Line Conditioning

by Romaz, Community Member
Excerpted from

Line conditioners can do a good job of eliminating HF noise in mains but many are current limiting (or at least stunt dynamics) despite the manufacturer’s claims to the contrary. Dan D’Agostino, for example, advises not to plug any of his amplifiers “into a power strip or power conditioner.”

Of the many that I have had a chance to try, a few have stood out, largely because I did not find that they stunted dynamics. In this preferred group are the Shunyata Triton V3, SR PowerCell 12 UEF SE, AQ Niagara 7000, and the Sound Application TT-7. Within this short list, the Shunyata Triton V3 sounded the most dynamic and amps plugged into the Triton V3 actually sounded more dynamic then they did plugged into my wall (and my wall is wired with 6awg wire). With the other conditioners, however, there was still generous dynamics displayed with no sense of compression when compared against plugging straight into the wall. Ultimately, it is the Sound Application TT-7 that rose to the top for me and the Extreme definitely scales to it.

Sound Application Power Grid Interface TT-7

@onlychild suggested his Sound Application C7 is an “entry level TT-7” and this isn’t really true. The C7 was first released by Jim Weil 8 years ago and was based on copper foil capacitors. From there, Jim released the T7, his first unit to utilize expensive virgin Teflon capacitors and finally, in early 2018, he released the first version of the TT-7. Since its initial release, the TT-7 has gone through 8 revisions culminating in what he considers to be his final version, the Power Grid Interface TT-7. Having had the opportunity to hear each revision, some revisions have resulted in small gains and others larger gains but the culmination of these improvements from his initial TT-7 to this latest TT-7 is a rather giant chasm. Against the C7, this gap is even larger.

All of Jim’s line conditioners, including the C7 provide 3-stages of surge protection without the use of MOVs that degrade with time. They also provide power factor correction and using Jim’s meter, I found my power factor go from 0.91 without his unit to a perfect 1.0.

While all line conditioner designers believe their way is best, Jim believes the problems with mains power is not common-mode noise but rather transverse-mode noise and so he filters for both. No one else seems to even talk about transverse-mode noise. Where most conditioners filter into the MHz range (for example, the Shunyata TritonV3 suppresses noise by >24dB to 30MHz), Jim claims his unit suppresses noise to 80dB up to 2.5GHz which addresses HF noise created by such things like microwave ovens. Ultimately, the only thing I care about is how my system sounds with this line conditioner in place.

Using the Stromtank S2500 for comparison, as previously stated, the S2500 resulted in a fairly significant drop in the noise floor compared against my dedicated 30A line. Against the TT-7, I could hear zero difference in noise floor. Zero. In blind A/B testing, it wasn’t a fair fight because where the S2500 results in soft transients, the TT-7 results in incredibly fast transients and so the resolution of my system was much higher with the TT-7 and anyone I blind tested easily picked up on this. What I did then was I plugged the TT-7 into the Stromtank unit and I blind tested my group with the Stromtank in hybrid mode vs battery mode. Without the TT-7 in line, it was fairly easy to hear the difference between hybrid mode and battery mode but with the TT-7 plugged into the Stromtank, no one could tell any difference at all. This told me that with the noise in my environment, the TT-7 was filtering as well as a battery.

While low noise floor and no dynamic compression are important, where the TT-7 runs circles around the other line conditioners and against the Stromtank is with transient response and in this regard, this latest TT-7 is what I consider to be the “Extreme” of line conditioners. Its ability to respond to transient demands is unparalleled from my experience and all the other conditioners that I listed sound slow and smeared in comparison.

Is the TT-7 perfect? No, it is not. The more things you plug into it and the more these things draw current (like amplifiers), according to Jim, line impedance actually drops and so this is a good thing. At the same time, if you plug a noisy component into the TT-7, such as a component with a poorly designed SMPS, that component will pollute the other components as the TT-7 only filters against mains noise and not against other components plugged into it. There are scenarios where you may require 2 TT-7s and so this becomes a more expensive proposition. This latest Power Grid Interface TT-7 is not inexpensive at $15k but I consider it just as foundational to my system as the Extreme.