McIntosh MC-30 purchasing pointers please...

Theron D

Active Member
I have an opportunity to "possibly" purchase some MC-30s from an individual who has owned since the 60's (though they bought "used" back then I am told). They are downsizing and the opportunity presented itself. I have read there are variations (circuit changes) and am looking for some quick pointers for when on the spot and have to make a decision. Please feel free to correct me/ad your experience. Very much appreciated in advance. I really want to get these (have wanted for many years) but also want to be cautious and dont want to get overzealous....thinking out loud here...

1. Dont turn it on! Unless they have been using routinely with no problems and connected to a proper load. I don't know the answer yet. If they haven’t been turned on in a while, should I at least check the output transformers resistance with a meter? Any other quick checks I can make with a DMM on site? How easy is it to open up (tools needed). Trying to be ready as possible.

2. Check to see if serial numbers are close. I have read possibly there were ten variations in ten years occurred with these amps? How close is "close" when it concerns serial numbers? I'll have to research what the range of numbers are by year (***update** found it http://mcintoshcompendium.com/Compendium Docs/Power Amplifiers/PDFs/MC30.pdf. variation unless someone has a link readily available?

3. Look at the overall cosmetics, any pitting? Do they have the original boxes(?), tubes etc.


Many thanks in advance. Theron D

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I honestly don't know about all of the circuit changes, but I will say that if you have any inkling that you might want to sell them down the road, that cosmetics is very important. Good looking cosmetics gives you at least a bit of understanding of how well they were taken care of. Sure, good looking chrome doesn't mean they are necessarily going to sound better, but it doesn't hurt.....After waiting for over two years for a decent looking/sounding pair, I finally purchased mine from Vintage Vacuum Audio. Very glad I did.
 
I honestly don't know about all of the circuit changes, but I will say that if you have any inkling that you might want to sell them down the road, that cosmetics is very important. Good looking cosmetics gives you at least a bit of understanding of how well they were taken care of. Sure, good looking chrome doesn't mean they are necessarily going to sound better, but it doesn't hurt.....After waiting for over two years for a decent looking/sounding pair, I finally purchased mine from Vintage Vacuum Audio. Very glad I did.
thank you! Point taken about the cosmetics!
 
I encourage you not to overthink this and miss your opportunity. Pairs of MC30s don’t show up often. Whatever performance problems they may have can be fixed by a good tech. Condition is important for top dollar resale. It’s not so important if you want to use them for yourself. Most of these were sold before stereo ruled so finding pairs with close serial numbers is pretty rare.
 
I encourage you not to overthink this and miss your opportunity. Pairs of MC30s don’t show up often. Whatever performance problems they may have can be fixed by a good tech. Condition is important for top dollar resale. It’s not so important if you want to use them for yourself. Most of these were sold before stereo ruled so finding pairs with close serial numbers is pretty rare.

thanks, yes im looking for something that will perform well for many years but understand that cosmetics do come into play. I currently have a beautiful Pilot Integrated 248b (very rare) that ive been impressed with (7591 output tubes), just always wanted some MC30s...( and then theres the preamp selection which will have to come later... but first things first...)
 
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thanks, yes im looking for something that will perform well for many years but understand that cosmetics do come into play. I currently have a beautiful Pilot Integrated 248b (very rare) that ive been impressed with (7591 output tubes), just always wanted some MC30s...( and then theres the preamp selection which will have to come later... buy first things first...)
As the ad copy implies, they do not require a preamp to work from a single line level source, and imo, would probably sound more "direct" and lifelike without a typical feature laden preamp.
 
would agree with the comments from Macyjim, and not over think this. For MACs, two key areas to look for are overall cosmetics, lack of pitting, etc. and are all transformers functional. also nice if the transformers have not dents in the top of the cans.

If they are completely stock, would replace the bias rectifier with a modern diode before even attempting to bring them up. Pop teh bottom cover off and check for component values, any obvious burned parts. Replace any that are out of spec. If you wish to keep the stock sound, stay with carbon comp resistors.

And when you are finally ready to power up, do so on a dim bulb tester and variac so you can watch the current draw.



good luck.

J
 
As long as they make sound and the cosmetics are acceptable, buy them. They can always be restored. From the pictures I would say you're a winner.
 
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more pics. service stickers indicate 1973 (latest)!
Serials 15964 and 1E715
when I arrived the seller had them connected to some pioneers speakers. One channel working fine, the older unit produced music but was noisey/crackling. Hopefully just a tube...
 
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Yikes! can't believe he just plugged them in :yikes:

I guess with him taking the risk you now know that there are no major problems.

Congratulations! they look to be in beautiful condition, must have been stored carefully...
 
Yikes! can't believe he just plugged them in :yikes:

I guess with him taking the risk you now know that there are no major problems.

Congratulations! they look to be in beautiful condition, must have been stored carefully...
Seller told me he used them last year. When i arrived he had them on....
 
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For a decent tube tech , they're easy enough to service.
As it appears , the iron is good. All other parts easily sourced.
Cosmetics look very good. They should clean up well.
62caddy told me what to use (having a senior moment).
But they clean up remarkable well. I'll post if I remember or i find . It was either a Mother's or Meguiar's product
 
For a decent tube tech , they're easy enough to service.
As it appears , the iron is good. All other parts easily sourced.
Cosmetics look very good. They should clean up well.
62caddy told me what to use (having a senior moment).
But they clean up remarkable well. I'll post if I remember or i find . It was either a Mother's or Meguiar's product
thank you!
 
For a decent tube tech , they're easy enough to service.
As it appears , the iron is good. All other parts easily sourced.
Cosmetics look very good. They should clean up well.
62caddy told me what to use (having a senior moment).
But they clean up remarkable well. I'll post if I remember or i find . It was either a Mother's or Meguiar's product
Avoid polishing lettered areas, it can/will come off.
 
Nice candidates for a full restoration if you intend to use them and want the reliability and performance they'll have when restored.

The alternative, given the really nice condition and all-original, is to leave them as-is but not use them. There are collectors out there for whom originality is of primary value over performance and reliability.

Your choice right now is which way you want to go with them. I've restored 2 sets of these amps and can attest that they'll perform up to their best when fully restored. There's lots of threads here on the procedures and details. I regret selling them, too.

Cheers,

David
 
If for listening, they could be traded to a collector as time capsules for properly restored amps with excellent cosmetic condition.
Fwiw;
I have a time capsule Sansui SM-80 and some other items that will stay unrestored.
 
Theron D, I would test the ESR on the power supply caps, If good, continue to use them.

at least replace the bias rectifier with a modern Diode. The originals are known failures over time.
With a modern diode in place, you will have to adjust the bias resistor value slightly to bring the bias voltage in spec.

if the coupling caps are not leaking, go ahead and use the amp.
 
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