[TheBIGKill1998]

Hello fellow Head-fiers!

I recently got a used little dot 1+ ver. 3.0 from ebay.
Voshkods tubes were included (of course i use em).

Everything is fine and im very happy with its sound, but there is one problem now...

there is a very audible buzzing in the background. It is extremely audible as soon as the music is quiter or if videos i watch have silent parts.

As an Info, im using my little dot with my beyerdynamics dt 770 80 Ohms.

Some things i already tried:
- using a different opamp instead of the stock one (did not help, now i have the lm4562 installed)
- setting the gain lower (by setting jumpers J3 and J4): this helped a bit by making the buzzing quiter, but it is still very audible


Some stuff i observed:
- it buzzes even without an input device plugged in (so its not the fault of my interface or of any other external devices)
- If i use an in line volume control and set the resistance of it to high whilst increasing the volume of the amp, the buzzing vanishes at a certain point. but this technique decreases the audio quality by quite a lot (i dont know whether this is due to the increased resistance or the extreme cheap quality of the volume control unit i used).
- As far as i can tell, its not a 50/60 Hz hum
- using my little speakers (unfortunately i dont know their impedance) with my little dot, there is no audible buzz



Now my questions:

How could i get rid of all this buzzing?

Would a sort of "Headphone attenuator" used directly at the headphone out of the amp help?

In some forums i read that the voshkods are a source of buzzing, is it possible that its their fault?


Thanks for your help, guys!

 

[TheBIGKill1998]

*BUMP*

 

[Geezer Rock 001]

I have used a Little Dot Mk II and a 1+ and never experienced what you are describing. i also used two different cheap in line volume controls. It sounds like you have eliminated most of the possible conflicts.

Have you tried a different set of headphones or a different connector to plug the phones into the amp?

 

[TheBIGKill1998]

I have used a Little Dot Mk II and a 1+ and never experienced what you are describing. i also used two different cheap in line volume controls. It sounds like you have eliminated most of the possible conflicts.

Have you tried a different set of headphones or a different connector to plug the phones into the amp?

Yes, i have tried a different set of headphones (low imp ones) aswell as different connectors. And the problem persisted. Currently i am using a higher quality in line volume control with which i eliminated my problem. But i still feel uncomfortable cause something could be wrong with my LD1+. Anyhow, new tubes are on the way (actual Voshkods), since i realised that the tubes it came with werent the notorious Voshkods, but another version of them.

 

[TheBIGKill1998]

So i could filter the source of the problem to be a ground issue. even with nothing else plugged in but the headphones, the buzzing is still there. even with no tubes in it, the buzzing persists. So it looks like something concerning grounding must be wrong inside the amp.
Another evicdence for that is, that electrical noise coming from my PC (e.g. a "scanning" noise as well as coil whining) seems to flood into my amp through the ground connection of the input cinch wires.

But i simply dont know how to fix it.

Anyone has any suggestions?

I can use my amp by using an external volume control, which seems to eliminate the noise. but i simply would like to use my amp without it.

 

[Chessblitzer2017]

youve been messing with this thing for 2 months? whatd it cost ya, 100 bucks used? just trash it nd get smth else. theres an smsl m3 dac/amp going for 70 on massdrop. I have had an smsl idea portable dac/amp for months now for 80 and never had 1 issue, its statistically better then the dragonfly red which costs 200. Z review

 

[TheBIGKill1998]

youve been messing with this thing for 2 months? whatd it cost ya, 100 bucks used? just trash it nd get smth else. theres an smsl m3 dac/amp going for 70 on massdrop. I have had an smsl idea portable dac/amp for months now for 80 and never had 1 issue, its statistically better then the dragonfly red which costs 200. Z review

Well, i have been using it for the last 2 months. but lately i felt like really getting rid of this issue once and for all. I really am not a big fan of this whole consumerism like trashin stuff and getting new stuff only cause it works sub optimal, instead of fixing it. Additional i already have a neat audio interface, so it would be kinda overkill to get another seperate dac.

But thank you anyways for this recommendation.

 

[dwinnert]

I have a Furman power strips/conditioner, it's on my main living room audio system that would get an ocassional ground buzz. I am in an old house with sketchy wiring from the 1920's. My PC, DAC and Amp are behind a UPS that conditions the line. Other than that, you might have a bad cap. The LD's are not known for their stellar build.

 

[TheBIGKill1998]

soo, i finally got to fix this problem.

i followed a hint from a comment on amazon, regarding the heater filament wiring of the tubes.

then i desoldered the wires on one of the tubes, twisted them nicely around eachother and resoldered them.
this helped a bit, but the humming was still quite audible.

i kept on researching the topic of correct heater filament wiring between tubes, and found out about the so called "artificial center tap".

this "artificial center tap" is built by soldering one 100Ohms resistor to each of the wires. those resistors have to be connected to ground later on.

i did exactly that. After i was done the humming was almost non audible. i hope this can help others who have the same issue.

 

[nofacemonster]

soo, i finally got to fix this problem.

i followed a hint from a comment on amazon, regarding the heater filament wiring of the tubes.

then i desoldered the wires on one of the tubes, twisted them nicely around eachother and resoldered them.
this helped a bit, but the humming was still quite audible.

i kept on researching the topic of correct heater filament wiring between tubes, and found out about the so called "artificial center tap".

this "artificial center tap" is built by soldering one 100Ohms resistor to each of the wires. those resistors have to be connected to ground later on.

i did exactly that. After i was done the humming was almost non audible. i hope this can help others who have the same issue.

I am having a similar kind of buzzing on my Little Dot MK 2, I basically tried everything. What you are describing above is very interesting.

 

[nofacemonster]

Artificial Center Tap works flawlessly on Little Dot MK2. Thank you so much for this thread. I fixed my amplifier today.

 

[Snuggums]

soo, i finally got to fix this problem.

i followed a hint from a comment on amazon, regarding the heater filament wiring of the tubes.

then i desoldered the wires on one of the tubes, twisted them nicely around eachother and resoldered them.
this helped a bit, but the humming was still quite audible.

i kept on researching the topic of correct heater filament wiring between tubes, and found out about the so called "artificial center tap".

this "artificial center tap" is built by soldering one 100Ohms resistor to each of the wires. those resistors have to be connected to ground later on.

i did exactly that. After i was done the humming was almost non audible. i hope this can help others who have the same issue.

I am having a similar kind of buzzing on my Little Dot MK 2, I basically tried everything. What you are describing above is very interesting.

Can you tell me exactly how to ground it? All I need to do is to put the resistors in-line?

 

[nofacemonster]

Can you tell me exactly how to ground it? All I need to do is to put the resistors in-line?

I soldered them to filament pin of the 6j1 tubes then grounded the other end. It worked.

 

[nofacemonster]

Can you tell me exactly how to ground it? All I need to do is to put the resistors in-line?

Check this diagram which i used. Place resistors on both pins and ground them. Pin #3 and #4