[Whitigir]

I had these options at current supplier. I ordered some balanced covers and some full length covers.

Why not gold filled Brass ? Could they do so if you provide materials

 

[Nayparm]

Maybe, I can ask (there are other companies)
I'll see what these are like first

 

[Nayparm]

 

[Maxx134]

Hand made Pure Silver backplate !!!

Wow nice job!
I can see the (wings)notches on the sides and the tiny tabs on the bottom.

Why not gold filled Brass ? Could they do so if you provide materials

Neither brass nor gold are as good for sheilding as copper, silver & aluminum.
I read Stainless steel is considered a cheaper solution as well.
I think the metals conductivity and another aspect for emf are what those metals need.

Since silver expensive, it not used, but should be a superior choice due to highest conductivity.

 

[Whitigir]

Don’t know about which one is good shielding, but any metal that can conduct, can shield against EMI and interferences. Ferrite beads can also help....different materials is more effective against some different interferences but whatever the case is

I can report back that I tried 3 metals on the back plate: Aluminum , Copper , Pure Silver

Somehow Silver has the best bass energy and improve Deep bass fidelity, density and decays while seems to also improve the airiness overall

It could have been placebo ....because this makes no senses to me. This backplate is simply a shielding on the back that conduct throughout the whole body....why would it alternate the sound performances while touching no where near the main PCB ground paths

 

[524419]

Don’t know about which one is good shielding, but any metal that can conduct, can shield against EMI and interferences. Ferrite beads can also help....different materials is more effective against some different interferences but whatever the case is

I can report back that I tried 3 metals on the back plate: Aluminum , Copper , Pure Silver

Somehow Silver has the best bass energy and improve Deep bass fidelity, density and decays while seems to also improve the airiness overall

It could have been placebo ....because this makes no senses to me. This backplate is simply a shielding on the back that conduct throughout the whole body....why would it alternate the sound performances while touching no where near the main PCB ground paths

Did this give you more clearance for thicker caps up top?

 

[Whitigir]

Did this give you more clearance for thicker caps up top?

Nope, it fit the same caps, just that you don’t have to modify and cleaning inside the plastic back-plate

Actually, you have to clean the plastic back plate in order to fit these caps from my recipe. So, it is better to make another back plate by metal of choices

 

[Whitigir]

Don’t know about which one is good shielding, but any metal that can conduct, can shield against EMI and interferences. Ferrite beads can also help....different materials is more effective against some different interferences but whatever the case is

I can report back that I tried 3 metals on the back plate: Aluminum , Copper , Pure Silver

Somehow Silver has the best bass energy and improve Deep bass fidelity, density and decays while seems to also improve the airiness overall

It could have been placebo ....because this makes no senses to me. This backplate is simply a shielding on the back that conduct throughout the whole body....why would it alternate the sound performances while touching no where near the main PCB ground paths

The only logical explanations I have is that the Pure-Silver back plate must be very effective in absorbing “stray-Magnetic fields/currents” emitted by the Inductors being used by the Balanced output. It must be much more effective than other materials I have tried as listed (Copper, Aluminum).

So, the stray fields are not hitting and bouncing toward the other “inductors” and close by “components”, which in turns improve the performances ?



Shielded and Unshielded SMD Power Inductors First, the magnetic field generated by the shielded power inductor keeps the magnetic field within the inductor. It emits few magnetic fields outside the package and has a less negative effect on others parts that are in close proximity to it, therefore minimizing the coupling to other components or modules. In an unshielded inductor, some of the magnetic flux field is radiated outside. If a sensitive component or module is in close proximity to it, its normal functionality may be affected. Since the entire magnetic flux field is contained within the inductor, the power efficiency is higher. The inductor also contains less wire turns if it has equal inductance with the unshielded inductor. This results in the DCR being smaller for a shielded inductor, as compared to that of an unshielded one. If the DCR is the same for both the shielded and unshielded inductors, then this implies that the inductors utilize the same wire and winding turns. The shielded inductor should have a higher inductance value than the unshielded one. However, the inductance change versus the current curve will drop earlier because of saturation characteristics. This determines that the unshielded power inductor is easier to work with in a larger current.

 

[Maxx134]

Shielded and Unshielded SMD Power Inductors First, the magnetic field generated by the shielded power inductor keeps the magnetic field within the inductor

The inductors edit**, "may not" be shielded.
They look like open core. So that pic would be correct that some of the flux lines are going up and hitting the top plate.
That's a different condition, than just having a simple plastic cover.

So, the stray fields are not hitting and bouncing toward the other “inductors” and close by “components...

Looks to me like the stray vertical flux lines hit the metal plate, and are shunted (bent & following now into the metal ) , but an AC signal (music) would make the flux lines go the other way as well...
So that flux line that went into the metal, now reverses and comes out, maybe more so, from other flux lines that went into the metal from the other inductors and diverted ...
Creating a more efficient flow of flux lines that would instead have been lost in the air instead of shunted.

Since the silver has higher conductivity, it makes sense to have more effect.
Yet, this is purely my assumption (from my own experience with components), so I could be wrong.

 

[Maxx134]

The inductors are not shielded.
They look like open core. So that pic would be correct that some of the flux lines are going up and hitting the top plate.
That's a different condition, than just having a simple plastic cover.


Looks to me like the stray vertical flux lines hit the metal plate, and are shunted (bent & following now into the metal ) , but an AC signal (music) would make the flux lines go the other way as well...
So that flux line that went into the metal, now reverses and comes out, maybe more so, from other flux lines that went into the metal from the other inductors and diverted ...
Creating a more efficient flow of flux lines that would instead have been lost in the air instead of shunted.

Since the silver has higher conductivity, it makes sense to have more effect.
Yet, this is purely my assumption (from my own experience with components), so I could be wrong.

I was wrong there is less shunt in that specific metal because of low permeability or magnetic attraction.
It is higher conductance would help any coil noise from the class D output filtering, so should have lower noise floors, with a higher conductivity sheild.

I also think I remember @Whitigir did not like covering the coils with copper tape, saying it actually increased noise, maybe because sheild wasnt grounded? Like the silver plate?

 

[Whitigir]

I was wrong there is less shunt in that specific metal because of low permeability or magnetic attraction.
It is higher conductance would help any coil noise from the class D output filtering, so should have lower noise floors, with a higher conductivity sheild.

I also remember @Whitigir did not like covering the coils with copper tape, saying it actually increased noise, maybe because sheild wasnt grounded? Like the silver plate?

Yes, that is correct, the shield has to have the ability to disperse the collected energies. Otherwise it becomes antenna and attracts the energies.

But even if you had it grounded....still isn’t doing anything like what you would think. I have done These

1/ foil without shielding = higher noises

2/ foil with shielding = still higher noises but less than #1

3/ magnetic EMI sheets is the lowest noises but loosing out extensions details and energies. These are TDK noises absorb any sheets. It is the best for Walkman though, and doesn’t need grounding

4/ Back plate shielding with copper and aluminum doesn’t exactly do anything To the sound or noises really....

5/ Pure silver back plating and nOw we are talking about observable performances improvements

 

[Maxx134]

magnetic EMI sheets is the lowest noises but loosing out extensions details and energies. These are TDK noises absorb any sheets

How about cutting tiny circles Of this TDK material, to cover & place only top middle of the coils?

 

[Maxx134]

Maybe the silver plate is indirectly Making grounding the board circuits better...

 

[Whitigir]

How about cutting tiny circles Of this TDK material, to cover & place only top middle of the coils?

It wont even help at the coils, unless you cover the whole plate which barely doing anything to the noises....very negligible

I did that for 1A-EM because I was lazy to measure and cut the metal sheets

Since @Nayparm has done that, I started hand making the back plate and as I mentioned

Even Aluminum or Copper plating, they are barely observable , the same as TDK sheets the whole plate

Only Pure silver does the job and improve the performances

 

[Whitigir]

Maybe the silver plate is indirectly Making grounding the board circuits better...

It can’t be, if so, the pure copper itself would have done the job. Beside, there is no grounding from the back plate toward the main PCB ground at all...it is only the extensions of the main chassis. The main chassis is already too much for grounding properties.....little more won’t matter. Case in point was that neither aluminum nOr copper did anything observable

As I mentioned, the only way to explain this phenomenon with pure silver back plate here was somehow the properties of pure silvers allow the coils to not be sending stray magnetic field that negatively effects the surrounding