If you really think about it, choosing studio monitors is strange – they shouldn't sound like anything. They need to be capable blank slates. We base most of our decisions on monitors, but if everything sounds great on them already, no matter what we do, we might not make the correct decisions needed to translate well on other systems. They should be inspiring and enjoyable for sure, but they also should be nearly inaudible. It's our job to get what's going into them to sound interesting.

Seeking out exactly the right monitors for your particular space is a familiar ordeal for many of us. I've tried at least 12 different brands over multiple years, until I finally found monitors that I loved. You never really know if the speakers are right for your room until they're in your room, since the room itself is a big part of the sound. Without using them you won't know if you can trust their translation abilities.

After a few happy years, I began to feel a lack of low end in my beloved Amphion One18s [Tape Op #105]. It's not that they're inadequate, but they are a bit bass light in my opinion, and a lot of the music I am tasked to work on lately is becoming ever more bass heavy. Amphion does make monitors with two woofers, but they don't feel voiced right for my particular ears and room – they sound too low mid forward at the cost of clouded higher frequencies. I needed an actual three-way system. I needed subs.

Adding another piece to my monitoring equation seemed like a losing proposition. If the volume of the low end isn't already a locked in part of the system, aren't you just turning up the bass in the room? Like poking the loudness button on a car stereo? My control room is fairly small, so it seemed a smaller subwoofer system would pair best with my One18s. Amphion makes two stereo sub systems (BaseOne and BaseTwo), both of which have two huge towers and are quite pricey, so that was not the right fit for my space or pocketbook. Also, accelerating this thought process, I had to suddenly move to a 5.1 surround system for a television show I began working on.

Happily, Amphion recently announced a new, smaller, adaptable, and more affordable sub system, the FlexBase25. Its design is simple but embodies some big ideas in a compact package. It may be a mistake to simply call it a sub – it's a complete low end extension system with flexible sub management. It effectively turns your stereo main pair into a true three-way system.

It's a single stereo speaker tower, matched with a two-space rack amp/crossover dubbed the FlexAmp. The Class D amplifier (600 watt RMS into 4 ohms) runs cool and clean, and its face features an adjustable frequency crossover (35 to 260 Hz) that sends the lows to the FlexBase25 tower (via supplied Neutrik speakON four-pole cable) and the rest of the signal to the main speaker pair (via XLR I/O). Additional controls include mono/stereo width, volume, and bypass. For use in a surround setup, there is also a mono LFE input.

The tower is compact (12.25" x 13.5" x 33") but is a heavy beast nonetheless (110 pounds). It's a single sealed box, sporting two side-firing 10-inch aluminum drivers. The handsome enclosure matches the charcoal and black aesthetics of Amphion's current speaker line.

Having an auxiliary system built by a manufacturer for their specific products means an easier experience in my opinion. Set up of the FlexBase25 system took all of five minutes in my studio, and placement was simple: the center line between the two main speakers. Amphions have a well-deserved reputation for phase accuracy, and I perceived no change with the FlexBase25 added.

So how does it sound? Seamlessly integrated. The One18s retain their characteristic sound, but with more detailed low end muscle. The center has a new pleasing solidity that I love, without disturbing the killer phantom center that these monitors have. It's like a problem I didn't know even existed got fixed! I keep the crossover frequency on the low side ([100 Hz), because as frequencies get higher, localization of sources relative to the main speakers begins to change. This is a factor of the distance between the main pair though – mine are seven feet apart. From my mix position, I can't tell what is coming from the FlexBase25, only that there is a more well-defined low end.

Since I also have the little One12s here (part of my 5.1 system), I gave those a run with the FlexBase25, and am I ever glad I did! It's a tight presentation – headphone-like clarity except out loud! The price ratio is kind of nuts (the FlexBase25 would be 1.7 times the cost of a One12 system with amplifier and cables), but if you have the dough, adding a FlexBase25 to them would be a huge upgrade. It could be the perfect complete mobile solution for a touring band recording live shows.

Speaking of costs, while the FlexBase25 is a bit less than the other Base systems, it's still got a hefty price tag. But if you consider the burly amp, its sophisticated crossover, and the efficient high quality of its build, it's still a great deal in my opinion.

I spend long days concentrating on small details (fixing and mixing), so I work pretty quietly(65 to 75 dB typically), so it was a truly unexpected pleasure that I was able to turn up the lows on the FlexAmp and get a much weightier experience while working at these levels. On the other end of the volume spectrum, a FlexBase25 enhanced system is capable of being louder without becoming strident.

If you want a true three-way set of Amphion speakers, the FlexBase25 is the most compact and economical way to get there, with maximum flexibility and no compromises.

Full disclosure: I have relationship with Amphion dating back to when I wrote to owner Anssi Hyvönen about my delight with my One18s. He used a quote from my email; "I'm tired of brutally honest – these are beautifully honest!" to create his brand's official slogan. I do still pay for my speakers though!

Tape Op is a bi-monthly magazine devoted to the art of record making.

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