Power Soak by Tom Sholz, Model II, (sn 82 1945)

For guitarists, it is often desirable to overdrive an amplifier to achieve just the right tone and flavor.  Often, this will result in excessive volume levels under many recording and performing conditions.  By reducing the wattage delivered to the speakers The Power Soak reduces the volume, without altering the quality of the tone produced by the amp.  The amp doesn't operate any differently, and the excess power is simply dissipated as heat.

The Sholz Power Soak does that and more.  It is similar to Marshall's Power Brake, the THD Hot Plate and other attenuators.  

The Sholz  Power Soak works with any kind of amp (tube or solid state), has a single input for the amplifier output, an impedance selector switch 4-8-16Ω, 2 output jacks to connect speakers, and an attenuator that ranges from Full Output to -32db in 8 steps.

A note regarding Tom Sholz, the designer, from www.rockman.fr:

"Tom Scholz has recorded the two first albums of Boston with these big, over-powered Marshall stacks, cranked up at 11. Since he's a clever man and knew that his ears are precious for a musician, he designed the Power Soak as a "Volume Control Device", as defined by the US patents 4,143,245, D256,798, 4,363,934 and D270,153. The Power-Soak not only attenuates the power of your amp: it allows a precise control over the global volume of your set-up. In other terms, tweak your sound first, then adjust your volume.

"The personal prototypes used by Scholz from 1975 (?) till 1980 allowed the new-born company SR&D to issue its first product, the Power-Soak, in the end of 1980. The first commercial ads appeared in 1981, and were rather product oriented: the Power-Soak is a tool, not a toy, and it really solves a problem for the guitarist.

"An updated version of the original Power-Soak, known as "Model II", was issued in the end of 1981: it has an extra switch made to adapt the Power-Soak to the solid-state amps (though its primary target is the tube amps market). The resistors network was tweaked a little, for a more precise attenuation control (?). No audible sonic difference with Model I.

"Discontinued in 1982 when the Rockman headphones amp was created, the Power-Soak was re-issued in 1992 as a PS-III model: the difference is in the jack positions (rear panel on the re-issue, front panel on the original). The solid-state switch has disappeared, and the manual says that the PS-3 can be used both with solid-state and tubes amps. The impedance selector has two positions only (4 & 8 ohms), but 16 ohms amps can be used at the 8 ohms setting.

"How many Power-Soaks were built? Around 10,000, if we refer to the number of eBay transactions per year. That's consistent with the serial number of a Power Soak I own, which has the serial number 81-3391 (approximately 3500 per year)."