Does a 260-pound loudspeaker that packs an 8- and 10-inch driver need any re-enforcement in the lower octaves? Add in a delicious amplifier that can generate 500 watts at 4 ohms with ease and you are off to the races, right? The engineer in me is always looking for opportunities to continue to move closer to that moment when the music was recorded. The release of a new Wilson Audio ActivXO stereo crossover designed by John Curl tickled my interest. I was fascinated to see what would happen if I added a pair of 211-pound Wilson Audio WATCH Dog subs and Wilson ActivXO into my room. Could these elevate my system further? If so, in what ways and by how much?
Wilson Audio ActivXO: Do I really need subs?
Over the years I have listened to musical systems where they added a set of stereo subs to various loudspeakers. In the setups that were done correctly, it was not about more bass. Instead, it was about creating more space. By “space,” I mean that feeling when you close your eyes and the associated soundstage grows and takes you a few steps closer to that feeling of being there at that moment when the music was recorded. You immediately get a better sense of the venue where the music was originally performed and recorded. It’s the extra little bit of pressurization that gets your body engaged, and instruments and vocals seem to fill in that last little 10% and there is a great sense of weight and gravitas.
Bill Peugh of Wilson gave the following analogy at Music Matters in early March 2020 at Definitive in Seattle, Washington:
“When you are in a concert hall, and all the doors are shut, except for one, and that last door is closed, you feel the room pressurize. It is an exceptionally low frequency feeling, and every sound that occurs in that hall happens on top of that noise floor. That is how you identify the hall and the space. The bonus you get from it, it adds dimension and body to voices and instruments.”
As Bill mentioned, when that door closes, that hall pressurizes. You are experiencing something low down around 20hz, you cannot hear it as much as you feel it. This is part and parcel of creating the time machine when you create a great listening system.
One of the first times I experienced this feeling with 2-channel reproduction was at RMAF 2013 when David Wilson demonstrated Wilson Audio Alexandria XLF with two Thor’s Hammers subwoofers. That evening showcased a recording done by David Wilson of a 50-piece symphonic wind band conducted by Lowell Graham.
In the featured recording, called “Liberty Fanfare” they used a special drum beater that they referred to as the MOD, or “Mallet of Death” to power down on an oversized 40inch bass drum. The sound of that drum reproduced is something I will not forget.
Now, can I produce similar results in my room using the Wilson Audio ActivXO and two Wilson WATCH Dog Subwoofers?
Wilson Audio ActivXO | What’s New
The Wilson Audio ActivXO ($4500) is a two-channel, fully analogue electronic crossover. The ActivXO was designed in partnership with the legendary John Curl. John Curl worked on Mark Levinson’s early electronics, built the Vendetta phono pre-amplifier, and now designs the reference products for Parasound.
Compared to the original Wilson Controller, the new Wilson Audio ActivXO provides a 24dB drop in signal to noise ratio (SNR). In addition to a lower SNR, the ActivXO provides an extra 8dB of gain, giving more headroom to integrate a subwoofer in case it is needed. The Wilson Audio ActivXO now comes in two colors (black and silver) and supports a stereo configuration allowing you to use a single Active XO to integrate a pair of subwoofers. My favorite new two features are the inclusion of small memory rings on each knob allowing you to remember your exact dial positions as well as four different 12volt triggers to integrate the Wilson Audio ActivXO into your room’s automation.
Wilson Audio ActivXO | Subwoofer LFE vs. 2-channel Integration
There are two common configurations for setting up a subwoofer. The first is to integrate the subwoofers into a 2-channel music listening environment. In this configuration, the Wilson Audio ActivXO allows me to extend my 3-way Wilson Audio Alexia loudspeaker into a 4-way speaker by integrating a Wilson Audio WATCH Dog ($10,000 each) with each channel.
The other and more common subwoofer configuration is adding a subwoofer to a home theatre setup. In this mode, the subwoofer acts as the LFE (Low Frequency Effects) channel. When most movies are mastered, the engineer uses five full range speakers and a subwoofer. The role of the sub is to provide 10db of headroom. It is there to create that explosive scene while you are watching cinema. In my multipurpose room, we listen to music as well as watch movies. Music stays pure two-channel and the surround system gets access to my front two loudspeakers using the home theatre pass-through on my D’Agostino Momentum Preamplifier.
You can setup both configurations on the Wilson Audio ActivXO and switch between them using a toggle switch or a 12V trigger on the ActivXO. Specifically, you connect both a Main Left/Right line-out from your preamplifier to your ActivXO (to integrate into a 2-channel system) as well as an LFE connection (to integrate for multi-channel) from your surround processor to the ActivXO.
Wilson Audio ActivXO | Setup is everything
A subwoofer’s setup correctly can create magic, but if you get it wrong it will destroy the ability for a system to create engaging music.
At CES 2019, I was invited to come and listen to a special presentation of music presented in Dolby Atmos at the Dolby booth. It was a demo that left a lot to be desired. Its failure was not the content, but rather the setup. The front speakers were pushed deep into the corners of the front of the room (I assume to look more appealing), and the subwoofers had issues stemming from being far too loud and out of phase with the main loudspeakers.
Wilson Audio ActivXO | Let us setup and let the dogs run…
Once we had the two Wilson WATCH Dogs out of their bullet proof crates, we rolled them into the room. I did not have much space to experiment with, so the Dogs were placed just inside each of the Alexia’s, equidistant from each loudspeaker and my listening position.
Hook-up was very straightforward:
- Balanced out from my pre-amplifier left and right out to the line-In on the Wilson Audio ActivXO
- Balanced out from my surrounds processor LFE out to the LFE-in on the ActivXO
- Balanced cable from the ActivXO to a Parasound amplifier
- Speaker cable form Parasound amplifier to Wilson WATCH Dogs
Integration with my Dan D’Agostino Momentum HD Preamplifier was seamless since it provides two sets of main left/right outputs.
The cables used to integrate the ActivXO and were AudioQuest Element Series Fire as well as their new AudioQuest Mythical Creatures Series FireBird BASS speaker cable for the subs. An AudioQuest Wind Series Blizzard power cable was used with the Parasound amplifier.
All other interconnects in my system during this evaluation were my reference Transparent Audio Opus Generation 5.
Let’s walk you through the journey to give a sense of what is involved in order to do this correctly. I will simplify the setup procedure here to give you a sense of the work required, but if you make this kind of investment, please work with a certified dealer as they are trained to do this. We started by setting the crossover slope to 18 dB per octave per the Wilson recommendation. Next the crossover point was set using a pot to 31hz. The Alexias can dig deep, and this allows for a smooth integration. We started at 31hz and ended up staying there.
From here, it is a dance very much like setting up a turntable stylus. It is an art of adjusting gain and phase per channel with the end goal of getting the loudspeaker and subwoofer to sing together as one unit. The challenge is that these parameters impact each other. Any adjustment to phase will impact gain so it is an iterative process and one that should not be rushed.
To aid this setup we used an iPhone running AudioTools for iOS to provide an RTA with associated pink noise (set at 1/3 octave with 3s decay). At our initial install, I could feel David Wilson’s presence with us, as we were using his personal USB microphone for the installation. I can only imagine how many Wilson products were voiced with that microphone.
The dial-in dance begins with establishing a basic gain level match of the right sub, with the right speaker and likewise for the left.
Now that the levels match, it is time to move to phase. Phase follows a similar playbook where you match the phase of the right sub to the right speaker, the left sub to the left speaker, and then finally ensure that both left and right subwoofers are in phase with each other.
You can get a sense that they are in phase as you will start to see the highest output in your RTA on the low frequencies when they are aligned. Now that the phase is correct, the level gains need to get adjusted since they were impacted by the prior phase adjustments.
The process requires many iterations and time staring down at the lower octaves of the RTA in AudioTools to see that everything is working together as one 4-way speaker.
After the dance, and lots of listening you get to the happy spot where the subwoofer and loudspeaker start to feel like a single 4-way speaker. Once achieved, you immediately set the memory rings to keep that perfection recorded. There is a master volume knob on the right that I used to make micro changes from time to time depending on my mood and taste.
Wilson Audio WATCH Dog Subwoofer | It is all about linear phase
The 211-pound Wilson Audio WATCH Dog is not new, but it is not something old either. Although it is the entry level subwoofer in the Wilson line, it is everything you would expect.
It starts with the same 12-inch dual spider woofer used in all the larger Wilson subwoofers (Thor’s Hammer, Subsonic, Master Subsonic). The outer enclosure is all Wilson proprietary X-material, and it sits on those heavy-duty spikes and diodes that we have come to expect on all large loudspeakers from Wilson Audio.
I was curious about why I was having success with the WATCH Dogs vs. other subwoofers that I had tried in the past in my room. I called Peter McGrath of Wilson Audio to see if he had some more insights into what I was hearing. As he is a tremendous recording engineer and I wanted to hear his thoughts, especially since he has an almost identical setup at his home.
Peter explained something that completed the puzzle for me. By now you understand that it is critical for each loudspeaker and subwoofer to be perfectly in phase, so they are moving precisely together. The Alexia loudspeaker in my case is oblivious to the subwoofer sitting beside it. When they are in phase, they will sing together as one. BUT….
This relationship MUST stay in sync as the speaker and subwoofer dig down into the lower octaves. Just think, if you drop 1/3rd of an octave below our 31hz crossover, imagine how much more power the amplifier is pushing. If the phase of the subwoofer shifts as it goes lower, it will be out of phase with the main and you lose your musicality.
McGrath claims that the Wilson WATCH Dog can maintain linear phase all the way down to 14hz. This stems from Wilson using a specifically selected driver and a cabinet that is large enough for them to achieve this without adding any EQ. Other products sometimes address this by adding EQ, and we know as you add EQ, you are adding gain, and thus impacting phase. This ability to provide a linear phase all the way down to 14hz is part of the secret sauce on why this setup has the ability to be so musical. This only works when you have two subs that were setup as described earlier. For 2-channel music, this is a necessity!
All of this matters less for cinema when you use the subwoofer in the LFE configuration. As an LFE, it matters less that the explosion isn’t in phase with the sound from your other channels.
Listening | Get Ready
I had the opportunity to keep the WATCH Dog over the quarantine period of 2020, which made for lots of listening. I always preferred them on, and from time to time used the master volume on the Wilson Audio ActivXO to make small adjustments to taste. Sometimes you just want to really turn up the base and let it rumble.
The best way for me to explain what I experienced is to have you imagine that when you drop the needle, you genuinely feel like you are whisked away to a far away place at that moment when the music was recorded.
On Coldplay’s live version of “Fix You” on the Live in Buenos Aires album, I get goosebumps when the needle drops. You feel like you are there, surrounded by 50,000 fans. It is one of my favorite ways to demonstrate time travel when people come over.
With the addition of the Wilson Audio ActivXO, the reproduction was taken to another level. The additional pressurization, weight of the 50,000 fans singing in support, depth in the vocals, and the tonality of the drum kit as it slides in…this will change your perspective on reproduction of music. If you are a die-hard fan, I’d be passing you the Kleenex box.
Listening Part 2 | Digital vs. Analog, not what I was expecting
During my chat with Peter McGrath, he reminded me that so much of what I was hearing and feeling was the low frequency details. Although I was having some beautiful moments with my LPs, he explained that I might even have a better experience with some high-resolution digital recordings. This is due to the fact that many LPs when mastered have low frequency rolled off at 40hz or have their low frequency converted to mono under 40-60hz.
I wanted to understand this more, so I reached out to my fellow contributor and mastering engineer Dave McNair to get more details:
More than a low end theory | Dave McNair
“It’s an overly complex situation that has no black and white answers. Generally speaking, the low end (and in fact the rest of the frequency response) of a recoding will sound different when comparing the same release on vinyl and digital. In a very wide bandwidth playback system, all other things being equal (which they never are!) the digital version will sound tighter and seem to go lower in frequency than vinyl.
Why is this? It’s too complicated to reduce to a simple answer but in essence the response of a cutting head and a phono cartridge is not as linear as no head and no cartridge! Then add in the fact that many times (although not always) some amount of low-end filtering via an elliptical equalizer is done to get the music to physically cut to a lacquer.
Basically all the RIAA equalization, both pre- and post-, plus any eq used to get troublesome program material to cut, makes the entire low end very non-linear. This disrupts the frequency response AND phase of the original material, none of which happens to the digital release.
So even if the record is cut ‘flat’ and no elliptical eq is used, the record will still sound different in the low end than the digital version of the same release. “
Let’s get serious, this does not mean your LPs can’t dig deep and be super dynamic. Of course, they do! I’ve loved every LP I have played with the Wilson Audio ActivXO and the WATCH Dogs. It does mean that I do need to get my hands on some well recorded digital music to see how good this can get.
Listening Part 3 | Peter McGrath’s Live Recordings
Peter McGrath was kind enough to provide me some high-resolution masters of his orchestral recordings. On Peter’s recordings, everything was exactly as he recorded it, in some incredible halls. He felt this may even further my ability to hear even more when using these as a test.
One of my favorites is Kalichstein Laredo Robinson Trio with Cynthia Phelps, performing at Gusman Concert Hall at University of Miami from Feb 2016.
I listened to the album with the Wilson Audio ActivXO off to get acquainted to it. It was as expected a fabulous recording from Peter, that even without the fancy subwoofers would have been a dream to listen to. Flicking the switch on the ActivXO and activating the hounds certainly brought gifts. Piano tonality improved further with additional weight in the keys and improved transient response. It was like the keys of the piano were dancing in a gigantic hall with no re-enforcement.
Strings received more texture and weight. This added up to a beautiful tonality. The cello, in particular, delivered an emotion to my chest, something I hadn’t experienced in a while. This feeling was similar to what I had experienced in person when I visited a small symphony hall in Basel Switzerland a few years ago. That night a small quintet ignited the room with no sound re-enforcement. Just the sound from the instruments was all that was required to energize the hall.
Back to my listening room, I toggled off the Wilson Audio ActivXO and listened again. At this point, it was clear that I had lost a little life in the piano keys and strings, and everything felt a little soft this time.
Another memorable recording was Valentina Lisista & William de Rosa also at Gusman Hall in 1996. The track of interest was Rachmaninoff: Sonata in G minor for Cello and Piano.
The experience this time was very similar to the other recordings I tested from Peter. You definitely get a better sense of the space at Gusman Hall and the reproduction of the piano and cello would be hard to beat with perfection in tonality, weight and transient speed.
Listening Part 4 | Let the music flow
Peter has convinced me I had to listen to little more digital to fully get an appreciation of what we had assembled. Time for a little EDM with low frequency.
Boris Blank – “The Time Travel” on the “Electrified” album on qobuz.
With the Wilson Audio ActivXO on, a wall of sound formed as my room exploded in size. This track is full of instruments and synthesizers that dig down around 30hz. I had heard this a few months prior on a pair of Wilson Chronosonic XVX driven by a D’Agostino Relentless amplifier. I was gob-smacked back then, and then deflated when I returned home since my system didn’t have the same impact.
With the addition of the precisely calibrated WATCH Dogs, I wasn’t jealous anymore. With the subs on, I wanted to LOUDER LOUDER, almost not top (except here my ears asked to stop), transients once again had attack and speed and grip. When the subs were off, it felt like the legs got shorten It was still great, but no longer blew me away.
The next few tracks I’ll provide just quick notes, since if you read this far, thank you.
Carola King – It’s Too Late on “Tapestry” – DSD
Room ambiance definitely improved, and the kick drum became a little more weighty. You know good stuff is happening when you start tapping your foot, but the party really brings loose when you start singing along with your terrible voice and don’t have a care in the world.
Fleetwood Mac – Gypsy on “Mirage” – MQA 192k
If you didn’t ever experience what it meant to have a cushion of air under your music, you do now after listening to this classic Fleetwood Mac track. Texture on the vocal and bass was sublime and yes I was singing again since no one was home.
Radiohead – Everything is in Its Rights Place on “Kid A” – Qobuz FLAC 44.1
Similar to Boris Blank, synthesizers can go deep. His voice was full, and it slide over the keys and soundstage in my room had more ambiance and size. You feel as if the speakers disappeared into the room.
Roots – Silent Treatment on “Do you want More?!!!??!” – Tidal FLAC 44.1
This is fun track and always puts in a good mood. It is a great test of the ability of your system to deliver fast and clean transients as well textured low frequency. Here the kick drum and snare had so much more weight. Reproduction went from amazing to hypnotic with the addition of the Wilson Audio ActivXO.
I started this review with a question: could the addition of two Wilson WATCH Dogs elevate my listening experience? After seven months of listening, I have no doubt that the addition of two Wilson WATCH Dogs can elevate the performance of two already world class loudspeakers.
The improvements seem to come with no downside, no boom, no overhang, and no loss of speed. Instead, I experienced a little more hall ambiance and everything had more dimension, weight and just the right level of gravitas.
I am not looking forward to packing up the WATCH Dogs and Wilson Audio ActivXO and returning the review samples. Highly recommended.