Mercury Magnetics O50-PLM Output Transformer
This output transformer is produced by Mercury Magnetics for an unknown
boutique amp manufacturer. It was supposedly based on their O50-JM 50-watt
Plexi toneclone, but was modified at the request of a boutique amp maker
who needed a plexi style OT to accomodate a pair of 6L6 type tubes
running in push-pull operation. Although the primary impedance is not specified, my measurements show that the primary impedance is about 6K ohms. It has secondary taps for 4/8/16 ohms.
This transformer has fewer interleaves than the original plexi-type OT and is
somewhat cheaper to manufacture. In addition to making the OT a bit less expensive to manufacture, stacking the laminations instead of alternating them tends to simulate the effect of air gapping. Although this unit isn't offered for retail sale and doesn't have an official retail price, I am able to get it from MM at a bulk price of $60 plus shipping and handling.
All wires are 20-ga UL type 1015 with PVC insulation. The wiring codes are as follows:
Primary:
6K ohms (measured)
Plate 1: Brown
Center Tap: Red
Plate 2: Blue
Secondary:
Ground: Black
4-ohm: Orange
8-ohm: Yellow
16-ohm: Violet
Photographs of the transformer are provided below. If you recognize this OT from
any amplifier porn, please let us know, as we'd like to know which company to thank
for designing this transformer!
Image # 1:
Image # 2:
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Photos Copyright 3/16/2003 by Bob Predaina. All Rights Reserved. Photos may not be copied, reproduced, or hyperlinked without the express written permission of Bob Predaina.