[Kentajalli]

There is a concept about noise that is misunderstood. Rob Watts has tried so many times to draw attention to it, but the misconception remains alive a well.
So if his words are falling on ...., why am I wasting mine?
Here is the misconception " We must screen against noise. Need a Faraday's cage"
first an analogy
There is an interesting (& relevant) experiment for school children, that has been going on for years. It goes as such:
- you need three bowls of water, one cold water, one warm water and one at room temperature. Kids are to put one hand in cold water & another in warm water for a minute, just long enough for their hands to get accustomed to the temperatures. Then they are to put both hand in room-temp water. Amazingly, one hand feels the water as being warm (previously in cold water) while the other hand feels the same water to feel cold!
Moral of this experiment (and relevance to "Noise") is that, the temp of the room-temp water is not that important, what is important is the fact that we feel the exchange of heat! If heat is flowing from the hand, it feels cold, if heat is flowing into the hand, it feels warm.
It is the flow of heat that is important.
Not convinced yet? here is another experiment to show the same in a different manner.
Get a wooden or plastic chopping board & a piece of glass or metal sheet. Both being in the same room for some time, both should be at same temperature. Put one hand on the chopping board, and another on glass or metal. One feels colder than the other. Again, it is all down to heat conductivity of glass/metal vs wood/plastic.

The existence of Noise is not the real issue!
The issue is, if it can flow from one point to another.
Hence why, RW keeps insisting, that a mobile phone (which is a noisy device) connected to a Mojo or Hugo and headphones, will not suffer from noise pollution.
Because the Noise can not flow through Mojo or Hugo! the loop is open.

@Rob Watts , correct me please.

 

[Digital Enigma]

Yes it's new with Mojo 2. Hugo 2 also has RF filters for preserving SQ whilst in desktop but always relies on the batteries' low impedance for dynamic currents. Static, steady state currents are supplied by the charger.



If you charge to blue it doesn't matter much if you disconnect the charger rather than waiting till it goes purple. You will get longer battery life if you wait till magenta (purple).

An hour on blue is not a problem as each battery has it's own voltage discharge characteristics. It will be green for a lot longer time!

Rob, what colour for Mojo2 max volume before it starts clipping? as my amp can take up to 6vrms on analogue line inputs.

 

[Hypops]

There is a concept about noise that is misunderstood. Rob Watts has tried so many times to draw attention to it, but the misconception remains alive a well.
So if his words are falling on ...., why am I wasting mine?
Here is the misconception " We must screen against noise. Need a Faraday's cage"
first an analogy
There is an interesting (& relevant) experiment for school children, that has been going on for years. It goes as such:
- you need three bowls of water, one cold water, one warm water and one at room temperature. Kids are to put one hand in cold water & another in warm water for a minute, just long enough for their hands to get accustomed to the temperatures. Then they are to put both hand in room-temp water. Amazingly, one hand feels the water as being warm (previously in cold water) while the other hand feels the same water to feel cold!
Moral of this experiment (and relevance to "Noise") is that, the temp of the room-temp water is not that important, what is important is the fact that we feel the exchange of heat! If heat is flowing from the hand, it feels cold, if heat is flowing into the hand, it feels warm.
It is the flow of heat that is important.
Not convinced yet? here is another experiment to show the same in a different manner.
Get a wooden or plastic chopping board & a piece of glass or metal sheet. Both being in the same room for some time, both should be at same temperature. Put one hand on the chopping board, and another on glass or metal. One feels colder than the other. Again, it is all down to heat conductivity of glass/metal vs wood/plastic.

The existence of Noise is not the real issue!
The issue is, if it can flow from one point to another.
Hence why, RW keeps insisting, that a mobile phone (which is a noisy device) connected to a Mojo or Hugo and headphones, will not suffer from noise pollution.
Because the Noise can not flow through Mojo or Hugo! the loop is open.

@Rob Watts , correct me please.

I don't follow. What do these temperature analogies have to do with electrical noise?

 

[Rob Watts]

Rob, what colour for Mojo2 max volume before it starts clipping? as my amp can take up to 6vrms on analogue line inputs.

So long as it's not white it can't clip under any circumstances even with the max digital input of 0dBFS.

 

[chelseafc]

It’s not an easy answer when it comes to “what is best”.

@Rob Watts says optical, due to other things, IIRC galvanic isolation and lack of noise. But the poly is widely considered one of the best sounding inputs to the mojo2.

Others say toslink “sounds like ass” and well implemented USB is better.

Unless you have a noisy USB source or crappy cable, the mojo should sound nearly identical from all inputs given equal quality sources. You probably are getting the best performance on your setup. You can continue down the “rabbit hole” chasing the extra 5% or just enjoy the mojo2.

I got a Mojo2 from Amazon a couple of days ago, connected via Toslink and hated it so much that it was packed in a hurry to be sent back.
I chose Toslink by default as both TT2 and DAVE sounded best with optical.
The only reason I could not return it immediately is that another part of that order has not arrived yet (I planned to return both).
By pure coincidence, someone sent me a few PGGB tracks to test, which I could only do through the USB (or DBNC with an external adapter).
I unpacked the Mojo2 and could not believe my ears.
Granted, PGGB sounded a lot better, but even the originals produced a sound so close to TT2 that I am likely to put the latter on sale now.
I have no idea why the optical sounds harsh on Mojo2, at least to my ears.

 

[Kentajalli]

I don't follow. What do these temperature analogies have to do with electrical noise?

The existence of noise is not the issue, what is crucial is whether noise currents can FLOW THROUGH a device.
The analogy, though not a perfect one, was pivoting on the flow principle.
Think of noise as heat, and noise-filters as gloves. Your hand can get affected by heat, only if the heat flows into it, or away from it.
Where the heat analogy fails, is the fact that with electrical current, you need an entry AND an exit to form a closed circuit.
From a phone >> DAC >> headphone has no exit point, like an open chain. Noise currents can not flow, therefore no problems.
From a mains operated DAP >> mains DAC can be problematic, because the mains electricity can act as entry and exit points. with a battery operated DAC, no problems again.
Can't explain it any better.

 

[evhvis]

The existence of noise is not the issue, what is crucial is whether noise currents can FLOW THROUGH a device.
The analogy, though not a perfect one, was pivoting on the flow principle.
Think of noise as heat, and noise-filters as gloves. Your hand can get affected by heat, only if the heat flows into it, or away from it.
Where the heat analogy is different to noise, is the fact that with electrical current, you need an entry AND an exit to form a closed circuit.
From a phone >> DAC >> headphone has no exit point, like an open chain. Noise currents can not flow, therefore no problems.
From a mains operated DAP >> mains DAC can be problematic, because the mains electricity can act as entry and exit points. with a battery operated DAC, no problems again.
Can't explain it any better.

Without galvanic isolation the DAC and the Phone can become a closed loop of electrical connections. Over USB you have a total of 4 physical connections between the devices so it would depend more on the implementation how the noise would flow.

 

[Kentajalli]

Without galvanic isolation the DAC and the Phone can become a closed loop of electrical connections. Over USB you have a total of 4 physical connections between the devices so it would depend more on the implementation how the noise would flow.

No, does not work that way.
The +5V and the data lines are isolated internally from the analogue section, and it is the analogue section that can get affected by electrical noise. The digital section is immune to electrical noise in practice.
The ground wire, the ground plane, is where the noise shouldn't flow through.
With a battery operated DAP >> battery operated DAC , what we have is an open loop.
Galvanic isolation is needed if you intend to connect the DAC to mains operated DAPs and Amps. So for desktop use, either use optical, or invest in a proper USB isolator.
The Topping HS01 oe HS02 comes to mind, cheap and very effective.

 

[Hypops]

The existence of noise is not the issue, what is crucial is whether noise currents can FLOW THROUGH a device.
The analogy, though not a perfect one, was pivoting on the flow principle.
Think of noise as heat, and noise-filters as gloves. Your hand can get affected by heat, only if the heat flows into it, or away from it.
Where the heat analogy fails, is the fact that with electrical current, you need an entry AND an exit to form a closed circuit.
From a phone >> DAC >> headphone has no exit point, like an open chain. Noise currents can not flow, therefore no problems.
From a mains operated DAP >> mains DAC can be problematic, because the mains electricity can act as entry and exit points. with a battery operated DAC, no problems again.
Can't explain it any better.

If all you're saying is that noise is electrical, well then, yeah, of course. Noise "flows" the same way all electrical signals do. From the perspective of our gear, there's no difference between noise and signal. It's only listeners who care about the difference. I'm just not sure what point you're making.

Galvanic isolation is needed if you intend to connect the DAC to mains operated DAPs and Amps. So for desktop use, either use optical, or invest in a proper USB isolator.

If this was your ultimate point, then I say again: well, yeah, of course. As for me, I use an Intona USB isolator.

 

[evhvis]

No, does not work that way.
The +5V and the data lines are isolated internally from the analogue section, and it is the analogue section that can get affected by electrical noise. The digital section is immune to electrical noise in practice.
The ground wire, the ground plane, is where the noise shouldn't flow through.
With a battery operated DAP >> battery operated DAC , what we have is an open loop.
Galvanic isolation is needed if you intend to connect the DAC to mains operated DAPs and Amps. So for desktop use, either use optical, or invest in a proper USB isolator.
The Topping HS01 oe HS02 comes to mind, cheap and very effective.

Generally the digital section of a DAC is more impacted by noise than the analog section.

 

[Kentajalli]

Generally the digital section of a DAC is more impacted by noise than the analog section.

 

[AussieMick]

Generally the digital section of a DAC is more impacted by noise than the analog section.

The noise we have to worry about is that which gets into the analogue circuitry. It’s only when it hits analogue components that it really starts to mess with the outcomes. So, DACs, preamps, amps are all affected, but the noise might well have entered the system at the mains, or through radiated EMI, etc.

 

[evhvis]

The noise we have to worry about is that which gets into the analogue circuitry. It’s only when it hits analogue components that it really starts to mess with the outcomes. So, DACs, preamps, amps are all affected, but the noise might well have entered the system at the mains, or through radiated EMI, etc.

Any noise that affects the digital to analog conversion will make it's way into the final analog signal as artifacts.

 

[AussieMick]

Any noise that affects the digital to analog conversion will make it's way into the final analog signal as artifacts.

There’s more to it than that. I’m talking about noise that travels independently of the data. Noise in mixed signal systems. Noise travelling on the ground plane, noise created by transceiver chips, conducted and radiated noise. It’s everywhere.

 

[Hypops]

There’s more to it than that. I’m talking about noise that travels independently of the data. Noise in mixed signal systems. Noise travelling on the ground plane, noise created by transceiver chips, conducted and radiated noise. It’s everywhere.

Looked at another way, there is no electrical signal that can be absolutely identified as "noise." "Noise" is just a way to describe any electrical signal added to the original signal that the end-user doesn't want (as opposed to "distortion" which is an alteration of the signal).

"Noise" is like the word "weed." There is no actual plant that is identifiable as a "weed." A "weed" is just a catchall term for any plant you don't want in your garden. Just like your garden doesn't care about the difference between a "vegetable" and a "weed," electronics don't care about the difference between "signal" and "noise." They just do their job, which is to conduct electrical currents. Designers do their darnedest to keep signal and noise separate, but electronic components could give a giant F. They just want to conduct.