Bryston 10B electronic crossover
By Steven Stone   •   May, 1994 "Crossovers? We don't need no stinkin' crossovers!" Most Stereophile readers probably feel this way when it comes to third-party electronic crossovers. In this day of proprietary "soup-to-nuts" speaker systems, nearly all manufacturers supply complete systems. Nevertheless, some brave (or foolish) souls still choose to sail in uncharted crossover waters. Most do so because they're insanely in love with their current speakers, and have an irrational desire for that last bottom octave. Others have "orphaned" speakers that are not readily upgradeable to the next level of performance. I fall into the second category.

While Apogee Full-Range speakers aren't exactly orphans—Apogee is very much in business, and still services their original Full-Range speakers (footnote 1)—they have no information in their files on the first passive crossover box that came with my set of Full-Ranges. Passive crossovers are fine, as long as you don't often change preamps and amps, since passive crossovers depend on the preamp's output impedance and the amp's input impedance being known and immutable quantities. Since I'm forever switching preamps and amps, a passive crossover can make an otherwise superb speaker sound rotten. Some of the preamp/amplifier combinations I've used with the passive crossover have moved the crossover point around, so the midrange ribbon was forced to do things it shouldn't. The result was a distressing display of quivering, flopping, and shivering during bass transients—not a pretty sight.

Even if I were technically able to figure out which resistors needed changing every time I swapped a component, I'd still have better things to do with my time than soldering and unsoldering resistors onto the crossover's circuit boards. I've also got a thing for balanced interconnects; but after nine months of trying several harebrained and expensive methods of using two passive crossovers so I could use balanced lines, I gave up and decided to find a reasonably priced balanced crossover I could live with. The Bryston 10B answered my prayer.

Enter the Bryston
The Bryston 10B is a remarkably flexible crossover with logical features—someone must've done some serious ruminating on the nature of crossovers to come up with this package. The front-panel controls for one channel, from left to right, are: a Low-Pass/Mute toggle switch, a Low-Pass crossover frequency-setting knob, a three-way Low-Pass slope-selector switch with 6/12/18dB/octave settings, a High-Pass output-level knob, a High-Pass/Mute toggle switch, a High-Pass Slope selector switch with 6/12/18dB/octave settings, and a High-Pass Crossover frequency-setting knob. In the center of the front panel are an On/Off button and three LEDs that indicate which mode the crossover is in: two-way stereo, two-way mono, or three-way mono. The unit's rear has all the input and output connections and a toggle switch to set for two-way mono, three-way mono, or two-way stereo. The 10B is available in either single-ended RCA or balanced XLR terminations—the unit tested was balanced (footnote 2). For preamps that only have single-ended RCA outputs, the XLR version can also be used with adapters—I used a pair from Boulder Amplifiers for this purpose.

The Apogee Full-Ranges are uniquely problematic when it comes to crossover selection: Unlike 99.9% of other speakers, the Apogees need crossovers that relieve the midrange ribbon of most upper-bass responsibilities, while also providing midrange dynamic power by allowing the large panel woofers to extend into the midrange. The original passive crossover was ideally supposed to feature 6dB/octave slopes for both the high- and low-pass filters, with the crossover point set to 400Hz. After experimenting with several other combinations of slopes and crossover points, I ended up setting up the Bryston 10B with exactly these parameters. Who am I to argue with Leo Spiegel and Gary Walker, the speaker's designers?

Sound
When I first installed the Bryston 10B in my system I noticed some low-level ground-loop hum. Usually I float the third grounding plug on everything but the preamplifier. I had to change the grounding scheme for the Bryston: I grounded the 10B and the power amplifiers, and floated everything else, including the preamp ground. This was the most successful scheme for eliminating ground-loop hum (footnote 3). Since the Bryston crossover draws very little power, I recommend leaving it on all the time. If you must turn the Bryston off, it's imperative that you turn your amps off first. If you don't, the Bryston will emit a loud, horrible, high-frequency squeal after about 10 seconds. If this screaming doesn't damage your speakers, it'll at least scare the hell out of you. Turn off your amps first (footnote 4).

Because of my previous experiences with passive vs active electronics, I was worried that the change from the Apogee passive crossover to the Bryston active crossover would include some trade-offs. Not only that, the Apogees' metal-ribbon drivers are very revealing of additional electronic or metallic edge; I was concerned that the solid-state Bryston would push the Apogees into hard steeliness. But after a few days of break-in, I was amazed at how little electronic signature the Bryston added.

I began listening with a nasty recording—the Super-Bit-Mapped CD of Dylan's Blonde on Blonde (Columbia CK 53016). I figured if I could tolerate the "Leopard Skin Pill-Box Hat" test, the mellower stuff would be fine—nothing like some Michael Bloomfield Telecaster rear–pick-up action to scare Katy, my cat. She barely stopped purring. And instead of grabbing for my earplugs, I was tapping my feet and playing the air guitar. Damn, sounded like music—I detected no added glare, glaze, or hash.

Next I played my favorite Jr. Wells/Buddy Guy recording, the Hoodoo Man Blues LP (Delmark DS-612). While listening to "Good Morning Little Schoolgirl" in anticipation of the Club Mondial jam session at the Las Vegas CES, I was again impressed with how little electronic haze the 10B added. Jack Myers' bass was especially well-reproduced, with excellent tone and impact.

I then listened to a German vinyl copy of Eric Clapton's Unplugged. "Signe," including the "Are we ready?" interchange between Clapton and Andy Fairweather Low, was very nicely rendered. Even the foot taps exciting the mike stands were very clean, with good impact and definition. The left-of-center bells sounded very natural and were well-articulated without sounding hard. I could really get to like this sound.

When active electronics are added to a system, I become concerned about what sort of subtractive colorations will be added (footnote 5). So I pulled out a PCM master tape of the Boulder Philharmonic performing Henri Wieniawski's (1835–80) Violin Concerto in d, Op.22, with soloist Anne Akiko Meyers. Through a combination of my beginner's luck and J. Gordon Holt's experience, we had managed to get an excellent recording of this violin showpiece using a Shure M/S mike and a Bryston BMP-2 mike preamplifier. This recording is very good at re-creating the dimensionality and dynamics of the Macky Auditorium performance.

Compared with the Apogee crossover, the 10B hardly reduced the depth or dimensionality of the reproduced space. While there was a slight reduction in soundstage depth, it was only apparent in direct comparisons, and was more than compensated for by the Bryston's additional dynamic range. Dynamic contrast, bass extension, and speed were far superior through the Bryston than through the Apogee—the Apogee's bass reproduction seemed soft, slightly woolly, and underdamped. I noticed no additional electronic coloration when listening to commercial recordings, but with the master tape, my system sounded a bit more "electronic"—similar to the difference in sound between a new cable and one that's been broken-in for a few days. On the positive side, the Bryston didn't raise the system's level of background noise or increase the electronic grain.

After more than four months with the 10B, I'm convinced that it's transparent enough not to obscure the difference between components upstream of it. While I wouldn't say the Bryston was sonically invisible, whenever I changed other components—cartridges, CD players, cables, amps, preamps—in my main system, the 10B never obscured the audibility of these changes.

Summary
I was prepared to make some sonic sacrifices in exchange for knowing that my Apogees' crossover points wouldn't vary every time I switched amplifiers—and for the joys of using balanced lines. With the Bryston 10B, the gains were far greater than the sacrifices. While there was a slight reduction in depth and a bit of an increase in electronic edginess, the gains in dynamic contrast and power, bass extension, and driver control more than compensated for such liabilities.

The Bryston 10B is a versatile, ergonomically sophisticated crossover. It's an excellent compromise between absurd bells-and-whistles flexibility coupled with sonic degradation vs unusable perfectionist passive sonic minimalism. While the 10B's additions to and subtractions from the original signal weren't as transparent as those of the proverbial "straight wire with gain," they were minimal, and will be more than compensated for by the improvements it will effect in most systems. I give it a solid "B" rating.

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Footnote 1: Last time I was at Apogee's Massachusetts factory, they were repairing a pair of Full-Ranges that someone had shipped from Germany. The shipping boxes alone cost more than most people's speakers.

Footnote 2: The tested version also was a custom-configured version with the 250Hz marking actually being 600Hz.

Footnote 3: To make room for a 10' Christmas tree, I moved the crossover closer to the preamp than to the amps, where it had been previously set up. Instead of running one 25' XLR line from the preamp to the crossover and two 1m XLR lines from the crossover to the amps, I ran a 1m XLR line from the preamp to the crossover and two 25' XLR lines from the crossover to the amps. Then, in order to eliminate the low-level hum, I tried every combination of floating and grounding between the preamp, crossover, and amps. The hum continued. Then I realized that the PAC IDOS floats the grounds of everything plugged into it. Everything was plugged into it. When I plugged both the Bryston and the amps directly into the wall without floating their grounds, the system was so silent I could hear a pin drop across the room. Ah, bliss...

Footnote 4: It's always best to turn your amps off first. I've fried my share of gear by disregarding this sage advice.

Footnote 5: Something of an oxymoron: detecting the presence of absence. Very Zen.