@roncagg you read my mind. My first Leben developed an issue shortly after the first tube change (new production tubes though). That unit remains in repair limbo, so I still have no idea how the tubes could’ve damaged the amp (which of course makes it tough to be more mindful in the future).
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.
Showing 10 responses by oceanandmountains
Sage advice @ghasley ;) Replicating Leben’s limited edition tube set is at the top of my list. And yeah, I’m already loving the chime-like tone and want to keep moving in that direction. Probably should also add that with the stock Sovteks and Klipsch, I haven’t experienced any brightness. So I’m also thinking NOS Amperex 12ax7s because of their reputation for clarity and, especially, dimensionality. Currently, the soundstage is tall and, according to my musician wife’s mutant ears, very deep. The only tubes I’ve tried so far are Genalex EL84s and 12ax7 (gold pin). The difference was relatively subtle, but the graininess was definitely reduced. So smoother than Sovtek seems fairly easy/cheaply achieved. But I’m greedy; if I can get more, I want it! |
@bjesien Thanks again! That's *really* good to know... Tomorrow I'm supposed to receive my second, new Leben CS300XS (hence the original purpose of this thread). Don't want to go into the long, boring details of my Leben saga here (at least not yet), but I'll soon be able to compare two different units and better distinguish amp behavior from tube behavior for myself ('cause there's no substitute for experience, right? Lol.) I promise to report back..
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@ghasley I bought the Genalex tubes from Amazon thinking (mistakenly?) new production tubes, unlike NOS, would be a low risk purchase. Viva Tubes filled the order and only matched the tubes. Again, the stock Sovteks produced the same low level noise via the tweeter (the Sovtek noise might even be slightly greater than the Genalex, but I’m not sure). As to the grounding questions: 1) the noise is present without a source connected 2) it is in both channels, same level in each 3) adjusting the volume dial does not alter the noise. The noise begins right after the red light on the Leben comes on. Someone somewhere described the Klipsch Fortes as a magnifying glass and I’m inclined to believe that’s what I’m experiencing here: since they reflect every change in the system, I guess that means they will also find noise where other less sensitive speakers probably would not. Thoughts?
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Thanks @bjesien and for sure the Leben/Klipsch combo responded to different/better cables. Not a subtle change at all. BTW I can hear a slight tube buzz from the tweeter (with my ear to the speaker) with both Sovtek and Genalex tubes. Can NOS tubes reduce this noise at all or is this just part of life with the Klipsch driven by tubes? |
@bjesien Even with the Klipsch and ear at the tweeter? |
@ghasley Unfortunately, I don't have wired headphones. But yeah, definitely shopping 5751s from Brent or VTS (good point on the speakers). In addition to the GE version, the Sylvania 5751 black plate, triple mica get some great feedback. |
@djspinner Thanks for the engagement. Since you mention owning the same Klipsch/Leben combo, can you hear any tube hiss/buzz/noise from the tweeter? |
@djspinner Yeah I seem to be on Brent's page (though I'd prefer @bjesien silence)... Leben #2 performs identically to Leben #1 in this regard: ear at tweeter has low level noise once the operation light comes on and it remains the same no matter the volume. Two different units, two different sets of tubes, same speakers. Hardly a deal breaker (the noise is inaudible during playback or without music at listening position), but...hmmm. . On a positive note: I can strongly recommend Auditorium 23 cables between the Klipsch and Leben and sources. The impact has been so across the board awesome, they really seem essential for maximizing *this* system's synergy. And no, wouldn't have believed this was possible beforehand.
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