30 year idle MC75's

[SteveBB]

You might consider restuffing the elyticap cans or using Authenticaps to maintain appearance. I chose to drill them out and go with clamped cans on my rebuilds.
Going with the clamped cans allows upgrading the PS for enhanced performance with the McShane kits.

I will contact Jim McShane about kits as soon as the beasties are in hand and have been photographed. It is my understanding there were changes during this models production so having good documentation of exactly what I have seems a logical place to start.

In a perfect world Pio I would be able to get in and out with no visible signs any work had been done. At this point in time that does not seem possible.

 

[Pio1980]

I will contact Jim McShane about kits as soon as the beasties are in hand and have been photographed. It is my understanding there were changes during this models production so having good documentation of exactly what I have seems a logical place to start.

In a perfect world Pio I would be able to get in and out with no visible signs any work had been done. At this point in time that does not seem possible.

If they are going to be lifetime keepers, I'd be more concerned with a good full potential long term rebuild with no regrets than present collector value.

 

[mech986]

Sorry, missed the part about original packaging. Looks like you're good to go.

 

[SteveBB]

If they are going to be lifetime keepers, I'd be more concerned with a good full potential long term rebuild with no regrets than present collector value.

You make a valid point and I agree. If doing an overhaul is going to leave its marks regardless then, to me anyway, there does not seem much point in worrying about keeping the factory appearance. If I ever did decide to sell I would make full disclosure and include all of the original parts.

If I am going to listen to them every day I am at work I want them at their best.

Sorry, missed the part about original packaging. Looks like you're good to go.

No reason to be sorry. If you think you see something here I am missing feel free to save me from myself. I doubt there are many in this condition left floating around so to damage a pair through lack of knowledge would be a sad thing to let happen.

 

[nj pheonix]

You could variac them or DBT to get the e caps to reform. I'd bet at better than even odds they play fine just like that. That being said I agree with the mob. Do the standard rebuild and have a clear conscience for 50 more years. They're actually easy to work on. I've gotten parts sets from Jim Mcshane with great success.
Having said that, I'd go for the authenticaps for the big cans. Good luck and congrats and as the others have said already

 

[62caddy]

If you are personally transporting the amplifiers yourself, they'll be all the safer in their original packaging for the journey. Using the original boxes for shipping on the other hand may not be such a great idea. Had heard a few tales of Mc amplifiers being transported on motorcycles - successfully I might add - but a pickup is a much better choice.

That the 52 year old original packaging still exists is amazing in itself; it sounds like quite a treasure indeed.

Good luck with the restoration and by all means, please post some pictures when you can.

 

[SteveBB]

I never considered trying to move these with the bike. My pickup (my truck) will be much safer. Thanks for the heads up on shipping. For right now my plan is to do the refresh myself so I hope to avoid any shipping concerns.

When these were taken out of service they were packed in the factory boxes with all the documentation then double boxed for protection so there is not so much as any dust on or inside the factory boxes. I was shocked at the condition when I opened the boxes to see what I might be dealing with. At first glance they looked like new. His wife said she did not know why he stopped using them but is certain they worked when he put them away.

As soon as they are in my posession I will be posting images. I plan to procede with caution to avoid any possible mistakes. First do no harm is my main thought here. Thanks for all of the comments and advice

 

[ADKBob]

Great Karma here. If no harm comes from trying to reform the capacitors, I'd try that first. But, I have diddly squat knowledge about such restorations, so I bow to the expertise. If your friend was good ("anal") about his gear, you are showing the respect he deserves by giving you his "babies" to care for. Good luck with your research and I hope you can listen to tunes the two of you shared in the past on those beautiful amps.

 

[Thocom]

You'd have a heck of a time moving them on your bike. Mac amps aren't light. Lol
What a nice reminder of your friend that you will have.

 

[mech986]

SteveBB, did you also inquire about any spare tubes that may have been purchased and stored along the way, or tube testers that also may have been around if he did his own maintenance? Any idea what preamp he used with these?

And if it's not too difficult, what type of gear did your friend like to play in his system(s)? Sounds like he enjoyed the hobby?

 

[cduarte]

You could variac them or DBT to get the e caps to reform. I'd bet at better than even odds they play fine just like that. That being said I agree with the mob. Do the standard rebuild and have a clear conscience for 50 more years. They're actually easy to work on. I've gotten parts sets from Jim Mcshane with great success.
Having said that, I'd go for the authenticaps for the big cans. Good luck and congrats and as the others have said already

I agree 100% on the authenticaps, the have higher voltage ratings than the CE equivalents. I've used them in a a few amps without issue. BTW, as far as I'm concerned, "reforming" capacitors is a total waste of time. why risk irreplaceable output transformers when you can replace 50+ year old caps that are long past their use by date.

 

[SteveBB]

There is a box of tubes collected over the years but no idea what might be in there. He always owned a piece of tube gear with the last being a Dared SL2000a he got from me. He had it paired with a Carver amp of some kind.

He was big time into vinyl with all of his lp's going to his son. I do not know the model but there is a Mac am/fm tuner I am going to take with me in exchange for the Yamaha CR1020 currently in my office.

Before this is all said and done I will suscribe again so I can make some bartertown listings. There are two Linn turntables and a few things that will make the AR and vintage Klipsh guys go insane.

 

[Bill Ferris]

Ok Mac vintage tube amp guys, you should always take advantage of Mac`s vintage tube amp`s power transformer`s optional/mandatory(IMHO) primary 125 volt mains tap change over from the sixties default 117 volt tap rewire for the power transformer for all the older vintage Mac tube amps so current mains voltages are better handled by the Mac tube amp.. Hey !! Your "refurbishing" soldering iron is already warmed up, why not make the amp`s filaments and voltages much happier and closer to spec.. This doesn`t seem to come up often enough on these Mac AK threads as I`ve been reading"/lurking" for around 8~9 months, but I think is very important for the long term well being of the vintage Mac tube amp !! And if not(surprisingly already factory installed) you should install one and or replace the AC in rush thermistor-- CL80/CL90 as the case may dictate.... All the other weak/failed parts being taken care of as well !! Your pwr. xfrmr, tubes, & "original electrolytic cap`s"(which, should be replaced as a matter of course anyway) will last longer. Your vintage Mac tuber amp. will love you for it and the sound will be snappier and more natural "with tuby warmth".. You(IME) will find your power transformer feeling around lukewarm or so after many hours of playing, barring any yet undiscovered circuit/tube anomalies that have already been discussed in this forum.. All my long time audiophool "Bat eared" friend`s, customer`s, and my self`s 50 + year old Mac tuber amp power transformers run ~ lukewarm while running/playing for 8~16 hrs. at moderate to fairly high levels when used in a comfortable room temperature not much above 76`F w/n fans .. Oh did I mention that they all meet or usually exceed all factory specs. for THD+N, IMD, Sig/N/R and sound wonderful ?? Especially if you replace those way overly priced PS circuit worthless chassis mounted twist tab mount "capacitor cooking waste heat foolish tube rectifiers" with a quality SS plug in or soldered in.01 ufd 1000v bypassed disc cap bypassed SS 1N4007 or better rectifiers .. Oh my !! Is that statement controversial ?!?! JIMO&E !! Just my over 4 decades of tube amp ownership/use and professionally employed bench experience, FWIW. Gentleman/Ladies.. After all it`s your gear.. YMMV !? I know some "tube rectumfryer" advocate`s flame throwers are going to rear their ugly heads about my anti-tube rectifier statement.. Oh well---- I`m no Jim McShane, but some, tiresome deeply entrenched old wives tales are usually very hard to dissolve/dispel, from my decades of observations in this" Biz". !! IMHO.. , Mercy Sakes Alive !!(or is it Massive Steaks at Five, I can never be sure ??) HA !! Let the "subjective" tube rectifier benefit`s pouncing on me games begin !! And no, I`m not really arrogant, but just merely cursed with a butt load of experience in all kinds of tube/SS amplifier repair and modifications !! Regards, OKB (Damn--It`s great to be retired !! )

 

[SilverTpt999]

Of course, this depends on your home line voltage which can vary significantly. Everyone should measure their own line voltage. My line is stable at 120-121 volts. It's not 125 save the wee hours of the morning.

Somewhere along the way, one of my MC60s had this 'upgrade' (done very poorly) to 125 V. No crimping or removal of old solder, old lead just clipped (!!) and new laid on top with more solder glommed on. Bad joint. Even the thought of cutting any Mc transformer wires turns my stomach. Fortunately they clipped right at the joint, so I had enough to fix it. I returned it to the 117 windings with proper care. However, I also added a thermistor to soft-start the amp which drops the voltage the amp sees from what the line really is. Ergo, 117 is best - at least for me, where I am right now, with the thermistor in.

Some would benefit from the 125 windings. Just throwing it out there that doing moving to 125V windings shouldn't necessarily be the general case.

 

[Bill Ferris]

Of course, this depends on your home line voltage which can vary significantly. Everyone should measure their own line voltage. My line is stable at 120-121 volts. It's not 125 save the wee hours of the morning.

Somewhere along the way, one of my MC60s had this 'upgrade' (done very poorly) to 125 V. No crimping or removal of old solder, old lead just clipped (!!) and new laid on top with more solder glommed on. Bad joint. Even the thought of cutting any Mc transformer wires turns my stomach. Fortunately they clipped right at the joint, so I had enough to fix it. I returned it to the 117 windings with proper care. However, I also added a thermistor to soft-start the amp which drops the voltage the amp sees from what the line really is. Ergo, 117 is best - at least for me, where I am right now, with the thermistor in.

Some would benefit from the 125 windings. Just throwing it out there that doing moving to 125V windings shouldn't necessarily be the general case.

Well, Silvertpt999 sorry to hear that a trashy mains swap over job was done on one of your MC 60`s... Higher AC is more common than not... Consider yourself lucky indeed for having such stable and consistent mains AC supply... My statement on this site was based on reading posts for nearly 9 months(Mac, Fisher, Tube audio new & old, and general audio) concerning this.. And I read scores of threads/post of more people concerned about their consistently measured 120~125 volts and above outlet voltages.. A good amount of them also measured their amp`s tube`s filament voltages and found the values higher than the +10% recommended by the tube and manufacture`s specs. which can greatly reduce tube life, plus undesirable elevated heating in the tubes and pwr. xfmr. Mac. recommends it and a vintage tube power that`s owner`s/service manual/spec stipulate 117 volts AC.. I`m 61 and been around to have seen the AC mains rating migrate from 110 to 117, and then now ~120 + volts.. Mac is one of the very few audio tube amps to look to the AC mains migration future and provide a easy to change mains tap to address this.. I own a MC 60, a MC225, a pair of MC 30`s and they are quite happy after I changed the taps to 125, as well as my friends & past customers Mac tube amps because here in NE FL. the mains can easily during portions of the year easily rise to 127 for long periods and though I employ 20 amp AVRs in all tube amp power circuits they run cooler and will last longer.. I have been servicing all types of audio gear since 1975 for a living, and or for fun when I retired and my Macs have and will run 24/7 for months with no over heating related failures(output tube wearing out, yes !! I hate/despise to have to repair my own gear because I`m # 1: lazy and # 2 : I failed to properly restore and test/burn in the gear for 48 hrs. which I do. My Hi-Fi friends bring me their gear instead of taking it to the local Mac/Hi-Fi repair shop because I`m very demanding and down right anal about reliability and performance and they can sit and watch/ask questions while I fix their Macs, Fishers, Crowns, ect... Do as you wish Silvertpt999.. I only need bucking xfmrs for my Fisher 400, and 500 receivers because Avery`s price point didn`t include the foresight to include the 120~125 volt power transformer input tap availability.. Regards, OKB(Over Kill Bill)

 

[nj pheonix]

I do understand why you'd go SS on the rectifier on a 60. (Cost, reliability). That said the 2 5U4s run adequate current for that amp under any real conditions. I doubt the Sonics would improve. The 5U4s give it a soft start and they're still reasonably cheap and available.

 

[Bill Ferris]

I do understand why you'd go SS on the rectifier on a 60. (Cost, reliability). That said the 2 5U4s run adequate current for that amp under any real conditions. I doubt the Sonics would improve. The 5U4s give it a soft start and they're still reasonably cheap and available.

So do CL-80~90 thermistors inserted in the primary without 4 amps of needless filament PS. transformer/chassis mounted cap cooking dynamic sonic reducing I/R sponging lossy effect tube rectifier effects.. Go your own way !! Cost is not a factor, as I have a big bag full of 5U4`s from decades of tested (recently via a Amplitrex AT-1000) And I assure you Sir. the desirable sonic effects are very real IMHO and many, many other`s whom tasted .. "Tubyness" is still there, just not smeared in the "fastness response" !!!
We like music to be reproduced dynamically as accurate as possible...

Possible from years of experience as a 'real" qualified good, as rated by many others) FOH sound man..
Always trust your ears, for if you like then it`s the best for you....
And in the end that`s all that matters..

Kind regards, OKB

 

[BillWojo]

So what ever happened to these amps? Did they get restored and enjoyed, sold off or are they waiting for something?

BillWojo

 

[byoungman1]

So what ever happened to these amps? Did they get restored and enjoyed, sold off or are they waiting for something?

"Over Kill Bill" may have scared the OP away...

 

[Bill Ferris]

"Over Kill Bill" may have scared the OP away...

Really ?!? Unintentional, I`m sure.. Sorry about that if Idid..