Jeff Rowland Design Group Coherence preamplifier & Cadence phono stage Cadence Measurements

Sidebar 5: Cadence Measurements

I measured the Cadence only in the mode in which it will most likely be used: the "Lo-Gain Amp/Hi-Load" setting suitable for use with typical MC cartridges. The voltage gain in this mode was 62.4dB, the output impedance a low 79 ohms. Despite the high gain, noise levels were very low. The unweighted signal/noise ratios ref. 1V output were 70dB (10Hz-500kHz) and 71.7dB (22Hz-22kHz), these improving to 78dB when A-weighted.

The Cadence's RIAA error is shown in fig.6. A slight channel imbalance (0.09dB) can be seen, as can a slight rolloff (-0.6dB) at 20kHz. The distortion levels are very low, as is seen in the output spectrum with the Cadence reproducing 50Hz at a very high level of 6.7V (fig.7). Referenced to a standard MC output level of 500µV at 1kHz, the measured overload margin was around 20dB across the audio band—which is good.—John Atkinson

Fig.6 Rowland Cadence, frequency response into 100k ohms, "Lo-Gain/Hi-Load" (0.5dB/vertical div.).

Fig.7 Rowland Cadence, spectrum of 50Hz sinewave, DC-1kHz, at 6.7V into 100k ohms (linear frequency scale).

Jeff Rowland Design Group
P.O. Box 7231
Colorado Springs, CO 80933
(719) 473-1181