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McIntosh MC275 IV distortion on channels

4-2-7 said:
Or he can come by my house on the weekend with the amp and we can put a equal set of my power tubes in his amp and test it in my system.

BTW @entreat11 I'm in San Mateo
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Hello Dan,

Thank you for your offer, that is very kind of you, yes I would love to come by this weekend if you are free to diagnose the issue and see if it is the tubes or the amp itself.

I just got home and powered up and things sound a bit better, is that the drifting can start as the tubes warm up and get use?

Thank you,

Michael
 
entreat11 said:
Thank you for your offer, that is very kind of you, yes I would love to come by this weekend if you are free to diagnose the issue and see if it is the tubes or the amp itself.
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It should be pretty easy to just pull the center stereo amp on the floor and put yours in.

IMG_1015.JPG
 
4-2-7 said:
Tubes get hot and old ones if they are weak will fluctuate a lot.
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Regardless of what i test for in the next couple of days lets plan for this weekend if you are free to get them looked at, if it is tubes that are bad i can buy new ones. I have been listening for the lst hour or so and I do not feel like there is a drift yet. Yesterday i noticed and i used a DB test on phone ( i tried to center as best as I could between the two speakers) and it was showing less db on the left as well.
 
entreat11 said:
Yesterday i noticed and i used a DB test on phone ( i tried to center as best as I could between the two speakers) and it was showing less db on the left as well.
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If your holding a tester up to each speaker and getting a reading it will never be equal with music playing.
 
4-2-7 said:
If your holding a tester up to each speaker and getting a reading it will never be equal with music playing.
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i tried to just have the phone in the middle and leave is centered (as best I could) and just do it that way. Yesterday when i was doing it i was getting about 3-4 db difference today it is pretty even.
 
entreat11 said:
Yesterday when i was doing it i was getting about 3-4 db difference today it is pretty even.
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But with music they don't have the same sound coming out both speakers. If you got a mono switch that will equal both sides. Or hook a computer to your system and run a test tone though the system but turn down the volume first and the bring it up.

Test tone generator, AGAIN turn down all volume controls before starting
https://www.szynalski.com/tone-generator/
 
4-2-7 said:
But with music they don't have the same sound coming out both speakers. If you got a mono switch that will equal both sides. Or hook a computer to your system and run a test tone though the system but turn down the volume first and the bring it up.

Test tone generator, AGAIN turn down all volume controls before starting
https://www.szynalski.com/tone-generator/
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that is true. I do have mono on the preamp, i can try that. Previously I tried hooking a computer directly to the 275 and did use a test tone from youtube, there is one that goes for an hour but i couldn't stand it after a few minutes..... I will try the above link.

btw thanks for the help and suggestions. It's very odd things now sound ok so far, not like i was seeing yesterday. maybe there was some weird fluke?
 
entreat11 said:
that is true. I do have mono on the preamp, i can try that. Previously I tried hooking a computer directly to the 275 and did use a test tone from youtube, there is one that goes for an hour but i couldn't stand it after a few minutes..... I will try the above link.

btw thanks for the help and suggestions. It's very odd things now sound ok so far, not like i was seeing yesterday. maybe there was some weird fluke?
Click to expand...
Who knows maybe the new tube needed some burn in time?
 
@4-2-7 - Thank you for having me over today and explaining your wealth of knowledge on things. I enjoyed listing to you! It was a fun experience. Also thanks for your help with the 275 and taking the time to swap the tubes and such.
 
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