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300B advice

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#101
Compare it to the Same manufacturer's 300B:

JJ 300B

1677678687956.png



The EML300B shows little sign of ra-shifting, even at 600V+:

EML300B

1677678777197.png


I couldn't find curves for the ELROG 300B, but I suspect they might be good.


ELROG - products
 
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#102
There have been consistent opinions that after EML 2A3, JJ 2A3-40 is the best sounding tube of this type. Better than vintage types. I have limited interest since 45/2a3 are hardy usable except Mf/hf range of highly efficient extended range driver of Lowther type or compression drivers
 
#103
Maybe - but the usual operating point for 2A3s is at 250V. It may well work fine there.

But, the 2A3-40 claims 40W operation, and leads folk to think it can be interchanged with 300Bs.
The curves suggest this will not work well, since 300Bs are optimised for 350V operating points.
 
#105
My understanding from JJ many years ago was that the 2A3-40 shares the grid and plate structure with their 300B and that there is no actual difference between it and the 300B except for the filaments. I have seen/heard amplifiers using these tubes producing around 8W on 400V plate supply.

1677693866374.png
 
#111
Most data sheets showing curves for tubes are not good enough for comparison in most cases. This is because they are simply not that accurate, they represent an average expectation for behaviour. I read somewhere that the old data sheets from way back when were often drawn with the aid of french curves to create a smooth looking chart and had nothing to do with actual measured data.
 
#114
TheGimp said:
I don't know, push pull 300B theater amps were a thing at one time.
Click to expand...
I have this perception, from reading around, that some fold feel the 300B run single ended is a bit less linear than the 2A3 because it has more 2nd harmonic. Well, of course, this is so dependent on implementation and especially the operating point. But push-pull tends to sound different partly because it shifts the harmonic profile from a 2nd harmonic dominant profile to one where it may be 3rd harmonic dominant.

Choosing a 300B for push pull based on sound must be a different thing than for single ended.
My chassis has a high impedance OPT, higher than the usual for a 300B PP amp which will impose another factor on the sound.
 
#115
TheGimp said:
I don't know, push pull 300B theater amps were a thing at one time.
Click to expand...
Even more recently, some 24 years ago I had an OEM build 20 PP stereo 300B amplifiers of my design in HK, they sold well, but ultimately the business itself did not fare well enough to be viable. One of my PP 300B designs was published in VTV in the late 1990s when I had a relationship with SED, a number of people over the years have built copies of that amplifier.

These days I am all SE. I have no familiarity with LinLai, but have a friend who uses their 845 and thinks quite highly of it. I have heard good (if limited) things about their 300B and other tubes.
 
#116
Bigun said:
I have this perception, from reading around, that some fold feel the 300B run single ended is a bit less linear than the 2A3 because it has more 2nd harmonic. <snip>
Click to expand...
I really haven't seen measured evidence for this in my own designs, and have a marked preference for the 300B over the 2A3 although I did have a bit of a weakness for Kenrad dual plate 2A3 from around WWII. 😀
 
#118
kevinkr said:
I really haven't seen measured evidence for this in my own designs, and have a marked preference for the 300B over the 2A3 although I did have a bit of a weakness for Kenrad dual plate 2A3 from around WWII. 😀
Click to expand...
It might well be because the 300B takes more oomph to drive and it's not always implemented adequately ?
Dual vs Single - thankfully the 300B doesn't have that degree of freedom to confuse the selection process !
 
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#119
Bigun said:
Most data sheets showing curves for tubes are not good enough for comparison in most cases. This is because they are simply not that accurate, they represent an average expectation for behaviour. I read somewhere that the old data sheets from way back when were often drawn with the aid of french curves to create a smooth looking chart and had nothing to do with actual measured data.
Click to expand...
And yet, when you put them on a rather accurate curve tracer they are more linear than datasheet suggests in most cases. Especially DHT's. I suspect that sort of smoothing/make-up was related to average curves rather than individual tubes.
 
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#120
TheGimp said:
Has anyone made measurements of the Lin Lai WE 300B? Or any of their 300B series for that matter.

I have not found a datasheet or graph of curves on their web site.
Click to expand...
Lin Lai are basically the same tubes as PSVANE where they worked previously. It looks to me they have done very little changes in their production, mostly aesthetics.. Surely they have removed the very basic types and the weaker samples are likely sold under other names....that's my impression. So you pay a bit more money respect to PSVANE but get a bit better average quality.
 
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