Lifetime of the 45 tube

Evacuation of vacuum tubesThis is an article we have in preparation, about an amplifier with a pair of 45B, and an hour counter mounted inside. It documents lifetime of 40.000 hours, in an amplifier made by a Japanese manufacturer. The tubes show no significant loss of tube quality, on a tube tester. Specially because it is so difficult to predict lifetime we are happy to present a case here, which was carefully documented, since 2008.

Emissionlabs 45 tubes in Kurashima amplifier



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Picture 1. Tube tester: RD Instruments Model 1575 for Research and
Development; Hickok Electrical Instruments Company

Picture 2. Measurement of tube 1 ser# 514 M  2200 Micromhos  min 1100

Picture 3. Tube 1 ser#  514 M on tube tester

Picture 4. Tube 2 ser#  512 M on tube tester

Picture 5. Tube 2 ser#  512 M  2000 Micromhos min 1100

Picture 6. Kurashima 45 with EMT 986 CD player and elapsed time meter

Picture 7. Close up of elapsed time meter 20,440.5 hours since reset in 2013. 


Some of the email communication:


Total hours on the tubes are as of today 39,603. (13.09.2018)

I listen mostly to FM on the McIntosh and Marantz 10b tuners but it was easier to move the EMT 986 CD player to a spot with better light so I could take pictures.  Let me know if the pictures are ok or if you need more. This amplifier is now on between 10-11 hours a day, sometimes more on weekends.   I am amazed at how durable these tubes are.

Hope this helps,

Mo 11.09.2018 18:23

Hi George,

The tubes (EML 45) test almost the same as they did on:

Sept. 3rd 2013 at tube (1) 2225 min 1100 and tube (2) 2025
Mar. 15th 2017    tube (1) 2150 min 1100 and tube (2) 2000
Sept. 9th  2018    tube (1) 2150 min 1100 and tube (2) 2000

Not sure why these tube are so durable; they have been in constant use since purchased the Kurashima 45 back in Feb. 2008.  This amp is on every day except when I'm on holidays. 

Forgot to mention the tester:

RD Instruments. For Research and Development.
Same as  WE KS-15750-L2 Hickok Electrical Instrument Co.

Hope this helps,

Mo 10.09.2018 14:12

Hi George,

I am still using the same 45 solid plates and I changed to using the western electric 717a's after I spoke with you some time ago. The 45's have 39,569 hours on them now and they still sound great. I will test them tonight and let you know the results tomorrow. This 45 amp is great; I listen to it more than all of my other equipment. I have added an EMT 986 CD player so I can listen to my old CD collection but I mostly listen to FM through my McIntosh tuners and Marantz 10b. Hope all is well with you and you had some time to surf this summer.


Sent from my iPhone

Begin forwarded message:

From: "Peter Ellis" <>
Date: April 16, 2015 at 3:44:53 PM EDT
To: "George Lenz" <>
Subject: FW: Audio pictures

Hi George,

Here are a few pictures of the 45 amp and the elapsed time meter. The elapsed time meter was zeroed 22 months ago; I was originally planning to zero it every year but forgot June of 2013. It averages between 3400 and 3500 hours per year and the variance is due only to the number of days I am away from the house. This amp it turned on every day with a time clock switch so it wakes me up every morning and it is on for approximately 9.6 hours every day that I am here (almost always). I received the amp back in March of 2008 to the best of my memory and it has played every day since except for the rare holiday I take away from the house/ laboratory. I had difficulty with light so I had to move the amp to where I could get some pictures. I am going to leave the WE 717a tubes in because I prefer them to the original red 5693's. Both the 5693's and the EML 45 solid plates were in the amp since new. I tested both the EML 45's and the 5693's this week with my tester. I use a Hickok model RD Instruments 1575 for Research and Development - it appears identical to the Hickok Western Electric version KS-15750-L2 and uses the same roll chart to test all the Western Electric tubes.

It is stunning to me that the EML 45's still test nearly the same as when I received them 7 years ago and with somewhere between 23,000 to 24,000 hours on them. The results are as follows:

1. EML 45 2200 /min 1100 100% = 1692
2. EML 45 2025/ min 1100 100% = 1692

These tubes test better than my two NOS EML 45 Globe tubes that test at 1925 and 1800. I use these sparingly because they are rare. I tested the 45 solid plates back in Sept of 2013 and they tested the same as they did this week. I am amazed at how durable these tubes are.

After seven years the RCA 5693's tested as follows:

1. RCA 5693 1400 / min 1075 100% = 1649
2. RCA 5693 1250 / min 1075 100% = 1649

When these tubes were new they tested around 2000. Although they are considered 10,000 hr tubes they have also held up well considering they have in excess of 23,000 hr on them. The RCA 5Z3 rectifier also tests great so this Kurashima 45 amp is very easy on the tubes.

Sorry if the pictures are not great; our house is quite dark with the surrounding large trees. Let me know if you want me to try to take some better pictures.