Hi,

I currently own the Leben CS300XS a 15 watt EL84 and a very efficient set of speakers (single-drivers), essentially my amplifier is sufficient for driving the speakers. I was always intrigued by Leben's higher wattage amplifier (CS660P) which is a KT66/EL34 that puts out 40 watts and I now have the opportunity to buy it. I'm wondering what kind of difference this will bring: am I going to win something from the fact that I have more power? What about the different tubes? In the past I had A/Bed the CS300 with the CS600 (EL34) and I actually preferred the EL84. Generally is it that an amplifier like that puts-out more watts (so can work with more speakers) or given tube rolling/etc. I'm getting a whole new set of advantages? 

Hi Belbo, generally, it’s known that physically small, lower power valve output transformers work better than ones designed for more power by virtue of their lower inter winding capacitance. Also the EL84 is a very sweet sounding valve, the EL34 is less sweet but capable of more solid dynamics. You can tube roll with both valves. If you prefer the sound of your current 15w EL84 Leben I won’t be surprised.
I’d save the money and spend it on a phono stage that you prefer!

AMR-iFi R&D

In my experience I'd have to concur with everything colinf mentions:

- Many people find that the EL84 is a great sounding tube, overall lively & 'musical' - for many reasons I think, aside from the tube itself....

- Good point about the OPTs, the smaller OPT of the lower powered EL84, means less windings in the OPT core/coil & that means less capacitance to 'soak' away HF extension - audio TXs are always a trade off between big core/inductance for max LF power & minimising inter-winding capacitance.

My first & some of my favourite valve/tube amps have been EL84PP ones - I still always keep a Leak Stereo 20.
I've had a few EL34PP amps & they have never stayed around for long - Leak Stereo 60, Radford STA25.

However, a lot depends on the amp designer & unfortunately I have no experience with the (beautiful) Lebens.

Additionally, single driver loudspeakers often benefit from amps that have looser/fuller LF tone & lower Damping Factor (typically Single Ended Triode amps), because the loudspeaker's limited LF extension often works out well with looser bass control with such amps. (But in my case, ultimately I found SET amps did not completely satisfy on a wide range of music. YMMV)

DarkLantern blog - darklanternforowen.wordpress.com

As your speakers don't need the extra power its likely that it wont be better. My experience is that less is always more.

Thanks all! Still on my list to go at some point smaller (300B) but for the time being I will stay where I am, very happy with the sound I'm getting anyhow!

Nov 14, 2019 0:08:36 GMT 12 belbo said:

Thanks all! Still on my list to go at some point smaller (300B) but for the time being I will stay where I am, very happy with the sound I'm getting anyhow!

Good call mate!