Audio Technica AT-VM670xSP: An Audiophile Deep Dive

Audio Technica has spent decades refining the moving magnet cartridge, and few companies have distributed that expertise across as broad a catalog. The AT-VM670xSP sits in a specific and often misunderstood corner of that catalog. It is a VM (dual magnet) moving magnet design fitted with a 3 mil (0.0025 inch) conical stylus, and that single choice reshapes the entire purpose of the cartridge. This is not a fine line contact tracer built to extract the last microns of detail from a modern audiophile pressing. It is a specialist tool engineered for a different job. Understanding why leads directly into the mechanical and electrical decisions that define it.

Topology and Core Mechanism

What is the VM (dual magnet) design and how does it work?

The VM design uses two small magnets arranged in a V configuration at the rear of the cantilever, and each magnet is aligned with one channel of the stereo groove. This is Audio Technica's signature moving magnet architecture, and the geometry is the reason it matters. A stereo groove encodes the left and right channels on two walls cut at 45 degrees to each other. By orienting the two magnets so that their motion mirrors those two groove walls, the VM system positions each magnet symmetrically relative to its corresponding coil. The audible payoff is more consistent channel behavior and a compact, low mass magnet assembly that can respond quickly to groove modulation.

Why does this cartridge use a 3 mil conical stylus?

The 3 mil conical stylus exists because this cartridge is built to play coarse groove records, not standard microgroove LPs. A modern microgroove pressing is designed for a stylus around 0.7 mil, so a 3 mil tip is dramatically larger. That larger radius is intentional. It rides the wider grooves of 78 rpm shellac records and older coarse groove pressings, sitting at the correct depth in the groove wall rather than dropping to the bottom of a wider valley or riding on debris. A conical (spherical) profile contacts the groove wall at a single point on each side. It is simple to manufacture, mechanically robust, and forgiving of the worn, damaged, and off center grooves common on vintage media. For this application the conical profile is not a compromise, it is the correct geometry.

What does the aluminum cantilever contribute?

The aluminum cantilever transmits stylus motion back to the magnet assembly, and aluminum is chosen for its balance of stiffness and low mass. A cantilever must be rigid enough that it does not flex and smear the mechanical signal, yet light enough that the moving system can accelerate and decelerate accurately at audio frequencies. Aluminum tube construction has been an industry workhorse for exactly this reason. In a cartridge intended for robust playback of vintage discs, aluminum also brings practical durability, which matters when the media itself can be uneven and demanding on the stylus assembly.

Electrical Design and System Matching

What do the coil impedance, DC resistance, and inductance tell us?

These three figures describe the electrical character of the generator, and together they define how the cartridge interacts with your phono stage. The coil impedance is 3.3k ohms at 1 kHz, the DC resistance is 485 ohms, and the coil inductance is 240 mH at 1 kHz. The DC resistance is the pure copper resistance of the coil windings measured with no signal moving. The inductance of 240 mH is significant because inductance combined with the load capacitance of your cables and phono input forms an electrical resonant circuit. That resonance sits somewhere in or near the top of the audio band, and its exact position shapes the treble response. This is precisely why the load recommendations below are not optional suggestions but part of the design.

What load resistance and capacitance does the cartridge need, and why?

The AT-VM670xSP is specified for 47k ohms load resistance and 150 to 250 pF load capacitance, which is the standard target for a moving magnet input. The 47k ohm figure is the near universal moving magnet standard, and nearly every MM phono stage presents it by default. The capacitance window is the part enthusiasts most often overlook. Because the coil inductance forms a resonant network with total load capacitance, keeping the sum of your tonearm wiring, interconnect cables, and phono input capacitance within 150 to 250 pF keeps that electrical resonance in its intended place. Exceed it and the resonant peak drops in frequency and grows, which typically manifests as an exaggerated then prematurely rolled off treble. Fall short and the balance shifts the other way. Cable capacitance is the easiest variable to control here, so choose low capacitance interconnects if your phono stage already contributes toward the ceiling.

What does the 4.7 mV output voltage mean for matching?

The output is 4.7 mV at 1 kHz measured at 5 cm/sec, which is a healthy, typical moving magnet level. This tells you the cartridge is designed for a standard moving magnet phono input and needs no step up transformer or specialized high gain stage. A 4.7 mV output gives a comfortable margin above the noise floor of a well designed MM stage, so you are unlikely to run short of gain feeding a normal preamplifier or integrated amplifier with a phono input. It also means the cartridge slots directly into the same signal chain you would use for any of Audio Technica's mainstream MM models.

How should the 20 dB horizontal to vertical output ratio be interpreted?

Audio Technica does not publish a channel separation specification for the VM670xSP, because it is a monophonic pickup and separation between two channels is not a property it has. The figure to read instead is the horizontal to vertical output ratio of 20 dB at 1 kHz. Coarse groove and 78 rpm records are cut with lateral modulation, while a large share of the noise on aged shellac arises from vertical movement: wear, scuffing and warp. A generator that is strongly sensitive to lateral motion and comparatively insensitive to vertical motion therefore suppresses much of that noise before it ever becomes signal, and 20 dB quantifies that rejection. This is the same reasoning behind the heavy 5.0 g tracking force and the 3 mil conical tip. Every part of the design is aimed at recovering music from difficult grooves rather than at stereo imaging.

What does the 20 Hz to 20 kHz frequency response indicate?

The stated frequency response is 20 Hz to 20 kHz, spanning the full nominal range of human hearing. This confirms the cartridge is engineered to reproduce the complete audible band. In practice the actual recorded bandwidth of the vintage shellac and coarse groove material this stylus is built for is often narrower than a modern LP, so the cartridge is not the limiting factor in that chain. What the specification communicates is that the generator and stylus assembly are capable across the range, and any bandwidth restriction you hear will come from the source media rather than the pickup.

Setup, Tracking, and Physical Integration

What is the tracking force range and why is the recommended figure 5.0 grams?

The tracking force range is 4.5 to 5.5 grams with a recommended setting of 5.0 grams, and that comparatively firm downforce is deliberate for coarse groove playback. Tracking force is the downward pressure the stylus applies to the groove, set by the tonearm counterweight. A relatively high 5.0 gram figure keeps the large conical stylus seated securely in wide, sometimes worn or warped grooves where a lighter force would allow mistracking, chatter, or the stylus riding up out of the wall. Vintage shellac is also physically harder and heavier than vinyl, so a firmer, well controlled contact improves tracing stability. Always set this with an accurate stylus force gauge, and treat 5.0 grams as the intended target rather than the extremes of the range.

How does the half inch standard mount affect compatibility?

The cartridge uses a half inch standard mount, meaning the two mounting holes are spaced to the universal half inch (roughly 12.7 mm) standard used by the vast majority of headshells and integrated tonearms. This is the most important practical specification for system integration because it guarantees the cartridge bolts into standard headshells and tonearms without adapters. It fastens with two screws and connects through the four standard color coded output pins, so integration with a conventional turntable is straightforward. Because it shares this mounting standard with Audio Technica's other VM cartridges, you can swap it into the same headshell you use for microgroove playback if you keep a dedicated coarse groove setup.

Where the AT-VM670xSP Sits in the Lineup

How does this model relate to the rest of the VM range?

The AT-VM670xSP is the specialist coarse groove member of the VM moving magnet family, distinct from the microgroove focused models that make up most of the range. Audio Technica's broader VM line uses the same fundamental dual magnet generator but pairs it with styli intended for standard vinyl, ranging from conical and elliptical profiles up to advanced line contact and Shibata tips on the higher tier models. Those cartridges chase separation, tracing accuracy, and inner groove resolution on modern LPs. The AT-VM670xSP takes the shared VM engineering and redirects it toward 78 rpm and coarse groove media through its 3 mil conical stylus, firmer tracking force, and appropriately matched electrical parameters. It is therefore best understood not as a step up or step down from the microgroove cartridges, but as a parallel branch built for a job those cartridges cannot do.

Who is this cartridge really for?

This cartridge is for the listener who owns 78 rpm shellac or other coarse groove records and wants to play them properly rather than damaging them with an incorrect microgroove stylus. If your collection includes historic recordings that predate the microgroove LP, the 3 mil conical stylus, the 5.0 gram tracking target, and the standard 47k ohm moving magnet loading make the AT-VM670xSP a purpose built solution that drops into a conventional turntable and phono chain. For anyone maintaining a dedicated deck or a swappable headshell for vintage media, it represents Audio Technica's proven VM generator applied exactly where it belongs.