You are reading the older HTML site

Positive Feedback ISSUE 19
may/june 2005



AC and interconnect filters

as reviewed by Larry Cox






Ensemble Figura.

E.A.R. 509 amplifiers and E.A.R. 864 preamplifier both with a mix of Mullards, Telefunkens, JJ Electrics and a mish-mash of whatever gets good sound out of the system, and an ATC SIA 150 integrated amplifier.

Audio Note CD3.1x CD player. Amazon Model 2 turntable with a Moerch DP6 arm and a vdH retippted Koetsu Rosewood Standard.

Ensemble Dynaflux and Calrad balanced interconnects. Speaker cables are either Ixos 6003 or Belden 1219A.

A Lovan Classic Rack, Townshend Seismic Sink, Calrad balanced microphone cable as an interconnect, Silver Audio Silver Bullet 4.0's, assorted Vibarpods, Final Labs Daruma III isolation bearings, Black Diamond #3 and #4 cones, with Black Diamond Whatchamacallit's, DH Cones, Discsolution, ASC Tube Trap Bass Trap and assorted other stuff. I hear the differences these items make, but only use them to optimize if the review isn't going well. Too much work to swap out a piece and balance it on Darumas and then take that out and plop the next component on the Daruma's again. Using all these consistently is a pain as what works with one component isn't a welcome addition for another.


As I close in on the sound I want for my system, it is a bit more analytical and less emotional than I'd like. I'm not in pursuit of a romantic sound, but I'm also not a fan of very detailed, but dead-in-the-water sound. Although such systems can sound emotionally expressive, it's the exception rather than the rule. Often, these systems sound like an autopsy. There's a body, and all the parts are present and in the right place, but there's no life. Music is an emotional medium, and I want—no, demand—emotion in my system.

I heard an astonishing system at CES consisting of Reimyo electronics, Bravo speakers with a prototype subwoofer, and Harmonix wiring. The sound was the best at the show, by a good margin—engrossing, emotional, and detailed. Given the size of the components and the simplicity of the layout, I thought I'd misspent my audio money, though as often happens, I changed my mind when I learned the cost of the system, which was easily twice that of mine. I was taken by the sound, and told May Audio's Lance Van Schoonhoven that I wanted some of what they had working, but couldn't pay for it. At some point during the conversation, either Lance or a Combak rep said that there was no magic without the Enacom filters. As a recovering slut for good sound, I fell off the wagon quickly. What? Could the smoothness and emotional, inviting detail be attributed to the Enacom filters? At around $100, I could give them a try without having to replace my system, so I requesteds review samples, and Lance sent a set of AC, speaker, and interconnect filters.

I've always wanted little or no part of tweaks. I knew that they made a difference, but that they built upon the component architecture of a system. Once my system structure was in place, I'd be interested in tweaking, not before. This is why I passed on listening to the Enacom filters when they were review items for audioMUSINGS about ten years ago (see that review here), but now I thought that they might be able to give my system a bit more emotionality. From other reviews, I've gleaned that the Enacom AC filters reduce EMI and RFI in your power lines by means of parallel filtering, which means that they plug into an electrical socket in the same circuit as the components that you want filtered. I plugged two AC Enacoms into the spare electrical socket where I'd plug my API Power Pack and another in a spare socket on the same circuit.

Part of my interest in the AC filters arises from living next to a fanatical ham radio operator who has at least seven large antennas in his back yard. Fortunately, only one of these operates at a time, but occasionally, no matter how well my interconnects, power cords, and speaker cables are dressed, and depending on the frequency he's hamming on, I hear Stew loud and clear. I was hoping that the Enacom AC filters would do something that ferrite rings had not, which was to extract Stew from my stereo. With the AC filters in place, he was nearly banished. Although I heard him on one or two occasions, the volume level of his intrusions dropped. The AC filters definitely helped with the RFI, but they didn't eliminate it.

Aside from that, inserting the AC filters quieted the sound noticeably. Some unnoticed ringing in my system was attenuated, and music had a quieter, blacker background. With that increase in blackness came a more expressive musical presentation, which in turn delivered more emotionality and intimacy, especially in the vital and sensitive upper midrange. Top-end detail was sweetened and perhaps softened, though there was no loss of detail. All of the detail that I heard before inserting the AC filters was still present, but the spikiness of the sound was reduced. I preferred my system with the AC filters. I initially feared that I was losing musical information, but it wasn't so.

The Enacom speaker filters had a similar effect. The speaker filters are placed between the speaker cables and the speaker terminals, but the cables are not inserted into the filters. They simply share the same connection. A knowledgeable friend told me that the speaker filters might cause oscillation if I placed them between the speakers and a tube amplifier, but I did not hear oscillation, and the gains wrought by the Enacom AC filters were multiplied by the speaker filters. I heard a further lessening of the level of background noise and a purer quality to the tone—something I value very highly.

I enjoyed the sound, but over the course of a few weeks, a niggling sense that I was losing detail began to creep in. In a fit of audiophilia, I spent the better part of an afternoon going back and forth between speaker filters and no speaker filters. (I did leave the AC filters in place.) It did appear that I was losing detail, but the detail I was losing was added noise and ringing. On Ry Cooder's Jazz CD, when his fingers dance up and down the fretboard, you can occasionally hear a squeak of human flesh dragging across the strings. Without the Enacom speaker filters, the squeaking was more sibilant, louder, and leaner, with less color. With the filters in place, the squeaking had more body, or perhaps I should say that it had more sustain and less attack and decay? In short, I found the differences small, though worthwhile. My system is now quite resolving, with a purer presentation, but not at the cost of detail. This was a worthwhile upgrade.

The Enacom interconnect filters are plugged into your amplifier, where the filters sort of act as female RCAs. This time, the noise floor seemed to dropped a bit, but maybe I was only imagining it. I tried going back and forth with these filters, but couldn't definitely say that they made a difference. It may be that in another system—perhaps a brighter one than mine—the interconnect filters would make a bigger difference. In my system, they didn't raise the flag for a "yes." 

The Enacom AC and speaker filters helped me bridge some of the gap between my system and the megamegabuck Combak system I heard at CES. My system is now quieter, and there is less ringing. Even with a $159 Sony 875V DVD player temporarily acting as my reference CD player, my system sounds quite musical, with the sort of detail that allows musical expression. I'm certainly not making the Sony my long-term reference player, but I'm not suffering too much with it as my digital source.

I'm happy for the increase in the emotionality of my system. Although I probably have a unique set of RFI problems, they were definitely attenuated by the Enacom AC filters. All of the Enacom filters warrant a look. They will be worthy additions to most systems. Larry Cox

Enacom Filters
Retail: AC Filter, $85; loudspeaker filter, $99 a pair; interconnects, $150 (all priced as pairs)

May Audio
TEL: 423. 966. 8844