Van den Hul The FROG
Van den Hul The FROG, moving-coil cartridge
At Van den Hul, each cartridge is assembled by hand, to order, and models are built by drawing on other designs in the range. This one uses the coils from the Grasshopper III, the front pole piece and suspension from the Grasshopper IV, with a reworked magnet, copper coils and the line-contact stylus that made the Dutch manufacturer’s reputation. A low-output cartridge, to be paired with an MC phono preamp and a light or medium-mass tonearm.
Grasshopper coils in a green body
The FROG is a moving-coil (MC) cartridge: two tiny coils, attached to the rear of the cantilever, move within the field of a fixed magnet, unlike the more widespread moving-magnet (MM) cartridges, in which the magnet moves. The moving mass is very low, as is the voltage produced. Van den Hul combines the coils from the Grasshopper III, the front pole piece and suspension from the Grasshopper IV, and a modified magnetic circuit specific to this model. The coil wire is “matched crystal” copper, a proprietary process that reduces the number of boundaries between the metal’s crystals, each a junction the signal must cross. The cantilever, the thin rod that holds the diamond, is made of boron, a material that is both very rigid and light. The assembly fits into a green body weighing 8.2 g, assembled by hand in the Netherlands after each order.
A 2 × 85 µm line-contact stylus
The diamond follows the VDH type 1S profile, the line-contact stylus developed by A.J. van den Hul. Whereas a conical diamond touches the groove wall at a small point, and an elliptical one over a narrower area, this profile rests against it along a long, very fine vertical line, with two radii of 85 µm. This line follows the very short undulations that carry the upper frequencies more closely, and the pressure distributed over a greater height reduces wear on both the record and the diamond. The stylus’s equivalent mass of 0.32 mg reduces inertia when faced with rapid groove variations, and its tracking ability of 70 to 80 µm (measured at 315 Hz with 1.5 g) provides headroom for bass-heavy or highly dynamic recordings. The frequency response extends from 5 Hz to 55 kHz. The trade-off with this profile is familiar from all line-contact diamonds: it requires careful alignment, including overhang, azimuth and tonearm height, to keep the contact line properly parallel to the groove walls.
A compliant suspension that needs the right tonearm
With a compliance of 35 µm/mN, The FROG’s suspension is compliant. Together with the tonearm, it forms a mass-spring system whose resonant frequency should fall between approximately 8 and 12 Hz, below the music and above the undulations of warped records. A compliant suspension mounted on a heavy tonearm pushes this resonance too low, into the region where a record warp makes the cantilever pump up and down. Van den Hul therefore recommends a tonearm with an effective mass of between 6 and 10 g, which corresponds to most light and medium-mass tonearms on the market. Tracking force is set between 13.5 and 16 mN, or 1.35 to 1.6 g, and the vertical tracking angle is 22°, achieved by adjusting the tonearm height once the cartridge is mounted.
0.65 mV output: an MC stage is required
At 0.65 mV, The FROG delivers approximately 16 dB less than a typical MM cartridge at around 4 mV. It requires an MC phono preamp with around 60 dB of gain, or a step-up transformer placed before an MM input. The internal resistance of 21 Ω per channel is low, indicating a short winding, and the recommended load is 500 Ω, with a minimum of 200 Ω. This value is higher than the 100 Ω often set by default on MC inputs: it is worth checking that the preamp offers 500 Ω or a variable load setting. The channel imbalance remains below half a decibel, keeping the stereo image centred.
Technical Specifications
Physical Parameters
- Weight: 8.2 g
- Dynamic mass: 0.32 mg
- Tip: VDH-IS size, 2 × 85 µm
- Tracking angle: 22°
Tracking Parameters
- Tracking force: 13.5 to 16 mN
- Compliance: 35 µm / mN
- Tracking ability (at 315 Hz at 15 mN): 70 to 80 µm
- Recommended arm mass: 6 to 10 g
Electrical Characteristics
- Output voltage (1 kHz at 5.7 cm / s): 0.65 mV
- Internal resistance per channel: 21 Ω
- Recommended load impedance: 500 Ω (> 200 Ω)
- Channel imbalance: < 0.5 dB
Audio Performance
- Frequency response: 5 Hz to 55 kHz
Frequently asked questions
Can The FROG be connected directly to an MM phono input?
No. An MM input provides around 40 dB of gain, which is insufficient for 0.65 mV: the level would be low and background noise audible once the volume is turned up. It also presents a load of 47 kΩ, far from the recommended 500 Ω. An MC input or a step-up transformer is required.
Is a step-up transformer suitable for this cartridge?
Yes, the low coil resistance (21 Ω) is well suited to this solution. A transformer reflects the MM input load back to the cartridge divided by the square of its ratio: with a 1:10 ratio feeding a 47 kΩ input, the cartridge sees approximately 470 Ω, very close to the recommended 500 Ω, and the 20 dB gain raises the voltage to approximately 6.5 mV, a comfortable level for an MM input.
What’s the difference compared to The FROG Gold and The FROG High Output?
The FROG comes in three versions that share the same mechanical design. The standard version shown here has copper coils and outputs 0.65 mV. The Gold replaces copper with “matched crystal” gold for the same voltage. The High Output retains copper but delivers 2.25 mV, with a resistance of 96 Ω and a recommended load of 47 kΩ, making it compatible with an MM input.
Should the preamp’s capacitive load be adjusted?
No, load capacitance is not a critical parameter for a low-impedance moving coil cartridge like this one. Only the resistive load, around 500 Ω, needs to be adjusted.
How do you replace the stylus once it is worn out?
On an MC cartridge, the diamond stylus is not removable: it is attached to the cantilever, which is itself connected to the coils. Van den Hul provides stylus tip replacement in its workshop, upon request through the distributor, avoiding the need to buy a complete new cartridge.
Why is there a delay before receiving your cartridge?
Each unit is handmade after the order is placed. Allow approximately two weeks for production, plus shipping time through the distributor.
Can The FROG play 78 rpm records?
No. The VDH 1S profile is designed for microgroove records, both mono and stereo. 78 rpm records have much wider grooves that require a stylus with an appropriate tip radius, generally around 3 mil, fitted to a dedicated cartridge.
- Eco-contribution included in the sale price.
- Manufacturer reference: A-FRG
