Common Noise and Operation Troubleshooting for Little Dots

[DavidZheZhe]

I think 95% of the questions I field are related to some kind of noise/static/buzz, so I'll try to address the common causes and solutions here: Note: The first thing to do after receiving your Little Dot is to ensure the tubes are securely in place as they can and will shift during transit.  This also goes for any switches (gain switches, etc) - please make sure they are fully in their positions.    Constant Buzzing noise, independent of volume (all models):  This is most likely a ground loop.  You can test by disconnecting everything from your Little Dot except the power cord and headphones, turning it on and listening to see if the buzzing is still there.  At times you may also need to perform this test on a different wall outlet.  All our models are grounded and use a three-pin power cord.  Grounding generally makes electronics safer and more stable, which is why all our products are implemented this way.  That being said, such electronics (ground loops are an issue common to all A/V electronics) can lead to a ground loop if your setup is incorrect, as a ground loop usually occurs when your connected components have multiple paths to ground. The simplest and best way to resolve one is to make sure all your connected components are connected to the same power outlet.  If this is not possible (ex. you have TV cable connected to your system that is grounded miles away) or your home has funky grounding, a ground loop isolator or a cheater plug (last option) will work. Static/Hissing/Noise or Intermittent Drop-outs:1. For tube models, note the channel with the noise and begin by swapping the left side driver tube with the right side driver tube.  Has the noisy channel changed?  If so, clean the tube pins of any oxidation or replace it if it's on it's way out.  If the noisy channel has not changed, do the same thing for the power tubes.  If this occurs before 3 months of purchasing your Little Dot, we can send you replacement tubes for just the cost of shipping.2.  For the Little Dot portable models with gain switches: Power off, and then spray into the gain switch with electronics cleaner (ex. Caig DeoxIT).  Now move the switch through it's positions several times.  Wait for it to dry, and then check for noise again.  When the gain switch is new and stiff, it may take a bit of care to make sure it's fully in position.
3. Sources of nearby interference (wireless routers, telephone base stations, cell phones, etc) on the side of the amp corresponding to the channel with said noise.  Try your Little Dot in a different location and/or turn off interference sources to confirm.  Solution is to experiment with positioning your Little Dot further away from the interference source, capping the extra unused RCA caps in the rear (which can pick up interference), and/or get tubes that are shielded (most military tubes are).  4.   All models with user selectable gain switches - Move the switches back and forth several times to keep them loose, and then securely set them back into position.  Switches slightly out of position can cause both noise and non-functioning channels.5. Check the state of the fuse, which is located behind the panel near the power cord socket.  Remove the power cord and pry the panel off (with fingernail or some flat tool).  There should be a removable fuse along with a spare.  Inspect the fuse and replace if necessary.6. Replace the power cord, especially if you are using the stock power cord.   Little Dot will not Power on:1. Check the state of the fuse, which is located behind the panel near the power cord socket.  Remove the power cord and pry the panel off (with fingernail or some flat tool).  There should be a removable fuse along with a spare.  Inspect the fuse and replace if necessary.2. Replace the power cord, especially if you are using the stock power cord. 
 If Using Computer/Laptop as source - Static, warbling, electrical noises and/or noises whenever you open a window, move mouse, etc:1.  I you're using a laptop, you're most likely hearing your switching power supply, which was not designed for high fidelity playback (most switching supplies throw off tons of noise and interference).  If you remove your laptop's power cord to run on battery and the noise disappears, you've confirmed it's the power brick.    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. 

[DavidZheZhe]

This is a pretty good article on trouble-shooting common tube amplifier issues. It's written for guitar tube amps, but most of the tips apply for hi-fi tube amplifiers as well:

http://acruhl.freeshell.org/mga/main/troubleshoot.html

[paulo]

Guys, a noise I had on the beginning (almost 2 years ago, but never remembered to post) :

Wi-fi Noise: If your tube LD is near a Wi-fi router, depending on the antenna position you might get a little "clicking" sound.
Just change the antenna direction/position that you will notice an end/redutcion of the clicking.


Hope it helps.

[ ]'s

paulo

[pmvaz]

Guys, a noise I had on the beginning (almost 2 years ago, but never remembered to post) :

Wi-fi Noise: If your tube LD is near a Wi-fi router, depending on the antenna position you might get a little "clicking" sound.
Just change the antenna direction/position that you will notice an end/redutcion of the clicking.


Hope it helps.

[ ]'s

paulo

Paulo, uma pergunta, és tuga? Eu tb sou Paulo

[MaXMhZ]

I received my Little Dot Q today.

It had a very annoying distortion sound on silent passages, which I initially thought was from the power supply. NOT

I finally traced it down to my DECT phone which was placed near the Q. - I moved it 3m from the Q. That solved the problem completely.

So you can add Wireless equipment like phones, WiFi routers etc as a possible source of distortion. (at least for the unshielded Little Dot Q). I guess not much can be done about it if one wants to keep the acrylic case.

[hondo]

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.

[hondo]

I would add to the above post, that I hear the hum with my Sennheiser HD 600 and Audio Technica ATH-AD700 headphones. It starts several seconds after the amp is powered up. I assume when the tubes warm up.

[DavidZheZhe]

I would add to the above post, that I hear the hum with my Sennheiser HD 600 and Audio Technica ATH-AD700 headphones. It starts several seconds after the amp is powered up. I assume when the tubes warm up.

If you've isolated your MK III from sources of interference, and tested in various locations with no other components connected yet still have the issue, I would probably recommend you send it back for diagnostics.

[hondo]

Please provide me information on how I can return the MK III.

[DavidZheZhe]

Please provide me information on how I can return the MK III.

Please email us directly at

Code: Select all

little.tube@gmail.com

[tiramisu515]

Dear all,

My Mk IV Se is so far so good, no sound interference or noise whatsoever, it is dead quiet although it is just inches away from my plasma tv and is stacked up on the dvd/cd player.

I use a spare computer power cord (3 pin) since the original one that came with the amp isn't suitable in design. Singapore adopts the UK design.

I used a multi-plug power cable extension for my two dvd/cd players, a big home theatre amp, a 42 inch plasma tv and lastly the Mk IV SE.

My wi-fi router is about 6m away.

I have tried a Mk III, Mk VIIIse and now own a Mk IVse, I can only say the David and Sword have done an excellent job in this area. The Little Dot amps are very stable, statis, buzz free and clean sounding.

regards

tiramisu515

[DavidZheZhe]

Hi,

I'm using a Little Dot MK II.

First, thanks for the great amp, I bought it back in 2007 and I use it almost everyday since. I am very happy to have chosen this one as my first amp.

However for some months I hear cracks when I change the volume, I guess the potentiometer is just oxidized and should be replaced.

I would like to know which potentiometer I should buy. I searched for the ALPS16 model as indicated in the tech specs but didn't find this model.

The most appropriate potentiometer I have found is this one:

http://www.alps.com/WebObjects/catalog. ... 20A1B.html

It has a 15mm length shaft (I guess the 16 is for this) and a 100kΩ resistance which matches the reference 100KAX2 observable on the Little Dot MK II photography.

Am I right? Do you have any advice to replace the potentiometer?

If you want more feedback, please ask.

Best regards

You probably don't need to replace the potentiometer. After some time, oxidation can build up on pots and you can just spray deoxidizing cleaner into to the pot assembly to clean it.

[ppat]

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.

Regarding Hondo's question above. I had the same issue when using Nordost cables from my main preamp to the LD MKIII. Nordost cables are not very well shielded and they produce hum in this situation and when used with other analog gear such as turntable to phonostage. As a result I use them only now from digital sources to preamp and from preamp to main amp.

I also had some hum in the LD MKIII when my phonostage wires ran near the unit. I use a Clearaudio Basic Plus phonostage and it has a separate battery pack on a long cord and moving this away from the LD MKIII also helped in my situation. The cable on the phonostage was even picking up crosstalk and transmitting this to FM radio stations, in the form of other stations overlapping and louder than the station being listened to. Moving the phonostage batter pack and cable resolved that as well.

I also noticed that I would get hum switching from source input to the next on my main preamp, but not on all devices. Only on the input for my Oppo BDP-83. Changing the RCA cable on that unit to a different cable eliminated that issue.

Currently I have no hum now on any source when listening through the LD MKIII. Took some work though and a lot of troubleshooting to eliminate some cable hum issues that were affecting a few things.

[Roggae]

i've been using my mk III for a few hours now and i've noticed a few things. one when using my iphone with an apple dock i get a clicking or diginoise sound. i do not get this noise when i use the headphone out. this does not happen when i swap out the iphone for an ipod. with the ipod in the dock it is silet as anyone could ask for and sounds great. my questions is why would the iphone make these noises solely when used in conjunction with the dock. the dock does sound much better than the headphone out. any suggestions? i'm using an audio art 1/8 to RCA. thanks

[hammer65]

I,ve been using my mk VI+ for a couple of days and there is a background noise always present. Sounds like there is some earth problem. I tried with new driver tubes 6SL7GT and some of the noise was lowered but still present. I even tried new vintage powertubes RCA6080. The noise still remains. Another bothering thing is that the amplifier gives away some strange smell when it's warm. The smell is so intense that I get headache if I keep the unit on for a longer time. I think that noise and smell problems should not appear on a modern hifi product.

[DavidZheZhe]

I,ve been using my mk VI+ for a couple of days and there is a background noise always present. Sounds like there is some earth problem. I tried with new driver tubes 6SL7GT and some of the noise was lowered but still present. I even tried new vintage powertubes RCA6080. The noise still remains. Another bothering thing is that the amplifier gives away some strange smell when it's warm. The smell is so intense that I get headache if I keep the unit on for a longer time. I think that noise and smell problems should not appear on a modern hifi product.

The smell doesn't sound right. Did you purchase your Little Dot MK VI+ new and from an authorized seller or second hand? If second-hand, did the previous owner report the same? Please contact us directly for support.

[a1234c]

My Little Dot MK III also have the noise problem. My config is: PC > USB DAC > MKIII > HP. If the HP plug into the usb dac, no noise present. So I realized that it is the ground looping problem. I cut the wire on earth inside the plug of the power cord, no more noise comming out.

[necronaut]

Hi

I have an odd situation. I own the LD MK4. When using my headphones it is nice and silent through them. However, when it is connected via pre-out to my power amp there is a buzz through the speakers. The volume of the buzz does not change and remains regardless of how long it has been powered for. Without the LD the speakers and my other amp is silent. It seems the problems is only with the Pre-out of the LD.
Any ideas?

[rockage]

Hi

I have an odd situation. I own the LD MK4. When using my headphones it is nice and silent through them. However, when it is connected via pre-out to my power amp there is a buzz through the speakers. The volume of the buzz does not change and remains regardless of how long it has been powered for. Without the LD the speakers and my other amp is silent. It seems the problems is only with the Pre-out of the LD.
Any ideas?

Sounds like you have a ground loop issue.

[necronaut]

really? I'll have to do some investigating now :-s thanks for the reply