M1200 Tube Volume Drop

Changed tubes in all 3 of my M1200s to Gold Lions. Just tonight when watching a movie the center channel was wayy too quiet, almost 6db. I jacked the gain in my processor up and all is well, but am I to assume this tube is shot? I did confirm it is the amp and not the output, but dont feel like pulling the amp from the rack to swap the tube without first checking in with you guys.

(Im new to tubes)
Is it possible this tube is a lot quieter than others, but doesnt mean its bad, or is it likely this is a goner tube?

I have 2 M1200s with Gold Lion tube. I also use Gold Lion with the BHK Pre. Never had problem and never noticed volume differences.

Do the other 2 M1200s present the same issue or the only central one?

M1200 comes with a tube location pretty uncomfortable to manage, rolling tube may become very annoying and difficult to check that all the pins are correctly seated into the plate. Did you check it accurately?

Sorry for my question: did you check cables and connectors, are they tighten enough and correctly plugged both on amp and pre sides? Did you try swapping cables between units, still the same center M1200 with the issue or something different?

Thanks for the reply!
The L & R worked fine, both are the same with each other and the same to what was there before, It is just the center channel M1200 that is a lot quieter. (6db but sounds fine IMO).

I am 99% sure the tube was put in well. I will re verify….not easy but not that hard either. At this point though your response tells me its either not put in right or a bad tube

It’s a trial and error process, swap M1200 central with L/R and cables to investigate where is the problem, if the issue follows the unit (so the culprit may be the tube) or the channel, in this case you have to find different solutions.

Good luck!

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Super advice. Exactly what I would do.

Let us know what you learn.

Good luck!

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So I changed the tubes today, and no, that didnt help. Looks like my tube was fine. The gain is 6db quieter or so on one amp. Gonna swap them later today and try for sure but that explains something.

I previously was using this amp (matched pair) with my L&R. I recently switched orientation to this being my center, and my two others being L & R.

My left channel used to be a little quieter that my right, I always had to add more gain. Thats this same amp. I am leading to believe this amp for some reason is quieter.

Any advice? My next move is to email PS Audio which I am dreading as I dont have the original box and am going to be upset living without an amp for my center

This maybe a longshot but 6 dB is a magic number.
If you’re using XLR cables and one of the legs is missing your volume is reduced by 6 dB.

I would make sure you were getting a proper balanced signal into your power amp

Thank you I will try that!

Out of curiosity, what is the make/model of your center channel speaker?

Martin Logan Focus

Just wanted to say narrowed it down to a low output on my McIntosh Processor. I don’t know which I would have rather it been, but didn’t want to tarnish PS Audio since this is not an issue of theirs