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Validating use of TI-Shield on R-Cs (long)

Posted by bartc (A) on December 2, 2007 at 20:14:18

Al Sekela and I have been experimenting in our very different systems
and listening environments with R-Cs for parallel AC filtering (and
R-Cs for speaker cables, but that's another post). These are among many
AC tweaks Al has cooked up and I have duplicated in different degrees
under his tutelage. Since they work similarly in our disparate
situations, I'm confident that the changes are real and significant
improvements.

The first one in question is the common parallel AC filter using an array of X-rated caps declining in values by a tenth (.47uf, .047, .0047) and
120 Ohm resistors that he has described in other posts on Tweaks Asylum
previously. We have each used different 2 prong plugs, different cap
values (I tried doubling and tripling the above), and placed them in
different locations adjacent to the audio system outlets, as well as
around the house - all of which are sonic improvements and cumulative.

The experiment last week was driven by a desire to see if Allan Maher's
suggestion of the use of grounded/earthed TI-Shield would improve
sonics. It was inspired by the recent post by Chris (cdc) on Tweaks of his use of grounded TI-Shield on his speaker cable R-Cs per Allan's
suggestion.

This was a single blind test. Al knew what he was playing with and I
did not. Test CD was Al's favorite Shirley Horn "You Won't Forget Me".
Al's system is a Wadia 861 driving a pair of Gilmore Raptor monoblocks
and Magnepan MG-20s. Suffice it to say that it's very revealing and
quite sensitive to changes in cables, tweaks, etc.

We tested the following configurations:
1) No extra filtering in play on the audio system outlets.
2) Al's honking big transformer/R-C-on-secondaries filter (he's posted
this before) in play alone.
3) R-C parallel filter in 3 prong plug with disconnected ground wire (only on the first test).
4) R-C parallel filter in 3 prong plug with carbon fiber sleeve around
R-C and disconnected ground wire (only on the second test).
5) R-C parallel filter with R-C surrounded with microsorb and TI-Shield
and shield grounded.

Note that the R-Cs were all burned in for at least a week on Al's system before the tests.

The results were consistent over 2 trials separated by about 1.5 hours, with the change between tests noted above and the second not being blind on either side, and Al claims that they mirror his own trials alone previously.

The order of improvement in sonics is as listed above, from least to
most.

The TI-Shield is definitely a significant improvement over all other
configurations with these filtering schemes. Improvements noted were:
lower noise floor; more palpable and pleasing string reproduction in
piano and double bass punched up in presence; vocals receded into
proper soundstage place, became more nuanced and fluid; sax timber
improved and became more pleasant. Overall, a critical listener would
appreciate all the improvements quickly; as with all these more subtle
changes, I'm not sure a non-audiophile would get it, but that's not who
we do these things for!

On return home last weekend, I mocked up my own test. My R-C parallel AC filters was brand new and not burned in (though the one it replaced had burned in for several weeks). My test started with my existing double value R-C AC filters that had been burned in, then with those removed, then with a newly designed R-C. I used a new R-C array in a 3 prong plug with no ground wire attached and no shielding; then followed with a grounded TI-Shield and microsorb surround on the R-C. The results were the same as previously at Al's, with the grounded and shielded yielding superior sonics very noticably as described above.

Now here's the kicker: I've been reconfiguring my R-Cs for speaker cables to accept these grounded shields, so I now added boxes, microsorb, and grounded TI-Shield. The difference from Chris' experiment (other than that I used smaller boxes for the speaker ends and one large box with one large shield for the amp end) is that I tied the shield grounds as a star ground directly into the AC parallel R-C filter I just described. That required using 14 AWG from the plug to a set of Euro termination blocks into which I tied the 12 AWG ground wires from the speaker and amp side R-Cs. This also allowed me to test with and without this new grounding scheme.

Again, the results with the shields tied to ground were noticably better than without. The strongest result were with the grounded AC filter and with the speaker end grounded R-Cs, less so (or already less distinguishably so) with the R-Cs at the amp end of the speaker cables. At this point I may simply have reached some limit of my ability to discern the differences with these tweaks, but they are definitely there.

In fact, the whole setup consistently sounds cleaner grounded, TI-Shielded, with R-Cs on the speaker cables and AC parallel R-C as well. Background is significantly blacker. No other way to describe it than the word "clean". Actually more like CLEEEEEEEAN! It's not sharp, fatiguing or analytical, just dynamic, full range and very clear and pleasing on all sources (FM and CD). I like this!

Thanks to Al for the R-C work, Allan for the grounded TI-Shield work,
and Chris for the stimulating post on speaker cable R-Cs using these
tweaks!

This post is made possible by the generous support of people like you and our sponsors:

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