jstang, PB Audio, anybody else.....
Do you recommend exercising the "selector" or "mode" switches periodicly or is it not necessary on the 7 and 7t? Same with the 4 levers in the middle?
Yes, any signal carrying switch should be periodically cleaned, de-oxited, and exercised. Like anything electrical, corrosion of contacts is the enemy. Same can be said for any signal connection from RCA jacks to speaker connections. Some will even go so far as to refresh solder connections, especially those that carry high voltage, or high current, or even micro voltages and currents, hell some even refresh all solder joints.
If McIntosh could have engineered that upper-midrange edginess out of their MC-275 flagship tube power amp, don't you think they would have?
Does anyone believe for a moment, that the big MAC designers didn't kick themselves because the Marantz Model 9 out-classed their BEST effort?
If they could have jumped into their time machine and sourced a modern capacitor to solve that nagging upper-midrange edginess, don't you think they would have?
Get a clue...
Well, consider that maybe the MC275 did sound pretty good - on the speakers available when they designed and built it. And maybe it was pretty good with the damn good tubes they had back in the 60's (Genalex, MOV, Mullards, GE and RCA) instead of everything that has come since. If more modern and perhaps more revealing speakers then came in the decades to follow, it was already after Mc and most other electronics makers had moved on, for better or worse, to transistor designs.
A better question is whether the MC275 anniversary editions made essentially fundamental changes to the character and voicing of the amp and what would they sound like on vintage or modern speakers with vintage or modern sources - assuming the output transformers and output tubes are similar, a difficult assumption. I'm sure as a manufacturer, most are proud of their designs. If someone out in DIY land writes and tells them their pieces don't sound good, but if you mod it so and so and such and such, it'll sound great, how do you think they will respond?? Especially if its a vintage piece they may or may not support anymore? And what of the long term stability or reliability of any mod. They would then have to carry the engineering and liability for anything that goes wrong.
As for mods which simplify the circuit or remove inputs and switching options, well that's great, at least for someone who has decided on only a few sources and doesn't use controls. But that limits flexibility, and for some manufacturers, limits the potential buyers. For greatest appeal, the major manufacturers of the day provided real and perceived flexibility and features which were in vogue in the day (dating back from the preamps of the 50's with multiple phono compensations in inputs) and that was the norm. So called "Purist" and straight wire with gain designs were few and most short lived in the market until "hi-end" designs became more familiar and audiophiles sought them out.
As for ARC equipment, some of it is undeniably good, interesting, and evolutionary. But if you look at the schematics of many ARC preamps and amps, they are also undeniably complex, sometimes to the point where it seems there's tons of extra components and stages. Along with the idea that many parts are run at very high voltage or current levels and space and heat are huge concerns, is it any wonder that some designs had poor reliability, many had to be serviced frequently, and some upgrades were there for reliability improvement as well as sonic improvement, not to mention that they cost a lot too - and I'm trying not to pick on just ARC, many many "Hi-end" makers helped to create the never ending "upgrade" path in seeking Audio Nirvana, paralleling the automakers and other industries.
Ever see some of the big ARC amps - those with 6-10 6550's in two rows or more, along with one or two 6550's as series pass power elements? They're mounted on PC board sockets within inches of the other passive or active elements like resistors and capacitors, all housed in many times only passively cooled cages. Even with Mil-spec packaging of 105 C rated parts, excessive radiant, ambient, and passive heating cycles will eventually damage circuit traces, solder joints, passive parts, etc. But many "audiophiles" have been led to believe that's all worth it in the pursuit of audio perfection - like the tempermental sports car or hot rod of our youth.
But that is where some genuine improvements are pioneered and then made more accessible to the masses, if there is a trickle down at all.
