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Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 6:41 am
by Jon S.
These are new questions that the other McI-related threads don't appear to cover, unless perhaps in passing ...

I'm ready to ship my "new" MC50 out for servicing/upgrading to include the usual replacement caps and resistors where needed. As I'll be using the unit strictly for guitar amplification, I'm considering these additional mods. What do you think? Are they worthwhile? The tech I'm working with is fine with the work, that's not the issue, it's me wanting to be sure the changes are good ideas.

1) Replace stock stock cord with an IEc outlet for a detachable cord.

2) Replace stock input jack with a 1/4" female jack.

3) Replace output strip with a pair of 1/4" female jacks (@ 4 and 8 ohms; I would not need a 16 ohm output).

And is there anything I'm forgetting to consider?

Finally, I'm anticipating copping a 2U heavy duty road rack for my FYD preamp, seating that on my 1X12, and running the MC50 open on top of the road rack. I've not seen others do this. Is there any reason to avoid this approach?

Thanks as always for any and all feedback! :smile:

Re: Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 7:25 am
by Smolder
Hey Jon...

Not sure, but when you went through the Mac maintenance threads you might have come across a guy servicing an mc2100 (I think that's what it was). He serviced not only the electrolytic caps and the resistors (if out of spec), but also the transistors. You'll find two sets that reside in the big black heat syncs. The larger ones are easy to find... but I could never find equivalents for the smaller ones. The originals aren't made anymore and they've gone through several number revisions and equivalencies... they are also being counterfeited as I understand it... just a heads up. Most of the service guys i read from seem to think the large silver cap cans are very sturdy and typically don't need replacement.

The following is partially influenced by the fact that my mc50 is a bit of a beater... not even close to pristine and collectable...

I did put a three prong cord on mine because anything else makes me uncomfortable. Waldo and others warned of ground loops (large stages with complex electrical?) because the SMS also has one. When used together, they end up sharing a common ground anyway so only one really needs to be grounded. When I replaced the cord on the mac, I didn't have or realize the sms was three prong. I plug both through a furman and have not had an issue.

I replaced the rca input jack with a quarter inch because it's easier and a standard. It was a very slight enlargement of the existing hole.

I left the terminal strip and put a speaker cable with a quarter inch jack on the end for the cab. Replacing the terminal strip seemed excessive.

The other thing I did was drill a hole and put a power switch. Turning on the power amp at the same time or before the pre rendered some squealing... and I did not want to be messing with the power amps volume... so turning on the pre first, letting the tubes warm up and then the mac works (input from brad sarno here).

If you've seen my rig, I chose to inclose the mac... mostly so that it was one unit to carry. I don't expect heavy abuse so I did a cab, not a rack case and used rack mount strips for the furman/sms. The Mac is on a rack mount self inside. I don't access it much, so it works pretty well. The mac does look cool... and yours looks to be in really great condition... I'd show it off.

Sorry for the length... hope its helpful.

Re: Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 7:54 am
by Jon S.
Extremely helpful and appreciated, smolder. I'm inclined now to follow your lead on the input and output jacks and for the power switch, too. Some further reactions to your post:

>> when you went through the Mac maintenance threads you might have come across a guy servicing an mc2100

Not certain I'm using the same exact guy but as it happens a tech did service another RUKINDers' MC2100 and this person's the one who referred me to him: http://classictubeaudio.com/

>> Most of the service guys i read from seem to think the large silver cap cans are very sturdy and typically don't need replacement.

This is probably what my tech meant when he emailed me, "I do not think it will need main caps, just drive board caps and a few other coupling caps and a few trimmer resistors."

>> I did put a three prong cord on mine because anything else makes me uncomfortable.

I don't care what the gear is - anything I use gets a modern, 3-prong, grounded plug. In my case, I think I will indeed go with the IEc outlet option - bandmates or I have tripped in transit over t0o many power cords over the years!

>> Waldo and others warned of ground loops (large stages with complex electrical?) because the SMS also has one.

This could be a problem with the SMS but not ever with the FYD. The latter comes stock with a true ground lift switch (a minitoggle on the rear of the chassis).

Re: Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 8:26 am
by Smolder
Here is one of the videos... he does a 2100 and a 2200. In the video you can see the transistors I mentioned.

http://www.youtube.com/watch?v=w7OJ95To6_c

I searched a bunch of the audiophile sites as they are older and deeper users of macintosh gear. This is where I spent time tracking down the product numbers for those transistors and the replacement/equivalents. I did the work myself... you've chosen a qualified mac guy and he will have all of this easily under his belt.

Dr Z amps spoiled me with the IEC cords. I've even begun taking out the courtesy plugs in any old fender that I come across and installing these instead of the old cord. I rarely come across museum or collector pieces anyway. Any new build gets one.

A year or so ago I bought a handful of red IEC cords from Mercury Magnetics. They were touted as sonically superior (whatever)... I like them because I can see them after a gig on a dark stage... and I never trip on them. At the time, they weren't any more expensive than what I'd been buying at home depot.

A ground lift on the pre is brilliant. My guess was that for Brad and SMS, it was a safety/certification thing. His pre looks so professionally manufactured... far above most any boutique gear I've known.

Re: Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 9:36 am
by Bobbyg
As far as your thinking on setting up your rack........that is basically what I do, stacked bottom to top....1x12 cab with JBK K-120, 3U case with power conditioner and SMS, and the MC 50 on top of that. I use a piece of carpet non-slip between each piece and it makes it very stable. I probably should build a case for the Mac but have not had the opportunity. I always kind of feel safer just carrying it by itself.

Re: Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 11:18 am
by Jon S.
Cool, it's nice to have company! Curious if your 3U unit is a polypropelene lighter type or a plywood and metal case. An MC 50 is only 20 lbs. but even that, seems to me, could be too much for a poly case.

Re: Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 11:24 am
by Smolder
Jon S. wrote:Cool, it's nice to have company! Curious if your 3U unit is a polypropelene lighter type or a plywood and metal case. An MC 50 is only 20 lbs. but even that, seems to me, could be too much for a poly case.


Jon... if your planning to mount the mc50 on a rack shelf... reach out. I bought three and only used one... the others are not returnable (too late) and I don't see using them... you're welcome to them for the cost of shipping.

Re: Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 11:36 am
by mijknahs
I recommend the 1/4 input and some other kind of speaker connections (banana or 1/4") as long as you don't plan to sell this amp to anyone other than a guitar player. I've done it to my MC100s.

Re: Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 11:40 am
by mijknahs
Jon,

Have you tried out the MC50 in your rig at all yet? Or are you going to wait until it's been serviced?

Re: Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 11:46 am
by Bobbyg
Jon S. wrote:Cool, it's nice to have company! Curious if your 3U unit is a polypropelene lighter type or a plywood and metal case. An MC 50 is only 20 lbs. but even that, seems to me, could be too much for a poly case.


Yes, my rack is a inexpensive SKB 3U, but it is rock solid with the Mac on top. I keep thinking about doing something else, but I tend to forget (after a few after party drinks) what case I am carrying! I have been known to knock it over by accident, thinking it was a mic case. I just feel safer hand carrying the Mac.

BTW.....that is a sharp, clean looking rig Smolder.......

Re: Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 11:57 am
by Jon S.
Smolder wrote:
Jon S. wrote:Cool, it's nice to have company! Curious if your 3U unit is a polypropelene lighter type or a plywood and metal case. An MC 50 is only 20 lbs. but even that, seems to me, could be too much for a poly case.


Jon... if your planning to mount the mc50 on a rack shelf... reach out. I bought three and only used one... the others are not returnable (too late) and I don't see using them... you're welcome to them for the cost of shipping.

So kind! I'll let you know, thanks.

Re: Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 11:59 am
by Jon S.
mijknahs wrote:Jon,

Have you tried out the MC50 in your rig at all yet? Or are you going to wait until it's been serviced?

I'm going to have it serviced, first (I'm under the impression it's the safest approach with any 40 year old amp with its original caps and resistors).

Re: Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 12:48 pm
by gr8fl4295
Jon, is there any reason to believe that the MC50 doesn't work or sound properly?
I ask because I just won a MC50 on eBay and they had a video of it cranking some Led Zep. It sounded great.
Why would I need to have it serviced?

Re: Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 12:53 pm
by mijknahs
Jon S. wrote:
mijknahs wrote:Jon,

Have you tried out the MC50 in your rig at all yet? Or are you going to wait until it's been serviced?

I'm going to have it serviced, first (I'm under the impression it's the safest approach with any 40 year old amp with its original caps and resistors).


Over the years I've had about 3 different MC2100s, 2x MC100s and 1xMC50. They all worked fine from the get go except for the MC100 that I bought for $200 which I knew didn't work when I bought it. I had some of them "serviced" with upgraded caps, resistors and in some cases transistors but they all were working pretty much the same before and after servicing.

Re: Questions re: getting my new MC50 ready for action

PostPosted: Wed Jan 23, 2013 12:58 pm
by mgbills
I had my 2100 service because the inputs were a little intermittent, and the pots were as well.

In the Spring I'll have the 250 service, just to insure that it remains reliable. For me it's $250 well spent.