Valve curves traced at Owston

James · Post by **James** » Sun Jun 23, 2013 11:17 am

First up are Pauls 6B4G's

James · Post by **James** » Sun Jun 23, 2013 11:18 am

and the last one....

James · Post by **James** » Sun Jun 23, 2013 11:19 am

And Paul's PX25's

James · Post by **James** » Sun Jun 23, 2013 11:22 am

Now Colin's EH 300b's

James · Post by **James** » Sun Jun 23, 2013 11:29 am

And Thomas's 6J5's

James · Post by **James** » Sun Jun 23, 2013 11:30 am

Thomas's VT-62's

James · Post by **James** » Sun Jun 23, 2013 11:36 am

And last, Steve's 6B4G's

thomas · Post by **thomas** » Sun Jun 23, 2013 11:52 am

Thanks again for doing these James, a very nice piece of kit you've made there.
I've ordered a fibreglass pen to clean the pins of my rustling 801a, seeing as it traces well (no. 3 IIRC). I've junked the (chinese) UX4 socket.....

Paul Barker · Post by **Paul Barker** » Sun Jun 23, 2013 1:14 pm

The TJ meshplate px25 is not a px25 as I feared but neither is it a 300b.

PX25 is Impedance 1265 ohms this is 2,700 PX25 is mu 9.5 this is 6.6 PX25

So the TJ is not a PX25, but I was pleased to see on the day that neither is it a 300b.

It remains to be seen how it sounds.

At least it isn't a 300b rebadged.

Paul Barker · Post by **Paul Barker** » Sun Jun 23, 2013 1:22 pm

the crazy thing is that the worst 6b4G which we wrote off is actually right on the money at low level. the other 3 which we thought were great are over powerful. this is as compared to the RCA 2a3 curves. with the proviso the worst 6b4g can be seen to bend as dissipation increases, so it is definately going soft.

So it is possible the power of 6b4G's improved over the original 2a3 on the sly but the original curves were presented.

Things are not always what they seem.

It would also put Steve's 6b4g per in perfect condition.

the fact that the px25 tested is below on transconductance and the 6b4g's are above in conductance shows we are not looking at a trend in the curve tracer. so we have to assume the curves shown are what the valve condition is.

I can't wait to get mine and trace a few genuine px25's to build up a sample for information.

You can be sure I shall be posting results on the interweb, Chinease manufacturer's read on!

I can't wait to trace the 6em7's because my GE coin base are always a country mile from the published curves. I have sufficient sample to establish genuine curces for this particular version which will make curcuit design more predictable.

I don't mind all that much about the px25 as it is useful anyway and may even sound better than nos. We don't yet know do we?

Paul Barker · Post by **Paul Barker** » Sat Jun 29, 2013 2:36 pm

Couldn't find the correct thread so here I am stating components arrived but will to live looking at all this solid state on a low ebb.

May be a long pause before the Barker home has a curve tracer.

audio-talk

Valve curves traced at Owston

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