View Full Version : Holy cow! MC60's in the house!


Naptown Rob
03-05-2011, 08:24 PM
I'm excited...and a bit intimidated...
I picked up a pair of MC60's with an interesting history today from a friend's father. They had been in a house that he bought outside of Chicago in 1958. The house had previously been owned by one of the sons of Potter Palmer of Palmer House fame. I think he said the house had 24 rooms. In the early 60's they had a stereo installed & the guys that did the install found these - left by Palmer. They told him they were "worth something" and that he shouldn't get rid of them.
They have lived all over since then - New York City, California, Maryland - and he has carted these things through every move for almost 50 years.

About a year ago he overheard his son & me talking & said "Oh! You're an audiophile? I've got these two McIntosh things..."
I asked the son (gently) a couple of times since then but, well you know how it is.
Two days ago he calls out of the blue, says he found my card & am I still interested in these things, whatever they are!
Turns out they are MC60's with consecutive serial numbers.
I'm actually happy that he did a little research to get some idea of their value - which he did NOT percieve as being equal to museum quality examples sold on ebay. He gave me a more than fair deal & everyone is both happy & comfortable.
Except for the intimidation part. These things clearly need a lot of work. Everything I've worked on in the past has had an element of "well, if I blow it up it'll be a learning experience...". These are different.:yes:
One unit has a blown power tube - and both power tubes have been replaced before. Both 5U4GB's in that unit are bad too, as is the 12AU7. I'm wondering if this is going to be my problem child.
In the other unit all tubes test very good to excellent (Including the Genalex's!) except for 1 weak 5U4Gb.

If I'm going to try to get these beauties up and running it will only be with the help of the AK community. I've located a schematic & will seek the tubes I need. Tomorrow I plan to open them up to take a look underneath to see what I can see (particularly in Problem Child).

Any advice and all suggestions are sought & welcome.

Ohighway
03-05-2011, 09:23 PM
Wow! Nice find! I'll be watching this thread as I have a single that needs attention ....

Naptown Rob
03-05-2011, 10:33 PM
Say, I was wondering if anyone can tell me when these were made based on the serial numbers: 6F107 and 6F108?

Saint Johnny
03-05-2011, 11:55 PM
Say, I was wondering if anyone can tell me when these were made based on the serial numbers: 6F107 and 6F108?

Perhaps a PM to Terry DeWick is in order.
I was just reading a thread on MC-30s where Terry gave a SN timeline. Perhaps he has similar knowledge about MC-60s.

CountD
03-06-2011, 12:32 AM
Sweet...Mc pieces with history make them that more special. Make sure you write down your story and include it in the file of any work you have done to them. It's always a good feeling when both parties that are involved are happy with the end result. Awesome purchase.

Naptown Rob
03-06-2011, 08:40 AM
Sweet...Mc pieces with history make them that more special. Make sure you write down your story and include it in the file of any work you have done to them. It's always a good feeling when both parties that are involved are happy with the end result. Awesome purchase.

I agree - I love the history. The seller is going to dig up a picture of the home they were originally in & send it to me. It should also be fairly easy to find some biographical info on the original owner.
Interestingly, it seems that these were not part of the home's "main" system! One of them has a tag on the power cord that says "R SIDE OFFICE".

chuckworkb
03-06-2011, 09:04 AM
Very nice find.
If you call or email McIntosh, they can tell you when they were made.

drillher
03-06-2011, 09:19 AM
Congratulations.Are you going to do the restoration work yourself?Keep us posted on your progress.There is something very,very cool about tube mono blocks,so not only will those sound dynamite,but they will be major eye candy when you are sitting back and enjoying your music.Enjoy.
Dave

diamondsouled
03-06-2011, 09:52 AM
Congrats on the find. :thmbsp:

There is a couple ways you can proceed with these. 1.) Try and keep everything as close to stock as you can, which would require sourcing replacement can type electrolytics or having them restuffed. As well as keeping as much as possible original caps resistors etc. Thing is these components are likely 50 odd years old and many are not working optimally.

2.) According to my buddy Mike Samra the MC-60s respond very well to having their power supplies 'McShaned'. He owns a couple pairs that he's done this to and has done others for other folks.

http://pages.prodigy.net/jimmcshane/citpage.htm#parts.htm

If you look at this picture of a MC240 he's done you can see that he's also replaced the original coupling caps with a combination of Vitamin Qs and K40Ys.

If you plan on hanging on to these as well as using them I would suggest the second course of action. If you want to sell them fairly soon keep them as close to stock as you can but working so the first course of action would be best.

In either case keep whatever components that are replaced to be included in any future sale and well document what has been done so it can easily be reversed.

Improving the PSs on these vintage amps has a remarkable effect on them. It makes them run quieter, gives them more reserve and dynamics, which is especially noticeable in the bass response, and as well makes it so the power tubes are not run as hard increasing their life span.

Cheers

Lar

MX117.MC7150
03-06-2011, 11:48 AM
Great story and find. Suggest that you 'restore' rather than 'upgrade'. Any upgrade, such as the suggested power supply mods, will diminish their value and change their sound. If you want an 'upgrade' in McIntosh tube sound, purchase a new MC275 or Mc2301s.

dewickt
03-06-2011, 12:13 PM
Time line for MC60
Aug 55 = #500 to Mar 58 = #7116
Mar 58 = 1F001 to Aug 61 = 6F635
Looks like your 60's were built March or April of 1958

Ohighway
03-06-2011, 12:22 PM
Terry, what month/year would you estimate for my #1237?

Naptown Rob
03-06-2011, 03:47 PM
Thanks for all of the input guys, and the info Terry.

I am thinking "restore" rather than "modify" for a couple of reasons.

The first is that I want to hear these beasts in their original (highly regarded) form.
Second, my experience is limited, and replicating is easier than fabricating. I'll just work off the stock schematics.
And third would be the pernicious influence of my wife. Somehow I've made a tube amp fan of her, and she has decided opinions regarding the sound of the various EL34, EL84 & 7591 amps cluttering up the joint. She also brings an interesting viewpoint to anything "vintage". As I type this she is working on the restoration of a 19th century fresco. Fairly modern piece in her line of work. She finds those who "improve" works of art (and surely the MC60 is one) to be reprehensible cretins!:scratch2:
Good thing I don't always tell her what I've been up to...:smoke: Our game is a bit different from hers. But still, I do think there is something to be said for stock when we're dealing with a classic.

drillher
03-06-2011, 06:05 PM
I like your philosophy of restoration rather than alteration.As a fellow antique collector,I appreciate original,unrestored surfaces.I run a 200 year old tall case clock,and while restoration should be conservative,replacing worn bushings is akin to replacing those leaky caps and what ever else is necessary to restore function.It is nice that your wife appreciates accurate music reproduction with you.Saturday night my wife and I often sit back and listen to vinyl on tubes and I have made a true believer out of her.
Dave

diamondsouled
03-06-2011, 06:06 PM
I beg to differ, the Deuce, Citation II, is a classic as well but the improvement that McShaning the PS does with the Duece's overall performance makes it well worth it. You have to remember it was pencil pushers not engineers who had the final say on what filtering values were used and that was often the minimum required.

I guess it all depends on whether or not you want to own a classic in the sense of a stock museum piece or a classic in the sense of a tube amp which is operating and performing at the peak of it capability. I know which I personally would prefer. :D

There are those that do prefer stock museum pieces so that's why all original components should be saved even if they are leaky, not operating optimally, fried even.

Cheers

Lar

Naptown Rob
03-06-2011, 06:29 PM
I don't want to start a debate - or certainly not an argument.
Electronics are very different than fine art - although there is "eye of the beholder" & all that. Just explaining my decision to take the conservative approach. Once that is done, who knows if or how my position might change after I live with them, learn more, etc?...

"The journey is the destination".

Ohighway
03-06-2011, 06:36 PM
Your stuff, your decision Rob. Frankly I think the conservative approach is best, considering the fact that modifying them would decrease their value. Not that I expect you have any thoughts of selling, but depending upon the nature of modifications, some cannot be undone. And then you're stuck.

My rule of thumb is.... if an item is in pretty high supply, or not very valuable, or has been roached, modified, whatever by a previous owner then I have no problem modifying in order to tweak it to it's fullest potential. But with complete, clean, all original items that are of great value? I'd be hard pressed to deviate from stock unless anything I did was completely and totally reversible and would not leave any evidence of ever being modified. And maybe not even then!

diamondsouled
03-06-2011, 08:23 PM
For me modifying would entail changing driver tube or power tube types from stock, something along those lines. Increasing the PS filtering isn't modification, more along the lines of augmentation.

The Mac 275s, 225s, 240s, 30s, 60s are all true classics, as are the HK Citation II and V, Eico HF50 and 60, Heath W5 & W6, Lafayette KT550, Fisher SA-1000, etc. what do they all have in common other than being classics? their performance can be substantially improved with an increase/improvement in PS filtering.

Now if I'm dealing with another breed of classic say a 1964 Fender Twin Reverb I will stick to stock values in the PS, why? Because I want the amp to distort and break up just like it did in 1964. I want the PS to sag just like it did in 1964. Do I want those same qualities to be retained in audio amps as well, no way.

Only thing I can say is do one with totally stock values and then do the other with beefed up filtering and then compare. Make up your own mind. Wouldn't have it any other way actually. :D

Cheers

Lar

MrIgotNomoney
03-06-2011, 08:51 PM
Guys
I heard a set of Mac 60's on a JBL Paragon.
Ill never forget that experience.
IMHO, Id make sure they meet spec, working properly and stop there.
They are that good.
bob

michaelsamra
03-06-2011, 09:50 PM
Rob
Doing a power supply upgrade does not diminish the value in any way,shape,or form,if you don't cut or make holes in the chassis. I have six mc60s and a pair of mc240s and an mc275 and several preamps and integrated amps,all Mac,and if you look at the diamondsouled photo of my mc240,you will see how I did it.
On the mc60s tho,I put in motorruns and vitamin Q and k40 caps.The original coupling caps were paper so you don't change the sound one bit.You use tiedown mounts and straps,and you disconnect the filter caps on the mc60s and connect to your motorrun filter caps.A pair of 100s and a 50 fits underneath each amp perfectly. You can also use electrolytic and put them in with goop as I did on the mc240.Now if you ever go to sell it,take out of the motorruns and hook the filter caps back up on top of the chassis which are left in tact,and nobody is any the wiser.You can also put the stock coupling caps back in, but that isn't necessary as most are bad anyway.
Most mac amps now have had the caps changed and in 80s and 90s it hurt the value,but that is no longer the case.Caps are bad after 50 years.I would just leave your existing filter caps in the amp on top,disconnect them and put in the motorruns underneath.You will love the sound as it purifies its without changing it signature.The bumblebees should all be changed and k40s and vit Qs are my favorites being they are paper in oil but you can mix other caps in.

Naptown Rob
03-06-2011, 11:06 PM
Hmmm. I do believe I've got my research cut out for me! This adventure will be a slow one. Definately getting some sticker shock on the KT-88's I need. How do you guys feel about 6550A's?

drillher
03-07-2011, 06:54 AM
Jim McShane may be a good source for the K40 coupling caps and the other components that you will need.
Dave

MX117.MC7150
03-07-2011, 07:53 AM
Hmmm. I do believe I've got my research cut out for me! This adventure will be a slow one. Definately getting some sticker shock on the KT-88's I need. How do you guys feel about 6550A's?You must have been pricing the stock 'branded' tubes from McIntosh, which are quite expensive. You can get a new, matched quad of Gold Lions, which are the original design made by New Sensor in Russia, for about $220/quad. That said, I found the sonics of the reissue Tung-Sol 6550, also from New Sensor, to provide a very detailed and delicate mid-range. They did not sound as 'powerful' as do the Gold Lions, but were about $160 for the matched quad. You can purchase from such places as the Tube Depot, the Tube Store, etc. I've had good service over the years from both.

There have been at least two (2) extensive threads over the past couple of years on restoration of MC60s. If you are not skilled, then sending them to Terry DeWick is the best thing. You will read nothing but glowing reports on his work on this forum. You can get on Terry's website from a link below.

313guy
03-07-2011, 08:01 AM
Some Karma comin' back at ya, Rob. Very nice indeed. Good luck on the resto.

michaelsamra
03-07-2011, 05:19 PM
Rob
6550s are very nice and audio research swears up and down that the sonic curves between the 6550 and KT88 are virtually identical. I have many NOS/NIB Gec and Genelex KT88s but I also have several 6550 TungSol black plates. I prefer the TS because they sound more alive.The Gec and Genelex are very good also but they tend to be somewhat lifeless my comparison. Jim McShane and I were talking one day and we both concurred that the reissue Genelex bested the vintage Gens in many areas of the spectrum. They seem less analytical.I guess it comes down to a matter of taste.

Naptown Rob
06-28-2011, 08:07 PM
Holy cow. These things sound wonderful. The depth of the soundstage is stunning. I can't believe how long I sat on them before finally firing them up.

For inititial pre-rebuild use I got a quad of Electro-Harmonix KT-88EH's. That way if everything blew up at least I wouldn't be in the poor house. Tested all other tubes, made some substitutions from my stock.

First I opened up the unit that I expected to be the Problem Child for visual inspection. It had 6550's rather than KT-88's, & one was blown.
Everything inside looked perfect...except...what's that?

The fuse holder was broken in half inside the cabinet, & had some kind of odd looking fuse in it. Took the fuse out, Super Glued the 2 pieces of plastic holder back together, swapped in the fuse from the other unit.

Put in all tubes except the 88's. Hooked up a speaker & a CD player, turned down the gain. Brought it up on the Variac. Seems OK.
Put in the output tubes, bring it up again, increase gain.
Whaddaya know! For the first time in over 40 years this beast was making music.
That was enough work for one Sunday evening. Repeated with the other unit this past weekend. This one was spotless inside. Looked literally brand new.

I hooked 'em up to the living room system & was wowed. They were dead black silent. Until I pressed play. These are absolutely keepers.

Now the trouble - I was planning a recap anyway, but I'm pulling them out of service now.
One of them (not the Problem Child) has developed a sporadic kind of a rustling sound & I don't want to take any chances.
Can anybody tell me what the likely cause is?
My other main question remains "what kind of parts advice can you give me (brands/sources)".
Also - how do you read those striped caps? I have functional schematic literacy, but it's nice to be double certain...

Ohighway
06-28-2011, 08:09 PM
Very cool ! :thmbsp:

DeafbyKhorns
06-28-2011, 08:26 PM
:thmbsp: on the Gold Lions, they were the best in my MC275. I changed all the caps and resistors in my MC240 several years ago. It DID NOT lower the value when I sold them. I slept better knowing a 50 yr old amp wouldnt burn the house down. But, beware of power supply mods, lowering the resistance and installing high performance parts could lower the impedance and eventually kill your power transformer!
Terry would be the guy to bring this amp up to date unless you have some good soldering skills.
Try some deoxit first on the sockets, could be what your hearing or worst, a cap going bad.

Naptown Rob
06-28-2011, 08:36 PM
Indeed, WWTD - What Would Terry Do?....

My soldering skills are pretty good. I'd like to do these myself for the personal satisfaction.
What kind of caps did you use in the 240?

Ohighway
06-28-2011, 08:58 PM
One of them (not the Problem Child) has developed a sporadic kind of a rustling sound & I don't want to take any chances.
Can anybody tell me what the likely cause is?

I had a little pair of Bogen tube amps I used to use in my office at work. One exhibited the same problem. The more, and longer, I played them, the less it happened. Capacitor? Really not sure....

dshoaf
06-28-2011, 10:44 PM
Rob, first gremlins to get out of the system are mechanical ones. For the sounds you're describing, tube socket and tube pins are standard procedure. Nice and clean, they must be. Next, pots and switches.

Monitor the output tubes for redplating, too, until they're restored.

If you like what you've heard so far, you ain't heard nutin' yet! Wait till they're restored!

Cheers,

David

DeafbyKhorns
06-29-2011, 03:29 PM
Indeed, WWTD - What Would Terry Do?....

My soldering skills are pretty good. I'd like to do these myself for the personal satisfaction.
What kind of caps did you use in the 240?

Don't laugh, but I used standard sprague orange drop in signal path. They fit nicely and sound pretty good. Cant remember on the bias cap. I would ask Terry what he uses

Naptown Rob
06-30-2011, 09:21 PM
Rob, first gremlins to get out of the system are mechanical ones. For the sounds you're describing, tube socket and tube pins are standard procedure. Nice and clean, they must be.

You may have hit the nail on the head. I cleaned all pins & sockets. I've run it for over an hour now without a peep out of it.