From: Barry Schaede Date: Sun, 18 Feb 1996 12:14:50 -0700 (MST) Subject: Ampeg reverb tanks
Ampeg commonly used a 4AB3C1B type Accutronics tank in their amplifiers. The 4 means it is a long 4 spring type. The A means the input impedance is 8 ohms the B denote an output impedance of 2,250 ohms. 3 means the delay path is long vs short or medium. C is input insulated output grounded. 1 means no lock on the reverb. This is opposed to the locking type reverbs in outboard tanks like the Fender units. And finally the B means the tank should mount horizontally open side up. The previous information was compiled using reprinted Accutronics order forms from Dave Funk's column in Vintage Guitar and ordering information from MojoTone a tube amplifier parts and supply company.
The bottom line is that this is absolutely the most common type of reverb tank out there. The only thing I'd change is the delay a medium is much better sounding than the long the amp came with. Less mushy but medium tanks are tough to find. fjm
