Common Noise and Operation Troubleshooting for Little Dots

Talk all about Little Dot products!

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fw_nudist
Posts: 4
Joined: Sep 11th, '11, 05:54

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by fw_nudist »

I've noticed a buzz/humming noise coming from my LD III transformer last week. After doing some investigating I tracked the issue down... The incoming electric current to my house was 129!!!! Normal range should be 120. The spike in current started shutting down my Monster Power HTS surge protector. Not sure why the current was so high, it has now dropped down to 125. Hum/buzz has died down.

Gordon
Posts: 12
Joined: Dec 17th, '11, 17:45

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by Gordon »

I have found a possible source of noise and a fairly easy fix. The design of the Little Dot amps places the power cord parallel to the audio cables. Getting these too close will/can induce AC hum in the audio cabling. Upgrading the power cord by using a design with an integral full coverage shield braid _should_ eliminate this noise source.

A better solution, at least potentially, would be to integrate a TOSlink DAC into the Little Dot amplifier and run only optical audio cable from source, putting the electronics for the Optical DAC into a heavily shielded cage within the chassis of the amplifier.

Any plans along these lines David? If not, what would you say to building a "one off" for a customer as an experimental model?

mataugust
Posts: 2
Joined: Jul 13th, '12, 22:28

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by mataugust »

I have some left side noise on an app. 2½ year old MKIV se. The noise is there no matter the volume settings, also if volume is 0.
Can it be the gain switches?
I'm 3'rd owner of the amp and the first to change gain settings (I think).

julianjwatt
Posts: 7
Joined: Aug 23rd, '10, 07:52

Little dot mk iv se static in right channel

Post by julianjwatt »

I've got a little dot mk iv se and lately it's developed a static 'crackle' and intermittent static in the right channel.
I've tried swapping the tubes and it stays in the right channel.
I've also tried flicking the gain switches. Again, no help.
It seems to be getting worse and more noticeable.

Any ideas?
I've ordered a different set of tubes, but doubt that it's the tubes given that it stays in that one channel.
I've also tried changing up the rca cables. No luck.

Could it be that I need to open it up and spray for dust?

Any help, much appreciated.

User avatar
rockage
Posts: 275
Joined: Apr 10th, '05, 06:29

Re: Little dot mk iv se static in right channel

Post by rockage »

julianjwatt wrote:I've got a little dot mk iv se and lately it's developed a static 'crackle' and intermittent static in the right channel.
I've tried swapping the tubes and it stays in the right channel.
I've also tried flicking the gain switches. Again, no help.
It seems to be getting worse and more noticeable.

Any ideas?
I've ordered a different set of tubes, but doubt that it's the tubes given that it stays in that one channel.
I've also tried changing up the rca cables. No luck.

Could it be that I need to open it up and spray for dust?

Any help, much appreciated.
Yes, give that a shot. Sounds strange but also swap out the fuse and power cord to see if that helps.

jorourke
Posts: 1
Joined: Aug 26th, '12, 11:04

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by jorourke »

My little dot DAC II little blue light has gone out when the unit is turned on. Any simple way to fix?

xocoatl
Posts: 1
Joined: Dec 2nd, '12, 17:59

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by xocoatl »

I have a Little Dot Mk III. It has a hum when it is powered with only the headphones connected. The volume control does not affect the hum. The gain is set to 3 (on on switches). The jumpers are covering pins 1 and 2. I have lifted the power cord ground and moved the amp to other locations and outlets. I have used several high quality after market power cables. I have changed the 6H6P tubes. I have tried a variety of tubes GE and Amperex 5654's, GE JAN 5654W's, and Mullard M8100's. I have cleaned the fuse, gain switches, and tube pins with Deoxit. The hum remains. After the amp is off for a while, the hum is not present after it is powered up. After several seconds the hum appears --- as if it is present after capacitors are charged up.

I need help.

Hello Hondo

I have the same symptoms with my LD MK IV - I have moved at home from plug to plug : no difference - I have rolled up my valves to NOS french RTC 5 stars : no difference - I have changed cables from my dac to the amp : no difference - I have set the switch of the amp to the impedancy of my headphones (Senn HD 800) : the hum decrease but not desappear completely.
I thinck it's a problem of components because it seems that the hum appears after little time (capacitors charging ?)
But I must say that I am a little exigent because I am used to my other system which cost 10 times the cost an silent like a grave
Perhaps the solution is in the LD mk IV SE (capacitors of hight quality) ?
Have you find a definitive solution ?
Thanks

gibosi
Posts: 2
Joined: Jan 14th, '13, 21:09

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by gibosi »

I just purchased a Little Dot 1+ from Shenzhen Audio/Amazon and received it a week ago. It has been fine until last night. When I turned it on, I heard a strong ground hum that became louder when the volume was increased. If I touch the chassis, the volume of the ground hum is reduced, but it is still very objectionable. I have exchanged tubes and power cords, but no change. I have disconnected the DAC, but no change. So the cause seems to be internal to the amp. Any suggestions as to what the cause might be and how I should proceed? Thanks!

gibosi
Posts: 2
Joined: Jan 14th, '13, 21:09

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by gibosi »

gibosi wrote:I just purchased a Little Dot 1+ from Shenzhen Audio/Amazon and received it a week ago. It has been fine until last night. When I turned it on, I heard a strong ground hum that became louder when the volume was increased. If I touch the chassis, the volume of the ground hum is reduced, but it is still very objectionable. I have exchanged tubes and power cords, but no change. I have disconnected the DAC, but no change. So the cause seems to be internal to the amp. Any suggestions as to what the cause might be and how I should proceed? Thanks!
Well, I have solved this problem. A while back, I mistakenly removed the top screws. When I realized my mistake, and replaced them, apparently the right front screw between the tube and the front panel didn't make a good connection. When the ground hum appeared, I noticed that if I pushed down on the top of the chassis, the ground hum was reduced considerably. On a hunch, I noticed that that top screw was quite loose. Further, I was unable to tighten it securely. So, I took the unit completely apart and managed to get everything tight. And now everything is back to normal. :)

Rinkydinkpanic
Posts: 2
Joined: Mar 3rd, '13, 16:54

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by Rinkydinkpanic »

Hi

Enjoying my new Mk II David, many thanks. Anyone help me with the following. There is a sort of wispy noise in my left earphone, this only appears when I'm listening to my squeezebox touch as source (via amp). The noise disappears completely when my turntable is the source. Music on SB is via laptop / external hard drive.

Any ideas kind folks?

Andy

oleoleole
Posts: 1
Joined: Apr 6th, '13, 09:31
Contact:

Re: Re:

Post by oleoleole »

DavidZheZhe wrote: ...

2. A computer throws off a lot of interference and noise, and will be picked up by your sound-card if it's not shielded/rejecting well enough or if it's a driver-related issue.  This noise will be made apparent by a resolving amplifier like our Little Dots.  If you are using an external DAC with the sound-card, try the optical connection instead of USB or Coaxial as optical is electrically isolated.  If you are using your sound-card directly to the amp, in your Volume Control (Windows) try muting everything except Master Volume and Wave. 
I had this problem, and everything was grounded as it should be, and checked and tightened everything in my computer. I could use my regular headphones without any trouble connected directly to my Asus Xonar Essence STX (with 6,3mm jack), as well as my non-grounded amp. Connecting the little dot made something else and the noise came, and as I allready had done everything listed here, I tried to use a ground loop isolator (not a $5 unit, but paid a bit more, (maybe $5 unit will just work as well)) as a final solution. And it did work.

For those who wonder, I bought an Argon Ground Loop Isolator (but I guess most would do).

martybu141@yahoo.com
Posts: 7
Joined: Mar 27th, '12, 09:00

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by martybu141@yahoo.com »

I am having an issue when I turn my little dot mkiv on it makes two loud bumps, only on the right channel. would anyone know what would cause this?

DavidZheZhe
Posts: 1718
Joined: Mar 14th, '06, 01:25

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by DavidZheZhe »

Have you tried swapping the tubes to see if the noise changes channels?

DavidZheZhe
Posts: 1718
Joined: Mar 14th, '06, 01:25

Re: Re:

Post by DavidZheZhe »

oleoleole wrote:
DavidZheZhe wrote: ...

2. A computer throws off a lot of interference and noise, and will be picked up by your sound-card if it's not shielded/rejecting well enough or if it's a driver-related issue.  This noise will be made apparent by a resolving amplifier like our Little Dots.  If you are using an external DAC with the sound-card, try the optical connection instead of USB or Coaxial as optical is electrically isolated.  If you are using your sound-card directly to the amp, in your Volume Control (Windows) try muting everything except Master Volume and Wave. 
I had this problem, and everything was grounded as it should be, and checked and tightened everything in my computer. I could use my regular headphones without any trouble connected directly to my Asus Xonar Essence STX (with 6,3mm jack), as well as my non-grounded amp. Connecting the little dot made something else and the noise came, and as I allready had done everything listed here, I tried to use a ground loop isolator (not a $5 unit, but paid a bit more, (maybe $5 unit will just work as well)) as a final solution. And it did work.

For those who wonder, I bought an Argon Ground Loop Isolator (but I guess most would do).
Very nice. Thanks for the feedback and write-up!

gabylis
Posts: 3
Joined: Apr 24th, '14, 15:28

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by gabylis »

There should be a removable fuse along with a spare. Inspect the fuse and replace if necessary....

gabylis
Posts: 3
Joined: Apr 24th, '14, 15:28

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by gabylis »

It's written for guitar tube amps, but most of the tips apply for hi-fi tube amplifiers as well...

iamleo
Posts: 1
Joined: Sep 1st, '14, 22:46

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by iamleo »

Thanks for the great information.

My LD3 is connected through a USB DAC to my laptop. I have had this noise problem for about a year now. It sounded like faint static noise. I tried swapping cables, using different DAC devices but couldn't fix the noise problem. After reading this troubleshooting document. I tried to plug the LD3 to a different AC power outlet (same power strip as my laptop) and voila, the noise is gone. The LD3 now is dead quiet. I can finally enjoy my music.

niseko
Posts: 1
Joined: Nov 25th, '14, 05:49

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by niseko »

Hi there,

Sorry if this is a newb question, but just got my Little Dot MkIII and sounds nice when the volume knob is set to zero (but I need to turn my DAC/audiocard up to get some decent volume)

If I try to turn up the volume on the Little Dot I get a hum in the left ear and the volume of the music doesn't increase at all, just the hum.
I'm listening on Senny HD 650s so quite high impedence but haven't touched the gain switches yet.

Am I doing something obviously wrong?

Thanks!

//edit the music volume actually decreases the higher I turn the volume knob on the little dot :|

User avatar
rockage
Posts: 275
Joined: Apr 10th, '05, 06:29

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by rockage »

niseko wrote:Hi there,

Sorry if this is a newb question, but just got my Little Dot MkIII and sounds nice when the volume knob is set to zero (but I need to turn my DAC/audiocard up to get some decent volume)

If I try to turn up the volume on the Little Dot I get a hum in the left ear and the volume of the music doesn't increase at all, just the hum.
I'm listening on Senny HD 650s so quite high impedence but haven't touched the gain switches yet.

Am I doing something obviously wrong?

Thanks!

//edit the music volume actually decreases the higher I turn the volume knob on the little dot :|
You should check that your inputs are connected correctly

Pifouglop
Posts: 1
Joined: Dec 27th, '14, 00:03

Re: Common Noise and Operation Troubleshooting for Little Dots

Post by Pifouglop »

hondo wrote:I have a Little Dot Mk III. It has a hum when it is powered with only the headphones connected. The volume control does not affect the hum. The gain is set to 3 (on on switches). The jumpers are covering pins 1 and 2. I have lifted the power cord ground and moved the amp to other locations and outlets. I have used several high quality after market power cables. I have changed the 6H6P tubes. I have tried a variety of tubes GE and Amperex 5654's, GE JAN 5654W's, and Mullard M8100's. I have cleaned the fuse, gain switches, and tube pins with Deoxit. The hum remains. After the amp is off for a while, the hum is not present after it is powered up. After several seconds the hum appears --- as if it is present after capacitors are charged up.
Hi,

I have the same issue than hondo some years ago with my LD Mk IV SE. The hum is more audible as the headphones impedance is low (very audible at 48 Ohms, quite audible at 300 Ohms, almost inaudible at 600 Ohms). I can't tell when the hum occured or if it was from the beginning as I used a DT880 600 Ohms and had the two other headphones lately.

Is there a way to fix it without sending the amp back ?

Thanks.

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