 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
12.152.73.126
I was considering this tweak and wanted to know if anyone had tried it yet. I searched the forum and did not find it.
I was going to take an aluminum or 302 stainless steel (the type of stainless steel without iron and is not magnetic) duplex outlet wallplate and then put EMI shielding tape on it. The tape adhesive is electrically conductive so that the metal of the EMI tape would be conducted to the metal wallplate and then the wallplate would be conducted to the duplex outlet through the metal wallplate mounting screw. Consequently, it seems that it should be safely grounded. Of course, the openings of the wallplate for the outlets and the mounting screw would not be covered.
Here are some of the 3M EMI Shielding Foil Tapes that have conductive adhesive:
All of the shielding effectiveness is for far field 30 MHz to 1 GHz.
Copper Foil Tape 508SN, 50dB to 60dB
Aluminum Foil Tape 1170, 60dB to 75dB
Copper Foil Tape 1181, 60dB to 80dB
Tin-Plated Copper Foil Tape 1183, 70db to 85dB
http://solutions.3m.com/wps/portal/3M/en_US/AdhesivesForElectronics/Home/Products/EMIEMC/ShieldingFoilTapes/
Is this kooky or might it work for less than some of the audio wall plates sell for? Thanks for any thoughts
Follow Ups:
What exactly are you trying to shield against? Anything EMI related that is happening in your outlet box is going to be carried right through the shield by the power cord and into your equipment. It will not make one iota of difference. The proof is easy. When you touch the center conductor of a cable to the input of your preamp do you hear 60Hz hum? Yes, you do. Your listening room is full of EMI radiated by your house wiring. (and cell phone and any other electrical device in your home) Your cover plate being shielded can do nothing to change this. It is avoided or controlled by using shielded cables and good grounding. I'm an engineer and I have EMI experience. The psychological effect of shielding your cover plates could make a massive difference to the sound, however.
After lots of tweaking here are the results:
1. I have a friend who is a physicist and also an audiophile and he tells me that continued tweaking to lower any interference will usually result in lowering the soundfloor, making the music darker but also making it sound more "solid-state". And I have to agree with him.
2. The tweaking I did resulted in noticable changes but it seems that they are all mechanical energies involved.
3. Maybe I have misunderstood all the talk about damping but to me it seems that it is not about isolating the equipment from the room as much as it is "isolating the room from the equipment".
Here is my room: It is a rectangle measuring 12 by 13 feet. But two adjacent angles are cut across at 45 degree angles with custom cabinets and desk space. So the result is a hexagon. The walls are raised wood panels fastened onto plywood and not onto plaster or wallboard. The ceiling is coffered wood. It has a wood floor with a large rug and two leather recliners. The counters are granite.
There are lots of hard resonant surfaces but the angles are all over the place so sound reflections do not really get a chance to form many standing waves.
I got some aluminum sheets from Home Depot and used silicone caulk adhesive to fasten them to the bottom of each granite counter. (These sheets are all hidden by cabinet doors.) This did cause the sound to "tighten up".
Then I used the EMI tape to connect all the aluminum plates. There was no change. Then I grounded the plates to the house ground. There was no change.
I replaced the industrial grade electrical outlets with Leviton Hospital Grade outlets. They have no copper or iron in them. All of the outlets are dedicated ten gauge circuits. (I will mention later how not having copper in the outlets may be important)
Then I replaced the thermoplastic wallplates with Leviton Jumbo 332 Stainless Steel Wallplates (non-ferrous) obtained from Leviton online and there was a big change. Not necessarily good. Things got darker. For appearance sake, all of the electrical wallplates in the room were replaced.
I also installed some 3M 2552 Damping Foil that I got from Graingers. Here is a tangent. This foil is absolutely amazing. I ended up in the attic putting it on the outside of the housings of all my bathroom exhaust fans and also the ductwork for the cooktop exhaust fan. This foil is also good on the sides of computer cooling fans.
But the foil is a thermal insulator and will make any warm component hot quickly. So I learned to install it only on things that were cold at operating temperature. I had to remove it from the outside of one side of my computer case since it reduced the radiant energy dissipation needed by the motherboard. It also is electrically conductive.
I ordered some fo.Q TA-102 tuning tape. I ordered it from The Cable Company and it took a couple of weeks but then it was drop shipped from The Lotus Company which is the US distributor.
I used my electrometer and neither the adhesive side nor the external side of the TA-102 tape was electrically conductive.
I ended up putting the fo.Q tape on the outside of the connectors for the powercords. I put small strips of both the 3M 2552 damping foil and the fo.Q TA-102 tuning tape on the new wallplates.
When I was finished the sound was almost unlistenable. It was absolutely dead. I had tuned out the "Liveliness" and gotten sterile clean sound. My knees almost buckled from despair. That had been hours of work and some money and then even my kids thought the sound was terrible.
I changed two signal tubes in my amplifier and noticed some change but then I went to my Martin Logan Depth subwoofer and made some adjustments. I had to increase the volume level. Also, there is a 25 Hz control that defeats the volume in that frequency range. Interestingly, I had to decrease the level of sound damping. (ie I ended up increasing the 25 Hz volume) When I was finished the sound was "listenable". After tweaking the subwoofer sounds and amplifier bias over time this sound has really grown on me so that I am extremely pleased with the results.
After conducting and living through this effort I came to a conclusion. It may be correct or not but it sure seemed to work this way for me.
The audio equipment makes the room "sing". We are all familiar with how adding a piece of furniture or opening or closing the drapes can have a big effect on the sound. But this is all about how the produced sound waves interact with the environment.
Everyone may have been saying this but I did not really grasp it. The audio equipment is vibrating both from being hit by the soundwaves of the loudspeakers and the vibrations caused by the device itself. These vibrations can travel through the powercord to the outlet and then to the electrical system of the house.
Like most houses in the US, my wiring is the standard Romex style sheathed 2 conducter with ground fastened to wood studs with metal staples. This makes for a very stiff device (the electrical wiring of the house) coupled tightly to the structure of the house. My wiring goes up the studs into the attic and then along the rafters to the load center. The vibrations (mechanical energy) can be transmitted through the copper wire of the audio powercords, through standard copper electrical outlets to the Romex copper wire fastened to the studs and rafters. The studs and rafters then send vibration to the walls of the room creating "extra" acoustic energy.
Having materials that have different resonant frequencies can result in the inefficient transfer of the vibration. By having the damping tape on the powercords, having thick stainless steel wallplates with damping tape, having an electrical outlet that has no copper that then connects to the copper wiring of the house there can be a change in the vibrational energies created by the audio system.
I found that this was very important for the audio system but not important for what was going on in the kitchen in the next room. The dishwasher or mixer may be annoying but they did not really change the audio experience. Consequently, I think that it is not just silence that is different but that maybe there are musical different order harmonics produced by the energy coupling before sound damping. These may or may not be objectionable but would be considered "Lively".
So, the "improvement" may be due to decreased sound or just the change of the sound (different order harmonics). I can also see why some people may not get any change at all if the electrical wiring is fed straight through a wall from another room.
One experiment for this would be to get long ten or twelve gauge extension cords and then connecting all the audio equipment to these and then powering the audio through wiring from outlets that are not near the room.
I would like to thank everyone who contributed to this thread. All of the posts were considerate and generous.
Sure your idea might stop EMI from directly in front of the outlet.
If you receive AM/FM radio reception and your cellphone works inside your house. Then your walls are pretty much transparent to EMI.
On the one hand I know that tweaking is kind of like philately, an obscure passion which very few others relate to. My grandfather was a big philatelist. When he died we took all his stuff to the store and got about three hundred dollars and I (a young lad with Dickinsonian dreams of switching from pauper to king) was expecting thousands.
But on the other hand, I live in a CBS house (concrete block stucco) on a monoslab of concrete with impact resistant windows and a concrete tile roof. Cell phone, TV, radio and satellite radio reception is almost non-existant in the house. Though cell phone has become slightly audible over the past two years.
Regardless, I have gotten a suggestion for using the fo.Q tape and may try that.
Just finished installing new Non-Magnetic Stainless Steel AC outlet covers in my Two Channel system and my HT system.
Thought there may be a subtle improvement,but was blown away with the difference.In my HT system I am getting deeper more saturated colors with lower noise floor and better dynamics. Best bang for the buck in a long time.
My old AC outlet covers were mild steel.Mine are Double Gang and I use floor mounted AC outlets. They were about $6.00 each.
Made from 302 Stainless Steel and Non-Magnetic.You probably need Single Gang AC outlet covers.
I got mine at Amazon.
Then put a couple strips of Fo.Q TA-102 dampening tape on the back of the AC Covers and got another sonic improvement.If you have a Facebook account please check out all the other things I have applied Fo.Q TA-102 dampening tape too.
Edits: 10/13/10 10/13/10 03/22/14
Metal wall plates offer rigidity for vibration control intents and low dielectric effect rather than conductive benefit. Energy dissapation via semi-conductive carbon rather than trying to drain noise to ground via metal shielding is the effective mode of choice as available from Oyaide, Furutech, Acoustic Revive, et al.
Shields reflect electromagnetic energy. Dampers dissipate it as heat. Reflected energy results in resonance, while damping prevents resonant structures from storing too much energy.
Optimizing an audio setup requires judicious selection of shielding and damping.
Applying resistive materials, such as carbon fiber, to outlet plates helps damp the standing RF waves that would otherwise exist on the AC wiring and power cord. Applying shielding to the plates will simply make them better reflectors, and increase the magnitude of the standing waves.
Thanks, that makes lots of sense.
Or would the metal in the tape not have as much effect as the larger mass of aluminum or stainless steel that is already present in the wallplate?
"Or would the metal in the tape not have as much effect as the larger mass of aluminum or stainless steel that is already present in the wallplate?"
Yes.
Post a Followup:
| FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
||||||||||||||
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
