[hexalamb]

I bought this a while ago and never really used it. Now I'm trying it out and it has some pretty apparent distortion if you listen to it at low volume/quiet music or with nothing playing.
 
I'm hoping the problem is in the tubes and not the amp, but I don't want to buy new tubes just to find out the amp is the problem.
 
The sound is almost similar to what you would hear if you plugged headphones into a crappy onboard soundcard. Once the amp warms up there is also a very apparent buzzing in the left channel.
 
 
Assuming I can get rid of the distortion, I would like to use the Little Dot with a pair of HD650s that I'm thinking of buying. Is this amp enough to drive them? Also, I've been using a uDAC and I'm wondering if passing the signal through this is a bad idea. It's the only DAC I have, but it seems like you can't use it in straight DAC mode because the LD doesn't have S/PDIF in.
 
 
Thanks for any help you can offer on the subject.

 

[hexalamb]

bump.

 

[elwappo99]

Hey there! 
 
Seems no one has helped you out which is a bummer, let's see if I can.
 
It's hard to tell what the "distortion level" you are talking about is from. Tubes in their nature will give off some low level distortion. It's hard to tell if the amount you are hearing is in the normal realm of distortion, or if it's a higher level. Let's run a few questions.
 
1. Is it in both channels, or only one?
2. Does it get better, worse or stay the same if you put your finger on the tube (make sure it hasn't gotten too hot!)
3. Is it noticeable when you're playing music?
4. Does it happen when you have a source plugged into the back.
 
You should be able to run a RCA cable from your uDAC straight to the MKII without any issues. The MKII also definitely has enough juice for the HD650. I have read it is a good pairing, but I haven't personally tried it. 

 

[fraseyboy]

I have a Little Dot MK II and every now and then I get buzzing in one of the channels. Sometimes simply removing and replacing the tubes is enough to fix it.
 
Try swapping the left and right tubes and seeing if it moves to the other channel. That way you can isolate it to an individual vacuum tube. Maybe the contacts need cleaning or something.

 

[hexalamb]

Hi, thanks for the response and sorry for the late reply. I'm actually away from home for a while, so I don't physically have access to the little dot. This might not have been the best time to post about it. I can, however, answer some of your questions:
 
There are two different sounds, both of them only occur once the amp has warmed up some. The first is present in both channels if I remember correctly and is a bit more subtle kind of distortion. This is the one I described as the sound you might get from an onboard soundcard, although I would say this is a bit louder. I can still hear it when I have quiet music on.
 
The second sound is more of a buzzing and starts up later than the first, when the amp is even more warmed up. This one only happens in the left channel but is significantly louder than the first noise and I can hear it unless I have very loud music playing. 
 
Both sounds/types of distortion do happen when I have a source plugged into the back. I can't test the touching the tubes thing right now and never tried because I thought that was bad for them. 
 
Anyway, I hope this provides you with some more diagnostic information. Thanks for any help you can offer.

 

[hexalamb]

Oh, thanks for the ideas fraseyboy, I guess you responded right before my last post. I'll give that a try.