When an electrical signal is applied to the input coil a magnetic field is generated which acts upon a tiny magnet on each of the springs. This field causes the magnet to twist. This movement then propogates up the helical spring until it reaches the output coil. So, at the output coil, the twisting motion of the magnet produces an electrical signal that is a delayed version of the original. In addition, the twist is reflected back up the spring to the input and then again back to the output coil. The process continues with sound bouncing up and down the springs, getting quieter each time so giving a seres of reflections just as though you were between two walls.
These movements are very small, therefore it is important to prevent any external vibrations from getting into the mechanism. This is done in two ways. First the springs are mounted on a metal tray which is then suspended into the larger outer housing. Second, the outer housing has four rubber mounting feet with brass inserts to damp vibrations transmitted via the mountings.
What's Your Orientation?
Reverb tanks are pre-adjusted to be mounted in certain orientations. On the short 9.25in long tanks the inner tray mounting springs are strong compared to the weight of the tray and so can usually be mounted in any orientation as gravity has little effect. For the longer 4 and 9 series ones the tray is much heavier and so the tray mounting springs are located in different holes on the outer chassis to prevent the inner tray from touching the chassis. So, if you were to take a tank specified for open side down mounting and turn it upside down you will see that the inner tray is touching the chassis. Similarly for input connector up and down mounting. It's just a matter of moving the mounting springs to keep the inner tray away from the chassis. It's quite easy using a pair of needle nosed pliers to move these springs if you can't get the style you want off the shelf. The last letter of the part number specifies the pre-adjusted orientation.
- A - Open side up
- B - Open side down
- C - Connectors Up
- D - Connectors Down
- E - Input Connector Up
- F - Input Connector Down
There is an old Accutronics tank application note in which they state that the magents are set differently between orientations. Since the mangnets are rotated by the applied signal and the displacement due to gravity is negligiable, this does not seem to apply to the modern tanks that we supply. This has been confirmed by the tests we have done. Therefore, by simply adjusting the suspension springs you can use them in any orientation.