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post #991 of 2101

My CS300XS is completely silent, no hiss nor hum, and a very full and pleasing tone, and this is with the stock tubes.  Of course, it sounds even better when I tube roll through my stash of vintage RCA, Mullard, and Philips.  I would suggest you have the amp serviced since it most certainly sounds like there is something amiss.  Also,  I suspect the computer sound card is your tonal bottleneck in that system,
 

In fact, I have heard many superlatives to describe the Leben sound, but 'thin' is not one of them.  :)  Best of luck sorting things out.

post #992 of 2101

Quote:
Originally Posted by starfish View Post

My CS300XS is completely silent, no hiss nor hum, and a very full and pleasing tone, and this is with the stock tubes.  Of course, it sounds even better when I tube roll through my stash of vintage RCA, Mullard, and Philips.  I would suggest you have the amp serviced since it most certainly sounds like there is something amiss.  Also,  I suspect the computer sound card is your tonal bottleneck in that system,
 

In fact, I have heard many superlatives to describe the Leben sound, but 'thin' is not one of them.  :)  Best of luck sorting things out.


 

The amp was supposedly serviced about a year ago, don't really want to send it

off to service when I just got it... I'd rather return it to the seller in that case :/

 

Hehe, yeah, the sound improved with just the Compass as dac, I'm hoping a

proper one will do a lot more for it.

 

So, no chance all my problems are down to bad tubes? The seller said he had

some new ones, I guess I could try to get him to send them to me so I could try

it, but it would help my case with some input from you guys :)

 

Btw, I'm using a pair of LCD-2r2, so the volume hiss isn't because of sensitive

headphones or anything like that.

post #993 of 2101
Quote:
Originally Posted by martook View Post


 

The amp was supposedly serviced about a year ago, don't really want to send it

off to service when I just got it... I'd rather return it to the seller in that case :/

 

Hehe, yeah, the sound improved with just the Compass as dac, I'm hoping a

proper one will do a lot more for it.

 

So, no chance all my problems are down to bad tubes? The seller said he had

some new ones, I guess I could try to get him to send them to me so I could try

it, but it would help my case with some input from you guys :)

 

Btw, I'm using a pair of LCD-2r2, so the volume hiss isn't because of sensitive

headphones or anything like that.


Oh, I didn't know you purchased a used amp.  In that case, yes, replace the tubes before doing anything else, especially if you already have some spare tubes.

 

post #994 of 2101
Quote:
Originally Posted by starfish View Post


Oh, I didn't know you purchased a used amp.  In that case, yes, replace the tubes before doing anything else, especially if you already have some spare tubes.

 



make sure you get good/matched tubes though. I've got few friends owning the Lebens and they are more delicate/fragile than the average tube amp.

post #995 of 2101

Quote:
Originally Posted by starfish View Post


Oh, I didn't know you purchased a used amp.  In that case, yes, replace the tubes before doing anything else, especially if you already have some spare tubes.

 

Quote:
Originally Posted by metalgear View Post



make sure you get good/matched tubes though. I've got few friends owning the Lebens and they are more delicate/fragile than the average tube amp.


 

The previous owner will send me a set that I think is more or less new,

hopefully that will improve things. Don't really want to spend hundreds

of dollars on tubes until I know the Leben is working as it should.

 

I'll return with more information when I've received the new tubes :)

post #996 of 2101
Quote:
Originally Posted by metalgear View Post





make sure you get good/matched tubes though. I've got few friends owning the Lebens and they are more delicate/fragile than the average tube amp.



 

The Leben is not really "more delicate/fragile" than any other push/pull, cathode biased amp. In fact, the p2p construction and circuit design is anything but delicate or fragile, unless we're talking about dropping a glass filled amp off a building, well that's another story.  :)

 

Where people run into problems with cathode biased amps is when they interpret "self biasing" to mean any old 4 tubes are good enough because the amp biases itself.  Well, that's not really the whole story.  In a cathode biased amp, the more current flowing, then the greater the bias voltage, which reduces the current in turn, thus self biasing for small variations.  A slightly hot running tube will bias itself slightly cooler.  This means if you're running a quad of tubes of the same type you don't need to rebias so long as they are relatively close in measurement.  Cathode bias does not handle wide variations, different tube types, and out of spec tubes.  For these conditions, the amp can be rebiased by changing the resistors.  But why bother?  A cathode bias amp makes it easy for you so long as you follow some common sense parameters - Just be sure to use at least matched pairs, with the pairs in relatively close tolerance to each other.  It's always best to get a matched quad if available, especially if using new production tubes where quad matching is almost always available.  


Edited by starfish - 11/26/11 at 10:41am
post #997 of 2101
Quote:
Originally Posted by martook View Post


 

The previous owner will send me a set that I think is more or less new,

hopefully that will improve things. Don't really want to spend hundreds

of dollars on tubes until I know the Leben is working as it should.

 

I'll return with more information when I've received the new tubes :)


If the amp was shipped or transported a distance to you, you might check that the tubes are all properly seated and functioning.  It is very common for tubes to become partially unseated during shipping if the tubes were left in the sockets.  Typically removing and reseating the tubes will also clean off the pins a bit too.  But if you have some electrical contact cleaner like Deoxit you could remove the tubes and apply a little to the pins and push them back in.  The above recommendation is just a quick check you can do while waiting for new tubes.

 

I would not implicitly trust the seller who may have given you a faulty amp, or at least worn out tubes, to provide known working replacements.  If you're not willing to buy a new set of tubes from a reputable dealer, then try taking both quads to a service technician who can test the tubes for you.  Most guitar amp repair technicians have an industrial tube tester.  This only takes a few minutes to test and rule out a worn or faulty tube.  I personally use a calibrated and maintained military surplus Hickok TV-7 retired from the U.S. Navy.

post #998 of 2101

It does sound thin with all Telefunken tubes for both stages, at least in my experience, probably because the Leben is already a neutral sounding amp.  Works great with Amperex / Mullards/ Sylvannia IMO.

 

Quote:
Originally Posted by starfish View Post

My CS300XS is completely silent, no hiss nor hum, and a very full and pleasing tone, and this is with the stock tubes.  Of course, it sounds even better when I tube roll through my stash of vintage RCA, Mullard, and Philips.  I would suggest you have the amp serviced since it most certainly sounds like there is something amiss.  Also,  I suspect the computer sound card is your tonal bottleneck in that system,
 

In fact, I have heard many superlatives to describe the Leben sound, but 'thin' is not one of them.  :)  Best of luck sorting things out.



 

post #999 of 2101

Tend to agree with the above statement. Getting very good results with Amperex bugle boy driver tubes and Baldwin/Sylvania black plate output tubes. The sound is punchy, authorative and very engaging, quite a bit better than the standard compliment of tubes the amp came with ( CS300XS ).

Must admit though, I too can hear a low level hum but it doesn't detract from the listening experience. Might try swapping the Sovteks back in to see if it's a tube derived hum.

post #1000 of 2101
Quote:
Originally Posted by googleli View Post

It does sound thin with all Telefunken tubes for both stages, at least in my experience, probably because the Leben is already a neutral sounding amp.  Works great with Amperex / Mullards/ Sylvannia IMO.

 



 


This hasn't been my experience at all using TFs.  I have a pretty good assortment too having used them with various guitar amps.  TFs sound neutral to me, not thin.  They don't have the mid bump of something like "B" code Mullards.

 

Plenty of detail, not recessed in any way.  I just don't describe them as thin in any application.  Of course, the point of trying different tubes is finding a type that matches your particular preferences, and most tubes do have a sonic signature.  Claiming the Leben CS300XS is "thin" (I'm not saying you originally made this claim), is really contrary to every reputable review of the amp and just about all forum feedback around the web.   I'm trying to understand if the point of your post was just to imply TFs are not your preference and sound "thin" to you, then that is a worthy opinion.  But if the implication is to say that the Leben CS300XS is a "thin" amp just because you don't like TFs in it, then that is somewhat colored and unrealistic, IMO.  


Edited by starfish - 11/27/11 at 2:20pm
post #1001 of 2101

Sorry, just to clarify, I wasn't agreeing the Leben sounded thin, but that it sounds better to my ears with Amperex and Sylvania tubes rolled in.

post #1002 of 2101
Quote:
Originally Posted by alvin sawdust View Post

Sorry, just to clarify, I wasn't agreeing the Leben sounded thin, but that it sounds better to my ears with Amperex and Sylvania tubes rolled in.



Indeed it does.  And I think the point is right on that the Leben, in itself, is pretty neutral, and so if you roll in bright sounding tubes like Telefunkens, the Leben can indeed sound bright.

post #1003 of 2101

I primarily use my Leben CS300xs with headphones, but this weekend I wanted to do a comparison with speakers.

 

I tried using the same speakers on my Leben and my Onkyo home theater receiver.

 

It is just amazing how much better the Leben sounds, I guess there is a reason why people pay $2,500 dollars for a Leben.

 

BTW, my Onkyo is pretty decent and sounds good enough for watching TV, but for music, the Leben sounds so much better.

 

 

post #1004 of 2101
Quote:
Originally Posted by Skylab View Post


And I think the point is right on that the Leben, in itself, is pretty neutral, and so if you roll in bright sounding tubes like Telefunkens, the Leben can indeed sound bright.


Neutral in itself, yes, but IMO also much more transparent to tube changes than almost any push-pull amp I have had.  For instance, TF drivers and TF power tubes are a too-bright combination in practically any amp, IMO, but TF drivers and Siemens power tubes in the Leben dial it back just right - which is a distinction I haven't heard with such precision elsewhere.  Usually TF and Siemens EL84s sound very close to each other, IMO - but not in the Leben.  I don't know how it is achieved, but I like it.

post #1005 of 2101


I primarily use the Leban with my HD800s. But I set up some Proac Tablettes in near field. Sweeeeeeeet!

Quote:
Originally Posted by arnesto View Post

I primarily use my Leben CS300xs with headphones, but this weekend I wanted to do a comparison with speakers.

 

I tried using the same speakers on my Leben and my Onkyo home theater receiver.

 

It is just amazing how much better the Leben sounds, I guess there is a reason why people pay $2,500 dollars for a Leben.

 

BTW, my Onkyo is pretty decent and sounds good enough for watching TV, but for music, the Leben sounds so much better.

 

 



 

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