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Form Factor Bi1000Di Review

Form Factor Bi1000Di Review

Many class-D bass amps promise "tube warmth," but this sleek contender unabashedly proffers a meticulously clean take on your instrument's innate voice.

All clips recorded with a 50/50 mix of post-EQ DI from the Form Factor amp and an Audio-Technica AE5400 microphone on a Mesa Boogie Subway 1x15 cabinet via an Mbox into Logic X.
Clip 1: Squier PJ with Kloppmann pickups. No equalization.
Clip 2: Spector Euro4 LX. Bass at 1 o'clock. Mid cut at 1k set at 10 o'clock. Limiter at 10 o'clock.
Clip 3: ’84 Yamaha BB3000S with bridge pickup favored 70/30, and tone rolled off halfway. Bass boosted on amp to 4 o'clock. Mids boosted at 1k to 1 o'clock. Limiter at 11 o'clock.


Focused sound. High power. Pre and post XLR outs.

No volume control for clean XLR out. No preset EQ-curve quick dial or switches.


Form Factor Bi1000Di


Ease of Use:



Southern California’s Form Factor is an interesting player in the world of bass amplification. The company uses its extensive experience in large PA speaker enclosures and electronics for its designs for bass gear, while incorporating new methods, materials, and practices to differentiate themselves in a crowded market. Since the launch of their bass line at the 2013 NAMM show, Form Factor has built a solid reputation as a respected manufacturer with an ear toward modern, clean bass tone. This review was my first encounter with a Form Factor amplifier, but already knowing the forward-thinking design that goes into their cabinets, I was anticipating hearing what their new 1,000-watt Bi1000Di had in store.

Sleek and Understated
The 10-pound Bi1000Di is elegant and minimalist in an era when so many class-D bass amps have lit-up tubes, decorative lighting, and different control sizes. The front panel, which has thin white lines dividing the controls from the inputs, is so simple it appears designed by an upscale Scandinavian furniture company. It’s noteworthy that the Bi1000Di’s front houses a number of jacks that would typically be found on a back panel, including the headphone out, tuner out, and effects send and return jacks. There are also separate inputs for passive or active instruments.

The 3-band EQ section has a midrange selector dial, and gain, master volume, and limiter dials round out the controls on the front panel, which also includes a very large mute button. It’s obvious the designers purposefully created a mute button you can’t miss on a dark stage—a simple detail that is strangely overlooked by most manufacturers. (The button itself also lights up.) Finally, next to the power switch are small indicator lights for clipping, input signal, and on/off.

The result was a brighter version of a Jaco-inspired tone that made me want to keep playing and playing.

The back panel has no switches or controls and looks even more understated. In addition to the obligatory two speaker outs, there is a power connection that locks into place and requires its own Speakon-like cable called a “Powercon.” The amp ships with the cable, and it feels very solid. The only drawback here would be if you forgot to pack the power cable for a gig, because borrowing one from a buddy or the venue would most likely not be an option.

The most exciting feature on the back panel is the pair of completely separate DIs. No need to select pre or post, as is necessary with most other amps. The ability to send an unaffected signal to FOH and send your EQ’d tone to your in-ear mix is quite valuable. The volume of the post-EQ out is controlled by the gain control of the amp, while the pre-EQ out has no volume control of any kind.

Punch Factor
Plugging in a Squier PJ bass with Kloppmann pickups and strung with flatwounds, the Bi1000Di impressed right away with an authoritative, clean midrange I haven’t heard from any other class-D amp. The punch is best described as immediate. It feels like the amp wants to punch you in the gut before your finger has even finished playing the note. The tone of this amp without any equalization whatsoever is undeniably great for fingerstyle playing. It took my warm-sounding P bass and gave it some extra oomph in the low mids without touching the EQ section at all.

Wanting to see if the amp could go the opposite way, I plugged in a Spector Euro4LX with brand-new steel strings and EMG pickups. For a slap tone, I engaged the limiter slightly to get a little bit of natural squashing happening, set the midrange-frequency selector to 1 kHz, and cut the mid dial back to 9 o’clock.

Instead of a traditional, super-scooped slap tone à la Marcus Miller, the Form Factor delivered more of a Mark King-like sound that retained some of the midrange from my fingerstyle tone. The result was a tight, more focused slap tone without any unnatural top-end to my active bass, which I find some amps create.

The natural voice of the amp made me curious about what a fairly traditional, growlier Jazz bass tone would sound like, so I grabbed my ’84 Yamaha BB3000S, favored the bridge pickup over the neck at a 70 percent to 30 percent ratio, and rolled just a little off my onboard tone control. I also boosted the mids at 1 kHz ever so slightly to 1 o’clock, and rolled the limiter to 11 o’clock. The result was a brighter version of a Jaco-inspired tone that made me want to keep playing and playing.

Once again, the Bi1000Di proved it’s perfectly capable of providing very quick and aggressive tones, while remaining crystal clear and not sounding brittle or harsh in the least. The limiter on Form Factor’s amp does a very musical job of limiting volume without affecting the punch much.

The Verdict
Even though the Bi1000Di is designed to be a transparent amp without much color, it does have a personality that’s all about the extremely strong midrange foundation, thanks to the immediate attack that gives every note an undeniable center. This amp separates itself from the pack by offering the direct opposite of many other class-D amps, where the manufacturers are purposely trying to add the sound of tube warmth to modern, lightweight amps. The Bi1000Di just wants to deliver the sound of your bass, and it does this with a merciless, clean attack that permits it to stake out its own very solid and powerful corner in the modern-amp market.

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