Note: for the full suite of measurements from the SoundStage! Audio-Electronics Lab, click here.

Keen-eyed readers of my previous reviews and blog articles have by now picked up on my preference for DIY gear and relatively simple, class-A circuitry, usually based on discrete components. And it’s true, I generally eschew complex designs, integrated circuits, and high part counts in my preferred equipment.

In fact, my reference system for nearly two years has included a line stage built from a Wayne Colburn design paired with a single-ended, no-negative-feedback phono preamp that uses passive RIAA equalization, both of which are products of my own labor. I’m not sure if many SoundStage! readers share my values—and I imagine some of the SoundStage! staff must think I’m nuts. But the existence of Darlington Labs’ JFET-based, passive RIAA MP-7 phono preamplifier is confirmation that someone else out there gets it. When I first heard about the MP-7, I knew I had to get one in for review. Naturally, I also got my hands on an SU-7, the MP-7’s moving-coil step-up companion.

Despite being a small, young company, Darlington Labs offers a fully evolved ecosystem of moving-magnet phono preamplifiers and moving-coil step-up amps. The MM-5 MM phono preamp and SU-5 MC step-up, both starting at $199 (all prices in USD unless otherwise noted), represent the ground floor, though you could add options that bring the price of the top-of-the-line MP-7 up to $729—more on those options in a bit. The $299 MM-6, the company’s first product, is the mid-tier option, and the SU-6 (also starting at $299), fills the mid-tier step-up amp slot. Darlington Labs’ products are arranged this way to maximize their value. Customers can purchase only what they need without spending extra for unnecessary features, and they can mix and match products as they see fit when they’re upgrading their vinyl rigs. All Darlington Labs products are made by hand in the US, and all share a common design philosophy of simple, JFET-based circuitry.

Description

Darlington Labs products, including the MP-7 and SU-7 (both starting at $499), have similarly appointed enclosures, and they’re all housed in well-built but austere aluminum chassis. Standing about 2″H on their squishy hemispheric feet and measuring 5.125″W × 7″D, the chassis of both units feature a brushed silver front with a Darlington Labs logo and a blue LED indicator, with a black-anodized aluminum clamshell forming the top and sides. Around back, both have a knurled ground terminal, RCA input and output jacks, and a small power jack. The two review components were identical, and it would have been impossible to tell them apart if not for the model numbers Sharpied on the bottom of each chassis. This small, minimalist, metal-box approach is old school, and I like it—the good stuff is all on the inside.

However, Darlington Labs does offer a couple of aesthetic and functionality options if the basic package is too basic for you. For an additional $30, both their MM-6 and MP-7 moving-magnet phono preamps can be configured with a black front panel, and your choice of a blue, red, yellow, green, or white LED indicator, available in either normal or “dim” brightness. If you buy a phono preamp with the custom appearance package and a step-up amp at the same time, the company will match the two at no cost. For $100, you can also upgrade from the standard RCA jacks to more reliable and more attractive heavy-duty jacks. One final option, also for a hundred bucks, is a mono switch for optimal playback of mono records. My review samples both had the standard silver face and blue LED and the upgraded jacks, but neither had a mono switch—a bit of a shame because I’d like to have tried it with some of my mono records. No doubt this is one of the most common configurations beyond the basic package, so the MP-7 and SU-7 I received were just fine for the purpose of my evaluation.

I’ve already mentioned the appeal of the MP-7 and SU-7, which lies in their unique design philosophy and bang-for-buck pricing. Rather than relying on op-amp chips—a staple of virtually every phono preamp in this price class—these Darlington Labs units use discrete JFETs in a single-ended configuration. JFETs (junction field effect transistors) are a more expensive, less conventional choice for amplifier design, but they have noise and distortion advantages over conventional bipolar transistors or op amps when driven from high source impedances. Moving-magnet cartridges present high source impedance to the preamp, so JFETs are well suited to the task. I asked Darlington Labs why it chose to base its products on JFETs, and I was told that the company believes it can offer the best value in this price class by using them. The company stated that tubes could offer better sonics, but only at prices many times higher than what you’d pay for any of its JFET-based products. Indeed, another benefit of JFETs is that they’re supposed to behave—and thus sound—much more like tubes than op amps or conventional bipolar transistors.

MP-7 (left) and SU-7

The MP-7 and SU-7 each have interesting design features that further distinguish them from other phono preamps in this price range. The MP-7, like the other Darlington Labs moving-magnet phono preamps, uses a passive RIAA equalization scheme with precision resistors and capacitors and does not use negative feedback. It also runs at a higher-than-typical voltage to maximize headroom and overload margin. Darlington Labs claims these design approaches make surface noise, ticks, and pops less noticeable. Remarkably, the SU-7 uses eight input JFETs in parallel to provide a low-noise interface when coupled with notoriously sensitive MC cartridges. Both the MP-7 and the SU-7 use several cascaded stages of discrete voltage regulation to minimize power-supply noise, and each comes with a simple wall-wart-style AC-to-AC plug, which keeps transformer hum away from the electronics. The resulting specs are not state-of-the-art, but they’re still quite good for this price range: the MP-7 claims a THD of 0.08%, an A-weighted SNR of 78dB, and an RIAA deviation of ±0.2dB with 40dB of gain. The SU-7 has gain settings of 12dB, 18dB, 23dB, and 26dB, with cartridge loading settings of 47 ohms, 100 ohms, 220 ohms, 470 ohms, 1k ohms, 5k ohms, and 47k ohms, and claims a THD of 0.01% and an A-weighted SNR of 73dB.

Setup

As you’d guess from the MP-7’s straightforward design, setup is almost trivial. I used a Micro Seiki DQ-3 direct-drive turntable equipped with a Micro Seiki MA-707 dynamically balanced tonearm. I used my Audio-Technica AT95 moving-magnet cartridge and a nude Shibata stylus with the MP-7, and both a Sumiko Blue Point No. 3 Low Output moving-coil cartridge and a Grado Labs Sonata3 Low Output moving-iron cartridge when I used the SU-7 and MP-7 in concert.

Because the MP-7 has no user-adjustable parameters, all I did was plug the ’table into the MP-7 input, tighten the screw down on the turntable ground wire, and connect the phono preamp output to my McIntosh MA6850 integrated amp. The speakers used throughout were my trusty DIY Paul-Carmody-designed Amiga tower speakers.

Setting up the SU-7, with its various gain and loading settings, was a touch more involved, but it’s not rocket science. Using the included Allen key, you can unfasten the screws on the front and back, allowing the top to come off. Inside the SU-7 are a series of headers that allow the loading and gain to be configured using jumpers—they’re small, so needle-nose pliers or tweezers work best.

While not “officially supported,” a cool feature is that you could theoretically dial in dozens of custom loading options using the extra jumpers Darlington Labs provides. There’s math involved, and not every resistor value you could conceivably achieve is useful, but it’s doable. I started with 23dB of gain and 220 ohms as a load on my Sumiko but eventually settled on 1k ohms and 26dB of gain. The Grado Sonata3 required a load of 47k ohms and slightly less gain (18dB). These figures are in addition to the 40dB of gain provided by the MP-7, for a total of 63 and 66dB for the Sumiko and 58dB for the Grado.

Sound

Starting with the MP-7 mated to the Audio-Technica AT95 phono cartridge, I quickly formed an impression of what the Darlington Labs units are about. The overall presentation leans fairly strongly towards warm and musical as opposed to cool and analytic, but that doesn’t mean it was missing musical details. While listening to “The Logical Song” from Supertramp’s Breakfast in America (A&M Records SP-3708), I noticed good separation between instruments and vocals and an especially solid center image. Roger Hodgson’s voice had a natural-sounding tonal warmth and good separation from the music going on all around him, and the soundstage depth was really quite good. In fact, soundstaging and separation immediately struck me as the strengths of the MP-7, and that impression remained as I transitioned to Eric Clapton’s Slowhand (RSO RS-1-3030). On “Wonderful Tonight,” Clapton’s voice was dead center and had a lifelike quality, while things happening to the left and right, like Marcy Levy’s and Yvonne Elliman’s backing vocals, were strongly off to the sides and presented with good depth and layering.

Changing gears to Death Cab for Cutie’s We Have the Facts and We’re Voting Yes (Barsuk Records bark11lp) solidified these impressions. This is an album I’m very familiar with, and despite its ostensibly lo-fi aesthetic, the recording is well engineered, with great texture and detail packed into each song. A solid phono preamp should be able to pull out the detail in a recording, and the MP-7 did an admirable job. Some lower-level details on the track “405,” like the fuzz of the dial-tone-esque synth, were pushed to the fore, while others were a bit more shaded. Nonetheless, the overall performance was satisfying. The phono preamp did a bit of “the JFET thing” I’ve become accustomed to, with the panned vocals on “Little Fury Bugs” having an “in-the-room” quality. But on all three of these discs, I found myself wishing for more solidity and muscle from the frequency extremes. High-frequency transients like cymbal crashes and guitar-pick attacks on strings were precisely placed but seemed a touch splashy. The bass, while achieving an accurate timbre, was too light for my taste. I need more thump, dammit!

Such observations may come across as nitpicking when considering a phono preamp under $500. But before you decide that I’m here to trash-talk this unit, I must admit that the MP-7’s stoic disposition in the face of surface noise borders on magical. It doesn’t actively filter or reduce noise; it’s simply unperturbed by the errant static crackle or dusty pop. In my notes, I found myself using the term “CD-like” to try to capture what I was hearing. A bit of noise was still present here and there, but it was difficult to notice on most records. Points for you, MP-7!

At this point, I added the SU-7 in front of the MP-7, with the Sumiko Blue Point No. 3 now dragging through the grooves. My overall impression of the SU-7 was that it was more of the same, but I don’t mean this in the negative sense. I mean it more in a “why-don’t-we-open-another-bottle-honey-what-could-it-hurt?” kind of way. With the moving-coil pickup, I expect to hear more vibrant tones and images and a more refined and lifelike sound, and I got that, but with the same basic tonal and soundstaging traits I heard with the MP-7. I spun Rival Schools’ 2011 effort, Pedals (Photo Finish Records 524540-1). Lead singer Walter Schreifels’s voice was vibrant and front and center, popping out of the soundstage as guitars and drums danced and jerked around him on “Racing to Red Lights.” The instrumentation was presented with good clarity and imaging, especially in complex, tension-building passages. I noticed that the rhythm section in this song provided a strong groove, but as before, highs were splashy, and the bass, while a bit stronger and woodier, still lacked the precision and heft I’d hoped for.

I replayed “Goodbye Stranger” from Breakfast in America with the Blue Point No. 3 and SU-7 to try to gain some perspective on how the step-up amplifier was affecting the sound. I noted the nice, thick midrange and some improvement in the bass and treble frequencies. However, the surface noise benefit was less noticeable than with the previous combo. Together, the cost of the MP-7 and SU-7 is approaching the $1000 range, so these shortcomings aren’t as easy to forgive.

But then I tried the SU-7 and MP-7 with the low-output Grado Sonata3, and the pairing seemed highly complementary. As I noted in my review of the Sonata3 cartridge, the soundstage seemed very flat, but the separation and tonal accuracy gave the impression of an astoundingly natural and true-to-the-source sound. Gone was any hint of splashiness in the treble. What’s more, the surface noise was a bit less noticeable. These Darlington Labs units seem to do well with any cartridge, but they perform best when paired with devices with complementary sonic characteristics.

Comparison

In this price class, the Darlington MP-7 and SU-7 do not want for competition, although hardly any of the phono preamps currently available are JFET-based. In fact, the under-$500 class is perhaps the most densely populated phono preamplifier segment, and I can think of many other products you might consider. I’m best acquainted with the Parasound Zphono, which now retails for just $249 following the release of an upscale version, the Zphono XRM ($499). With the Audio-Technica cartridge, the Zphono was tonally a bit more reserved and generally grayer, but also a bit more neutral than the MP-7. It competed neck-and-neck with the JFET preamp in terms of separation and imaging across the soundstage. Although I can’t comment on the Zphono XRM in terms of performance, I will briefly state that it’s designed to be much more versatile than the standard Zphono when used with moving-coil cartridges, and it also has XLR outputs. Because the Darlington Labs MP-7 lacks MC functionality, you would need to add the SU-7 if you have a moving-coil pickup. But if you need a lower-priced option that works with a moving-coil cartridge, and you want to stick with Darlington Labs, the MM-5 and SU-5 combo comes in at just $398.

It would be a disservice to try to compare the SU-7 with a step-up transformer, the sort of product that dominates the space for amplifying MC cartridges to MM levels. In fact, the only other electronic step-up I found was the Graham Slee Elevator EXP, an older product that retails for $1195 on this side of the Atlantic. It should be noted that, while the Graham Slee and the previously mentioned Parasound products are no doubt solid, both are chip-based designs and thus lack much of the appeal of the Darlington Labs components.

Conclusion

Darlington Labs makes unique products that offer solid value for their price. If not at the pinnacle of performance for its price range, the MP-7 at least offers something that’s far from the beaten path for a budget moving-magnet phono preamplifier. The MP-7 has a ton of cool points, and matched with the right system, it could really shine.

The SU-7, on the other hand—although it may be a less popular choice than its moving-magnet siblings—strikes me as the truly incredible bargain. There’s nothing like it on the market right now that I’m aware of that isn’t being offered by some ludicrously high-priced boutique manufacturer. At a time when vinyl has made a miraculous comeback but most amplifiers and receivers on the market—even so-called high-end ones—lack facilities for moving-coil cartridges, a good but inexpensive plug-and-play head amp is a godsend. The SU-7 may open the door to moving-coil cartridges for you if your vinyl rig is built around an A/V receiver or vintage amplification.

The products offered by Darlington Labs, like any others in the budget class, should be carefully considered against their competitors to balance your wants and needs, and the potential for upgradeability. That said, the flexibility and uniqueness of this small Massachusetts-based company’s products are, as far as I know, matchless. If, like me, you’re a junkie for intriguing hi-fi at a great price, can you beat that?

. . . Matt Bonaccio
mattb@soundstage.com

Note: for the full suite of measurements from the SoundStage! Audio-Electronics Lab, click here.

Associated Equipment

• Speakers: DIY Paul Carmody Amiga speakers, built from Parts Express kit.
• Integrated amplifier: McIntosh MA6850.
• Turntable: Micro Seiki DQ-3, Micro Seiki MA-707 tonearm.
• Phono cartridges: Audio-Technica AT95 with AT-VMN95SH Shibata stylus; Sumiko Blue Point No. 3 Low Output, Grado Sonata3 Low Output.
• Analog interconnects: Shielded quad-conductor Belden cables with Switchcraft connectors.

Darlington Labs MP-7 Phono Preamplifier and SU-7 Step Up Amplifier
Price: Starting at $499 each; $599 each as reviewed.
Warranty: One year limited warranty.

Darlington Labs LLC
43 Fawndale Road
Roslindale, MA 02131
Phone: (617) 459-0780

Email: sales@darlingtonlabs.com
Website: www.darlingtonlabs.com