Leben CS300XS Tube Rolling


Of course there are older threads, here and elsewhere, that cover the subject. But I’m looking for fresh takes from new users (and given how quickly used units move, I’m guessing there are a few of us around) as well as feedback from seasoned experimenters (maybe even some dating back to those mind numbingly long threads of 10+ years ago).

Some say the Leben CS300XS is responsive to different tubes, both EL84 and 12ax7. Others say only the signal tubes noticeably impact the sound. Given that versions of the amp have been around for ~20 years, this seems like something that should be already settled, but here I am…

New production or NOS and no hard budget, I’m open to trying anything anyone else enjoyed. What am I trying to achieve? Occasionally, I hear some random graininess and/or hardness at higher volumes (could this be tube related? I don’t know). Beyond that, I’m really looking for anything that brings more of the Leben’s great qualities forward (like when I added A23 cables to the mix, *everything* improved).

Speakers are Klipsch Forte IV and sole source at the moment is a Chord Qutest DAC. Thanks in advance for any advice/help you care to share.

oceanandmountains

Showing 6 responses by bjesien

I have e a set of NOS Mullards in both positions for just a glorious listening experience. If I want more detail and extention I have a set of Amperex that I put in the 12ax7 and Sovtek in the  EL84. I will have to try the Aperex/ Mullard combo together. 

The amp is responsive to cable changes too. I haven't tried a fuse change but I'd swear that I put a purple fuse in the Cobra will noticeable results. Never did a blind swap however. 

It's a great amp I've owned it 3 times now. A new stock EL34 that I really like is the Mullard, but never tried the new 84.

Best of luck!

Agree with ghasley, you get what you pay for.  The amp should be silent. 

Seems like the amp and probably not the tubes. The speaker can be a magnifying glass but if all the tubes are producing the same result, again, something with the amp. IMO.

Ear at tweeter zero noise...however I'm 50 years old. 45 could have been another story!