MFA, MC Reference, Original Prototype - Mono Blocks
Looking to make a 2017 year end deal. email, text or call.. Info below.
Original MFA Mono Blocks built to be the paring to the MC Reference Preamp. I am the original owner and have held them since they were built and purchased in 1991. Those of you who know about the MC reference preamp know what a quality piece of gear it was. You also know this was MFA's all-out, cost no object, preamp that set the bar of what HiFi tube preamp technology could be. These mono's were slated to be the pairing to that preamp. There were only 10 preamps ever built and these amplifiers are the ONLY pair in existence.
Product Description: The amps are completely hand built, 100% point to point wired with custom hand wound transformers manufactured and tested to be identical in specs and measurement. The amps are hard wired in triode so there is no Ultra-linear or Pentode switchability. There are no meters or extra components like one would find on the MFA 120 or 200. The output tubes and AC balance must be biased using a separate multi meter and there are plugs for this on amp. All the non-signal equipment that would normally be present on the 120 or 200 has been eliminated. The only two switches on each mono block are power and a negative feedback elimination circuit. The Negative feedback circuit was a test switch of which would likely be eliminated on a production run. The regulation is so good, the negative feedback loop has approximately 8db when switched on. (Normal for a stock MFA120 would be around 20db or more and has proven to knock down the sound stage.) You can also run them without any feedback for a monstrous sound stage but the specs fall off a bit. One cannot do any of this on a stock MFA 120 or 200. The speaker cable binding posts are not traditional posts but are a panel type, non magnetic mounts that accommodate 4 & 8 ohm loads and are era correct for this Amp. All tubes have been upgraded to the Mil-Spec 8 and 9 pin 5687 and octal 5691. Output tubes are real (Not fake) OEM GE 6550's but you can run kt88"s or kt90's or Gold Aero's or 300B’s if you can find some NOS. There are several capacitors, resistors and diodes, including the power bridge that were upgraded over a stock 120 or 200, too much to list and most forgotten due to time.
I have held them now for more than 26 years, the last 15 sitting in boxes with occasional use to see how other gear stacks up. They are impeccably well preserved, stored indoors, no smoke or pets. Why am I selling? My tastes have evolved and I simply don't use them enough to warrant holding them, besides, it's time for the next Audiophile to enjoy them. Absolutely-positively no disappointments. They really are special amps, nostalgia and sound quality.
Disclosure and condition: The only unfortunate part about these amps is that they are original prototypes that were built on prototype chassis. Hence they are not the most attractive amps and have mounting stamp-outs and drillings that were never used. I suspect that is what makes them special. For that I rate them 8 of 10 but they are very clean for 90"s gear.
For more information, please write me. I have documented the development of the circuit as much as possible given the product never saw formal production and I will be more than happy to disclose all I know.
Payment: It's my preference to take a check or wire transfer but I will entertain Pay Pal if you cover the 3%. email me to work it out.
Shipping: There never were boxes or manuals for the amps and if you are not local they will require special boxes and/or creates with appropriate packaging to be made from scratch. Don't worry, I will make sure the packaging is bullet proof. I will cover the creating expense, you will need to cover the shipping expense.
Thanks for looking. firstname.lastname@example.org 408-489-1414