The Leben CS300XS Thread
Nov 29, 2011 at 3:19 AM Post #1,007 of 2,299
The characteristics of the tubes in the Leben are more prominent on speakers than on headphones, in my experience. Allows me to adjust the sound easily with different tubes whenever I change power cables or interconnects on different parts of the system. An amazing tube amp.  
 
 
Nov 30, 2011 at 3:05 AM Post #1,008 of 2,299
My Leben buzzes when I connect the HD800 and T1. I'm assured by many this is not normal. So should I try cleaning / re-seating the tubes? They're stock, not old or anything.
 
I've tried moving the amp around to make sure it's not interference buzz, but alas it's still there.
 
Edit: I should mention that these are the only headphones in my collection that buzz with the Leben. The HE-6 doesn't buzz. The LCD-2 doesn't. The Audio-Technicas don't buzz (which is odd since they buzz on just about ANYTHING save the Zana). There's nothing wrong with the headphones in question either, since they don't buzz on anything else. It's a bit perplexing.
 
Nov 30, 2011 at 7:45 AM Post #1,009 of 2,299
Aren't both those headphones high impedance as opposed to the LCD-2 and HE-6 which are low?  That seems like the common denominator.
 
Nov 30, 2011 at 8:20 AM Post #1,010 of 2,299
The Sony Z1000 buzzes as well, so it's not just high impedance headphones.
 
Really, I'm just wondering what I should do to troubleshoot. I'm going to open the amp later and try re-seating the tubes. I may try some other tubes as well, in case one or some of them is/are bad.
 
Dec 3, 2011 at 6:51 AM Post #1,011 of 2,299
I have just fitted rubber damping rings to the Sylvania/Baldwin 6BQ5 tubes, two each tube, which has reduced the hum considerably.
 
Have to say this amp gets better and better each time I listen to it, well recorded vocals just tickle my ears, a very engrossing experience.
 
It's what ya pays yer money for 
smily_headphones1.gif

 
Dec 3, 2011 at 7:11 AM Post #1,012 of 2,299
I still having this channel imbalance, although small, but quite hmm, annoying.
My distributor (or service center) recommend me to change the volume pot.
I can choose the normal Alps or more expensive ones.
 
Do you think what his recommendation make sense?  if yes, could you recommend me a better volume pot for my Leben.
Anyone change your Leben volume pot?  is it going to be better?
 
Thanks.
 
Dec 4, 2011 at 8:02 AM Post #1,013 of 2,299
Two new (well, old, and not in great shape) set of tubes arrived, and I have exactly
the same problems with them :frowning2:
 
Still a constant annoying hum in right channel, and a hiss that is affected by the
volume (feels pretty much like a hiss I should get if I connected a pair or really
sensitive HPs, not the LCD2), both sounds are detectable with speakers as well,
but I have to put my ear close to the tweeter to hear it.
 
 
 
I think the EL84 tube on the far left might be burning warmer than the others by the
way... thought it was down to the tube having more clear glass on the top (as I saw
it with the lid on), but it's the same with the other tubes, and that's a bit weird...
another guy in here seems to have had that problem, due to loose tube sockets.
Don't really feel like operating on an expensive piece of gear I just got :frowning2:
 
 
 
Going to have a word with the seller tomorrow, anyone has any suggestions for me?
 
Dec 4, 2011 at 8:31 AM Post #1,014 of 2,299
I would either get the seller to agree to having the unit sent to Leben and repaired at his expense or return it to him for a full refund. 
 
 
Dec 10, 2011 at 4:30 AM Post #1,015 of 2,299
After suffering with a humming Leben I tried the output tubes fitted with rubber damping rings. Initially my thoughts were positive but on extended listening I found that the hum was very little reduced and the sound seemed robbed of some life.
 
This morning I decided to clean all the tube pins with Caig Deoxit and after refitting I can happily report that I now have a dead silent Leben.
 
I highly recommend this to all Leben owners 
smile.gif

 
Dec 10, 2011 at 9:25 AM Post #1,016 of 2,299
That's good news, and good advice for owners of ALL tube amps.  Clean those pins!
 
Dec 11, 2011 at 4:28 PM Post #1,017 of 2,299
Hello,
I guess this question have already been asked before here in this topic...
But, is it safe to keep the Leben on without any speakers connected and the front switch set to "headphones" position?
What is the main danger if the switch is briefly set to "speakers"?
Thanks!
 
Dec 14, 2011 at 4:23 PM Post #1,018 of 2,299
*sigh*
 
Tried putting some resistors on the headphone output (idea from here: http://www.highfidelity.pl/@main-135&lang=en )
and it did help with my LCD-2 (but not the HD600), but instead of the buzz, I got massive distortions on loud levels :/
 
So... still no real progress, it's now going back to the importer, where they will have a look at it.
Not very hopeful though, apparently their opinion is that "tube amps always make some noise" ...
 
 
How many here have a 230V Leben, and if you do, do you have any problems with hum / hiss? Especially
interested about how it works with the LCD-2, but all my headphones had the problem with this amp...
 

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