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Audio Files: The Return of Tone Controls

The ability to tweak frequency levels had practically disappeared from high-end audio equipment. So why is it coming back?

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Schiit Audio's Loki Mini+ features tone controls.
Schiit Audio’s Loki Mini+ features tone controls.

Back in the 1960s, tone controls were considered a must-have feature for audio gear. But in 1974, their reputation sank when famed audio entrepreneur Mark Levinson introduced his JC-2 preamp, which omitted the controls. The pitch was purity—audiophiles had noticed that some gear sounded better with tone controls switched off—and within a few years, the ability to tweak frequency levels had practically disappeared from high-end audio equipment.

In the last 10 years, though, tone controls have started to reappear. Perhaps their most high-profile re-emergence occurred when audio product designer Dan D’Agostino began including bass and treble controls in his ultra-pricey preamps, including the $40,000 Dan D’Agostino Master Audio Systems Momentum HD. Tone controls have also appeared on some less costly products, such as Parasound’s $1,595 Halo P6.

When I asked D’Agostino why he brought tone controls back, he replied simply, “I missed them,” and went on to explain that having some control over tone gives the listener the power to make old recordings or poorly mastered new recordings sound better.

Parasound's Halo P6
Parasound’s Halo P6

Four and More

The tone-control trend isn’t limited to costly gear. A few years ago, Schiit Audio introduced the Loki Mini, a simple $149 equalizer with four controls: bass, treble, and two different midrange frequencies. They’ve now launched an improved version, the Loki Mini+, for the same price. The Loki Mini+ is a line-level device that connects between a preamp and an amp, or perhaps between a source (such as a computer or DAC) and a set of powered speakers, or between a source and a headphone amp. A similar product, the $119 Bellari EQ570, has the same controls, tuned to somewhat different frequencies.


What distinguishes the Loki Mini+ from simple bass and treble controls—and from professional equalizers—is that it gives the user enough power to make fairly major changes, but not enough to mess up the sound. The bass and treble controls have a wide range of plus/minus 12 decibels, but the two midrange controls, at 400 Hz and 2 kHz, are limited to plus/minus 6 dB. Why? Because the human ear is more sensitive in the midrange, so large changes in this range can make recordings sound unnatural.

When I tried connecting the Loki Mini+ between my preamp and amps, I quickly came to appreciate the control layout. I’m usually cautious when adjusting equalizers, because with most of them it’s too easy to turn okay sound into unlistenable sound. But I found that the Loki Mini+ rewards aggressive experimentation: Just flick each knob back and forth to see how it might benefit the sound, and then return it to its center detent position if it doesn’t improve things. The compact, five-inch width of the Mini+ made it easy to adjust all the knobs in a few seconds. And four controls seems like a just-right number; the EQ app in my smartphone gives me 10 different bands, which makes it impractical for adjusting on every tune.

The downside is that the Loki Mini+ must be operated by hand, which can be a pain if your stereo rack is across the room—and also less effective, because due to room acoustics, the system won’t sound the same at your equipment rack as it does in your listening chair.

Bellari EQ570
Bellari EQ570

A Test of Tone

For recordings made since about 1960, the Loki Mini+ seldom made much improvement, but part of that is personal—my philosophy is that if the recording is reasonably good, I want to hear what the artist and recording engineers intended, and I prefer not to impose my own taste on their work. But for albums made in the early days of recording, the Mini+ often improved the sound greatly.


For example, on the generally dull-sounding recordings of Charlie Christian, I usually found that setting the treble to about three o’clock livened up the music, and dialing the mids back to 10 o’clock made it less muddy. The uncharacteristically harsh recording of Coleman Hawkins on Body & Soul Revisited demanded more extreme action: turning the treble and the 2 kHz midrange knob down all the way, and kicking the 400 Hz knob up to about two o’clock to add warmth. The Loki Mini+ couldn’t save every recording—no settings I tried did much to help Emergency!, the notoriously lo-fi debut of Tony Williams’ Lifetime—but every recording I played from the swing and bebop eras benefited.

Any jazz fan who regularly listens to pre-Kind of Blue recordings should at least consider finding a way to get tone controls back into their systems. While changing DACs, amps, or cables will have at most a subtle effect on what you hear, adding tone control will be an improvement that’s easy to appreciate every time you soften a harsh-sounding sax or fatten up a thin-sounding bass.

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Brent Butterworth

Brent Butterworth has been a professional audio journalist since 1989, and has evaluated and measured thousands of audio products. He is currently a writer at Wirecutter and editor of the SoundStage Solo headphone site; served as an editor at such magazines as Sound & Vision and Home Theater; and worked as marketing director for Dolby Laboratories. He also plays double bass with several jazz groups in Los Angeles.