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Severe Sound Distortion from MC225

M

Mil Gnoh

New Member
Hi, a total newbie here. I hope you are all well. I have a MC225 which I bought about 25+ years ago. I hadn't used it much in the past. Like many people, I started listening more during the pandemic. Everything was fine until a year ago. One day, all of sudden, the sound got very distorted from both speakers. The setups I have are usually either Speakers-MC225-DAC(Shiit Modi)-Streamer(Raspberry Pi) or Speakers-MC225-CDPlayer. I have never used a preamp and I always use the gain nobs on MC225 for volume control. I hardly increase the gain over like 25%.

I have uploaded the sound I recorded while playing three songs (a little each).


I have another amp so I tested the speakers, DAC, streamer, and CD player. All sound fine with the other amp. I also tried to test the tubes on MC225 using a method I found in YouTube. I don't have any tube testers. I just used a multimeter. So I am not 100% sure, but the tubes seem to be okay although I am not 100% sure. I don't know how new the tubes were when I bought this amp 25+ years ago but since then I never replaced any of them. So although they were not used much, they are still very aged I believe.

I am not sure if this caused the issue or is even related or very much coincidently but I think the problem started happening right after I switched around the connections between 4 ohm and 8 ohm on MC225 with the speakers.

Can someone please let me know what potentially could cause this issue? Has anyone experienced the similar problem? If so what was the reason? Could it be due to bad or aging tubes? Or something inside the amp went bad or got broken?

Any help or guidance will be really appreciated. Thank you for reading my post.
 
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@Mil Gnoh even if the amp had ben serviced when you bought it (25 years) it certainly needs service by now. I agree it is probably in the PS. If you tell us where you are located someone can recommend a good service tech.
 
stereocuuple said:
@Mil Gnoh even if the amp had ben serviced when you bought it (25 years) it certainly needs service by now. I agree it is probably in the PS. If you tell us where you are located someone can recommend a good service tech.
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Hi @stereocuuple. Thank you so much for the quick reply and suggestion. I live in the San Francisco Bay Area. In fact, I found a couple of service shops near me from the McIntosh web site. And I also found in eBay some in other states. I definitely prefer anyone local since I do not wan to ship the amp back and forth. When I spoke to the local shops over the phone, they said it could go from several hundreds to over $1000. So honestly I got bit overwhelmed and wanted to see if this is something I can fix myself. Anyways, if you or anyone in this forum can recommend a good server center or individual in the San Francisco Bay Area, that would be great. Thank you.
 
@Mil Gnoh honestly considering what these amps sell for on the market I wouldn't think twice about shipping to Audioclassics. If your amp is in good cosmetic condition and rust free it is the best bang for your buck. Packing a MC 225 is no big deal. Also AC will be a bonus as their repair cost is going to be less than in your area. If you post some pics of the condition it would be easier to tell you if it is worth the investment. Audioclassics will likely have a flat rate for repair and then you have documentation from the very best shop there is. Tubes can be packed with ease but my guess is that it is time for new tubes.
 
stereocuuple said:
@Mil Gnoh honestly considering what these amps sell for on the market I wouldn't think twice about shipping to Audioclassics. If your amp is in good cosmetic condition and rust free it is the best bang for your buck. Packing a MC 225 is no big deal. Also AC will be a bonus as their repair cost is going to be less than in your area. If you post some pics of the condition it would be easier to tell you if it is worth the investment. Audioclassics will likely have a flat rate for repair and then you have documentation from the very best shop there is. Tubes can be packed with ease but my guess is that it is time for new tubes.
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@stereocuuple, thank you for the suggestion. I will call Audioclassics and ask them about it. They may be able to tell me how much it would cost to ship the amp and I assume I need some sort of insurance. I have some bad experiences on shipping and receiving gears in the past. I have attached some pics of my amp. Besides some dings and a few broken pieces on the terminal, I think it's in a fairly good shape. Oh, the major one is the fuse housing that is broken but the fuse can stay in. Now I am wondering, can the fuse that is not completely secured in the housing cause my issue as well? Anyways, I really appreciated your replies.
 

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Mil Gnoh said:
@stereocuuple, thank you for the suggestion. I will call Audioclassics and ask them about it. They may be able to tell me how much it would cost to ship the amp and I assume I need some sort of insurance. I have some bad experiences on shipping and receiving gears in the past. I have attached some pics of my amp. Besides some dings and a few broken pieces on the terminal, I think it's in a fairly good shape. Oh, the major one is the fuse housing that is broken but the fuse can stay in. Now I am wondering, can the fuse that is not completely secured in the housing cause my issue as well? Anyways, I really appreciated your replies.
Click to expand...

Looks like that amp has been messed with. Hacked on.

The broken fuse holder would not likely cause this distortion problem - if anything, it would cut power completely to the amplifier. However. It's hard to tell from the picture, but that fuse holder might be exposing 120 VAC line current where someone might touch it and get badly shocked. That looks dangerous.

Also someone put a 3-prong AC receptacle in there which is also a bad idea. The amplifier was not designed to work that way and it may actually be less safe depending on how it was hooked up. Also, that's not the correct power switch.

I would ship it to AudioClassics and have the fuse holder fixed (replaced), the 3-prong power receptacle replaced with an original type 2-conductor cord properly wired and maybe get a proper power switch. They can also fix the distortion issue. Note, when they open up the bottom, they may find more hacks from whoever worked on this that must be fixed. You might ask them about you sending email pictures of the amp, including the insides with the bottom cover off before you ship it so they can get an idea of how hacked up (if at all) things are underneath.

When shipping, of course remember to get packing instructions from AC which likely include the instruction to remove the tubes and wrap separately for shipping and / or get an MC225 shipping box from AC.

Mil Gnoh said:
. . .I live in the San Francisco Bay Area. In fact, I found a couple of service shops near me from the McIntosh web site. And I also found in eBay some in other states. . .
Click to expand...

BTW, I've been searching the Bay Area for a few years looking for a repair person who I would trust with my McIntosh gear. 10 years ago, we had some good options, but they're all gone / retired. So I would like to find a good McIntosh tech in the Bay Area. Three shops are shown on the website two of which are up in Sacramento and the one actually in the Bay Area is probably not the best for McIntosh. Although I have not used them, the two listed in / near Sacramento have good reps, so might be worth a road trip. Rainbow might be best for older stuff.

These are beautiful amps and worth fixing, so I'd do it right.

Good luck and let us know how it goes.
 
You can go to McIntosh's website and find authorized service centers in your area.

I would say that sending it to Audio Classics is a great option with the exception of what it would cost to ship the unit. They do good work, and they offer fair pricing.

But I'd start with local authorized shops and do some research on them.
 
I would say that I would like to see what things look like underneath but something tells me that I don't. Send it to Audio Classics, if you can afford them.
 
TSmith8605 said:
Looks like that amp has been messed with. Hacked on.

The broken fuse holder would not likely cause this distortion problem - if anything, it would cut power completely to the amplifier. However. It's hard to tell from the picture, but that fuse holder might be exposing 120 VAC line current where someone might touch it and get badly shocked. That looks dangerous.

Also someone put a 3-prong AC receptacle in there which is also a bad idea. The amplifier was not designed to work that way and it may actually be less safe depending on how it was hooked up. Also, that's not the correct power switch.

I would ship it to AudioClassics and have the fuse holder fixed (replaced), the 3-prong power receptacle replaced with an original type 2-conductor cord properly wired and maybe get a proper power switch. They can also fix the distortion issue. Note, when they open up the bottom, they may find more hacks from whoever worked on this that must be fixed. You might ask them about you sending email pictures of the amp, including the insides with the bottom cover off before you ship it so they can get an idea of how hacked up (if at all) things are underneath.

When shipping, of course remember to get packing instructions from AC which likely include the instruction to remove the tubes and wrap separately for shipping and / or get an MC225 shipping box from AC.



BTW, I've been searching the Bay Area for a few years looking for a repair person who I would trust with my McIntosh gear. 10 years ago, we had some good options, but they're all gone / retired. So I would like to find a good McIntosh tech in the Bay Area. Three shops are shown on the website two of which are up in Sacramento and the one actually in the Bay Area is probably not the best for McIntosh. Although I have not used them, the two listed in / near Sacramento have good reps, so might be worth a road trip. Rainbow might be best for older stuff.

These are beautiful amps and worth fixing, so I'd do it right.

Good luck and let us know how it goes.
Click to expand...
Hi, @TSmith8605. Thank you so much for your message and valuable information. I really appreciated it. I will contact AC to see what they say. I went to the McIntosh site and searched for local service centers. I found one in the Bay Area (R&B) and one in the Sacramento (Paradyme). Rainbow Electronics is not listed in their site but I found them in Yelp. I am wondering who else you found near Sacramento. Anyways, it's so nice to meet someone here who lives in the Bay Area. Thanks.
 
Yamaki said:
You can go to McIntosh's website and find authorized service centers in your area.

I would say that sending it to Audio Classics is a great option with the exception of what it would cost to ship the unit. They do good work, and they offer fair pricing.

But I'd start with local authorized shops and do some research on them.
Click to expand...
Hi, @Yamaki. Thanks for the suggestion. I will definitely talk to Audio Classics. Appreciated your message.
 
ramjet said:
I would say that I would like to see what things look like underneath but something tells me that I don't. Send it to Audio Classics, if you can afford them.
Click to expand...
Hi @ramjet. Thanks for the message. I can share inside photos here as well if anyone including you wants to see. I just didn't because I wasn't sure how people in the forum feel about spamming with bunch of photos. Anyways, yes, I will have to talk to AC to see how much I will have to pay for shipping and for estimated repairs.
 
Hi @Mil Gnoh

I'm in Oakland, and when looking into somebody to help with a couple of McIntosh pieces that I have I found out about a fellow AK'er in the San Jose that evidently is very capable. He was mentioned in this post [URL="https://audiokarma.org/forums/index.php?threads/the-crow-called-mcintosh-i%E2%80%99m-about-to-eat-mc-2105.1004301/page-3#post-15836203"]The Crow called McIntosh I’m about to eat - MC 2105[/URL] about another local's AK'er (@jobrewer1983 ) adventure acquiring a Mac amp and how Ben did the work on it. I had a good offline discussion with him but haven't yet used him but probably worth contacting for information.

https://www.bensaudiorestoration.com/
 
The only other common mode component is the input stage 12AX7 twin triodes, which are independent including the heaters wiring in 6V.
No apparent problem with it would likely cause this problem other than heater connections @ the socket
 
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sberger said:
Hi @Mil Gnoh

I'm in Oakland, and when looking into somebody to help with a couple of McIntosh pieces that I have I found out about a fellow AK'er in the San Jose that evidently is very capable. He was mentioned in this post The Crow called McIntosh I’m about to eat - MC 2105 about another local's AK'er (@jobrewer1983 ) adventure acquiring a Mac amp and how Ben did the work on it. I had a good offline discussion with him but haven't yet used him but probably worth contacting for information.

https://www.bensaudiorestoration.com/
Click to expand...
Hi @sberger. Thanks for the message. This is awesome. Although I will check out all the shops suggested by others above, anyone local would be still my preference. I will try to contact him. Much appreciated your suggestion. Great to meet another Bay Area neighbor here.
 
sberger said:
Hi @Mil Gnoh

I'm in Oakland, and when looking into somebody to help with a couple of McIntosh pieces that I have I found out about a fellow AK'er in the San Jose that evidently is very capable. He was mentioned in this post The Crow called McIntosh I’m about to eat - MC 2105 about another local's AK'er (@jobrewer1983 ) adventure acquiring a Mac amp and how Ben did the work on it. I had a good offline discussion with him but haven't yet used him but probably worth contacting for information.

https://www.bensaudiorestoration.com/
Click to expand...

I actually have 3 amps rebuilt by Ben, and he has one currently he is going through. Fantastic tech, Quick work and doesn’t break the bank.
 
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