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In Reply to: RE: Validating use of TI-Shield on R-Cs (long) posted by bartc on December 02, 2007 at 20:14:18
As per Chris and Alan, the earthing wire gauge does make a difference to the sound. As per Al and all of the above, these things do sweeten up further with a week or more of burn in. I"m really having fun here!I just started replacing my older R-Cs on AC cables with these Ti-Shielded newer versions and so far no adverse affects. I'll report on this later as I go along and they burn in.
Meantime, here's a crappy picture of the first one with the speaker cable grounds crudely tied in. (I realized after posting that this photo showed only 2 ground wires from the speaker/amp R-Cs and there are actually 3; one had come loose!) What you should see if you were here is: 3 ground wires coming from the speaker cable R-Cs (one is in a combined box at the amp end, rather than 2) wirenutted into 3 14 AWG ground wires from the AC R-C filter; a white PVC plumbing fitting as the base of an eventual housing; inside the fitting is a Ti-shield and microsorb strip surrounding the X rated R-C filter array of 3 C values as described previously. What you cannot see is that the TI is grounded into the same plug as the AC filter below with a 12 AWG ground wire, nor can you see the 3 prong plug at the bottom.
I like housing these things in the plumbing fittings for safety and aesthetics, but you don't really have to do that at all.
Edits: 12/09/07Follow Ups:
Hi,
Thanks for sharing your great work.
I am interest in this project and would like to consult you on the followings :
1. Is the TI shield easy to cut and shape ?
2. How do you connect the 12 AWG ground wire to the TI shield ?
3. Is the TI shield placed around the R-C filter in an open tube form ?
4. What is the thickness of the microsorb material used in your project ?
5. Do you think this 'TI shield' project can be applied to other parts of the audio system such as DAC and speaker X'over ?
Thanks
YC
A smaller iron won't provide sufficient heat. Clean the surface carefully: start with Brasso if it is corroded, and remove the residue with a powerful solvent such as Goof-Off (sold for removing dried latex paint spatters). Use some liquid electronics grade soldering flux and a good solder such as WBT. Clean off the residual flux when the joint is cool.
:-)
1) Yes, I cut mine with ordinary scissors, shape it by hand. It's just a thin sheet, mostly copper, so it forms reasonably easily.
2) First I punch a hole in the TI, then I crimp roughly the stripped wire end through the hole and onto both sides of the TI. Then I solder it (not the easiest to do), then I close a flap of TI over the soldered wire joint. So it's really both soldered and physically held in place. Sometimes I add electrician's tape.
3) Yes, and you don't need to overdo it. My big caps are about an inch wide and that's about all that's really needed of the TI, an inch strip or slightly larger. Make sure you do the Microsorb first, because you'll discover that you need extra TI due to the width and bending involved, plus the flap over to solder a complete tube together. I'm not actually sure you even need a complete tube - you clearly don't on the speaker cable R-Cs at all, BTW - but I'm using that.
4) I'm using the quarter inch version, the thinnest. Al's using the larger size I think. It doesn't appear to be a major factor here at all.
5) Have no experience, but thinking of these applications. Somebody else in the archives did post that it does help in these places, as well as with torroids. I'd try the microsorb and TI layer, but not sure about grounding in such applications at all and wouldn't know how to do it properly myself.
Another consideration: TI-Shield is highly conductive. So I wrap the ones in my AC filters with a layer of electricians tape, having discovered the magic of a short in tight places! In the speaker cable R-Cs you can see that Chris advised a spacer that's non-conductive - cotton in his case and Microsorb in mine - for that very reason.
Hi,
Thanks for your kind reply.
Do you solder the overlap areas of the TI shield to form the open tube ?
TI shield seems to be a wonderful material. Chris used TI shield on one side of the RC filter and got the improvement. How about the influence by the electro and magnetic field on the RC filter from the side that not protected by the TI shield ? This is the point that I cannot understand.
YC
Shielding reflects energy, while damping absorbs it. Contrast a mirror with a piece of black velvet. If you were to build a dark room, would you line the walls with mirrors or black velvet?
TI-Shield in this application is acting as a damping material. RF noise travels along wires and through components as electric and magnetic fields. The center layer of TI-Shield is a high-permeability alloy that provides a low-reluctance place for magnetic fields to go. Since these fields are time-varying, they induce eddy currents in the copper outer layers. The copper has some resistance, so these eddy currents dissipate energy from the RF noise.
A shield, such as a thick piece of copper, would reflect the RF energy much more than it would absorb it. Shielding, to be effective, requires complete coverage of the circuit with the shielding material, and then you still have the RF energy bouncing around inside.
Damping, on the other hand, does not require complete coverage. This is why Chris' design works. I should also point out that I do not know if the cylinder shell of TI-Shield is optimum for the AC damping networks: it may be overkill, or too little. It is clear, though, that you do not want the TI-Shield piece to be able to vibrate in response to room sound. Putting a vibrating piece of high-permeability material next to a circuit invites severe microphonic behavior. The Microsorb or equivalent acoustic damping material is very important.
Hi Al,
Thanks for your explanation on the concept of noise energy reflection versus absorption. I learn a lot from you.
That helps. I'll stop incorrectly using the term "shield" when I mean "damping", though the manufacturer obviously capitalized on it.
At long last I'm starting to get it!
I was trying to understand how a one sided shield would work, when what I understand of Faraday cages requires a virtually complete surround. Never got an answer that I could fathom, but did find that you simply have to experiment to know what works and what doesn't. Some of these shielding schemes can be easily overdone for audio purposes (ERS, carbon fiber, etc.). What works where and why is still a mystery to me other than what I've tried myself.
The TI in cdc's post is one-sided, but his is for a low current speaker cabling system. I'm duplicating that to good results. He experimented with this, so between his results and mine, I'd say follow that recipe for speaker cabling.
However, I thought you were asking about my use of it in AC filtering R-Cs. In that case, Al's results and mine were with a TI tube, open on bottom and top. This is a different application with different kinds of caps (X rated for AC vs. silver mica for speakers), different values of caps and resistors, that has to carry the full current of your AC input at 120V. In this case the full tube of TI doesn't seem to be any problem, though I can't honestly say I experimented with other configurations here.
Yes, I solder the overlap of the TI tube together, but not like a joint for the hull of a ship! Just enough to make secure electrical contact. I don't try to solder the little flap I hand close over the drain wire where it's soldered into the hole in the TI, though. That seemed overkill to me.
As to solering, I got a 40 Watt iron and used the liquid flux as Al suggests. This wasn't particularly easy for me to solder either, but I'm really a complete novice at soldering.
Hi,
Thanks for the input.
It seems the optimum usage of the TI shield involves many factors. I will purchase some TI shield and microsorb to do some experiments.
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