RIAA Phono Preamplifier
Phonos is a preamplifier for record players using either moving magnet (MM) or moving coil (MC) cartridges. The equalization curve is according to RIAA and suitable for all vinyl records since 1954.
This phono preamplifier is equipped with the best sounding capacitors and built after the legendäre Douglas Self design.
The control parameters are adjustable on the front and therefore always accessable to make the search for the best sounding setting a fun experience.
MC cartridges offer very low inductance and impedance, which means that the effects of capacitance (in the cable that goes from the cartridge to the preamp) are negligible. The impedance of cartridge can be set in six values: 100, 220, 470, 2.2k, 4.7k, and 10kOhm. If in doubt which impedance matches the cartridge’s impedance you can empirically determine the value for the flattest frequency response.
The purposes of the RIAA equalization, which is a form of pre-emphasis on recording and de-emphasis on playback, are to permit greater recording times by decreasing the mean width of each groove, to improve sound quality, and to reduce the groove damage that would otherwise arise during playback.
A recording is made with the low frequencies reduced and the high frequencies boosted, and on playback the opposite occurs. The net result is a flat frequency response, but with attenuation of high frequency noise such as hiss and clicks that arise from the recording medium.
The RIAA equalization curves for recording (blue) and playback (red) of vinyl records. The recording curves perform the inverse function, reducing low frequencies and boosting high frequencies.
RIAA equalization has transition points in three places: 75 µs, 318 µs and 3180 µs, which correspond to 2122 Hz, 500 Hz and 50 Hz (rounded values).
|Transition Frequencies||Time Constants||Relative Level|
|50 Hz||3180 µs||-17 dB|
|500 Hz||318 µs||-3 dB|
|1000 Hz||159 µs||0 dB|
|2120 Hz||75 µs||+3 dB|
The construction of the RIAA equalizer follows a design made by Douglas Self. In this design larger single capacities are exchanged against smaller multiple capacities.
The Normal gain is +46 dB (MM) and +67 (MC).
In the -10dB position the Phonos produces enough output level for standard consumer electronics products operating on -10dBV.
In the +4dB position the output is equally loud as modern DA converters at 0dBfs = +15dBu.
The Phonos: High-End In Compact Design
- RCA, unbalanced, gold-plated
- Input impedance (MM): 47 kohms
- Input impedance (MC): switchable
- Output impedance: < 5 ohms
- Crosstalk: -80dB (at 1 kHz)
- RIAA equalizer (after Douglas Self)
- Amplification: 46 dB (Norm.), 36 dB (-10 dB), 50 dB (+4 dB)
- Switchable capacitance: Off, 150 pF, 220 pF and 330 pF
- Noise (A-weighted): -85,3 dB
- Amplification : 67 dB (Norm.), 56 dB (-10 dB), 71.5 dB (+4 dB)
- Schaltbare Impedances: 100, 220, 470, 2k2, 4k7, 10 k ohms
- Noise (A-weighted): -61,7 dB
- +/- 60 V
- Mains voltage (switchable): 230 V AC / 50 Hz or 115 V AC / 60 Hz
- Fuses: 230 V: T 500 mA; 115 V: T 1 A
- Power consumption: max. 30 VA
- Stand-by power consumption: 0.7 W
- 278 mm W x 57 mm H x 330 mm D
- 10.95 in W x 2.24 in H x 13 in D
- 3.2 kg; 7.05 lbs (unit only)
- 4.3 kg; 9.5 lbs (shipping)
0 dBu = 0.775 V. Subject to change without notice.