I feel like OOS old old stock or out of service. Both work.
1 Like
I have never “looked” close enough to see the actual blue led light source, but have had tubes for 24+ years and know that tubes emit a different color and different kind of light,. I also recognize the blue light as LED lighting.
1 Like
Not sure why only one monoblock was lit (while the front PSA light was off) for many hours after use. There is an explanation, just not sure what it is.
Seemed like I noticed more than just blue, but the bright orange I know from spending a good part of my life pondering them. I’ll report back, just looking for others who might have also noticed. It hasn’t happened often that I know of.
I was doing some tube discover stuff a number of days ago, and had the tube seated poorly. My bad, and now it turns off in stand-by. There goes a few hundred hours on just one monoblock, since it was maybe just over a week ago. 
2 Likes
Mystery solved, I thought you may have a tube that’s dying. (This is supposed to reply to @WATChad by the way).
1 Like
I missed my 50s so much already. Welcome to the young 50s group!
1 Like
I’ve bitten the bullet and ordered 3 matched pairs of NOS Mazda 12AU7 Triple Mica 5 Star tubes from a dealer in Hong Kong. At US$110 a tube, this is most reasonable as in Australia they are selling NOS tubes at A$650 a tube.
I’ll let you know how I go once the tubes have arrived.
2 Likes
Very curious to know your thoughts as soon as you can.
The more I use, the more I like the NOS 12AU7 Telefunken “Mazda” silver plated, I ordered a second matched pair as spare from Brent Jessee.
I’m afraid the one in the left M1200 is starting to become old. When I switch on the mono from idle to on, I hear a sort of modulation hiss from the left speaker almost for 10 minutes, then it attenuates and vanishes. Only the left one.
Also when I turn the volume on 0 mute on the BHK Pre or I switch off the M1200 I hear a little thump from the left speaker.
I already tried swapping the tubes on the BHK Pre, the issue still here in the same speaker, so I suppose the culprit is the tube in the left mono.
Too lazy to try to pull it out and reseat but I know this is the right thing to do. Some more day and I’ll do. The sound is always spectacular, as the first day I installed these tubes last May (if I remember well - before turning 50’ - when I was less lazy).
You should definitely switch around the tubes in M1200. Sometimes a reseat may cure the problem. Mine is still going strong. I really like these tubes and they should give you a couple thousand hours of life, if not more.
1 Like
I know I know, thank you Donald. I just hope that next gen Mxxxx amps will have the PerfectWave chassis to make rolling tubes easier as for the BHK Pre.
Now I have to disconnect speaker cables and bare wire REL cable, so I have to move the rack disconnecting all units and fighting with fingers in a little hole to reseat the tube and… mmm it’s a very annoying work. I know, I know, it’s necessary, just waiting the right inspiration!
That is one thing I do not like about M1200, they put the tubes in the wrong orientation. It is not easy to change tubes and my back hurts every time I do it. The tube puller PSA threw in did help a little bit.
1 Like
Hi Luca
The Mazda Triple Mica are sooooooo good. Everything is better, even sound staging.
I left comments on the stub about tube rolling, if you are interested.
Regards
Paul
1 Like
Hi David
I highly recommend the Mazda triple mica 5 star tubes. Just got mine and they make the amps sound like a different beast.
Paul
Hi Paul, this is Donald. I am glad to know you like these NOS Mazda 3 mica 12au7 tubes. It will be interesting to compare them to the NOS Telefunken “Mazda” that I like so much. I will ask Brent if he can tell me their difference. I may be interested in getting a pair too, although I have three spared set of Telefunken already.
1 Like
@phrozario happy to know you are enjoying them. I followed @dchang05 advice purchasing the Telefunken “Mazda” I consider really impressive (some pair here as spare, too), even better than the Gold Lion I was using since years.
Next week I have scheduled a re-setting of my Solid Steel rack: I need to replace all the components (unplug all, out of the rack, clean all, modify a shelf, reseat all, re-plug all - a real PITA job for almost a hard day of work!) to give more space to some upcoming units. I will take the chance to clean also the tubes in my M1200s. One in particular is producing noise when I switch on from idle the left amp, after a few minutes back silent, mah?
If Donald finds new routes in this tube-valley I will follow him again. Thank you for investigating with Brent and sharing his opinions about these similar NOS tubes.
1 Like
Do you still have the noisy tubes, or did the hum go away?
Hi Donald, unfortunately the noise is still present when I switch-on the left amp from idle status, a few minutes later it goes away and comes back silent.
Hopefully resetting the tubes help, but more likely you have a noisy tube. Good luck!
Both Telefunken “Madza” and Madza NOS tubes are excellent! Many prefer Telefunken more because their accuracy while some like Mazda’s lush mid-range. It is system depending. So, we are all good.
1 Like
Adding to the discussion here. My M1200s are definitely “fully broken in” now, so I just swapped out the stock tubes for some NOS Telefunken Select Medical red tips from Brent Jesse.
They have literally been playing only a few minutes, so I can’t say where they’ll settle, but holy moly, has the sound changed for the better so far.
And I wasn’t disappointed with the stock tubes. They might’ve been a touch bright in the upper midrange, but it didn’t sound overdone and was far from harsh or fatiguing.
Which is the point I want to emphasize: the ability to materially alter the profile of these amps is why I bought a pair. It’s one helluva feature.
2 Likes