McIntosh MC60s - advise on what’s been restored

TriodeLuvr said:
Gear this old needs new sockets. That's particularly true of bakelite, which becomes brittle and prone to cracking due to the long term heat.
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I have two things to add. If you are going to do a complete DIY socket changeout.

1.) Do only one socket at a time. And take good "before" photos.

2.) Be sure all wiring is correct before soldering.

I started out years ago, rescuing several first-time DIY attempts at complete socket and/or pot R&Rs in vintage gear (read: $$$). I do not do those anymore.

:)
 
I just noticed one of your pictures is of a 5V3 rectifier tube. The silk screen on your unit (which is in outstanding condition BTW) shows 5U4GA for the two rectifiers. My two MC-60's are marked for 5U4GB which are backward compatible with the 5U4GA. This made me curious, so I just consulted Sibley's "Tube Lore II" and it looks like the 5V3 is a "re-etched 5U4GB per RCA" with uprated characteristics. I never knew that, so I learned something new today! Just so you know, the 5U4GB tube is often legitimately marked 5U4GB/5AS4A, too.
 
Mr Boochie said:
I have two things to add. If you are going to do a complete DIY socket changeout.

1.) Do only one socket at a time. And take good "before" photos.

2.) Be sure all wiring is correct before soldering.

I started out years ago, rescuing several first-time DIY attempts at complete socket and/or pot R&Rs in vintage gear (read: $$$). I do not do those anymore.

:)
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I worked on an MC30 where someone had done a shoddy DIY job replacing not only the sockets but the whole chassis, with one of those Korean reproductions. It looked great from a few feet, but there was nothing left of the excellent Mcintosh workmanship, and the internal turret board got cracked because the thin chassis twisted in shipping. Wiring and soldering were a complete mess. I had no idea what I was getting into with that one!

I only change sockets when they've seen a lot of operating hours. A lot of these mono amps from the 50s got used for a few years and then cast aside when stereo appeared. If that's the case, the sockets are likely still fine. If on the other hand it's a high hours VTL or a Dynaco which also had an owner obsessed with "tube rolling", then they could be on the brink of catastrophic failure, where pin 5 loses contact and the tube red plates.
 
tuberadios69 said:
I just noticed one of your pictures is of a 5V3 rectifier tube. The silk screen on your unit (which is in outstanding condition BTW) shows 5U4GA for the two rectifiers. My two MC-60's are marked for 5U4GB which are backward compatible with the 5U4GA. This made me curious, so I just consulted Sibley's "Tube Lore II" and it looks like the 5V3 is a "re-etched 5U4GB per RCA" with uprated characteristics. I never knew that, so I learned something new today! Just so you know, the 5U4GB tube is often legitimately marked 5U4GB/5AS4A, too.
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A bit more info on the 5V3 rectifier tube. According to Co-Pilot (Microsoft AI), the 5V3 draws 3.8 amps on the 5 volt transformer winding versus a 3.0 amp draw by a 5U4GB or GA. Since each MC-60 has two rectifier tubes, that means the heater current at 5 volts is 6.0 amps versus 7.6 amps when using two 5V3. The 7.6 amps is not a good idea as it may stress the McIntosh transformer (due to heat). A better substitute would be a 5V3A which draws 3.0 amps at the 5 volt heater current just like the 5U4GB. My humble recommendation, however? Get some 5U4GB's for the rectifier, not 5V3 as the 5V3 was never recommended for the MC-60's.
 
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maxhifi said:
I worked on an MC30 where someone had done a shoddy DIY job replacing not only the sockets but the whole chassis, with one of those Korean reproductions. It looked great from a few feet, but there was nothing left of the excellent Mcintosh workmanship, and the internal turret board got cracked because the thin chassis twisted in shipping. Wiring and soldering were a complete mess. I had no idea what I was getting into with that one!
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I even seen so-called pro techs booger up the rivets and chassis replacing Mac OEM sockets.

This brings up a very bad situation that I had. A guy, I don't even know, sent his amp to be upgraded by "The Mac Guru." After 6 months, the Guru says he's suddenly too busy to finish the job, somehow finds my email address, and then recommends that I finish it. I get it and have never seen such shoddy work before.

In the meantime, the customer is bouncing my suggestions off the Guru, who, of course, criticises every one that I make.

Gaslight Electronics 101.

Never again. :(
 
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nathan88 said:
No I do not. I'll have to make arrangements to find someone with a great tester or buy one and learn how to use it. I'm leaning towards the latter right now.
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If you can't find anyone locally to test your tubes, I'll provide another option. Contact me off line, mail me your tubes and I will test them for you for free and ship them back to you.
All appear to be recent Russian tubes, so my guess is this amp in the photos has been in regular service. It may be plug and play. The power supply caps are of more recent vintage. You may want to spend some time and investigate the MX110 power supply caps and see if they are newer as well.
 
What kind of speakers do you pair with MC60? I owned MC60 for a short time; it is a bass monster. How is your MC60 doing in bass? I sold mine and kept 2 pairs of MC30, one pair with original parts, one pair is Yazaki version.
 
Seamaster

Thread 'McIntosh MC30 Vs. MC60'

I recently bought a pair of MC30 that were restored by Vintage Vacuum Audio. Yves did really great job, and they sound fantastic. MC30 and MC60 are the only two power amps that were made by McIntosh using tube rectification, which gave them a more vivid tube tone compare to other McIntosh tube amps. I had a pair of modern MC75, sold them right after I got my MC30, never regarded that decision.

Now, I found a pair of MC60 that were resorted by the same gentleman at Vintage Vacuum Audio in 2015. It is very interesting to compare the MC30 and MC60 side by side and figure out the mystery of...

Here is my MC30 Vs MC60 story

Here is a sample video of MC30:
 
Seamaster said:
Seamaster

Thread 'McIntosh MC30 Vs. MC60'

I recently bought a pair of MC30 that were restored by Vintage Vacuum Audio. Yves did really great job, and they sound fantastic. MC30 and MC60 are the only two power amps that were made by McIntosh using tube rectification, which gave them a more vivid tube tone compare to other McIntosh tube amps. I had a pair of modern MC75, sold them right after I got my MC30, never regarded that decision.

Now, I found a pair of MC60 that were resorted by the same gentleman at Vintage Vacuum Audio in 2015. It is very interesting to compare the MC30 and MC60 side by side and figure out the mystery of...

Here is my MC30 Vs MC60 story

Here is a sample video of MC30:
Click to expand...
It would be nice to properly restore a pair of either Mc30 or 60 mono amps.

:thumbsup: :)
 
gadget73 said:
working on well-engineered gear is honestly fun. Its easy too, which probably is part of why its enjoyable.
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Yes! The one thing I like is the logic behind how many of these circuits are laid out. From input to gain to phase inverter to output. And a separate power and bias supply.

It makes troubleshooting so much easier.
 
ramjet said:
I have restored two Mc60s. I wonder if the OP is going to give us pictures of "under the hood"?
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Here you go, the Yazaki MC30:
 

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Arizona coupling caps, nice! Authenticap for the power supply. I'd say those have been very nicely, even lovingly, refurbished. I wouldn't touch a thing.
 
Mr Boochie said:
It looks like some tech has been through that amp. Any receipts for the work?
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The MC30s were rebuilt by Mr. Pat Hickman of Whammerdyne Heavy Industries, formerly Classic Tube Audio (they were ONLY working on McIntosh), and Pat is well known in the audio industry. Here is his website:
whammerdyne.com

Best sounding 2A3 Single Ended Tube Amplifier | Class A Made in USA

the Best pure class a tube amplifiers in the world | Highest quality components combined with the latest inovatiive technology .make ground breaking sound.
whammerdyne.com whammerdyne.com
 
zackthedog said:
Arizona coupling caps, nice! Authenticap for the power supply. I'd say those have been very nicely, even lovingly, refurbished. I wouldn't touch a thing.
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The boxy caps in the power supply were ordered from Japan; they were designed and produced by Yazaiki San's SPEC crop. Yazaki San also mixed two Arizona Caps to achieve the tone he is looking for.
 
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