[gzone3lement]

Quote:

Thanks for the suggestions. Regarding the buzzing, I'm not too concerned since I've heard several other Leben owners report buzz with various sensitive headphones. I'm sure Skylab and others are right about it being a tube issue. I'll make trying a different set of tubes a priority. If there's still buzzing with a different quad of tubes, then I'll get in touch with whoever handles the warranty.
 
Today I experienced a truly amazing setup: the Leben CS-300X paired with the Ultrasone Edition 10. Sweet, sweet euphony. There was no buzz with the Edition 10, but I'll try the Edition 8 as well.
 

Wow, it's like they both are made for each other!

 

[Jian]

I play street fighter 4

 

[illkemist]

I hope maybe someone can give me some guidance.
 
I bought a CS-300 from a fellow forum member in 2009. Everything seemed to be fine for a while and then I started having problems with the volume fading in and out of the right channel. There was also static in the channel as well. I wanted to have the unit inspected for problems, but I couldn't find any authorized repair shops in Taiwan. People were suggesting that the voltage regulator might have been to blame. But after consulting Leben, it was decided that Taiwan's power standards (110V) were within the tolerable range.
 
I sorta forgot about it for a while since I had another amp and was busy with work. After a few months, I pulled it out of the closet, determined to fix the problem. So, I ordered new tubes, installed them and had the same problems. Somehow, after emailing Leben about the problem, the unit started to perform regularly. The fading was gone. The static, nonexistent. Great! Once I told them that the problem no longer existed, we concluded our correspondence. Then, it started up again. I emailed them but received no further responses. Not exactly sure why. Perhaps the person I had been talking to left the company.
 
I became too busy to care for a while and only pulled it out again last month after the arrival of my LCD-2s. Only this time, the static was still there, occurring sporadically, but noticeably. Only, after a couple of days, I decided to adjust the volume (I normally keep it about 12:00, because I am feeding it from my Grace m902, which controls the levels). Now, the unit functions well. Actually, it sounds great with the new headphones (no, FANTASTIC). Now, if I hear static or have volume problems, I just make a slight adjustment to the volume up or down, and the problem goes away.
 
Has anyone ever had any similar problems? What should I do about this?
 
I live in Taiwan and the amp is originally from Japan. Shipping there and diagnosing it could be expensive and uneccesary. I've been offered help by a friend's father, who happens to own a high-end audio store. Only, I don't want to hand him a machine which has a problem that is sporadic and cannot be replicated.
 
Any suggestions?

 

[mrarroyo]

Long time no see! Hope you are doing great and judging by the equipment you are indeed doing fine. Have  you looked at the tube sockets? It may be something as simple as a loose or dirty pin holder in the sockets for the right channel, if so just clean/retighten them. Good luck.

 

[illkemist]

Quote:

Long time no see! Hope you are doing great and judging by the equipment you are indeed doing fine. Have  you looked at the tube sockets? It may be something as simple as a loose or dirty pin holder in the sockets for the right channel, if so just clean/retighten them. Good luck.

Thanks, Miguel. Things are going well here. Unfortunately, I haven't been spending as much time on the forum, but I have been lurking quite a bit. It's great to live abroad, but I sorta miss home too. I went back to Florida in December to visit my family, but for now, Taiwan is my home. I wouldn't mind making it to a meet, though. Good times.
 
Now, when you say clean them, how do you do it? Is it as simple as using a bit of air to remove dust and debris, or is there more to it? I have a Giottos rocket that I use for cleaning my photographic equipment. Can I use something like that, or do I need to get down and dirty?

 

[dminches]

From 30,000 feet it sounds like the attenuator (volume control) could be dirty.  Do you hear any crackling noises when you turn it?

 

[Skylab]

I occasionally spray a little electronic contact cleaner in my tube sockets - the kind that comes in the high velocity spray can.  In the US you can get it at any hardware store.

 

[illkemist]

Quote:

From 30,000 feet it sounds like the attenuator (volume control) could be dirty.  Do you hear any crackling noises when you turn it?

Actually, I do. But I don't hear it every time I adjust it. More accurately, I only hear it occasionally and it's not in the same position each time.

 

[Rufus1974]

Thanks for the advice.  I have pulled out the Gold Lions and put the stock tubes in and also replaced the RCA 5751s with another set I had.  The sound is a lot clearer now, albeit with less bass response which may be due to the tubes being brand-new.  All in all, the amp sounds so much better now with no noticeable distortion.  Due to the HE6s being so finicky as far as their cable connectors are concerned (the left connector keeps coming off and Warren Audio's after-market cable puts a lot of extra weight on these sensitive connectors), I will probably go for the LCD-2 depending on how well they harmonize with the Leben.  Time will tell.  Thanks again for your help.

 

[mrarroyo]

Yes Fred it is simple to clean I would have a clean and lint free rag to catch any overspray. Also you can clean the tube pins using a brush and electronic cleaner. Good luck.

 

[mikecole]

I agree with dminches. illkemist, you might try turning the unit off and turning the volume knob back and forth rapidly a dozen times to see if it cleans the contacts off. I have had to do this with vintage equipment, but I would not think a newer unit like the Leben would develop this sort of problem. Then again, I am no electronics expert
 
Mike

 

[illkemist]

Thanks for all the responses. Fortunately, the unit works just fine if I adjust the volume pot. If I hear some kind of static, I just step up or down and it's gone. I'll try the suggestions you've all given me. Thanks for the help.

 

[mourip]

My (new to me) Leben has the same crackling issue. It is intermittently in one channel even after replacing the input tubes. It is not affected by changing the volume or rocking the tubes but can be influenced by touching the chassis. Someone mentioned that it might be induced noise via the headphone jack. It is quite pronounced when using my HD650's but not really noticable when running my K1000's off the speaker taps. I am thinking that it is my high impedance 300ohm 650's although using a 4:1 impedancer does not help. What did help was placing a sheet of mu-metal shielding under the amp which is on a shelf above my DAC. Perhaps the HP output is picking up something from the DAC.
 
On another note. I open up the Leben to check the solder joints on the input tube of the affected channel and noticed that the power transformer has two terminals: one labeled 100v and the other labeled 110v. I am wondering if the 110v is what they use for the US model and of course the 100v is for Japan as my unit is wired for. I am wondering if wiring it to the 110v would be close enough for using here in the US without the external stepdown transformer. I am not so worried about the B+ voltage being high as for running the filaments a bit over spec. Anyone with a US model looked under the hood yet?
 
Enguring minds want to know

 

[Anders]

Quote:

What did help was placing a sheet of mu-metal shielding under the amp which is on a shelf above my DAC. Perhaps the HP output is picking up something from the DAC.
 
On another note. I open up the Leben to check the solder joints on the input tube of the affected channel and noticed that the power transformer has two terminals: one labeled 100v and the other labeled 110v. I am wondering if the 110v is what they use for the US model and of course the 100v is for Japan as my unit is wired for.

It is also possible that the DAC picked up radiation from the headphone amplifier, DACs work with small voltages and can be very sensitive. The shielding of the DAC is not always as good as it should be.
 
It seems that you have found a possibility to rewire the Leben from 100 to 110 V. Many transformers have output taps for dual voltages, but answers from the DIY-experts are more reliable, maybe ask in the DIY forum. Very interesting indeed!

 

[mourip]

Unfortunately my mains voltage runs about 124v so it still may be a stretch from 110v. I might wire it up with some "beater" tubes and check with my meter...