The HK250 os a beautiful stereo amplifier built on an all copper chassis(!), which is something you don’t see very often, or at least under 1K$.
It uses the wonderful 6cg7 driver tube (which is a 9-pin version of the 6sn7, but MUCH less expensive to source), and a pair of 6L6's per channel.These amps were built in 1959, and also featured a very carefully designed output transformer with taps for 4 ohms, 8 ohms, 16 ohms, and 32 ohms. They are also bridgeable to mono operation at the flip of a switch. I purchased this amplifier at an estate sale several years ago, with a mind towards refurbishing the passive components. The chassis is incredibly beautiful (it's really the nicest all copper chassis I have ever seen), and it is in amazing shape. The amplifier was playing in a mono configuration when I purchased it, but I did not power it up since that time due to the older capacitors in the circuit. However, the DCR on both output transformers is a steady 20 ohms (actually 20.5 ohms in one channel, and 19.8 ohms in the other). The circuit is quite simple, and this would make a marvelous amplifier to really max out with modern boutique parts. I just do not have the time for a new project right now, and a certain someone (yes, the Mrs.) is asking for more room in our closets and garage. I am sure an audiohile would have a real blast refurbishing this and maxing it out. It is a classic circuit, and uses transformers wound in the true heyday of excellent transformer winding technology and design. Some interesting links: http://marantzhallo-fi.blogspot.com/2016/02/harman-kardon-250-tube-power-amplifier.html http://audiokarma.org/forums/index.php?threads/harman-kardon-hk250-corrected-schematic-and-restoration-photos.270846/ http://audiokarma.org/forums/index.php?threads/what-is-a-harman-kardon-hk250-worth.261685/ I also have 100% feedback on eBay. Please contact me for further info. Thanks ! I am willing to ship to the USA or Canada at my expense. For other locations, please contact me for an estimate.
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