WTL Phono

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A word from the Chief Engineer

The Well Tempered Phono stage is designed to accommodate both moving magnet (MM) and moving coil (MC) cartridges and has a maximum gain of 66 dB for MC cartridges and the gain is switched for MM cartridges. The necessary break points for the RIAA equalisation are distributed throughout the circuit in order to ensure
optimum overall time response of the circuit as well as to ensure the necessary frequency response. Normally, the RIAA equalisation is effected with an arrangement of interconnected resistors and capacitors. Since the RIAA recording process requires that the treble frequencies be substantially boosted relative to the bass frequencies, control of the time response is an important requirement.

The MM/MC Phono circuit employs state-of-the-art operational amplifiers. Using these devices ensures a low noise, high gain, stable and predictable design result.

I prefer using resistors of the carbon film type although metal film resistors might have an edge for noise considerations. I prefer capacitors with polypropylene dielectric.

The input shows a switch selected resistor to accommodate both MM and MC cartridges. In my experience, MC cartridges loaded with 47K ohms yield an excellent result and 47K is what I have used for some time now.

Testing of the Well Tempered Phono Stage will reveal excellent results both in the frequency response and the time response. Testing with square waves equalised for the RIAA recording characteristic (the inverse of the RIAA playback) will yield excellent results, verifying overall performance.

William Firebaugh
Chief Engineer

Specifications

- Harmonic Distortion (2V RMS Output): 0.001%

- Input Impedance: Variable

- Input Gain: Variable

- Input Connectors: 1 group RCA

- Output Connectors: 1 group RCA

- Ground Connector: Screw terminal

- Signal/Noise: 96 dB

- Consumption: 20 watts

- Dimensions (H x W x D): 105 x 150 x 260 mm, 220 x 360 x 440 mm (Shipping)

- Weight: 7.6 kg, 8.6 kg (Shipping)

Where to buy