[Docere]

10,000 or perhaps even 40,000 hr
Well, this looks like exactly the WE site speech talk for its new 300B.

I have not seen the new WE site. My opinion is based on an older data sheet and a discussion with some engineers and audio friends probably over a decade ago. Running a quality 300B at 300V and circa 55mA, with reasonable care, might approach a 40K hr lifetime. Might. Even with a moderately higher dissipation, 10K hr might be achieved and is quite reasonable, I think.

YMMV.

[FullRangeMan]

This is quite extraordinaire at least, a friend with Dynaco 70 EL34 driving JBL L90 have to put new tubes at each 6/9 months.

[Docere]

Different tubes and different use cases. I use my 2A3 tube amps for many hours daily (sometimes left on for days), for many years, and have not had to change an output tube (either JJ or EML). The EMLs were not treated kindly in one amp, probably have >5,000 hours on them now, and sound like new. I expect them to last for another decade at least, if I continue to use those amps.

I have been through a few pairs of nice NOS driver tubes though.

[/mp]

I would not want to use them [300b] in parallel though.

Why? To what other tubes does this also apply?
TIA,

[FullRangeMan]

Four 300B are expensive and are hard pushed in parallel.

[Docere]

Why? To what other tubes does this also apply?
TIA,

My comments obviously refer to a SE topology, within reasonable power limits - just want to be clear about that.

A single 300B can provide enough power for a decent selection of speakers and listening preferences. Paralleling adds cost and complexity, and according to some, introduces sonic compromises (I don’t have an opinion about that).

If I wanted more power than a particular single tube can provide, I’d use a different single tube. Now, once our power needs pass a certain point, this becomes impractical.

Again, YMMV.

[Kw6]

Yeah I would definitely find a speaker that only requires 8 watts to come alive. Or it has to be active like Daniel Hertz speakers designed by the Mark Levinson.

[Kw6]

I have decided for me I am going to the 300b set route.I may get audio note kit interstage monos. 8 watts. What changed my mind. The availability of Chinese 300bs which sound decent. I can get match pr for $146 usd. Other big triodes generate too much heat and are expensive and I read 6c33c are very hard to get a match pr.

[FullRangeMan]

I read 6c33c are very hard to get a match pr.
Correct. This is solved by using auto-bias or manual bias, I use manual bias. Also 300B cannot use Self Adjusting bias.

[Kw6]

Ok I didn't know thanks! My Cayin 300b integrated uses the toggle switch to match up to centre of the metre to bias

does that count?

[Kw6]

My comments obviously refer to a SE topology, within reasonable power limits - just want to be clear about that.

A single 300B can provide enough power for a decent selection of speakers and listening preferences. Paralleling adds cost and complexity, and according to some, introduces sonic compromises (I don’t have an opinion about that).

If I wanted more power than a particular single tube can provide, I’d use a different single tube. Now, once our power needs pass a certain point, this becomes impractical.

Again, YMMV.

Just like Jadis I300 300b in parallel for 10 watts. I'd rather have SET two 300b's for 8 watts. And a cheaper amp for customer.

[FullRangeMan]

Maybe you want order the new Decware 300B $4,200 without tubes, with OPTs so small they are place under side.
https://www.decwareproducts.com/sarah