Sloober makes a point here that took me a couple of years to sink in through my thick head
- that we will never know just exactly what an MC30 sounded like when it rolled off the line.Back around 2003-2004, when the collective knowledge base on this and other forums had yet to develop on this topic to the level it has today, the typical response from most vintage Macheads was "keep it original as possible - fix only what needs fixing", and that "much of the 'magic' that the MC30 possesses is in part due to the caps". OK, fair enough - except that I was unable to keep MC30s operating for long with all original parts....so the question of "what parts to use" became a question borne of necessity.
THAT questioning is what prompted a fellow forum member to get in touch with me and "use me" as a "lab rat" by allowing me to listen to various MC30s with differing cap sets. This was an education beyond my wildest dreams - nothing like getting to demo real MC30s in such a fashion!
One of my primary concerns was avoiding turning the MC30s into "modern sounding amps". I got a taste of just what that could sound like with my second set of MC30s - stuffed full of Wima and various other poly and mylar caps. Those amps worked OK electrically - but OH BOY were they bouncy:nono:
I can tell you beyond doubt that the Sonicap Platinums did NOT make the amps sound "modern". Lack of fog, yes. Truly clear, yes. But still an MC30, by way of that superb midrange, and the comfortable, warm, and easy-to-listen-to character that we've come to expect from these vintage Mac amps. They have some of that McIntosh RICHNESS....that full, "comfy like your dad's La-Z-Boy" kind of sound that we all love about those vintage Macs.
Now I would say that I think the K40, or a K40 blended with a "middle of the road" kind of cap would be a build that might be more of what vintage lovers might expect.
I couldn't choose the original bumblebees, as those are very old caps, and is a big question whether 50 year old caps (even NOS) would hold at real world operating voltages. So I HAD to look at modern options. And there are a LOT of options.
I find that the resistors are just as much "in play" WRT the sonics as the caps can be. I like carbon comp or carbon film in these generally (carbon comp A/B's are hard to do because of the drift issue, carbon films are easier because there are new options available).
Now I think the world of Terry - dude is a walking Mac encyclopedia, and I would rarely if ever ignore his advice. Similar comments toward the AC crew. However, I think our collective experimentation has added a great deal of light to the beacon that Terry provides to us here. Some of us had to ask "what if", and that persistence is a big reason I am with these MC30s for life.
And that's quite a feat for me, because I'm one of those superbly anal high efficiency speaker loons, who as stated previously is crazy enough to want two MC30 build pairs to satisfy as much of my audio fetishes as could be possible via MC30s:yes:
As a collective, the idea of rebuilding/"blueprinting" the innards is an accepted norm today for many, particularly for amps not working, and MUCH more is known about the options within the build, which is a huge advancement for all of us over just five years ago.
As is so often the case in this hobby, there is a whole range of "workable" correct answers. My suggestions are two of a host of possible ways to do this.
