Accutronics Products and Specifications

There are a number of different types of reverb tanks available. Use this guide to help you determine part number based upon your specifications and application.

Accutronics Type 4

Accutronics Type 4

The industry standard for years, the type 4 is still manufactured today using Hammond's original design. Four counter-wound and coupled springs deliver superior mechanical performance and the classic sound that helped make the Fender Twin Reverb amp famous. Outer channel dimensions are 16.75" length x 4.735" width x 1.313" height.

Accutronics Type 8

Accutronics Type 8

Designed for applications in which the overall sound quality is important and a compact package is required. Small in size, this three-spring reverb approaches the rich textural quiality of the larger reverb units. Outer channel dimensions are 9.25" length x 3.375" width x 1.313" height.

Accutronics Type 9

Accutronics Type 9

Six springs, counter-wound, coupled and placed in parallel, combine to create Sound Enhancement's fullest, richest reverb effect throughout the full range of musical sound. Ideally suited for keyboard, sound reinforcement and pedal steel applications. Outer channel dimensions are 16.75" length x 4.375" width x 1.313" height.

Size Comparison

Comparison of Reverb tank sizes

Part Numbering System

Reverb tank part numbers consist of a seven digit code, i.e. 4EB2C1B. Each digit in the part number represents a specification. The meanings of these digits are as follows:

1stReverb Type
2ndInput Impedance
3rdOutput Impedance
6thLocking Devices
7thMounting Plane

Part Numbering Specifications

ValueType 1 or Type 4Type 8 or Type 9
Digit #1 - Reverb Type
1Type 1
4Type 4
8Type 8
9Type 9
Digit #2 - Input Impedance
A8 Ohms10 Ohms
B150 Ohms190 Ohms
C200 Ohms240 Ohms
D250 Ohms310 Ohms
E600 Ohms800 Ohms
F1,475 Ohms1,925 Ohms
Digit #3 - Output Impedance
A500 Ohms600 Ohms
B2,250 Ohms2,575 Ohms
C10,000 Ohms12,000 Ohms
Digit #4 - Decay Time
1Short (1.2 to 2.0 s)
2Medium (1.75 to 3.0 s)
3Long (2.75 to 4.0 s)
Digit #5 - Connectors
AInput Grounded/Output Grounded
BInput Grounded/Output Insulated
CInput Insulated/Output Grounded
DInput Insulated/Output Insulated
ENo Outer Channel
Digit #6 - Locking Devices
1No Lock
Digit #7 - Mounting Plane
AHorizontal, Open Side Up
BHorizonta, Open Side Down
CVertical, Connectors Up
DVertical, Connectors Down
EOn End, Input Up
FOn End, Output Up

Example: 4EB2C1B

Consulting the table above, we can see that a 4EB2C1B can be broken down in the following way:

  • Digit #1 = 4, meaning this is a Type 4 tank
  • Digit #2 = E, meaning the input impedance for this tank is 600 Ohms
  • Digit #3 = B, meaning the output impedance for this tank is 2,250 Ohms
  • Digit #4 = 2, meaning the decay time for this tank is Medium
  • Digit #5 = C, meaning the connectors for this tank are Input Insulated / Output Grounded
  • Digit #6 = 1, meaning there is no locking device
  • Digit #7 = B, meaning the mounting plane is Horizontal, open side down

Example: 8EB2C1B

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By Kurt Prange (BSEE), Sales Engineer for Antique Electronic Supply - based in Tempe, AZ. Kurt began playing guitar at the age of nine in Kalamazoo, Michigan. He is a guitar DIY'er and tube amplifier designer who enjoys helping other musicians along in the endless pursuit of tone.

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