300b lovers

What separates the Euro super tubes is massively higher electron emission. For example, what separates the EML 320B XLS from the EML 300B XLS is 50% greater heater current, with correspondingly higher emission. But even the EML 300B XLS, although consuming the same heater current as a standard 300B, has significantly higher emission.

Same story for the thoriated-tungsten Elrog tubes. Thoriated-tungsten is used in high-power transmitter tubes, not "radio tubes" with the typical coated filaments. The peak emission characteristic will sound more like the Eimac giant transmitter tubes than a 2A3 or 300B.

What’s fun about these is they are plug and circuit compatible with classic 300B’s, but they are not replicas. Not at all. They are modern high-power designs, optimized for both linearity and peak emission. And they sound like it ... powerful and blazing fast.

But ... the amp circuit has to match the peak power and speed, or you never hear what they can really do. They sound like just another 300B with generic RC-coupled drivers, for example, and the potential is mostly wasted. Give them a driver that is a powerful Class A amplifier that is transformer coupled, and whoa, stand back. It’s not a meek little flea-power amp any more; put on Mahler or Mastodon and frighten the neighbors.

One unique feature with transformer coupling is 97~98% of the plate power is presented to the following grid. The plate power doesn’t disappear into a resistor, choke load, or MOSFET transistor current source, or jump through a plastic-film dielectric in a capacitor. It’s right there at the grid, with only tiny losses in the transformer.

This is audible as vivid and tactile tonality, speed, and power. Basically, less electronic cruft in the sound, which is what you’d expect. Don and Whitestix will attest to that.

The regulated filament supplies for each 300b can deliver 3 amps, and the tubes draw 1.2 amps, so they are coasting along, like the B+ supplies.   As Lynn described, the amp is lightning fast.   I would love to audition the Elrog 300b in it.  I have to admit the Linlai replica WE300b is just superb though.  I cannot imagine it needing more slam, but my speakers are 97 dB and an easy load, so the amp is just cruising along and is really not stressed.   Whitestix told me he tried a pair of Dynaudio C1 on his shoebox earlier edition amps and they drove them with no trouble at all in his smaller room.  That is the third or fourth time someone has put a more difficult speaker on the mere 27 watt amps and they had no trouble.  I don't suggest you power some horribly inefficient speaker with these amps, but don't let the 27 watt rating fool you.  Any rational speaker load is fine.

I suspect any electrostat is fine. The weird capacitive/inductive load will not bother a zero-feedback amplifier.

What will not work is something like Wilson Audio or B&W speakers, with low efficiency, a band split into three or more drivers, complex crossovers, and big woofer arrays. Or MBL. They really do need 200 to 500 watts with a high damping factor (lots of feedback). Transistor amps, in other words.

Hi @lynn_olson ,

According to your comparison between RC coupling and IT coupling, IT coupling between input and driver stage should increase slew rate (dynamics, trancients, speed) similar as it does between driver and output stage. Isn't it?
On the other hand, the input stage doesn't have a big voltage swing, and as result of it a linearity issue. It shouldn't drive the driver stage in class A2. 6sn7 with IT has less wide bandwidth compared to 6v6, 6f6, 45 that can be used in driver stage (in my amplifier 6sn7 18Hz-35KHz vs 6f6 6Hz-95KHz -3db ).
Is It wars to try interstage transformer after the 6sn7 input stage in my 300B SET?

I certainly confirmed that the 300b monos will drive the Dyn's to the full measure of their sound in my 13'X26'X9' room.  Lynn points out the need for speakers of a certain design, as he listed examples off, to have lots of power (current) to those speakers with amps which have a high damping factor.   My main speakers are Cube Audio Jazzon single driver speakers which by design, require an amp with a very low damping factor, such as most tube amps I can imagine and ss amps like the Enleum 23R and most of the Pass Labs First Watt amps.  

I am very happy that these 300b monos drive both my Cube speakers as well as the Dynaudio C-1's so I conclude that these monos are much more compatible with a larger variety than probably typical ~8wpc 300b amps would drive. 

I started this thread with reference to my Willsenton r300 300b tube amp with 8 wpc.  I swapped that into the rack to try to drive the Dyn's and it ran out of clean power pretty darn quickly, while the 300b monos cruised along easily and cleanly at very high SPLs.   It is a very unfair comparison, but here it is... a 300b tube amp that will drive a lot of speakers that many others likely would not.  This fact dramatically broadens the selection of speakers one could pair with these fantastic amps because having a tube amp that only pairs with high efficiency speakers is awfully limiting as one's choice of speakers today might not be the same speakers you have down the road.