Shawn Kernes Blog

Choosing the right phono gain is about amplifying the cartridge's tiny output voltage so it reaches approximately the same level as other line-level audio sources without overloading the phono stage or your preamp. The basic calculation Use this formula: Gain (dB) = 20 × log ⁡ 10 ( Desired output voltage Cartridge output voltage ) \text{Gain (dB)} = 20 \times \log_{10}\left(\frac{\text{Desired output voltage}}{\text{Cartridge output voltage}}\right) Where: Cartridge output voltage is the manufacturer's rated output (usually measured at 1 kHz, 5 cm/s). Desired output voltage is typically around 300–500 mV for a line-level input. Example 1: Moving Magnet (MM) Cartridge output: 5 mV Desired output: 500 mV 20 × log ⁡ 10 ( 500 / 5 ) = 20 × log ⁡ 10 ( 100 ) = 40  dB 20 \times \log_{10}(500/5) = 20 \times \log_{10}(100) = 40\ \text{dB} So a 40 dB phono gain is a good match. Example 2: High-output Moving Coil (HOMC) Cartridge output: 2.0 mV Desired output: 500 mV 20 ...

To match a tonearm with a phono cartridge, you're actually matching the tonearm's effective mass with the cartridge's compliance . The goal is to achieve a tonearm/cartridge resonance frequency between about 8 Hz and 12 Hz , which keeps it away from both record warps (typically below 6 Hz) and musical bass frequencies (above 20 Hz). Step 1: Gather the specifications You'll need: Tonearm effective mass (M) in grams (from the tonearm manufacturer) Cartridge weight (C) in grams Mounting hardware weight (H) (typically 0.5–1 g unless integrated) Dynamic compliance (D) of the cartridge in µm/mN (or "cu") Step 2: Use the resonance formula The commonly used formula is: f r = 159 ( M + C + H ) × D f_r = \frac{159}{\sqrt{(M + C + H)\times D}} ​ Where: f r f_r  = resonance frequency (Hz) M M M = effective tonearm mass (g) C C C = cartridge mass (g) H H H = screws/hardware mass (g) D D D = dynamic compliance (cu or µm/mN) Example: Sup...