Home » Audio » Thermionic Emissions » Some test results on JJ 5751
Some test results on JJ 5751 [message #72921] Tue, 05 June 2012 08:56 Go to next message
Aki is currently offline  Aki
Messages: 36
Registered: May 2009
Have been testing a batch of newly released JJ 5751, and came up with some test results that I thought I might share with folks here.

Visually, JJ 5751 is identical to JJ ECC83S. Same glass, same plate structure. Electrically, they are definitely different creatures.

The numbers below were from a batch of 20 JJ 5751, tested at Ip=1mA, Ep=200V. Average numbers from JAN GE 5751 and JJ ECC83S on the same tester are listed for comparison.

                JJ 5751      JAN GE 5751    JJ ECC83S
Conductance :    2000           1650          1800
   Mu:            82             75            95

From the numbers above, calculated plate resistance are similar between JJ 5751 and JAN 5751.

Of course, this is only a test at a particular operating point and not a full curve trace by any means. But you get a general idea as to how JJ 5751 would behave.
Re: Some test results on JJ 5751 [message #72923 is a reply to message #72921] Tue, 05 June 2012 09:23 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18328
Registered: January 2001
Illuminati (33rd Degree)

That's good information, thanks!

Re: Some test results on JJ 5751 [message #75817 is a reply to message #72923] Fri, 15 March 2013 17:35 Go to previous messageGo to next message
gofar99 is currently offline  gofar99
Messages: 1728
Registered: May 2010
Location: Southern Arizona
Illuminati (4th Degree)
Hi, I just saw this thread and wanted to add a bit of information to it. I use 5751s in several designs. Mostly Jan Phillips and Sovtek ones as they cover the warmer and hotter ends of the range. I find both to be great in Oddwatt amps. I tried a batch of JJ ones in the same amps and they do not work well. The sound was quite inferior to either of the other two types. The ones I got were constructed differently as well. The internal structure looked more like a 6J6 RF tube than any of the 12A_7 or variants. Certainly not like the 5751s I was using. They have small square anodes set low in the bottles. I made the recommendation (as much as I really like JJ tubes) to not use them in any of the Oddwatt designs.

Good Listening
Re: Some test results on JJ 5751 [message #78470 is a reply to message #72921] Thu, 28 November 2013 06:11 Go to previous message
bestfriend is currently offline  bestfriend
Messages: 1
Registered: November 2013
The title says it all. Why? Why do so few manufacturers use them?

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