Phono Preamp Reviews

Julie Mullins's review of the $1999 Pro-Ject Phono Box RS2 in the August 2021 issue piqued my curiosity. The preamp, as described by Julie and measured by John Atkinson, seemed a good fit for my transfer-and-mastering studio.

In my work, I oversee and consult on vinyl releases, and I often remaster material originally released to the public on LP records; in such cases, I listen to the LPs in order to hear how the material was first presented. What's more, it has been an ongoing project to transfer my favorite LPs to my digital library for more convenient listening in a wider range of settings and systems. Even though I am a digital-centric listener, I spin black discs frequently.

When she had the Phono Box RS2, Julie took it to the vinyl-music playground and had a good romp. That's how most Stereophile readers should and will use it. The Phono Box RS2 is a good-sounding phono stage with options that can be tweaked to find each person's ear-favorite loading and gain for a wide array of cartridges. But I was interested in something a bit more structured and rigorous. I took it to the training gym.

One of my studio's digital interfaces is made by RME in Germany. Among its many features is the excellent DIGICheck software (footnote 1), which includes precise level metering, a phase/stereophony scope, and a frequency-spectrum graph, displayed in a visually intuitive manner on the audio workstation computer screen.

Being analytical by nature, one of my record-collecting interests is test-and-alignment records, with a focus on the era when vinyl was mainstream, the 1950s through 1980s. A longtime star in my test-records collection is RIAA System Response Test from the late, great CBS Laboratories (LP, CBS STR 130). At one time it was the industry standard for testing cartridges and phono preamps. It contains precisely balanced, RIAA-accurate test tones with which you can observe output level, frequency response, and channel-to-channel balance of your cartridges. In practice its precision is only so-so (as with all things vinyl), but it's about as good as was ever made. The Ultimate Analogue Test LP (LP, Analogue Productions AAPT 1), produced by the late George Marino at Sterling Sound and still in production, is in the same league.

The combination of CBS Labs STR 130 and RME DIGICheck software allowed me to compare and study the channel balance, phase integrity, and frequency response of various cartridges. It also let me test the effects of changing the capacitance settings on the Phono Box RS2, watching the frequency spectrum of the top few octaves with the high-frequency tone-sweep tracks on the test record. I connected the Pro-Ject's balanced outputs directly to two balanced line-input channels on the RME interface.

When it comes to turntables and cartridges, I don't do exotic or fussy. What I use was standard in mastering rooms, the listening rooms at record companies, and radio stations during vinyl's heyday: Technics SL-1200 turntables with moving magnet cartridges plus high-output Denon MCs. My pair of 1200s have been restored and modified by KAB Electronics, the lightweight tonearms damped with fluid and rewired from the headshell to the gold-plated RCA jacks on the back with low-capacitance Cardas cabling. My SL-1200MK5, which I bought new from KAB, has the three-speed modification, with 78rpm added. My SL-1200MK2, which I bought used and sent to KAB for restoration, has the external KAB power supply. My goal is very precise speed and pitch, low rumble, and no audible noise. Plus, I want it to be gentle on my records.

In contrast to most of the mastering rooms and studio control rooms I saw in the '70s and '80s, I don't own a Shure V15 cartridge. I wish I did. I kick myself for not buying a V15 before they went out of production; nowadays they are ridiculously priced on the used market, in unverified condition. I do own one accurate-tracking star, an old ceramic/piezoelectric oddball from Micro-Acoustics, the 3002 (footnote 2). My daily go-to for vinyl playback is an Ortofon 2M Black. My second choice, and sometimes first, is a Denon DL-160, which I use sparingly because it's out of production. (So is the Micro-Acoustics.) For very old mono records, I have an Ortofon OM and a Stanton 500, both with 1mil conical diamond styli.

For run-of-the-mill rock'n'rollers, I use an Ortofon 2M Blue once owned by the late Art Dudley (RIP). Some records sound better with my Goldring 1012GX, but not most. Rounding out the herd are two cartridges that are known to be precise and not warm and so get described as "clinical": a Shure M97xE and a Denon DL-110.

All these cartridges are mounted in either Technics or Ortofon headshells, so switching is quick and easy.

Once I set up the Phono Box RS2 and read the brief user manual, I set about researching what sort of capacitance loading is recommended for these cartridges. Among the instruction sheets for my cartridges, few of them mentioned recommended capacitance, likely because this option is missing on 99+% of all phono preamps ever made. I asked Jeffrey Coates, national sales and marketing director at Pro-Ject Audio Systems and Sumiko Analog, if the company has a list of recommended settings for various MM cartridges. He referred me to the manual, which states specific values for only one moving magnet, the Ortofon 2M Red. Asked for more detail, he replied: "Capacitive loading is going to be dependent on the recommended value of the specific cartridge, and the capacitance of the interconnect cable used." Which is true—but how many of us know our turntable cable's capacitance?

It matters. As Coates noted, "extreme loading (over 300pF in most cases) will cause a treble peak followed by a steep drop-off. It may sound a bit more exciting for a moment, but ultimately will lead to fatiguing high frequencies combined with poor high frequency extension." Conversely, underloading dulls the sound, often with the upper midrange scooped out a few dB. This is part of why some MM cartridges don't sound good with certain preamps but sound great with others.

Lacking solid answers from RTFM (reading the ****ing manual) and my preliminary research, I turned to the interwebs, encountering, predictably, many conflicting opinions and no measured data. I read that the Denon and Shure cartridges are reputed to be sensitive to capacitance and to work best with relatively heavy loading. Sure enough, the Shure M97xE delivered nearly flat HF response (±1dB, 1kHz–20kHz) with the Phono Box RS2 capacitance set at 150pF with my specific setup (low-capacitance cabling on the turntable; vintage SME RCA cable from the turntable to the preamp). The same setting used with the Denon DL-110 resulted in razor-flat HF response. The Ortofon 2M Blue measured best at 100pF despite a 150pF recommendation for the 2M Red, which uses the same generator engine.

The Phono Box RS2's output-balance controls are very useful, because few cartridges have equal left and right output levels. In my fleet, the most out of balance was the Goldring. Only the Shure and the Denons were close enough in output to the point that I opted to take the balance trimmer out of the circuit.

This is all interesting and important to know for audio-transfer purposes, but now it was time to shift focus to listening to how the Phono Box RS2 played music records. I returned to my usual setup, the 2M Black on the 1200MK2 connected to a preamp built for me by Dan Kennedy at Great River Electronics in Minnesota and based on hyperaccurate RIAA de-emphasis circuits by Stanley Lipshitz. Dan's preamp, like the Pro-Ject, is all-discrete with balanced outputs and a very low noisefloor.

I spun a few familiar platters on the usual setup and then connected the 2M Black to the Phono Box RS2 and spun the same platters. Not much difference! The records sound "like they should" (ie, as I'm accustomed to) on both systems, with equal or near-equal tonal balance and stereophony. Reverb tails and image depth were also "as it should sound." With the Pro-Ject RS2, I immediately appreciated being able to correct the half-dB channel imbalance without having to adjust anything in my studio monitor controller or digital interface.

To say the Pro-Ject preamp sounds about the same as my Dan Kennedy preamp is major praise. It also shows there's more than one way to design a highly accurate, low-noise phono preamp.

Next, I put the Shure M97xE, which never lit my fire much, on both preamps. Speaking of lighting fires: I spun the new remaster of the Doors' L.A. Woman, cut by Bernie Grundman. When I played that record through the Phono Box RS2, with the capacitance set to 150pF, it sounded all there, with precise stereophony and more detail than I recall from past spins with that cartridge. This is probably a matter of capacitance loading, since most preamps don't have enough built in for the Shure's top end to emerge in proper balance. I had the same experiences with the Denon DL-110: It sounded more alive and naturally present with the Pro-Ject preamp.

The last thing I did with the Phono Box RS2 was install the Micro-Acoustics cartridge, set the gain to 43, and listen to newly pressed production copies of LP reissues that I had produced. I wanted to hear how the preamp dealt with dynamic, sometimes complex classical music, tracked accurately.

For a reissue producer used to working in the precise, enumerated world of digital, the vinyl Wild West is a black box, sometimes scary. I send master files to a craftsman who cuts a lacquer, which then gets plated (another craft) and pressed (a mass-manufacturing process that must be done correctly to get a good-sounding LP). The sound in the grooves of that production platter is always different—not necessarily better or worse, but always different—from the master file I sent down the line.

Then there's the issue of playback: Any cartridge/turntable/preamp combo is more likely than not to sound noticeably different from any other combo, so, even if I craft the master carefully, it's not possible to know how it will sound in a particular home system. Of course, this is also true with digital releases and streaming: There, the biggest variable is the listener's particular choice of loudspeaker (or headphones), but the other parts of the system are also somewhat variable.

To my relief, the records I produced sounded good!

Key elements of the sound picture I'd hoped would make the journey through the manufacturing process were clear and present. In a couple of cases, I pulled out the reference lacquers and was even more impressed with the balance of impact and detail the Phono Box RS2 delivered. Very loud peaks played clearly and unclipped. The circuitry is so quiet that low-level information fights only the surface noise inherent to grooved discs.

As Julie said in her review, this preamp is the opposite of set-it-and-forget-it. But if you have a few cartridges in rotation and you want to spend some time dialing in a favorite sound profile, it's a great option. The balanced outputs, all-discrete circuitry, highly accurate RIAA reproduction, and a low noisefloor make it a good value and a solid choice for all manner of record playing.—Tom Fine

Footnote 2: Micro-Acoustics made record-cutting styli and modeled their playback styli to mirror the cutter. Theirs was the most hi-fi iteration of a ceramic cartridge, with a beryllium cantilever like a V15, designed for light tracking and fast movement.