Looks like you can tell by the tube compliments. See here:
What arthur says plus: All the 65's say 'Stereophonic' front, and 'stereo' back. They were basically mono but had an output for an external multiplex adaptor. There was also an optional muiltiplex section available for them which you could order with the unit, or have installed later.
The 65B's all carry the "B" designation and are stereo units.
Thanks Author and Nsgarch!
I just inherited all this tube equipment. Aside from the McIntosh I have:
Cary Audio CAD301 amp,
Cary Audio CD 300 cd player,
Joule Electra LA100 preamp,
Moscode Minuet preamp,
Tice MBF-3 AC conditioner,
as well as some sweet Tice 416 speaker cables and interconnects.
I am trying to figure out 1) what the heck I have 2) if I really want to get into this tube audio stuff or just sell it and buy me some new Revels!
Thanks again for your help!!
The MR-65 had no MPX output for an outboard stereo decoder.
The MR-65A was still monaural but included an mpx input on the top of its chassis to add the MA-5 stereo multiplex unit.
The MR-65B included this MA-5 unit installed from new (it was known as the MX-1 and is virtually identical to the MA-5). The only other McIntosh stereo mpx is one which was dedicated for use with the MR-66 AM/FM mono tuner -- the MA-6. The MA-6 is extremely rare can fetch hundreds of dollars when it occasionally surfaces on the used market.
The MR-65B was McIntosh's first factory installed stereo tuner, and in my opinion, one of the best sounding tuners that McIntosh (or for that matter any other manufacturer) has ever built.
It is a darn fine looking piece of gear too, especially when in its solid walnut case.
The difference is in the multiplex unit. Unlike the MR-66 which had an outboard MPX unit, the MR-65 multiplex had an internal adaptor.
The early version of the MR-65 was a monaural tuner that included a stereo mpx input on the tuner chassis; which the MA-5 stereo multiplexer attached to.
In the later MR65B, this unit was already installed at the factory, and while virtually identical to the MA-5, called the MX-1.
After the MR-65B was introduced to the market, the MR-65A became the designation for the mono version of this tuner, to distinguish it from the factory stereo version.
I have two beautiful MR-65B's and think they are among the best sounding tuners that I have ever owned.
There is much hype over the later MR-67 and MR-71, but I seriously doubt that there can be much of an improvement in sound quality, given the similar circuit topology -- especially considering the nearly identical tube complement of the MR-65B and MR-71. I expect that the differences between the two has more to do with DX'ing capablities than actual sound quality.
I would imagine that all of McIntosh's tuber tuners sound excellent when properly aligned, be they mono or stereo.
Jimmy, the 71 has that SDS? unit (almost worthless then and totally worthless now ;-) It's the smaller square black can and was for tuning private/subscriber Muzak-type programming that some regular broadcasters attached to their primary signal. Also the 65B and 71 have 4-gang tuning condensers. All the others have 3-gang. (I have two 65B's also, but I think I'm going to sell one of them ;-)
Sounds good .. just don't take any of those nearly worthless Federal Reserve Notes -- try to get some "gold" instead. ; )
-- see Aaron Russo's America From Freedom To Fascism To learn more about what I am talking about -- the Federal Reserve System's counterfeiting operations and how they have completely devalued the U.S. Dollar.
BTW, for "Good" value in a tuner, just got a Pioneer TX-7800 for $59 which is "dynamite" for the money.
Did you know Aaron Russo was Bette Midler's original manager/producer (gosh I wish I could get that sort of data out of my head!!) Yeah, for this country to finally realize it's promise, the illegal Fed. Res. and the illegal IRS will both have to go. In the meantime ;-) I have a Technics ST9030 I'm going to sell soon as well (8-gang tuning condenser!!) so that's my Japanese tuner for now ;-)