 or 4 for Type 4
DIGIT #2 - INPUT IMPEDANCE
A = 8 Ohm
B = 150 Ohm
C = 200 Ohm
D = 250 Ohm
E = 600 Ohm
F = 1475 Ohm
DIGIT #3 - OUTPUT IMPEDANCE
A = 500 Ohm
B = 2250 Ohm
C = 10000 Ohm
DIGIT #4 - DECAY TIME
1 = Short (1.2 to 2.0 sec)
2 = Medium (1.75 to 3.0 sec)
3 = Long (2.75 to 4.0 sec)
DIGIT #5 - CONNECTORS
A = Input Grounded / Output Grounded
B = Input Grounded / Output Insulated
C = Input Insulated / Output Grounded
D = Input Insulated / Output Insulated
E = No Outer Channel
DIGIT #6 - LOCKING DEVICES
1 = No Lock
DIGIT #7 - MOUNTING PLANE
A = Horizontal Open Side Up
B = Horizontal Open Side Down
C = Vertical Connectors Up
D = Vertical Connectors Down
E = On End Input Up
F = On End Output Up
PART NUMBERING SPECIFICATIONS FOR TYPE 8 & TYPE 9
EXAMPLE: 8EB2C1B
DIGIT #1 - REVERB TYPE
8 for Type 8 or 9 for Type 9
DIGIT #2 - INPUT IMPEDANCE
A = 10 Ohm
B = 190 Ohm
C = 240 Ohm
D = 310 Ohm
E = 800 Ohm
F = 1925 Ohm
DIGIT #3 - OUTPUT IMPEDANCE
A = 600 Ohm
B = 2575 Ohm
C = 12000 Ohm
DIGIT #4 - DECAY TIME
1 = Short (1.2 to 2.0 sec)
2 = Medium (1.75 to 3.0 sec)
3 = Long (2.75 to 4.0 sec)
DIGIT #5 - CONNECTORS
A = Input Grounded / Output Grounded
B = Input Grounded / Output Insulated
C = Input Insulated / Output Grounded
D = Input Insulated / Output Insulated
E = No Outer Channel
DIGIT #6 - LOCKING DEVICES
1 = No Lock
DIGIT #7 - MOUNTING PLANE
A = Horizontal Open Side Up
B = Horizontal Open Side Down
C = Vertical Connectors Up
D = Vertical Connectors Down
E = On End Input Up
F = On End Output Up
For more information go to http://www.accutronicsreverb.com/prodspec.htm
For The History of Spring Reverberation go to http://www.accutronicsreverb.com/history.htm
For Spring Reverberation - Theory of Operation go to http://www.accutronicsreverb.com/rvbtheop.htm
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