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The Asylum forum has always been a wealth of information. I have the bug again to upgrade and tweak/improve my gear. In the last few days I have read for hours and hours and the TI Shield posts from several members including John Curl and Alan (audionutge) really peaked my interest. All of my gear is by Proceed and I also have custom built isolation transformer units (for the front end) that I would like to mod further with the TI Shield.I have some specific questions and any info would be much appreciated! The goal is to improve the sonics by eliminating as much EMI and RFI from the gear and system as possible. Here are the questions:
* Aside for transformer isolation devices, is this tweak also recommended on transports, DACs, amps, preamps, passive Xovers or power cords?
* As I understand it, the TI Shield is conductive. When you wrap the transformer, is there anything that should be placed between the TI Shield and the transformers? How about on the outside (otherside) of the TI Shield to protect the other electronics near by from contact/shorting? I am not clear if the TI Shield is actually coming in contact with the transformer.
* I have experimented with ERS cloth. The ERS cloth can actually degrade the sound if not really careful. ERS cloth does next to nothing in my system if placed above and or below my gear. Also no effect what so ever on my power cords. Only effect is near my passive Xovers. Does or can the improper amount of TI Shield effect the sonics?
* When wrapping a toroid transformer, should the entire transformer be wrapped, or just above the transformer? Also the amount of the TI Shield to use, same size as the transformer, twice the size, etc?
* When grounding the 12ga. wire, I read reference to "earth ground" and "chassis ground". Earth ground and a localized chassis ground within the piece of gear is the same thing isn't it? Or what am I missing?
* Any other recommendations, especially from members that have had success with the TI Shield or other similar tweaks while I am inside the gear that I can employ or try?
Too bad I cannot just hire John Curl or someone of his experience to just come to my house and do the work! :o)... Thanks in advance for any info or recommendations, it will be much appreciated!
Kindest Regards,
Chris
Follow Ups:
Ti shield is definitely conductive, to both electric and magnetic fields. This is precisely what makes it an effective shield.Usually shielding is most effective and easy to implement when it is at the source of the radiation. However there is a tradeoff, as Al Sekela points out here regularly the shielding material can alter the current flow of desired signal due to inductive coupling. Because of this undesireable but unavoidable tradeoff shielding should only be used if necessary and if it is necessary there will be a benefit to reducing the inductive coupling as much as possible by adding distance between the desired signals conductor and the shield material.
IMO Earth should always be tied to signal ground back at the service entrance no where else. Also IMO there should always be a earth ground tied to the chassis for safety reasons. My interpretation of NEC indicates no current should be flowing into or out of earth connection in a properly functioning system.
I appreciate the input and not only understand what you wrote, I also agree. I am a tweakaholic. I admit it, and have fun with it. I am just looking for insight on the most effective way of implementing this tweak. If the tweak provides any sonic improvement it was worth the price of admission. So any comments, assistance or ideas would be greatly appreciated.Thanks again,
Chris
I should have mentioned in my other post In my world chassis is always tied to earth but never tied to system ground or AC return inside the sound system. AC return and Earth should be tied at the box.Ideas? OK you asked for it. heh heh
To be succesful in designing a useable sheild you must base system layout/configuration with the end goal of assuring that effects you hold dear are maximized and effects you despise are minimized.
For example you could wrap power transformers in some spacer/insulator/non conductor of electric or magnetic fields type material to gap the shield wrapping away from the signal such that there is less of this problematic coupling between shield material and the power signal. Of course the other side of this is that circuits on the outside of the shielding must also be protected from coupling to the shield material as well. From the transformer example this means that you must also consider the protection of the circuitry the transformer is there to power in the first place from the shield material as well since it too may couple to the shield material to an undesireable end. How do they say? Don't throw the baby out with the bathwater? Physical seperation by distance between potential victim signals and shield material is good.
I think it is also important to note the idea of a Farraday cage when considering shielding layout. This is your ultimate goal in order to maximize the benefits of shields. Large apertures and any deviation from the perfect goal of a perfectly enclosing cage with only electromagnetically *small* or smaller apertures will reduce the effectiveness of the resulting attempt at shielding.
What the other poster was saying about good high frequency grounding via physically larger conductors is right on. My understanding is: because of skin affect the conductivity of a conductor is related to frequency of the signal and shape of conductor. A way to guarantee a usable low impedance ground connection is to have conductors that have large dimension/s. Low impedance Erths are important to the effectiveness of earth grounds just as they are in other grounding aspects such as circuit board ground planes for example.
Chris,First of all TI Shield is NOT conductive. It must be grounded with a minimum of 12ga. Next, you will need to experiment when it comes to placement. I have found over the years my system sonics played a major role in placement and amount used. In some systems placing a 12" x 12" grounded square on the top cover (internal) offered a major step forward in top end harmonics, and in other systems it offered very little. The space gap between the top of the transformer and top cover plays a major role in the capacitance build up created by the magnetic interaction between the TI Shield and transformer. Pending what value x-caps you have across the line also plays a role in creating a transparent filter between the shield, trannie, and ac filter. In systems with no parallel filter I found wrapping the transformer offered the best results. In this application I tackle ringing isolation, shock mount, and harmonics. First start by removing the transformer from the case. Install a 1/4" thickness of Microsorb. The material does a fantastic job of reducing vibration in the transformer. Reducing vibration does wonders for odd harmonic filtering. Next, place a 1/4" sheet of EAR C-1002 on top of the Microsorb. C-1002 will isolate harmonics created by the chassis. Install the transformer. I assume the isolation transformer has the standard cardboard jacket around the outside. In this situation add the TI Shield over the cardcoard and solder the shield to connect the edges. Solder the ground wire to the shield and ground back at chassis star ground. To step it up another notch, place a thin layer of C-1002 (.015") between the outlet and chassis. In this location the C-1002 will reduce the ringing caused by the outlet. You may find expensive outlet upgrades not required after this tweak is applied.
Keep in mind I no longer use this product in my power conditioner designs.
Alan
Thanks for responding and the information. The Isolation transformers (I have two of them) started out as 7amp Hospital grade Powervars. There are two Auricap .47 uF 600V in parallel installed in the units. I also have already upgraded the recepticles to Furutech outlets. I have tried to remove the bolt that holds down the tranny with no success. The bolt is epoxied into place. The tranny does not have cardboard surrounding it, the sides are wrapped with nylon type material. The unit cover is approx. 3/4" above the top surface of the tranny. Ok, allow me to translate and recap what you wrote to make sure I understand correctly.* Because there is an in line cap filter, afix the TI Shield to the underside of the top metal cover of the Isolation unit, instead of wrapping the tranny. Is this correct?
* You mentioned, a minimum of 12ga. for the ground. Will 12ga. do or can you recommend a larger gauge wire?
* I gather from your post that I will have to experiment with the amount of TI Shield to use for best results in my system. Can too much of the TI Shield material degrade the sonics in my system?
* Aside the transformer isolation devices, is this tweak also recommended on transports, DACs, amps, preamps, passive Xovers or power cords?
* The last question that beckens to be asked. Since you no longer use the TI Shield for your power conditioner designs, what are you using? :o) I obviously understand if it is a secret...
Thanks for your patients and assistance. I know I have many questions, I like to do things right.
Chris
"Because there is an in line cap filter, afix the TI Shield to the underside of the top metal cover of the Isolation unit, instead of wrapping the tranny. Is this correct?"I know you don't want to hear this, but you still need to experiment between top side and wrap. There are so many factors that play a role in this type of tweaking. You may find wrapping the transformer and removing the Auricaps offers the best frequency balance and noise rejection. I no longer advise Auricaps to be used across the a/c. If you really want to build a kick ass plc for little bucks, e-mail me and I will help you design something that will knock your socks off. In my opinion, parallel caps are a thing of the past.
"You mentioned, a minimum of 12ga. for the ground. Will 12ga. do or can you recommend a larger gauge wire?"
12ga is the bare minimum. You have to make sure that the wiring can carry the frequency you are trying to suppress. 12ga to 8ga does a very good job of reducing frequency in the high EMI range. A dual 12ga ground would be even better because the twin ground lowers the impedance.
"I gather from your post that I will have to experiment with the amount of TI Shield to use for best results in my system. Can too much of the TI Shield material degrade the sonics in my system?"
I have played with TI Shield for over 10 years now and I have never run into that problem.
"Aside the transformer isolation devices, is this tweak also recommended on transports, DACs, amps, preamps, passive Xovers or power cords?"
Digital and transformer based components work best. Switch mode power supplies, dac chips, and transformers respond the best. I never tried it with a x-over. I did try the power cord idea a couple years ago and hated the result.
"The last question that beckens to be asked. Since you no longer use the TI Shield for your power conditioner designs, what are you using? :o) I obviously understand if it is a secret..."
It's not a secret....I build a custom system for a/v studios called The Washer. The system is based on Plitron NBT transformers, Quantum products, Shakti Innovation products, and our magnetic filter. To my knowledge it is the only professional a/c system to be able to reproduce 24/192KHz noise levels. Keep in mind it's not a one box solution, and it requires a lot of hours for the install.
Let me know if you want me to give you a hand.
Alan
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