[Ttvetjanu]

I've recently noticed a significant decrease in sound quality for my Little Dot MKIII headphone amplifier. It seems as if the amplifier is unable to drive my headphones (HD650) properly. It is especially noticeable in the lower end of the sound. This change in sound can have been gradual, I only recently started paying attention to this, as my friend who has a similar setup claimed that mine sounded much worse.

Well, when I came to his place I noticed this quite clearly, especially in the lower end. It was a night-and-day difference, and the only difference in our setups was that his soundcard is internal and mine is external. I've now tried plugging my headphone directly to my soundcard (E-MU 0404 USB) and the sound is better driven than through my Little Dot amplifier (yet still not what I remember it being a while back). His setup is also a tad newer (I've bought all my gear, except the little dot, used).

Since I noticed this I have changed tubes (the frontal ones, can it also be the backer ones?), to eliminate the possibility of the tubes being used up. The next thing I have now started considering is if the power cable to my amplifier is working properly, i.e. if the amplifier is getting enough power. Is it possible that daisy chaining can cause that the amplifier is not getting enough power? (I did not think this was possible)

Thanks a lot for your time. I hope someone here has a solution, as a poor student I cannot afford buying a new amp in quite some time.

 

[Bowedtoothdoc]

Sounds like your power tubes ( Back Tubes ) may be going. How many hours are on them?

 

[Ttvetjanu]

Quote:

Originally Posted by Bowedtoothdoc /img/forum/go_quote.gif Sounds like your power tubes ( Back Tubes ) may be going. How many hours are on them?

100's, if not 1000, been using quite active for almost 2 years.

 

[Trapper32]

Sounds like your power (back) tubes are on the way out.....

 

[Frank I]

Change the tubes and see if you hear a difference. If you used them for 1000 hrs should not be going yet but remember these are NOS so unless you have a tube tester no way of knowing how strong or weak they are. Also remember these are Class A amps so they run much hotter which could lead to shortened tube life.

 

[Palpatine]

Yup...check the powertubes. Be careful when you replace them.

 

[Ttvetjanu]

Yeah, sent an email to Little dot, they said the same. Too bad the tubes seem to be rather hard to find, at least here in Finland, and my payment options are rather limited since Paypal and credit cards are not an option.



Quote:

Originally Posted by Palpatine /img/forum/go_quote.gif Be careful when you replace them.

With what?

 

[Oskari]

http://www.vacuum-tube-shop.com/ in Espoo has Russian 6N6Ps.

 

[Bowedtoothdoc]

You may also want to check your gain switches. For the HD650 they should all be set to off for 10X gain. When you are running on the 10X setting the life of the power tubes is shortened.

 

[Ttvetjanu]

Quote:

Originally Posted by Bowedtoothdoc /img/forum/go_quote.gif You may also want to check your gain switches. For the HD650 they should all be set to off for 10X gain. When you are running on the 10X setting the life of the power tubes is shortened.

It should be on the 10x setting. Little Dot said that the expected life of the power tubes is approximately 2 years, which has almost gone by.

Quote:

Originally Posted by Oskari /img/forum/go_quote.gif Vacuum-Tube-Shop in Espoo has Russian 6N6Ps.

Kiitos/Thanks! Will check it out tomorrow.