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Review of Little Dot MKV Dual Mono Solid State Headphone Amplifier - Page 49

post #721 of 735

hi Penchum,

do you  tried to listen both  mrk V and IV , together as a combo pre amp (IV) and amp (V).

i'm shure u did.. 

which settings for both potentiometers ?

post #722 of 735

Can somebody weigh their Mk V ? I know the specs say 3.5kg's, but i need the exact weight. Thanks.

post #723 of 735

If anyone could help me...currently looking to upgrade from the amp on my Essence STX and for 200$,found a MKIII and a MKV. Currently with DT990 600ohm,what would be my best bet?

post #724 of 735
I have a MKIII as am preamp in a MKV as an amp. I enjoy my setup!
post #725 of 735
Quote:
Originally Posted by Radical_53 View Post



Even though I hadn't found a solution to the noise problem I thought about rolling opamps. Thought, I had to take a look. Strangely I found a temporary solution to the problem this way:

Can someone explain to me why the intereference and noise is compeletely gone when I pull the PCB out of its case on this amp?
When I close it again the intereference comes back. I also get some sort of hum as soon as I touch the volume knob, it's silent again when I let go of it.




PS: I think I just found the solution. There was a small grounding cable in the back of the amp, just one wire with a ring on its end. As soon as I take this off the case and isolate it the noise goes away even when the case is closed. I'm curious if it's needed for something.

 

Oh it's nothing important, it just stops you from killing yourself :cool:. It's a grounding cable for the metal chassis. If the case goes live due to a short that cable will cause the current to go through it rather than you. Do not under any circumtances play with that cable unless you independantly ground the chassis. The humming you're experiencing is a groud loop, which is why it's effected by playing with the grouding cable. It's often caused by devices sharing a ground wire, for example if your amp and source are connected to the same sockets. There are ways to get around it but disconnecting that cable is one way I would never recommend to anyone. Just google ground loop and have a read.

 

As a general rule; if there's a wire it is needed for something. Why would the company waste money on putting it there otherwise?

 

Also, don't change the op-amps. In general op-amp "rolling" is a lot of rubbish anyway. But more specifically little dot have said, after being asked about "rolling", that the implementation is so finely tuned to the op-amps they have used that any other would cause the device to malfuntion. If you love the sound of distortion changing the op-amps is the way to go. This is actually the case in 9/10 times changing an op-amp. Unless you are a fully trained EE who knows how to re-wire the entire circuit to implement the new op-amp correctly you should never change an op-amp. Different op-amps have very different requirements and the sonic changes most people hear after changing them isn't a different "flavour" it's a correctly operating circuit beng compared to the new op-amp being tortured and failing to operate correctly.

post #726 of 735
Quote:
Originally Posted by Radical_53 View Post
 

Well, that's just what it is ;) An additional grounding wire. It gives a higher level of safety (as any plug with 3 pins) but it isn't exactly needed (as far as I know ;) ).

 

It does depend to a degree on where you are due to voltage differences. In the USA you run low voltage so you don't even have a ground pin in your sockets. If your sockets have 3 pins you are running a lethal voltage and you need that ground wire. It's certainly not worth risking killing yourself for the sake of some humming, especially when it's caused by a well known and easy to fix cause.

 

To be honest I think the reason the US doesn't have a ground is more to do with unfortunate decisions long ago when people didn't care about saftey. 120V could still kill you. But i'm sure glad we have an earth on our 240V devices.

 

Anyway, the important thing is that little dot decided that ground cable needs to be there it needs to be there. They will know that it can cause a ground loop (it's very well known to the point that a lot of radio sets are non-grounded) and have made the call that it is worth risking humming on thier outputs for the safety that grounding gives.


Edited by yblad - 2/26/14 at 4:36am
post #727 of 735

Well, I'm no electrician but as far as I know the additional cable is just that, an additional cable (for security reasons, yes). There's a grounding wire already. Not all countries have 3-wire sockets and house wirings so some devices come with a 2-point plug, some have the additional security contact. That's, as far as I know, the reason for this noise.

 

Of course it's better to use the contact but I don't see why I would *need* to use it. I can take off the wire inside the case or I can isolate/tape the contact at the wall plug, both solutions work.

I had to do the same to my subwoofer, for example, as my amp only has a "normal" plug with two contacts whilst the subwoofer has 3. Of course, not recommended, but sometimes it's the only solution. 

post #728 of 735
Quote:
Originally Posted by yblad View Post
 

 

It does depend to a degree on where you are due to voltage differences. In the USA you run low voltage so you don't even have a ground pin in your sockets. If your sockets have 3 pins you are running a lethal voltage and you need that ground wire. It's certainly not worth risking killing yourself for the sake of some humming, especially when it's caused by a well known and easy to fix cause.

 Volts don't kill, amps do. As you said, the solution is simple. It seems like we'd both be using a different "simple" solution though ;) 

 

I'm living in a newly build house with very clean electricity, still the difference between 2-pin and 3-pin sockets makes it impossible to get rid of the hum without evening the field. You'd either have to make every device 3-pin, with an additional grounding for example, or "cut" some of the (internationally very few) 3-pin devices down to 2-pin.

post #729 of 735
Quote:
Originally Posted by Radical_53 View Post
 

Well, I'm no electrician but as far as I know the additional cable is just that, an additional cable (for security reasons, yes). There's a grounding wire already. Not all countries have 3-wire sockets and house wirings so some devices come with a 2-point plug, some have the additional security contact. That's, as far as I know, the reason for this noise.

 

Of course it's better to use the contact but I don't see why I would *need* to use it. I can take off the wire inside the case or I can isolate/tape the contact at the wall plug, both solutions work.

I had to do the same to my subwoofer, for example, as my amp only has a "normal" plug with two contacts whilst the subwoofer has 3. Of course, not recommended, but sometimes it's the only solution. 

Both ways work to fix your humming, and both ways work to make the device potentially unsafe. You don't need to use it any more than you need to turn the oven off when you leave the house or you need to wear a seatbelt. It's entirely your personal choice provided no one else is ever going to touch the device. I just wanted to make sure you know the dangers of removing it.


 

Be aware though, if someone else does touch it and gets hurt because you disconnected that wire you could find yourself liable to civil and/or criminal charges. It's not illegal to self service an electronic device for personal use but it is if any other person is using it. To the point that if I want to bring my laptop into the lab to work on I have to get it PAT tested just in case a colleague touches it. So make sure you don't go lending it out.

 

Quote:
Originally Posted by Radical_53 View Post
 

 Volts don't kill, amps do. As you said, the solution is simple. It seems like we'd both be using a different "simple" solution though ;) 

 

I'm living in a newly build house with very clean electricity, still the difference between 2-pin and 3-pin sockets makes it impossible to get rid of the hum without evening the field. You'd either have to make every device 3-pin, with an additional grounding for example, or "cut" some of the (internationally very few) 3-pin devices down to 2-pin.

V is proportional to I in a system with a constant impedance. Meaning when you connect yourself to a 240V mains you get around twice the current as with a 120V. So although current is the worst part of the lethality, extra voltage = extra current and therefore extra voltage is exactly as deadly as extra current. The impedance of your body is constant across both situations so this holds true.


 

On top of that, it' actually it's a combination of the voltage and current and AC frequency. They all cause damage for different reasons. So even if current didn't get doubled on our 240V supplies it would still be more deadly.


 

It sounds like you have a bit of a wiring nightmare. So glad I only have to worry about one type of plug/socket.


Edited by yblad - 2/26/14 at 5:09am
post #730 of 735

Not exactly a nightmare, just "international design differences", so to say. Local standard is 3-pins, afaik "we" even invented that 3-pin Schuko plug. But, as not every device uses it, problems are foreseeable.

Luckily it's only a handful of audio devices that react to this. As I already sold the amp, the subwoofer is my only device left with a "modded" plug. As it comes with a wooden case, the risk of a lethal stroke of electricity is fairly small. 

 

I've tried several things already to get rid of the problem before I took the third pin out of the equation. Different wall plugs were the first thing. There's nothing coming in from an antenna or any other device, just the fact that the sub is connected to the amp and both use different types of plugs.

The same thing happened with the headphone amp, it's connected to my PC and both are using different types of plugs.

Wall outlets didn't help, I tried different power strips, even master/slave ones, without any success. Different cables, orientation of cables (yes, some manufacturers have this in their FAQs to cure the problem), nothing.

post #731 of 735
Quote:
Originally Posted by Radical_53 View Post
 

Not exactly a nightmare, just "international design differences", so to say. Local standard is 3-pins, afaik "we" even invented that 3-pin Schuko plug. But, as not every device uses it, problems are foreseeable.

Luckily it's only a handful of audio devices that react to this. As I already sold the amp, the subwoofer is my only device left with a "modded" plug. As it comes with a wooden case, the risk of a lethal stroke of electricity is fairly small. 

 

I've tried several things already to get rid of the problem before I took the third pin out of the equation. Different wall plugs were the first thing. There's nothing coming in from an antenna or any other device, just the fact that the sub is connected to the amp and both use different types of plugs.

The same thing happened with the headphone amp, it's connected to my PC and both are using different types of plugs.

Wall outlets didn't help, I tried different power strips, even master/slave ones, without any success. Different cables, orientation of cables (yes, some manufacturers have this in their FAQs to cure the problem), nothing.

 

You'll be fine with a casing made of wood they're already isolated by thier low conductivity. Unless you run 100,000+ V through them, in which case you have bigger things to worry about!

It can be an absolute nightmare to solve. I've been lucky so far with ground loops. Maybe my house is particularly well wired. Or maybe I just got lucky with exactly how the wiring works out

post #732 of 735

Don't know if anyone monitors this thread but if so I am looking to purchase a LD MKV, if anyone has one or knows someone who does I would be interested. I'd like it to be in very good conition if possible. I purchased a LDMKIII new a little over a year ago and really enjoy it.

 

 I just thought I'd try here before purchasing one on "FeeBay"

post #733 of 735

Hello, I have a Beyerdynamic DT 880 PRO 250 ohms with Little Dot MK5. Can you please recomend me a good DAC to use for this combination ?

post #734 of 735

Hello,

 

I have a pair of Beyerdynamic DT880 PRO 250 ohms. I used them with the combo FIIO E07K(DAC)+FIIO E09K(AMP) and it was fabulous... when I introduced E09K the sound was at least with 2 classes better (bass, soundstage, highs, etc).

I sold my FiiO combo and I bought FiiO E18 as I saw from reviews that is a better DAC even than E17 witch is better than E07K. Also for amplification I bough a Little Dot MK V solid state...

So now I am using FiiO E18 as DAC and Little DOT MK V as AMP and I am not happy with the sound on DT 880 PRO... It was so much better with FIIO E07K(DAC)+FIIO E09K(AMP)...

I mean Little DOT MK V amps the sound but I dont think adds quality, just volume booster... I even believe the sound is better if I use only Fiio E18 as DAC+AMP...

 

Can you please advise me on this ?

 

Thx

post #735 of 735

Well, that' what it's supposed to do. "Normally", you'd only want to add some "color" through the choice of the headphones themselves. No coloration from the source, or the amp.

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