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McIntosh MC275

Hi all. I recently purchased a used MC275 in very good condition. The original owner said he had it service not too long ago. The amp appears to work fine but the tubes are very dim. I had them tested and they are fine with about 1/2 life still on them. Not sure what to do. Do I need new tubes or is there an adjustment I need to make? If I need new tubes then could someone give me an idea what to get and where to place them on the amp (which slots)? I want quality tubes so please, ANY guidance would be appreciated. Thank you
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joeinid's avatar
joeinid
658 posts
 
What version MC275 did you buy? The tubes tested fine so I would not worry. How does it sound? Is this the first tube amp you’ve owned? 

McIntosh amps are usually very easy on tubes. If it sounds great, and the MC275 amps do, enjoy it.

What speakers are you using?
ceborg999's avatar
ceborg999 OP
4 posts
 
Sorry...It is a MC275 IV. The bulbs are just dim as hell. Was wondering if I could do anything. Yes it is buy first tube amp. Using Harbeth 30.2 speakers

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drrsutliff
858 posts
 
The “brightness” of the tubes does not reflect on thier function.  The “plate” can surround most of the cathode on most and obstruct the visual light to a great degree.  If the actual plate, which is what you predominately see on the power tubes, starts to “glow” (red plate) turn the amp off immediately and have the bias checked.  The small signal tubes also will only have a small amount of visual light present.  More glow noted in a fully dark room, but again does not relat to function.
roberjerman
4,319 posts
 
Only direct-heated triodes like the 211 and 845 emit enough light to illuminate a room! 
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