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In the Forum: Melquiades Amplifier
In the Thread: Is it the time to change those tubes?

Post Subject: Still have no answerPosted by Romy the Cat on: 7/29/2013

As much I did not answer back then as much I do not have it now. The gas tube I never changed. Well, as I moved out of city in 2010 I did changed them but not because I need but because I was “reviewing” the system sort of speaking. The 12AX7 in phonostage I never changed. In 2010 I opened the phonostage and measured the tubes – the show full emission – whatever it means… Those small signal tubes with 1mA on plate I think never die, not to mention that it is a phonostage – a devise that is not being use all time. The 6E5P/6E6P I change each year. I do not know if it right or wrong. They are Russian tube and they dies whenever they want. I do measure them after a year, some of them do lose some transconductance, some do not but I replace all of them juts to be on save side. The output DHT on MF channel I did not replace and I do not know how to test it. I do not believe in testing the DHT on my tube testers. They do maintain the original plate current, so I presume they are still fine but I do not know how to test the true cathode emission. This YO186 tube is used in very conservative way, so I presume it will be live for a long time. The 6C33C uselessly live for 1-1.5 year. I do not test them but hear what the amp begin to “ping”. This is very characteristic ping of dyeing 6C33C and as I hear it I try to figure out what channel it is coming from (sometime not so easy) and then replace the tube.

Frankly I do not hear a whole lot of difference what a tube or two are replaced and I do it rather as a preventive measure. I wish I would have a better way to do it, the way that would a tangible sonic feedback that the amp begun to use new tube or tubes. I do not have that sonic conformation. I remember when was changing the second stage on my Lamms power amps or rectifier on my Lamm’s preamp I was truly huge different. Not in my currant setup, unfortunately.

Rgs,
Romy the Cat

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