Leben CS300XS Tube Rolling

@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). 

Hi @roncagg been a while hope all is well! 

I had to send my leben for repair after borrowing some vintage amperex el84s from a tube enthusiast friend of mine, later found that one of the tubes was bad and that caused an issue in one of the channels. Just a caveat to make sure you know what you are putting into your amp!

Lol. Because the music still sounds great, think I'll just take a wabi-sabi view on this one and direct my neuroses elsewhere (e.g., grills on or off? NOS or new? MM vs MC, etc).

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

@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.

Not too long ago, I bought some new EL84’s for my DIY SE amp. 
 

The previous tubes were not very good - JJ’s

The new tubes simply changed everything about the sonic presentation.

They were The Tube Stores house brand.

Not very expensive, and sound amazing

I had previously heard some intermittent noise from the Gold Lioins - almost a grinding sound - coming out of just one channel.  I switched the tube positions and the sound switched channels.  So clearly had one bad tube.  When I changed them all out, that noise was gone. 

At normal listening volume - with the music paused - I currently hear no noise/hiss. If I cranked the volume knob up well past where I would ever do so with music coming through - I can hear some faint buzz.  That's fairly normal for tube gear though.  Brent Jesse has some good reading on the subject:

https://www.audiotubes.com/tubetap.htm

@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?

I've got a Leben CS300xs going into a Forte IV too.  The Leben came with Genalex EL84s and 12ax7s.  I'm not much of a tube roller, but I have replaced the EL84s with NOS Sylvania's that added a bit more "glow" to the sound.  I've been itching to upgrade to upgrade the 12ax7's.  Brent Jesse has never done me wrong with tubes and figure that his "butt ugly" tubes would make sense since the tubes are not visible.  

@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. 

@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..

@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. 

@oceanandmountains  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.

@bjesien Even with the Klipsch and ear at the tweeter?

@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?

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

@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.

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?

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!

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!
 

@ghasley nope I just misread thanks for the heads up and OP don't use KT77s 🤣

@jond

The cs300xs utilizes el84’s rather than el34’s, perhaps you are referring to the cs600x.

@oceanandmountains

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. 

What tubes are you using now that you're hearing graininess? Also what speakers are you driving? My favorite EL34 variant is the Gold Lion repro KT77. I haven't used 12ax7s in years so no recs on those from me.