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My Mc240 had a partial rebuild done about four years ago and I had been happy with it.I decided to have Mike go over the amp and make any upgrades that he found necessary.He can explain the particular upgrades to the power supply and coupling caps.I played the amp.last night for the first time.My wife and I both looked at each other and she said wow what a difference! The bass is much deeper and defined.The focus and imaging are way better with more air space around the individual instruments.Everything is just way more real and natural!Strings are not harsh,vocals are beautiful...I have much more to discover.I just wanted to thank the master for his expert work!
David
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I am sure he McShaned the power supply, and put better signal path caps and resistors in. Mikey will chime in, but what you are hearing is the difference between what a regular tech does to bring something up to spec and what those of us do when we want to improve the gear. We use the same circuit, but improve the power supply greatly and the parts available now are for the most part considerably better, and smaller than what the amp was built with. The old parts are fine, but, for example, most of the gear of that era was built with coupling caps that are just not as good as what we can use now. So you get the raging debate over restoration vs. improving. I land strongly in the improving cap, but there are those who do not.... You are hearing an improved amp. It undoubtedly made its specs after the work done four years ago, but if someone who cares and knows what they are doing changes some key parts then you can usually hear quite a difference. Enjoy it!
cheers,
Don
Don
McShaned power goes without saying..You can't use metal film resistors in the Macs except from grid to ground or some of the cathode resistors in the early stages especially when you are using Magnepans,or Electrostatics,or horns..He put metal films in and it developed a harshness with the old power supply caps..When I put the McShane power supply in,and those dual 100uf F&T caps,I bypassed each section with the 35uf poly and that was the added decoupling I used..I then put in 5 amp Schottkys and those are to die for..THanks Eli.Then putting the carbon films in,smoothed the rest of it out..On other speakers you can get away with metal films on these amps possibly but,Terry Dewick told me that Mac sent out an update years ago saying not to use metal films in the amp.
I then bypassed the negative bias filter wuth a 3.3uf poly to lower the ESR of the existing cap which was also changed..
The Cit 5 and 2 are just like the Mac in many ways and I use the same philosophy on both because all the ones I have built for people are run on Magnepans,or Quad ESLs,or Martin Logans or Avante Gardes.My pair of Cit 2s are running the big MArtin LOgans down the basement but I took my 3rd Deuce and am running it on my Ribbons..The Deuce is to die for..I don't know that there is a better amp ever made and the Macs are pretty much like them in many ways..Frank Mcintosh and Stu Hegeman were the God's of audio AFAIC.The .1uf film and foil solens are great on the input stage.
I also put EL34s in the Citation 2 and they sounded the best I have ever heard an EL34 other than in my Altec 1569s which are heavily modded.The Deuce is just a charmer anyway you slice as are the Macs when you do McShane's power supply upgrades but see how I did it in the Macs? You bolt the buss bar on the choke nuts.
Nobody ever went broke underestimating the intelligence of the American public
H. L. Mencken
Edits: 09/18/14 09/19/14 09/29/14 04/18/15
Nice neat job Mikey! Yes, I generally use modern carbon films on pretty much all cathodes, MF on the grids to ground, and usually a good MF on plate loads, but will make note of that on 240. With all of the K40 caps I wouldn't expect MF on plates to sound harsh, but anything is possible. Yes, I bypass most electrolytics with film caps too. I am sure it is a great amp, once the power supply is up to the quality of the iron!
Mike,
The listing and pictures of the improvements that you made to my 240 add up to a big upgrade.I am hearing things in LPs that I had frequently played that I had not been able to hear before.I'm looking forward to some good listening and relaxing this weekend.Thanks for your help!
Dave
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