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Showing posts with label Lectrolab. Show all posts
Showing posts with label Lectrolab. Show all posts

Saturday, July 2, 2011

Tech Talk - Lectrolab R200 (1953)

* 2 Inputs, one Volume, one Tone control.
* The filaments in these tubes are powered by 25 to 50 volts AC. This is in contrast to almost all modern amps which use 6.3 volts.
* 50L6 is the power amp tube, capable of 4 to 8 watts depending on the circuit. Without knowing the transformer specs, or measuring an example, we can’t state with certainty what the R200 output is.
* 35Z5 is the rectifier. These have been used in other designs with no power transformer, which can lead to the chassis being “hot” (117VAC) whether the amp is on or off. I believe the term “widow-maker” refers to that design feature. The R200 and R200b schematics both show a power transformer that would isolate the line voltage from everything but the tube filaments. One side of the AC line is tied to ground through a capacitor, creating a “signal ground”.
* This does not make them safe! The schematic does not show how the chassis is grounded.