Reliability of Mcintosh pre amps

[twiiii]

Having worked for a Mac dealer for 35 years, I would have to say the C-28 and MX-130 gave us the most problems in the SS. Category. Tube stuff always had issues. C-20, C11, C-22. and MX-110. In our dry desert climate, air pollution can tear up manual switches and variable controls. So it was important to keep up with preventative maintenance, otherwise replacement became a common. C-24's were always having issues with the slide switches. Having owned C-20, 22, 28, 29, 30, 32, 34 personally for the Stereo system, the 28 was the problem child. The 29 and 34 the darlings. My current 34 is approaching 5 years old for me, and has yet to make a single error.

 

[jchouston]

It seems quite silly for those earning 6 figures to complain about repair rates for their toys designed for the 1/10th of the 1%. If you expect professional service you need to expect to pay professional rates, as that reamerges we can help educate repair additudes to restoration additudes.

I think for a lot, if not ALL, of us, the issue isn't cost of repair, but quality of repair.

 

[kevzep]

Speaking of reliability, how does the C46 stack up in the scheme of things.....Im thinking this could be my next pre-amp.......

 

[c_dk]

Having worked for a Mac dealer for 35 years, I would have to say the C-28 and MX-130 gave us the most problems in the SS. Category. Tube stuff always had issues. C-20, C11, C-22. and MX-110. In our dry desert climate, air pollution can tear up manual switches and variable controls. So it was important to keep up with preventative maintenance, otherwise replacement became a common. C-24's were always having issues with the slide switches. Having owned C-20, 22, 28, 29, 30, 32, 34 personally for the Stereo system, the 28 was the problem child. The 29 and 34 the darlings. My current 34 is approaching 5 years old for me, and has yet to make a single error.

Same here, but one must remember, almost as many C28s were sold as the C29,32,33, and 34 combined, so just by shear numbers they would have more issues.

The early C28s had issues that Mac addressed with updates and we all addressed issues as DOB instructed us to...but we in hindsight did not do enough.

Mac made a number of construction changes in late production units that should be implemeted in all restorations done today. We probably should have done them 25 years ago.

 

[Bubo]

Same here, but one must remember, almost as many C28s were sold as the C29,32,33, and 34 combined, so just by shear numbers they would have more issues.

The early C28s had issues that Mac addressed with updates and we all addressed issues as DOB instructed us to...but we in hindsight did not do enough.

Mac made a number of construction changes in late production units that should be implemeted in all restorations done today. We probably should have done them 25 years ago.

Just a thought, should the factory (any factory) offer board swaps when they have a known problem child, MTTR 15 minutes at the dealer? Example, even though this unit is ancient offer board swaps for some nominal fee like $250-350 and Mac crunches the offending boards when they get them back? This would also offer an opportunity to service the rest of the system. I'm guessing that an economic run at macs factory or whoever makes their boards is 500 units. :scratch2:

 

[c_dk]

Well why not then have a,b,c d,e, f.........designs and make all your profit doing muti thousand dollar updates like AR.

 

[Bubo]

Well why not then have a,b,c d,e, f.........designs and make all your profit doing muti thousand dollar updates like AR.

You mean like MS-DOS, windows, xp, vista, 7, 8 etc.......

AR = Audio Research?

My background is (mostly) in high tech data comm and telecom infrastructure and high end private network equipment. 99.9% availability and 15 min MTTR as requirements, also lots of mil spec stuff, and enterprise business applications. We had factory, depot, and dealer VARs depending on the customer and the products. My fav was working with VARS, in all cases board level repair and rework was beyond anyone other than the factory; so one way or another, boards came back home if they were sick. Our clients wouldn't have accepted it any other way for quality reasons. This was never more true than with SMT.

Looking at an exploded BOM, the stuffed pcbs are one or more parts of many that are easily replaceable by a skilled technician who can do a systems integration and test to verify and if need be adjust or repair other more easily serviceable parts in the field. More than one honest repair shop has freaked out when I asked them for a quote to re-cap a system and bring the other components up to spec, op amps, diodes etc.

I had plenty of things I broke even on, while maintaining the highest margins and more importantly customer loyalty in companies where I was employed. Most of my customers wouldn't even take a meeting with competing vendors, why ..... customer service.

If board swaps were available, I have no doubt the same shops would eagerly take the business. A good analogy is the auto industry.....Almost no auto repair shop or dealer will rebuild an engine or transmission on site these days, this work all goes to factory like repair depots where the equipment and technicians exist to do the job properly.

If board swaps were available, I have no doubt more people would get their systems updated and brought back to new at local repair shops.

In audio equipment, I firmly believe that analog and digital components-circuits need to be kept separate preferably at the systems level but certainly at the board level.

My two cents, and last cup of coffee for the day....:beer:


It took me 2 minutes to find this company in Ohio that does SMT and thru hole. They have plenty of competition.

http://www.circuitpak.com/static/services/in_circuit_testing.php

 

[bondmanp]

I still love my C220, but... When I bought my first used C220 from Audio Classics, there was a loud hum from the main outputs. That was exchanged for the C220 I have now. After about three years, the same problem developed. I thought it was a bad cable, but the mains outputs now have a loud hum - prolly a failure in the jacks. Admittedly, I have long, heavy RCA cables running out of the C220, but I was surprised that the C220 isn't more rugged. I am using one of the other outputs and all is well. I now have the RCAs suspended so their weight is not pulling on the output jacks. But, yeah, my confidence in McIntosh build quality is a bit shaken at this point.

 

[wgrr]

Will send you a PM...I had a MAC1900 updated by a well known person here...Upon my close inspection I TOO found some Caps not replaced...The AM board caps not even touched.

I will do the Recap work myself and send it out.

I realize this is an old post but, sometimes old caps are left in vintage units for a reason. I have had several amps rebuilt by someone popular here and he left some old caps in for a very good reason. When one replaces almost all the resistors, the canned caps, and the axial caps what would be the point of not replacing a couple more. It is simple, they never saw much voltage and it would affect the sound if it was changed out.

I have recapped units and I have left old caps in like dog bones and ceramic caps in the controls. I have had no problems.

 

[Rich Andrews]

I realize this is an old post but, sometimes old caps are left in vintage units for a reason. I have had several amps rebuilt by someone popular here and he left some old caps in for a very good reason. When one replaces almost all the resistors, the canned caps, and the axial caps what would be the point of not replacing a couple more. It is simple, they never saw much voltage and it would affect the sound if it was changed out.

I have recapped units and I have left old caps in like dog bones and ceramic caps in the controls. I have had no problems.

I have come to the conclusion that you are correct. I shotgun recapped my C22 (1968 version) and saw no improvement on the RTA and heard no improvement at all. I wish I had not done it. I should have measured the caps both for value and leakage and replaced only those caps that were bad. I saved the old caps and one day I will go through them and see which ones, if any, are truly bad and reverse the re-capping.

 

[Gregory]

I have come to the conclusion that you are correct. I shotgun recapped my C22 (1968 version) and saw no improvement on the RTA and heard no improvement at all. I wish I had not done it. I should have measured the caps both for value and leakage and replaced only those caps that were bad. I saved the old caps and one day I will go through them and see which ones, if any, are truly bad and reverse the re-capping.

That's a good reason to keep the old components. Usually I remove them intact and they're reusable (re-installable.) Some are destroyed but not many. Go ahead and test the old ones and record values in your notebook. It's good to keep them even for forensic purposes. :yes:

As for sound.. the unit may sound different, but better? It's subjective.


-Gregory