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 first of all, friends dont let friends buy tubes on Amazon. The good news is you can probably return them. Can you hear hiss through the headphone section? If not, then perhaps try some low noise matched 5751’s from Brent Jesse. You dont need that much gain with those speakers.
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The cs300xs utilizes el84’s rather than el34’s, perhaps you are referring to the cs600x.
The graininess to which you refer is addressed at the 12ax7 position. it also depends if you like the tonal/texture but the ultimate “factory expression” was in the cs300x limited which came from Leben outfitted with NOS 5751’s (GE 5 star IIRC) and NOS Mullard el84’s. The 5751 lowers the gain somewhat and in my opinion, really made the amp communicate in a truly special way.
If you want to try the NOS Mullard or Brimar cv4004 you will also be quite pleased. |
@oceanandmountains it could be one of several things: 1) the new production tubes, from whom did you buy them and were they the highest grade, lowest noise offered by the seller?, 2) NOS tubes require the same attention to detail prior to purchasing, 3) The more likely culprit could be a grounding issue. Try unplgging everything from the Leben other than the power cable and speaker cables. Is the noise still there? Is it out of both channels or just one? Does it rise and fall when adjusting the volume of the Leben. Mine are quiet. |
