Rothwell Headspace: A Versatile Pre-Preamp for Moving Coil Cartridges

Introduction: The Rothwell Headspace is a moving coil headamp (also known as a pre-preamp), which serves a similar function to a step-up transformer. It raises the output of moving coil cartridges to moving magnet level, but does so using transistors instead of transformers.

Advantages of the Transistor Approach: The Headspace offers the ability to independently set gain and load impedance, and features an exceptionally wide bandwidth. With four gain settings and eight load settings, it can accommodate a very wide range of cartridges.

Uses for a Headamp:

1. For Low Output Moving Coil Cartridges: The Headspace allows low output moving coil cartridges to be used with moving magnet phonostages, ranging from budget mm-only phonostages to high-end valve phonostages.
2. To Add Flexibility to an MM/MC Phonostage: Phonostages without adjustable gain or load impedance can be set to MM mode, using the Headspace as a pre-preamp to set the optimal gain for the cartridge in use, independently setting the load impedance for the best performance.
3. To Improve the Signal-to-Noise Ratio of an MM/MC Phonostage: Phonostages that are noisy on the MC setting can be improved by using the Headspace as a pre-preamp with the phonostage set to MM mode.
4. To Boost the Signal from High Output Moving Coils: The Headspace has a low gain setting (10dB) ideal for giving high output moving coil cartridges, like the Denon DL-110, the extra lift needed to match them to an MM phonostage.

Design: The Headspace uses discrete transistor circuitry throughout, including the proprietary low noise voltage regulator. The audio amplification transistors are selected low noise devices, and audiophile resistors and capacitors are used for the lowest noise and best sound. The circuit configuration is an unusual variation on the complementary feedback pair, giving the Headspace superbly detailed performance with good separation and a wide, deep soundstage.

Gain Settings: Four gain settings are available for cartridges with output voltages within each of the specified ranges:

• 0.7mV - 2.5mV, 10dB (x3.2)
• 0.2mV - 0.7mV, 20dB (x10)
• 0.1mV - 0.35mV, 25dB (x18)
• 0.05mV - 0.3mV, 27dB (x23)

Load Impedance Settings: Eight load impedance settings are available:

• 55 ohms, 65 ohms, 80 ohms, 100 ohms, 140 ohms, 200 ohms, 360 ohms, 1.5k

Specifications:

• Gain: 10dB, 20dB, 25dB, 27dB
• Load Impedance: 55R, 65R, 80R, 100R, 140R, 200R, 360R, 1.5k
• Output Impedance: <100 ohms
• Headroom: >20dB
• Power Supply: 24 volts DC, center +ve
• Mains Voltage: 100V - 250V AC
• Power Consumption: 1W
• Dimensions: 60 x 155 x 92 mm
• Weight: [Not specified]

Conclusion: The Rothwell Headspace is a versatile and sophisticated solution for audiophiles seeking to extract the best performance from their moving coil cartridges. With its extensive setting options and high-quality components, the Headspace is a top choice for upgrading any vinyl listening system.