[zvovchik]

I have a mk vi+ and im experiencing which i think is an issue. Im having slight buzz in the left and right channel right after the right side warms up and "clicks on"
im guessing when the transformer turns on. this is happening when i use my sony7506 headphones(63ohms) SE in the back and when i use balanced preamp outs. when nothing is plugged in to the Little Dot except headphones or my power amp the buzzing is there, when i play hard music its not bothersome but it drives me nuts when im listening to classical. the symptoms are there no matter where the volume pot is at. Im using dacmagic ballanced as source and its not the dacmagic, my little dot mk ii is dead silent. I cant hear it when im using my hd600(300ohms) connected through 4pin xlr and that is fine, but i like to use it as a preamp and the buzzing is still there. I tried different tubes, i have changed the gain settings, and i have sent it back to china and extensively explained this and it shipped back just like it left. has anyone tried the preamp outs? Or has anyone tried the SE OUT with similar impedance headphones? Any help would be really appreciated.
 
I tubes that i have left in my unit are Power: RCA JAN 6as7g Driver: Tung-Sol JAN CTL-6su7gty and this combination is my favorite.

 

[reiserFS]

Sounds like a grounding issue to me?

 

[zvovchik]

I have looked inside my little dot, everything looks ok,(to me) i have tried all the plugs in my house, tried using a power cord without ground, tried power conditioner. i just had an idea, im going to hook up my 63ohm 7506 headphones to the 4 pin xlr in the front. seems i only get buzzing from the back. I guess i really want to know if anyone tried using the pre-amp-out to a power transformer or some headphones that are close in impedance at the SE jack in the back.
tha hd600 are doing great with 4pinxlr, cant hear any buzzing, and i have a akg 240m 600ohms recabled ballanced to 4pinxlr and they sound great, no bzz.
 
I like this amp, i want it to be buzz free .atleast at the pre outs.  It would be awesome if someone can test for this and let us know, maybe its just my amp acting up or it doesnt like lower impedance headphones.
 
BUT I WANT TO USE THE PRE OUTS and they buzz. its there when the right side warms up and clicks active then the bzz is audible.  using the pre-amp-out i have hooked up my peavey cs 400x which is 300w x2 to my magnepan smga and i hear a buzzing. also buzzing seems more pronounced when using my passive event 20/20. and yes i have hooked up a different power amp(yamahap2250) to my DOT and still the buzz.
 
IF it is grounding issue, what do i look for?
 
could i be the wires that connet to pre-out are prone to electromagnetic field emmitted by transformers? OR SOME OTHER "field".
 
needless to say i am frustrated andalmost ready to give up on this amp....thats too bad...IT SOUNDS SO NEUTRAL AND MUSICAL...but not during quiet passages.
 
thoughts?

 

[Audiogalore]

 
Quote:

I have looked inside my little dot, everything looks ok,(to me) i have tried all the plugs in my house, tried using a power cord without ground, tried power conditioner. i just had an idea, im going to hook up my 63ohm 7506 headphones to the 4 pin xlr in the front. seems i only get buzzing from the back. I guess i really want to know if anyone tried using the pre-amp-out to a power transformer or some headphones that are close in impedance at the SE jack in the back.
tha hd600 are doing great with 4pinxlr, cant hear any buzzing, and i have a akg 240m 600ohms recabled ballanced to 4pinxlr and they sound great, no bzz.
 
I like this amp, i want it to be buzz free .atleast at the pre outs.  It would be awesome if someone can test for this and let us know, maybe its just my amp acting up or it doesnt like lower impedance headphones.
 
BUT I WANT TO USE THE PRE OUTS and they buzz. its there when the right side warms up and clicks active then the bzz is audible.  using the pre-amp-out i have hooked up my peavey cs 400x which is 300w x2 to my magnepan smga and i hear a buzzing. also buzzing seems more pronounced when using my passive event 20/20. and yes i have hooked up a different power amp(yamahap2250) to my DOT and still the buzz.
 
IF it is grounding issue, what do i look for?
 
could i be the wires that connet to pre-out are prone to electromagnetic field emmitted by transformers? OR SOME OTHER "field".
 
needless to say i am frustrated andalmost ready to give up on this amp....thats too bad...IT SOUNDS SO NEUTRAL AND MUSICAL...but not during quiet passages.
 
thoughts?

I have had the same issue and this is David's respond from Little Dot!
 
[size=x-small]Hi David:[/size]
 
[size=x-small]Please advise on the reason why I am getting a hum from my speakers on both channels when I drive the Little Dot as a pre-amp using the left/right balanced pre-outs on the back of the MK6. The hum is a low noise hum heard with volume or no volume and does not change db level. The headphone phone out is clean and does not have this problem.[/size]
 
[size=x-small]Please advise and thank you for your support on issue.[/size]
 
[size=x-small]Best regards,[/size]
 
Hello Harold,

Sounds like a grounding issue.  The Little Dot MK VI does not connect ground to the chassis through the XLR connection.  If your power amp does, you may experience the issue.  If such is the case, you should use the other output.

Best Regards,
David
 
[size=x-small]Hi David:[/size]
 
[size=x-small]I appreciate your quick respond, as mentioned you believe this might be a grounding issue. Being that the little floats ground in the XLR configuration then the ground is being fed back to the pre-amp via power amp that is grounded?[/size]
 
[size=x-small]I have two other pre-amps that I use and they are XLR out and do experience the hum problem.[/size]
 
[size=x-small]Another note of interest. Is there any improvement other than the SE connection on the new MK6+ vs. older version like the present MK6 I have and that I should be aware of. [/size]
 
[size=x-small]Best regards,[/size]
 
Hello Harold,

Indeed - another thing you may also want to try a ground lift cable or a ground lift switch box in the XLR interconnects, like used in pro audio applications for grounding conflicts between equipment.  Regarding the Little Dot MK VI+, the only difference is the SE output. 

Best Regards,
David
 
[size=x-small]Hi David:[/size]
 
[size=x-small]When you say ground lift, is that on the pre-amp or the power amp.[/size]
 
[size=x-small]Best regards,[/size]
 
[size=x-small]Hi David:[/size]
 
[size=x-small]I was hoping to have heard back from you. I also need to make sure I understand that the design as previously mentioned is a "dual mono design" therefore I also understand if I may say so that the topology of the design is "fully balanced." left/right and in no way differential or shared.[/size]
 
[size=x-small]Please advise and thank you for your continuous support.[/size]
 
[size=x-small]Best regards,[/size]
 
Hello Harold,
 
You'll need to experiment yourself where to lift ground.  By definition dual mono is fully balanced.
 
Best Regards,
David
 
[size=x-small]Hi David:[/size]
 
[size=x-small]I understand your position and it is my risk to experiment. I understand the definition that dual mono should be truly balanced.[/size]
 
[size=x-small]Unfortunately there are many companies that state there design is balanced but do share common between paths in the left and right channels.[/size]
 
[size=x-small]The reason to my curiosity is the hum issue that I recently been exposed and hearing through both channels same common problem.[/size]
 
[size=x-small]Best regards,[/size]
 
Hello Harold,

It's not really an issue of risk, but rather since grounding issues are highly variable due to the various components in a system and now they are connected.   Thus experimenting on where to lift ground is required to resolve it. 

Best Regards,
David

 

[zvovchik]

Ok that is getting closer to diagnose, have you experimented with "lifting ground" and/or have you resolved this?  im thinking lift ground is not to connect the ground in the xlr interconnects to chasis or lift ground inside the amp? sorry i may need a bit more clarification.
Thanks to taking the time to answear, I really like how this amp sounds and hoping to fix this. it is also good to know that our amps are created equal.
 

 

[Audiogalore]

 
Quote:

Sounds like a grounding issue to me?

I would definitely 1st experimenting to lift the ground on your amp to assure and eliminating any possible ground loop. This can be done by putting a cheater plug on your amp AC 3-pin cord that can be had from Home Depot for less than a buck.

 

[reiserFS]

Huh, I thought they also replaced they loud fans that were in the early production MKVI? Seems like not worth a mention from David's point of view, I guess.

 

[rattesp]

I'm really interested in this amp to drive my T1. I might pull the trigger soon ! must resist !!!!!!!

 

[Audiogalore]

T1 is a real marriage to this amp!

 

[reiserFS]

I second this, although I'm not driving them with the stock tubes. VT-229 Tung-Sol + RCA 6AS7G are a match made in heaven. Having some Tung-Sol 5998 and round plate Tung-Sol 6F8Gs on the way to see if it can get even better. I still can't believe how many types of tubes one can roll in the MK VI. The 6F8G is electrically the same as the 6SN7 and the round plate pairs are much cheaper. You need a 6F8G to 6SN7 adapter though.
 
Quote:

T1 is a real marriage to this amp!

 

[elwappo99]

Definitely interested in this amp, but I'm finding very little in terms of user comments. I'm also debating between the MKVI+ and the MKVIII SE. I'm assuming the SE output on the back of the MKVI+ acts as a line-out, anyone confirm this?Aside from the physical outputs, is there any differences in these amps in terms of sound sig? 

 

[Maxvla]

The SE output is the same as any 1/4 jack, not a line out.

The main difference in the 6 and 8 is the power and fans. The 6 is by far more powerful and has fans to keep it from getting too hot. The 8 apparently is more refined, but its hard to imagine after hearing the 6.

The reason there isn't much buzz about these amps is this: Little Dot was flavor of the year for a few years about 4-5 years ago and like all FOTM their time in the light passed. The 5, 6, 7, and 8 were made about 2 years ago and newer, and newer enough to be after the wild popularity passed. Their amps are just as good as they've ever made but everyone's attention is on the latest greatest.

One thing about the 6 and 8 is that you are buying into a system that is both a blessing and a curse. The 6 (and presumably the 8) is a very average SE amplifier so don't expect anything special that way, but the balanced sound is excellent. This means your source must be balanced which means no turntables no tape decks or other purely analog sources. This also means no SACD unless you have a higher end player with balanced output. Additionally it also means all of your headphones have to be recabled or at least reterminated. The reward is great sound but there isn't much flexibility with this design.

On another note, I'm leaving the club here by selling my 6 to another head-fier since the 6 doesn't work with IEMs. Still a great amp but it doesn't suit my needs any longer.

 

[elwappo99]

I see. Interesting. So the 8 is just overall more refined. Very interesting recap on little dot. I think David should send out more units to be reviewed, but that's just personal opinion. I've hat a mki+,l mkiii, mkv, and dac_I, and definitely enjoyed them.  I've got a balanced dac and SS, but my tube amp is SE, so i've been looking to jump into a balanced tube amp, and this seems like it could fit the bill.  Posted in the LCD-2 amp thread, hoping to see if anyone had used to two together.

 

[reiserFS]

Well here we go, my power button just broke, it's literally stuck in the on position. Now I have to pull the power cord every time I want to turn it off. Thank god it's stuck in the on position or else I'd be without music. Send David a mail to see if he can manage to send me a replacement button.
 
Anyone else had a dead button?

 

[Maxvla]

Yes, it was an easy swap. Just take a picture of it and he'll send you a new one. Just have to solder 4 (I think?) wires. It was the spring that broke inside in my case, likely the same with yours.

Sold my MKVI a few days ago. Sad panda here, but excited about my new direction also.