LD MK III scratch noise

[Pagail118]

Hi,

I recently bought a Little Dot MK III and I sometimes hear a small scratching noise ( like when you are in seeking a radio channel ) on the right side. It is intermittent and sometimes it's pure silence. I can only hear it when the music is less loud or there is a silent passage. If i disconnect the source it is still there, so it's not the problem. I can hear the sound even if the volume is at 0.

Is it because of a bad tube ? If so, is it the big ones or the little ones ? Does it need more burn-in ?

I try to find when it does this, but it seems really random. I let my amp on for about 30 min before starting listening to it.

 

[Tridacnid]

Does it do this when you touch the volume knob? Could be a bit of dirt in the pot. Or maybe a little radio interference. What tubes are you using? Do you have a wireless LAN connection in your home?

 

[SemiAudiophile]

i think it's the tube. i had a similar experience with a set of my amperex's. try switch the tubes (front driver ones) around from the right to the left and see if you hear it on the left side. that will confirm if it is.

 

[Pagail118]

I have a wireless network at home. It does not change when I put turn the dial.

I will try to switch the tubes tomorrow, to see if there is any changes. I think that might be it. Does that mean I would need to order another set of tubes ?

btw, I am on stock tubes

 

[SemiAudiophile]

who did you buy it from? if you bought it from little dot directly, i would try contacting david zhe zhe and ask if he could send another pair of stocks.

 

[Pagail118]

Yeah I bought it directly from David. I will try to contact him if it really is the problem.

Another thought, could it be because of the D2000 low impedance ? It really is intermittent so that would be weird, but I wonder.

 

[Tridacnid]

No, the Denons wouldn't cause that. It sounds like it may be a tube. Make sure the amp is off when you switch the tubes.

 

[Pagail118]

OK here is what I did.

I power the amp, with my hp connected and put them on. I hear nothing, until the drivers start to glow. I clearly hear it on the right channel.

I shut it down and invert the tubes. Do the same process and clearly hear the same thing in the other channel.

With the power tubes, it does not changes anything.

I will email David to see what he has to say.

 

[Tridacnid]

Yep, bad driver tube. eBay is also a good place for cheap tubes. Search 6AK5 or 5654 and you'll get a bajillion good options.

 

[Pagail118]

I have email David and he said to try cleaning the tubes pin. I will try to find the product he as suggested. For new tubes, are these a good deal ? I would like to stay under 20$.Link

 

[SemiAudiophile]

cleaning the tubes pins does help. i actually went and cleaned my amperex's using sandpaper to get all that black gunk out and then used dexoit on them to finish them off. i popped them back in and now i can barely hear the static anymore. it's way more faint now. i think i just need to clean them a little bit more.

 

[Pagail118]

What type of sandpaper did you use ? He suggested deoxidizing cleanser, but I don't have any of this. I will try to see if that changes something.

Btw anyone can comment on the ebay link ?

 

[SemiAudiophile]

i think i used 180 grit, not sure. just cut a small piece and wrap it around the pins like you are flossing. you should be able to find deoxit in a local electronics store. i got mine from radioshack.

those mullards 8100 aren't bad. i haven't tried them. there's actually a tube rolling thread for the LD MKIII that you should check out that has lots of information here:

http://www.head-fi.org/forums/f5/lit...olling-276757/

 

[dukja]

Quote:

Originally Posted by Pagail118 /img/forum/go_quote.gif I have email David and he said to try cleaning the tubes pin. I will try to find the product he as suggested. For new tubes, are these a good deal ? I would like to stay under 20$.Link

Recently, there are many good sources at ebay have just been discussed in this thread:
http://www.head-fi.org/forums/f5/lit...olling-276757/
(OK, SemiAudiophile beats me. I just saw it)

I have quite good experience getting tube at ebay (up to now). The old power and drive tube came with it totally ruined my LD MKIII. It became a completely new amp after new tubes.

Good luck!

 

[Pagail118]

I think I will either get 8100 or the 8083 from Mullard ( saw your signature and search about it, seems good ! ) How much did you pay for those 8083 ?