McIntosh 40

Cosmic Chaz

Cosmic Chaz

Cosmic Charlie
Greetings,

I now own a pair of MC-40 amps. I have not powered these up, I have no tubes and I am new to the world of tubes and McIntosh. Any guidance on what my next steps could be, is welcome. I am doing a simple clean first, then I will open them and post what I find.
 
Good first step. Some of the armchair bench techs (some of whom were Mac clinic and ace techs) should help you assess the condition of the electronics. You have a fine set of amps there. Fully restored, they can be made to sing like the day they came out of the box.

Cheers,

David
 
Thanks John, you can imagine how exciting this is for a complete novice. I am going to move on to the second amp and research what to do!
 
My advice is to replace all the caps under there. The can caps need to go, as they are well past their effective date. The cardboard axials and the little silver ones need to go too. The striped black ones are known as bumblebees, and have a reputation for failing--every single one in my 3 Old macs was cracked. The black ones with red writing are black beauties, and guitar amp people claim they sound really good; I don't trust them and replace them myself. The can caps, there are three manufacturers: authenticaps in Germany, ce available at aes, and hayseed hamfest. The cardboard axial you can probably use illinois or any other electrolytic. The other axial caps, pick your favorite, from budget illinois all the way up to the ultra high end.

Also check out the rectifier to see what kind and condition it is in.
 
Hey
Unless your handy, my advice is to have an expert do the restore.
If you can afford McIntosh tube amps I'm pretty sure you can dig a little deeper and make these life time keepers.
Just my .02. Eric
 
100_1371[1].JPG
The second MC 40 appears to be a bit different, different components possibly a different vintage?
MMMNT, I will begin the search for the proper caps and thank you. I think that I may have seen kits which offer a selection of caps, I will compare them to your recommended types.
Eric, I agree with you, these are keepers and will be returned to proper operating specifications, I will look into tubes next and thank you.
 
Cosmic Chaz said:
View attachment 1155941
The second MC 40 appears to be a bit different, different components possibly a different vintage?
MMMNT, I will begin the search for the proper caps and thank you. I think that I may have seen kits which offer a selection of caps, I will compare them to your recommended types.
Eric, I agree with you, these are keepers and will be returned to proper operating specifications, I will look into tubes next and thank you.
Click to expand...


From your two photos they look pretty original. as others have noted, would replace the voltage doubler caps, the Main PS cap, the bias cap and the neg feedback cap as a min. Then may be bring it up on a varaic with the tubes removed say to 70-80 VAC and check some voltages on the inside.

also don't forget to replace the bias rectifier, as they are known to go open slowly which will result in your 6L6s going full on.

all the parts you need are available from several on line suppliers.

best
 
Here is a link to when I got my own MC40's. And yes, I still love them. They are on Altec's today and it's a great match.
http://audiokarma.org/forums/index.php?threads/mc40-monoblocks-up-and-running.686823/
I would contact Jim McShane about having him build you up some rebuild kits. He will need the schematics that match your amps, there are at least two different versions of schematics that I know of for the MC40. My amps had different build dates as one amp matched the earlier schematic and the other matched the later schematic. I elected to build them both to the later schematic.
Lucky for me, Andy (NJPhenoix) was looking for a project and lives close by. I've done a little PCB work before but never something like this. Andy explained to me that the Mac's were not something I should be learning on, and of course he was 100% correct. I couldn't be happier, they would have never looked this nice under the tins if I had done it.
I could have saved a few dollars by ordering my own parts but what to order? Having a legendary electronics restorer/wiz hand select the proper caps for each part of the circuit was well worth the money. Resistors, etc were all top notch quality as well.
Both set of components set me back roughly 300 bucks, I only had to add tubes. If your comfortable enough to restore a point to point amp, the best advise that I can give you is to contact Jim.
Keep us posted on your progress and we love pictures.

BillWojo
 
100_1375[1].JPG 100_1376[1].JPG
Only after a bit of cleaning, did I notice that I have two different transformers(according to sticker) what does this indicate other than the obvious and how might this influence the recap?
 
BillWojo said:
Here is a link to when I got my own MC40's. And yes, I still love them. They are on Altec's today and it's a great match.
http://audiokarma.org/forums/index.php?threads/mc40-monoblocks-up-and-running.686823/
I would contact Jim McShane about having him build you up some rebuild kits. He will need the schematics that match your amps, there are at least two different versions of schematics that I know of for the MC40. My amps had different build dates as one amp matched the earlier schematic and the other matched the later schematic. I elected to build them both to the later schematic.
Lucky for me, Andy (NJPhenoix) was looking for a project and lives close by. I've done a little PCB work before but never something like this. Andy explained to me that the Mac's were not something I should be learning on, and of course he was 100% correct. I couldn't be happier, they would have never looked this nice under the tins if I had done it.
I could have saved a few dollars by ordering my own parts but what to order? Having a legendary electronics restorer/wiz hand select the proper caps for each part of the circuit was well worth the money. Resistors, etc were all top notch quality as well.
Both set of components set me back roughly 300 bucks, I only had to add tubes. If your comfortable enough to restore a point to point amp, the best advise that I can give you is to contact Jim.
Keep us posted on your progress and we love pictures.

BillWojo
Click to expand...
HI Bill,
Wow! Thank you for the information and I do mean that...this is a great learning opportunity for me and I appreciate everything that everyone shares. I am a cautious and patient person in this process, I will only do this project in the correct manner. That being said, I really wonder what these will sound like? I cannot wait!
 
Chaz, they don't color the sound like some tube amps can. I'm not good at describing how an amp sounds but I can tell you that I have tried a few different types of tube amps in my system and the MC40's get top billing. Take a look at the specs for these amps, very good indeed. Mac tube amps are on the top of the heap, very few amps are in the same league. My poor Carver setup is feeling very neglected. I'm not really interested in SS amps anymore.
The top picture shows the same transformers as I have, M-224 and M-225. The other is possibly a replacement? One of the Mac guru's will know the answer.
I'm glad that you want to do these up proper, they deserve it.

A quick search with that Power Transformer number of 043-655 on this forum makes me believe it was for an export model and can be wired for 220VAC. So it looks like no big deal.

BillWojo
 
Last edited:
BillWojo said:
Chaz, they don't color the sound like some tube amps can. I'm not good at describing how an amp sounds but I can tell you that I have tried a few different types of tube amps in my system and the MC40's get top billing. Take a look at the specs for these amps, very good indeed. Mac tube amps are on the top of the heap, very few amps are in the same league. My poor Carver setup is feeling very neglected. I'm not really interested in SS amps anymore.

BillWojo
Click to expand...
Bill,
This all started because a friend purchased a pair of La Scala speakers, these must have had an exciting life. The carpet, which was glued to the cabinets, was quickly peeled off and most of the glue as well. My friend's bride refused to let the speakers through the door and into her home, my door was the next stop. Once I had treated the crossovers with the Crites Kits,I thought that I was listening to music for the very first time. I had enjoyed listening to my Boston Acoustics a400s and the Advent Smaller Loudspeakers for years, I prefer the Klipsch speakers.

Not more than two weeks later, I walk into the opportunity of a lifetime, the MC-40s and now, I have something that I think I will enjoy for the rest of my days. I have never listened to tube gear before and I read that Klipsch and McIntosh might be a good combination? I must admit that I become a bit confused when I stop and consider what preamp I might seek and why a particular model is desirable. Today, I have learned many things from fine folks, like you and I thank you all. Question; Might I be able to identify the serial number from each amp and therefore the year of manufacture, then from that, perhaps the schematics which I would then provide to Mr. McShane in order to request a rebuild kit?
 
The black tubular red letter Sprague capacitors are usually pretty good and shouldn't need replacement unless proven bad. They are part of the original "sound".
 
The third "sticky" down at the top of the page will lead you to some info. I suggest getting both schematics and noting the differences, only minor if I remember correctly. I think it was in the power supply.
So you still have the LaScalas? Your all set. Horn's and tubes are made for each other. Warning, never listen to a set of Altec's!

BillWojo
 
You must log in or register to reply here.

Similar threads

Cosmic Chaz
McIntosh 40
Replies
19
Views
561
jeremyjustic
jeremyjustic
B
McIntosh MC-40 Mono Amp Question
Replies
8
Views
2K
SoCal Sam
SoCal Sam
cad55ken
McIntosh C37 On the Way - Remote??
Replies
4
Views
2K
c_dk
C
J
MC 60 correct plate voltage
Replies
13
Views
983
JeffcoTech
J
S
Which Mcintosh Amp?
Replies
16
Views
2K
chrisf
chrisf
Back
Top Bottom