Scholz power soak schematic

[lowell]

Anyone got one? I heard it rocks and is cheap to build.

[teemuk]

US Patent 4,363,934 includes a schematic of the device.
Volume control device - Google Patent Search

[Enzo]

Thanks, teemu, that is a resource I just never seem to think to use.

[lowell]

brilliant... thanks! Only issue is resistor wattage is not mentioned. Weird, being how defined the patent text is.

Maybe resistor wattage could be calculated by first measuring the current through the speaker at preffered amp settings (volume), without the power soak? Then I guess you'd need a meter that holds the "max" AC current so you can accurately read the results? Then calculating each resistor independently as ((R*current)squared/R)? Then multiply that by 2 for safety?

Maybe there's an easier way.

[J M Fahey]

[Maybe there's an easier way.]
Sure enough: the resistors should dissipate safely somewhat more than the square wave power of your amp, about twice the "clean" power.
The resistance must reasonably match the rated impedance.

[oc disorder]

Some quick pics of my Aussie Tom Scholz power soak which of course has to be operated upside down (when used in the USA) for the correct electron alignment !
Took a couple of side shots so you can see some of the R values.
Excuse the whisky and coke stains they add the X factor to the sound.

[teemuk]

Some quick pics of my Aussie Tom Scholz power soak which of course has to be operated upside down (when used in the USA) for the correct electron alignment !
Took a couple of side shots so you can see some of the R values.
Excuse the whisky and coke stains they add the X factor to the sound.

I like the way how the power resistors are secured on place (without glue). Another Scholz patent, BTW.

[lowell]

right on thanks for those pics! Still no wattage but looks like 10-25w cement power resistors.