[Clayton SF]

Quote:

Thanks Skylab, that's re-assuring. Would you advise buying a set of backup tubes at abt the same time then? (With the current popularity of NOS tubes, who knows what will be left in 10 years.)
 
Also, I'd like to return to the question of the cover. Do you think it makes much difference whether it's on or off? I don't have any experience with tubes and enclosures. Or with the Leben: perhaps its tube temps remain in a perfectly acceptable range with the cover on, so removing it would not make much of a difference to tube life. What I do know is that heat is a number one killer of electronics. And I have seen significant temperature drops when removing the cover of a passively cooled computer. Not sure if that is a meaningful analogy though.

I leave the cover of my Leben on. Just yesterday I was reaching over the amp and noticed how hot the airflow was coming from the top of the amp. Which would lead me to believe that the top cover is well-vented for good airflow to enter from the bottom of the amp to keep the tubes within proper operating temps. The bottom of the amp has an ample amount vents as well for air to enter. When I visited the Leben Showroom in San Francisco, the cover of his Leben amp was off. I actually see no harm in leaving the cover off unless you have animals or small curious children whose quisitive fingers you may want to protect. Also the lid, if remained on, will limit the amount of dust that may want to alight on the innards.
 
 

 

[dminches]

The unit cover gets pretty warm to the touch after being on for a short time.  The ventilation could be improved by keeping the cover off, but you do risk something falling inside and doing damage.  Thus, I keep it on.
 
 

 

[Skylab]

Yeah, and I would also be worried about excessive dust build-up if you just left it off all the time.

 

[IntoTheMusic2]

Understood. Perhaps I could just leave the top cover on but unscrewed to keep the dust out, and then remove it only when the unit is turned on. (Fortunately, I don't have to worry abt anything else getting in there.) This might deserve some experimentation, to compare the temperature with lid on vs lid off.
 
I'm grateful for your insights: things that I thought might be show-stoppers are starting to look like non-issues now.

 

[dminches]

The other thing you would need to know is what operating temperature the unit is designed to run in. Generally one likes to dissipate heat, but if Leben did their work correctly they may have assumed one would operate the unit with the cover on which would set the temperature.

 

[IntoTheMusic2]

Yes, I see what you mean -- the change in temperature might change the sound too.

 

[InnerSpace]

IME like Clayton said the venting is as much about the bottom holes as the top holes.  I put some stick-on felt pads on the feet that raise the amp about a half-inch off the shelf, which I feel helps the airflow a lot.
 
Tube life should be fine.  Back in the day I once saw EL84s in an amp at a TV station that had been running - twenty-four hours a day, seven days a week - for 21 years.

 

[IntoTheMusic2]

I like this idea.
 
I have a stand for my laptop that serves the same purpose: it elevates the base to improve airflow. I can attest that it works -- the fan kicks up much less frequently than when I sit the laptop on a flat surface. I'd never thought abt doing this for a piece of audio gear, but it makes sense now that you suggest it.
 
Thanks folks.

 

[IntoTheMusic2]

I've got another question... How much granularity is there for controlling the headphone volume using the CS300XS' stepped dial?

From what I've read (going from memory here...), it seems that most Leben users tend to keep the volume control down in the bottom third of the dial (or under ~10 o'clock). How many steps does it take to go from a little too soft to one step above your "normal" listening level (however you define "normal")?

I'm very sensitive to volume levels, and especially don't like loud volumes while wearing headphones. I also have high efficiency, closed-back headphones (AT W5000). This means that there is usually a very narrow range of volumes that I find acceptable for headphone listening, and if I can't adjust it to within that range, I stop listening pretty quickly. (This is a major problem with my current setup -- one step is too soft and the next step can be too loud -- which is why I'm changing it.) So I'm very interested to know how the Leben behaves in this area.

Thanks again.

 

[Clayton SF]

Quote:

I've got another question... How much granularity is there for controlling the headphone volume using the CS300XS' stepped dial?

From what I've read (going from memory here...), it seems that most Leben users tend to keep the volume control down in the bottom third of the dial (or under ~10 o'clock). How many steps does it take to go from a little too soft to one step above your "normal" listening level (however you define "normal")?

I'm very sensitive to volume levels, and especially don't like loud volumes while wearing headphones. I also have high efficiency, closed-back headphones (AT W5000). This means that there is usually a very narrow range of volumes that I find acceptable for headphone listening, and if I can't adjust it to within that range, I stop listening pretty quickly. (This is a major problem with my current setup -- one step is too soft and the next step can be too loud -- which is why I'm changing it.) So I'm very interested to know how the Leben behaves in this area.

Thanks again.

The Leben uses a Blue Velvet pot, it is not a stepped attenuator; although the volume control has detents along its volume range, you can adjust the volume level to anywhere between the detents if you wish--I do it all the time when I remember. Sometimes I forget you can do that, though.

 
 

 

[IntoTheMusic2]

A continuously variable pot will definitely help. I'm still wondering though how much turn-of-the-dial it takes to go from soft to a bit too loud. Is it several clicks, a couple of clicks, or less than one? I know there will be some variability here -- depending on phones, source, personal comfort -- but I'd like to get a general idea of what others are experiencing.
 
In my current setup it is one click or less, and the detents are not far enough apart for the in-between position to be used. So the phones end up unused most of the time.

 

[Pingvin]

Thanks for pointing me to that. I doubt that I would be able to stay for the whole meet, but I will try. Hopefully someone will let me use their source as well -- the 600 is a big heavy lump by itself

 

[googleli]

You can set your volume in between clicks with no prob.
 
Quote:

A continuously variable pot will definitely help. I'm still wondering though how much turn-of-the-dial it takes to go from soft to a bit too loud. Is it several clicks, a couple of clicks, or less than one? I know there will be some variability here -- depending on phones, source, personal comfort -- but I'd like to get a general idea of what others are experiencing.
 
In my current setup it is one click or less, and the detents are not far enough apart for the in-between position to be used. So the phones end up unused most of the time.

 

 

[IntoTheMusic2]

The conclusion I'm drawing is that, even though the volume ramps up rather quickly, it's not really an issue because you can set the volume at any point on the dial (i.e. you're not limited to just the notched positions).
 
Thanks for sharing.

 

[Jian]

 

Quote:

You can set your volume in between clicks with no prob.
 


 

 
 
I think technically that's very bad for the amp and will made the sound abnormal.
 
With high end audio equipments, the attenuator usually will use stepped or series resistance design, which out perform the "continuously variable pot" by far from every aspect, and cost much more to build. This is important for the attenuator directly connect to you monitor and limits the sq of the whole system. The higher end will offer  more steps, thus shorter intervals.
 
My best suggestion to the stepped attenuator volume issue is to just get use to it.