[LarsHP]

No, I still haven't heard from Leben.
As of now, I use 10 Ohm resistors with the HE-6 on speaker taps. This makes a total load of 8.3 Ohm ("seen by the amp") and 2 Watts available to the HE-6.

 

[LarsHP]

Quote:

 
(...)
And here is a question if you can here a little hum when there is no music playing what difference does it make???
What is important is the amp sounds good with the music playing.  I don't understand this total black background
thing most SS amps don't even achieve this.

First of all, I agree that not all SS amps a dead silent, but then this is high end territory, and in this neighborhood things aren't as most things are.
 
Then, as I said earlier: The hum is audible while listening to low level passages and solo instruments or voices. The hum or noise adds a "veil" to the music in these cases.
 
While I really appreciate the way my CS300 sound - especially with slow or soft types of music as well a music recorded in larger spaces or stages - the humming noise is in fact a serious issue to me. I think - considering the very high price of the amp AND the low wattage it has - that "faults" like humming should be either non-existent or hardly audible.
 
Generally speaking and IMO: It may be hard to achieve this with tube amps, but that's why we have high end amps. They should deliver this kind of no-compromise achievements. I could better accept a very high powered amp with noise and hum, but a 12W amp with hum or noise will make a quite small useful range in terms of selection of headphones and speakers: They need to be efficient enough to be driven by the low wattage, but not too efficient, because then humming noise will be messing with the music.
 
Unfortunately the CS300 sits between these two chairs: It has humming noise with the 91dB speakers I have (although lower than with my headphones) as well as my LCD-2 (which is has a relatively low sensitivity at 91dB) via the headphone output. With HE-6 there is no humming noise via headphone output, but then there isn't enough power to drive it to needed levels. In other words, I can choose between having the humming noise or a quite low maximum sound level.
 
Bottom line: "Houston, we have a problem".
 
Hopefully I will be able to fix it with either a choke as Raaf suggests, or finally by changing the mains/power trafo. The latter solution seems a bit far-fetched considering the cause of the issue is the component choice made by the amp designer - in an expensive high end amp.
 
Sorry to complain about this beautiful and otherwise wonderfully sounding amp, but I am a bit disappointed.

 

[victorcc]

Quote:

No, I still haven't heard from Leben.
As of now, I use 10 Ohm resistors with the HE-6 on speaker taps. This makes a total load of 8.3 Ohm ("seen by the amp") and 2 Watts available to the HE-6.

Thanks, I am using the same configuration for now in my 230V CS300XS. Before I had, besides the 10 Ohm resistors in paralell, two 3 Ohm resistors connected in series that eliminated the hum but also reduced the dynamics so I came back to the "dynamic hum" situation
 
I totally understand your feelings as noise has been the main factor that kept me far from tube amps for a few years until I heard the Leben and liked it so much. Still, I did not expect that the Leben would hum with the HE-6s. It was a disappointment for me too that does not prevent me to enjoy the combination a lot but I would love to get rid of that noise as noise is noise and I would like to feel the music as transparent as possible.
 
In my case I can hear the hum as soon as the Leben is switched on when I am close to the amp. Then, with the HE-6s on, I can hear a very distant hum. The hum is always independent of the pot position.
 
I tried with cheap dampers in the tubes but the hum did not change at all. I would like to try also the choke option but my DIY abilities are so poor that I am afraid of not using the proper component and kill the amp.
 
Let's keep trying to find a solution for the sake of all Leben lovers that have hum and do not appreciate it.
 
 
Cheers,
 
   Victor.

 

[LarsHP]

Quote:

Thanks, I am using the same configuration for now in my 230V CS300XS. Before I had, besides the 10 Ohm resistors in paralell, two 3 Ohm resistors connected in series that eliminated the hum but also reduced the dynamics so I came back to the "dynamic hum" situation
 
I totally understand your feelings as noise has been the main factor that kept me far from tube amps for a few years until I heard the Leben and liked it so much. Still, I did not expect that the Leben would hum with the HE-6s. It was a disappointment for me too that does not prevent me to enjoy the combination a lot but I would love to get rid of that noise as noise is noise and I would like to feel the music as transparent as possible.
 
In my case I can hear the hum as soon as the Leben is switched on when I am close to the amp. Then, with the HE-6s on, I can hear a very distant hum. The hum is always independent of the pot position.
 
I tried with cheap dampers in the tubes but the hum did not change at all. I would like to try also the choke option but my DIY abilities are so poor that I am afraid of not using the proper component and kill the amp.
 
Let's keep trying to find a solution for the sake of all Leben lovers that have hum and do not appreciate its.
 
Cheers,
 
   Victor.

I don't recall hearing mechanical hum (the hum you hear directly from the amp, not through speakers/headphones). This implies you have quite a lot of DC offset from the wall outlet, because I have problems with that on my SS speaker amp, but not the Leben - it's dead silent in that way.

 

[LarsHP]

QUESTION to DIY'ers, PRO's and others who know about tube amp design:
 
Would it be possible to get rid of the hum if the mains trafo is shielded?

 

[LarsHP]

Today I talked to the NOS tube grand old man here in Norway who is an engineer and he asked me if the hum was 50Hz or 100Hz, because if it was 50Hz, then the source of the hum is the main trafo, but if it is 100Hz, then it is in another place where a choke (as described by Raaf) will do the job removing the hum. I haven't checked yet, but I expect the hum is 100Hz, so this seems promising!

 

[victorcc]

[size=small]Hi Lars,[/size]
[size=small]  [/size]
[size=small] How will you know if the hum is 50Hz or 100Hz?[/size]

 

[RedBull]

^ good question, would like to know as well.

 

[Skylab]

Since the hum is audible, the difference between 50Hz and 100 Hz is VERY easy to distinguish by ear.

 

[Anders]

It's very easy if you hear two tones after another but more difficult with a single tone. I have a CD with test tones (sinus tones) for speakers and listened to 100 and 50 Hz. I have another amp for the speakers and compared not directly but the slight hum I can hear from Leben should be 50 Hz taken from memory. The 100 Hz tone differs clearly from the Leben hum.

 

[RedBull]

I see, hmm, I can guess, but just can't be sure sure sure. But I guess, just download 50 amd 100 Hz tone and memorize, should be fine, I guess.

 

[longbowbbs]

CS300X up on Audiogon
 
http://app.audiogon.com/listings/tube-leben-cs300x-integrated-tube-amplifier-with-nos-mullard-el84-tubes-2013-09-02-integrateds-23505-norfolk-va

 

[vert]

Does anyone know what type of screws are for the top lid? I've lost 3 of them and I'm looking for a replacements.
 
I will be putting my CS300XS (230v) for sale for $2k if anyone is interested.

 

[Xenophon]

Gentlemen, forgive me but I have to ask as I've been reading a largish part of this thread with mounting astonishment:  why do most of you seem to consider it normal or at least acceptable that a supposedly pretty high-end product (sells online in Germany for about 3000 EUR new) behaves in such a way?  I certainly understand LarsHP's disappointment; myself I'd be furious in stead of just disappointed if I paid what isn't exactly pocket change for an amp that imho is simply a flawed product?  What does this money get you, a pretty wooden box with a set of specs that makes for very limited usefulness except if you open it straight away and start swapping out/adding parts (even without this hum).  Flabbergasted by the suggestion to 'just ignore it and focus on the music'---> for a 100 EUR amp that might fly but imho 3000 EUR entitles one to more.
 
I don't intend to make a mockery out of it but to me the situation described above just seems to be way beyond reason, the fact that Leben doesn't answer a mail with questions just adds insult to injury.  I'm trying to find a redeeming quality in the setup that would make it worthwhile to accept all these limitations but for the life of me, I don't see it.  The same amount of money (give or take) could purchase you a Burson conductor + a pair of HE-6 or a Violectric V-800/V-200 dac/amp combo that's generally accepted as top quality + a HE-6 that could be driven to its full with ease.  Admittedly I'm a solid state  guy although not a rabid one but stories like this certainly don't stimulate a person to give tubes a try.

 

[RedBull]

Not try to defend the product, but if you happened to get it right, it sound is quite difficult to beat (preference apply), maybe that's why some people are still willing to place a 'bet'.