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Old 5th November 2014, 01:53 PM   #1
needsp is offline needsp  United Kingdom
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Default EML300B reliability

Hi

Is anybody using the EML300B? (Not the XLS or the mesh plate versions). Are they reliable? Back in the day, some users reported premature failure, and even poor shelf life (?)

I use EH300B at the moment. They sound and measure great and are relatively cheap but after about a year, the filament of one of each of two pairs has failed.

Paul N

Last edited by needsp; 5th November 2014 at 04:38 PM. Reason: Corrected spelling
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Old 5th November 2014, 03:16 PM   #2
ColinA is offline ColinA  United Kingdom
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One of each pair filament failed?
I would be checking the filament voltages with an accurate meter before blaming valves.
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Old 5th November 2014, 03:20 PM   #3
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I wouldn't rely on hearsay when making an expensive purchase like this, particularly when there seems to be general confusion between Kron, AVVT, KR tubes and EML and their respective quality issues. Contact the distributor and find out what his experience is with defects and what the warranty policy is.
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Old 5th November 2014, 03:21 PM   #4
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Quote:
Originally Posted by ColinA View Post
One of each pair filament failed?
I would be checking the filament voltages with an accurate meter before blaming valves.
Exactly
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Old 5th November 2014, 03:31 PM   #5
45 is offline 45  Italy
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Quote:
Originally Posted by needsp View Post
Hi

If anybody using the EML300B? (Not the XLS or the mesh plate versions). Are they reliable?
Yes they are. After many years reliability has improved a lot and latest versions also have other desirable features like gold plated grid and center tapped filament. I have a friend that has been using these for over 2 years now. They have lots of hours and still run perfectly fine. Just don't use them above specs and will have no problems. For current production, chance of failure is minimal in my knowledge.

Quote:
Originally Posted by needsp View Post
I use EH300B at the moment. They sound and measure great and are relatively cheap but after about a year, the filament of one of each of two pairs has failed.

Paul N
That has always been an issue with Russian 300B's. It was extremely common with the first Svetlana 300B and has never been sorted 100% with successive variants. They are very sensitive to actual supply variations and mechanically weaker.
Better to go with JJ 300B. For these you only need to check the filaments work as they should and gm is within spec and they are pretty reliable as well.
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Old 6th November 2014, 07:11 AM   #6
waltube is offline waltube  Italy
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With EH300B I got some problems; with filaments and some difficulty for matching.
The JJ are robust and the Shuguang 98B are fine.
These last two was compared on same pp amp and the 98B seems to be better as sound.
I tested also 98C (graphite anode) with a good results but to call it 300B is not very true!!!



Walter
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Old 6th November 2014, 09:11 AM   #7
45 is offline 45  Italy
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I tested also 98C (graphite anode) with a good results but to call it 300B is not very true!!!
Walter
Graphite plate with oxide-coated filaments? Not a good idea if it is bare graphite. Sooner or later that plate will kill the filament. Graphite plate is good with thoriated tungsten filament.

Golden Dragon 4-300BLX were excellent but they are gone......
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Old 7th November 2014, 03:15 PM   #8
kevinkr is offline kevinkr  United States
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I'll echo 45 on the JJ300B, I've never had a problem with any of them, and can also confirm a very high filament failure rate on very early Svetlana 300B - in a few cases one half of the filament failed and in all others the filaments actually shorted to the grid. I've had at least six failures of SV300B where the filament shorted to grid, and several with half filament failures. I stopped using the SV300B more than a decade ago as a result. I have avoided all Russian made 300B since, but have former clients who have reported some issues with EH300B filament reliability more recently.

Note that these tubes were run either on AC or with tightly regulated DC (or a CCS) within a couple of % worst case of their nominal filament voltage.
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Old 7th November 2014, 05:06 PM   #9
hottube is offline hottube  United States
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I have used Emission Labs 300b for 6 years. [ the solid plates ] . in my amps they sound better than WE's , or any thing els . I have 3 amps using them. When I test them ever
year they change about 5% year to year . I use my stereo about 200 hours a year.
thanks Ric
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Last edited by hottube; 7th November 2014 at 05:08 PM.
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Old 8th November 2014, 02:14 AM   #10
45 is offline 45  Italy
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Quote:
Originally Posted by hottube View Post
I have used Emission Labs 300b for 6 years. [ the solid plates ] . in my amps they sound better than WE's , or any thing els . I have 3 amps using them. When I test them ever
year they change about 5% year to year . I use my stereo about 200 hours a year.
thanks Ric
Ric, 5% of what? It sounds a lot to me if you talk about current and/or gm. I haven't seen such a degradation over such a short usage (hours I mean).
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