EL34 vs 6L6 for HiFi

[sprinter]

I know, there must be hundreds of such discussions everywhere, but they all seem to be regarding guitar amps where the interest is in distortion characteristics. I need to know the subjective and the objective differences between the two, especially in SET application.

Any subjective listening opinion on the qualitative differences?

What should I know about the technical differences to build a SET amp around them?

Thanks

[GorengGuy]

I have Winged C EL34 on my SE UL amp with Silk opt comparing to 6p3S-E(6n3C-E in Russian). The EL34s have a more prononuced mid-high, so they are good for pop-rock. While the 6p3s-E(=6L6CG) sound balanced form low to high with good detail and any kind of music is OK.

Some times, more power is needed. A KT88 SEUL is better if you listend to classical music. I have another KT88 SEUL amp with popular James JS6123HS opt. KT88 Gold Lion Reissue is great, but it has nothing close to original GoldLion, so I rename it as Russian Lion. Svetlana KT88 sounds sweeter with bit weaker bass. Shuguang KT88-98 is not bad, sound like Chinese 300Bs.

Anyway, my favorite tube is 6p3s-E. It performs excellecnt in PP UL amp.

[kenpeter]

EL34 was designed with as little curvature as possible, for linearity in
single ended and class A push pull. They cross with a slight wiggle in
class AB, the "Marshall" sound. HiFi amps operating in AB might need
a lot more global feedback to get rid of that wiggle.

6L6 was deliberately curved to cutoff on a square law, optimized for
better linearity in A and AB push pull crossing, "California clean". Most
beam power tubes share this same curve, for same reason. Ex: KT77
replacement for EL34. In SE, 6L6 type requires more feedback than
EL34 type to remove that curvature where it isn't actually helpful.

According to Schade, square law was a feature designed into his G1.
Its not at all clear that every beam power tube or upgraded clone of
his 6L6 will automagically inherit the original curve? I got feeling from
Schade's writings that he could just as easily have made it cutoff like
a normal Pentode if he'd wanted it that way. And if so, may be that
regular pentodes could be designed with square law curvatures too...

I have noticed EL84 pentodes crossing suspiciously smooth in AB.
Looking at XRays of G1, you see the grid coiled tighter at the ends.
Same what I see in 6L6. Though EL84 is not a beam power type.
Except one oddball RCA I have, actually is beam type. Go figure...

In short: For SE, best use EL34. Least curve is what you want.

[danzup]

Originally Posted by kenpeter

EL34 was designed with as little curvature as possible, for linearity in
single ended and class A push pull. They cross with a slight wiggle in
class AB, the "Marshall" sound. HiFi amps operating in AB might need
a lot more global feedback to get rid of that wiggle.

6L6 was deliberately curved to cutoff on a square law, optimized for
better linearity in A and AB push pull crossing, "California clean". Most
beam power tubes share this same curve, for same reason. Ex: KT77
replacement for EL34. In SE, 6L6 type requires more feedback than
EL34 type to remove that curvature where it isn't actually helpful.

According to Schade, square law was a feature designed into his G1.
Its not at all clear that every beam power tube or upgraded clone of
his 6L6 will automagically inherit the original curve? I got feeling from
Schade's writings that he could just as easily have made it cutoff like
a normal Pentode if he'd wanted it that way. And if so, may be that
regular pentodes could be designed with square law curvatures too...

I have noticed EL84 pentodes crossing suspiciously smooth in AB.
Looking at XRays of G1, you see the grid coiled tighter at the ends.
Same what I see in 6L6. Though EL84 is not a beam power type.
Except one oddball RCA I have, actually is beam type. Go figure...

In short: For SE, best use EL34. Curve is not what you want.

Do not agree with you after years of listening to SE amplifier diy or factory made.
In short : use 6P3S for best sound in SE and music of different type .

El 34 tend to be very unevenly for some music ....
It is only in my years maybe , but this is what I am hearing when compare .

And 6L6 original (NOS) I will never use but for guitar amplifier !