• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Little Dot MK2 (Noise) please help (Audio files are provided)

bikingbuddha

bikingbuddha

Well-Known Member
Hi everybody, I hope everyone is doing good. I have been trying to live with this noise that is coming from my little dot mk 2 for last 1 1/2 years until I realized it is not its nature, something is wrong with it.

What I Tried

* Changing tubes / Capping unused ports / New cables / New source / Ground loop stuff / Almost everything.

It is very audible in all my IEM's and not audible in GAIN 1 on HD6XX, very mildly audible in the silence 75% pass the volume port at GAIN2, Half past GAIN 3, and audible all over past 10% on GAIN4 (highest).

I initially thought this is something wrong with my IEM's being super sensitive but even though I can't hear it, its in my HD6XX in all possible settings too.

I managed to record two audio files of the noise and I really appreciate your professional advice on what it is. If its the nature of the Little dot MK2, Then it can't be helped. But if its something wrong with it, I can always get it fixed.

So far I felt that it is coming from the Gain Stage of the amplifier.

Amplified audio file https://voca.ro/nzwrqmzR05l
Unamplified audio file https://voca.ro/f3dJACghizH
 
Register to hide this ad
I almost forgot to mention that the recorded audio file is at full volume GAIN STAGE 3 of the amplifier. If i go to stage 4, it will be louder.
 
Hi buddha; great to be able to talk directly to the buddha :). I can't hear your audio files on my laptop, so it would also be helpful if you could describe the noise. Have you compared it with any other tube headphone amp? I ask this because I really did not get on with my Little Dot Mk 1. The tubes were really microphonic and I didn't like the sound. But I'm not a headphones guy and have no experience of the Mk 2. Using headphones with other vintage tube amps, I find that there is some residual hum in all of them. My guess is the noise is normal at higher gain levels.

I hope other LD Mk 2 users can chime in and help you.
 
Dandy said:
Hi buddha; great to be able to talk directly to the buddha :). I can't hear your audio files on my laptop, so it would also be helpful if you could describe the noise. Have you compared it with any other tube headphone amp? I ask this because I really did not get on with my Little Dot Mk 1. The tubes were really microphonic and I didn't like the sound. But I'm not a headphones guy and have no experience of the Mk 2. Using headphones with other vintage tube amps, I find that there is some residual hum in all of them. My guess is the noise is normal at higher gain levels.

I hope other LD Mk 2 users can chime in and help you.
Click to expand...

Thank you so much for the reply. I have those two files zipped. I can send it you directly.
 
Dandy said:
Hi buddha; great to be able to talk directly to the buddha :). I can't hear your audio files on my laptop, so it would also be helpful if you could describe the noise. Have you compared it with any other tube headphone amp? I ask this because I really did not get on with my Little Dot Mk 1. The tubes were really microphonic and I didn't like the sound. But I'm not a headphones guy and have no experience of the Mk 2. Using headphones with other vintage tube amps, I find that there is some residual hum in all of them. My guess is the noise is normal at higher gain levels.

I hope other LD Mk 2 users can chime in and help you.
Click to expand...
It is more than a hum, like a tiny motored vibration.
 
They sound pretty much like I remember my LD Mk1 sounding. I don't think there is anything faulty, but I would be interested if others can identify a fault.
 
bikingbuddha said:
Hi everybody, I hope everyone is doing good. I have been trying to live with this noise that is coming from my little dot mk 2 for last 1 1/2 years until I realized it is not its nature, something is wrong with it.

Amplified audio file https://voca.ro/nzwrqmzR05l
Click to expand...

This sounds like you are picking up some EMF or AC line noise? At volume, I can hear pitch changes in the noise (around 0:10 mark). Like something digital, doing work. Does your pre-amp have a switching power supply?

You have anything digital plugged into the same AC outlet or multi-outlet? Laptops? Wall-warts?

Would you happen to own an isolation transformer? One that can handle the load of your unit? Hopefully, drop the AC line noise down? A quality Variac can act as a temporary isolation transformer, if settings are 1:1 voltage-wise.

Good luck!
 
Mr Boochie said:
This sounds like you are picking up some EMF or AC line noise? At volume, I can hear pitch changes in the noise (around 0:10 mark). Like something digital, doing work. Does your pre-amp have a switching power supply?

You have anything digital plugged into the same AC outlet or multi-outlet? Laptops? Wall-warts?

Would you happen to own an isolation transformer? One that can handle the load of your unit? Hopefully, drop the AC line noise down? A quality Variac can act as a temporary isolation transformer, if settings are 1:1 voltage-wise.

Good luck!
Click to expand...
I plugged it with nothing connected to the amp. I tried separate power outlets. Nothing worked so last thing left to do was take it to neighbors house and see.
 
I could hear the noise you are referencing in your first sample. Does it seem to be coming primarily from the left channel? That's how it came across on my speaker system.

And I agree that it seems to be coming from some sort of external interference. The kind of sound that one gets from fluorescent lighting?

I'm currently having a hum issue with my Dynaco preamp, but it's the notorious 60 cycle hum. The noise I hear on your first file, though, seems to be a higher frequency. Maybe an upper harmonic of 60 cycles?

I'm just guessing, so I'm sorry to have been of no help to you. I guess if I'm able to contribute anything at all, it's only to confirm that you definitely have the noise. And it shouldn't be there.

Please keep us updated on what you find.

GeeDeeEmm
 
Looking at pictures of this amp with the chassis opened up it doesn't look like it has a switching power supply unless it's stuffed into that top cover with the output transformers. I wouldn't think a switcher would be under that cover with the output tranys though. I get a faint hum out of the tube headphone amp I have, but that's at max volume. The one i have uses a switcher, but its inside it's own shielded housing.
 
Mr Boochie said:
One other thing to try... cleaning & treating the socket and tube pins. I like Deoxit G100L on new parts. Work the stuff in, by removing and inserting the tubes several times.

You'd be surprised at how many of these noise issues are contact related. Even, in new equipment.

https://www.amazon.com/G100L-2C/dp/...xit+G100L&qid=1589986640&s=electronics&sr=1-2
Click to expand...
I know this could be a super stupid question...! will WD40 work? I mean not sprayed directly... just use it to clean the pins?
 
gdmoore28 said:
I could hear the noise you are referencing in your first sample. Does it seem to be coming primarily from the left channel? That's how it came across on my speaker system.

And I agree that it seems to be coming from some sort of external interference. The kind of sound that one gets from fluorescent lighting?

I'm currently having a hum issue with my Dynaco preamp, but it's the notorious 60 cycle hum. The noise I hear on your first file, though, seems to be a higher frequency. Maybe an upper harmonic of 60 cycles?

I'm just guessing, so I'm sorry to have been of no help to you. I guess if I'm able to contribute anything at all, it's only to confirm that you definitely have the noise. And it shouldn't be there.

Please keep us updated on what you find.

GeeDeeEmm
Click to expand...

Thank you so much for information. I am still trying to figure out what it is because I Spoke to MKII owners online and they don't have it. So it definitely has to be my amplifier... probably our local electricity is not clean enough? I don't know anyone who owns a Little Dot MKII locally...! Yep! I live in a wasteland for audio equipment.
 
Lavane said:
Looking at pictures of this amp with the chassis opened up it doesn't look like it has a switching power supply unless it's stuffed into that top cover with the output transformers. I wouldn't think a switcher would be under that cover with the output tranys though. I get a faint hum out of the tube headphone amp I have, but that's at max volume. The one i have uses a switcher, but its inside it's own shielded housing.
Click to expand...
IF you don't mind me asking...! what is a switcher?
 
bikingbuddha said:
I plugged it with nothing connected to the amp. I tried separate power outlets. Nothing worked so last thing left to do was take it to neighbors house and see.
Click to expand...
You should have shorting plugs connected to the input, if your normal inputs are disconnected. Did you try it at your neighbour's house?

I agree with those who suspect mains interference. I hunted for a soft slow oscillation noise in a tube amp with excellent B+ smoothing for ages, only to find that it went away when I switched off the TP Link extender plugged into a nearby mains socket.
 
Dandy said:
You should have shorting plugs connected to the input, if your normal inputs are disconnected. Did you try it at your neighbour's house?

I agree with those who suspect mains interference. I hunted for a soft slow oscillation noise in a tube amp with excellent B+ smoothing for ages, only to find that it went away when I switched off the TP Link extender plugged into a nearby mains socket.
Click to expand...

So far no luck, I still couldn't check it at my Neighbors place. However I managed to check it connected to our main power meter. Still the noise is there at full volume Gain 3 on HD6XX and beyond 25% Gain 3 on Monk Plus. The strangest part is this noise goes up and down with the volume controller. Could it be something wrong with the volume pot?
 
From a hand full of reviews I read, there was only a minimal amount of hum at high volume. Does it make noise with nothing plugged into it but headphones, and with everything you had plugged into it turned off and disconnected? Did you try setting the dip switches inside to better match your headphone impedance?
 
You must log in or register to reply here.
Back
Top Bottom