EMI Absorber - How to read the graph chart.

[NAIDIVER]

I don't know each values are represent for?

The lower one or higher one is better?

Thanks.

[JJJ]

Cyan is better. Attenuated more as a result of being thicker.

[NAIDIVER]

Cyan is better. Attenuated more as a result of being thicker.

 

Thanks JJJ

[Speedskater]

That's not EMI, it's extremely high frequency RFI, in the cell phone & BlueTooth range. Not a very useful produce for audio equipment.

[NAIDIVER]

That's not EMI, it's extremely high frequency RFI, in the cell phone & BlueTooth range. Not a very useful produce for audio equipment.

 

http://multimedia.3m.com/mws/media/644628O/3mtm-emi-emc-solutions-brochure.pdf

I got this from 3M website. There are many kind of EMI absorber sheets. Each of them work on each specific range (according to 3M user guide).

 

I tried to search for this issue on Google and found each part of PC generate EMI on many freq such as

133 MHz, radiation is almost exclusively via I/O cables.

At higher frequencies, usually above 500 MHz

Narrowband EMI or RFI interference, such as radio and TV stations, usually considered to cover frequencies 300–3400 Hz.

Broadband EMI or RFI interference such as electric power transmission wireless networking specification that extends throughput up to 11 Mbit/s using the same 2.4GHz band.

The computer runs at a certain clock rate as determined by an internal oscillator. Most of the time the rates are something like 4.77 mHz, 8 mHz, 12 mHz, 16 mHz, 20 mHz, 25 mHz, 33 mHz, 40 mHz, 50 mHz, 66 mHz and 80 mHz

This is not the only clock involved, there is also another oscillator on the video generator card. The video card also generates RFI because the data-pixel-rate is often high enough to fall into the HF regions.

The PC keyboard also generates an amount of RFI. This is because it contains a microprocessor on board which runs off a clock in the 3 mHz range.

The monitor probably has an on-board crystal at about 14.316 mHz so you will find a strong carrier there too.

 

I don't know it is righr or wrong. Just for the information.

[Speedskater]

I'm not at all sure why a big company like 3M would call 1 GHz interference EMI. But looking through the brochure, I don't see what hi-fi problems that it would solve.

Random placing a sheet is not is not going to solve any real problems.

[NAIDIVER]

I'm not at all sure why a big company like 3M would call 1 GHz interference EMI. But looking through the brochure, I don't see what hi-fi problems that it would solve.

Random placing a sheet is not is not going to solve any real problems.

 

I think you should try to downclock cpu speed, ram timing,vga card to run at 800 mhz. Lower voltage to their min in power range. You will see how they impact to SQ. It caused from EMI or not. I don't know. I try searching it.

 

Wifi and wireless mouse/keyboard are also impact to SQ. You should try to compare them between connect and disconnect.