Replace pwr cord w/IEC socket on vintage gear?

Rrog on vintage fisher amps/preamps ive bought and replaced out of spec original caps and resistors the sams and fisher schematics for those units shows the a/c plug feeding the power transformer power windings and service receptacles with no polarity marked hot or neutral and the instructions do not mention a right or wrong way to plug these units in. these power amps and integrateds have a so called death cap installed for the shock hazard you mention on fridges due to there super high stepup voltages. these units are late 50s early 60s built when life was simple and much better.

Marakanetz thats very true on the cost of iecs and the added connection but in the end worth it for better sound imo.

If that Heathkit is a tube amp without a protective cage, you do not want a grounding power cord for the same reason toasters and lamps are not furnished with three-prong plugs -- live parts exposed from damage have no bond to earth. Also, the grounded power cord can put the signal and chassis to the same ground, possibly causing sonic problems such as humming from ground looping. This really should be done by a pro.

Stltrains, I am also referring to vintage Fisher, Scott, Dynaco, Sherwood, Harman Kardon, Audio Research and any other vintage equipment with a non-polarized plug. This is especially important with mono amplifiers and preamps since it does affect the sound depending on how they are plugged into the wall. This is also true with vintage turntables and tuners.

The procedure Rrog describes for orientation of two-prong plugs is good practice, although it may or may not make any difference with any given component in any given system. And in many cases the measurements being compared for the two orientations will be low and pretty much the same.

What the procedure does is to minimize low level leakage between the hot side of the ac line and chassis, which may particularly occur to some degree as a result of stray capacitance, and perhaps also degraded insulation, in the power transformer. Besides conceivably having effects on the sonics of the particular component, it could also result in extraneous low level ac hum and noise currents flowing through the return conductor of cables connecting that component to other components it may be driving, which would be indistinguishable by those components from signal voltages.

Regards,
-- Al

Rrog, you really think the engineers at Heathkit listened to the amp with different power cords and "voiced" it to their sonic preferences? You need to be careful when applying modern sensibilities to times gone by.