Subsonic filter vs RIAA

chinoy

New Member
Joined
May 31, 2022
Messages
17
Points
3
Location
Bangalore
The RIAA standard. Already drops 20-100 Hz signal by -15 DB or more.
So then why would I need a subsonic filter if Im already using a RIAA phono preamp.
Do I really need something like this if I already have a RIAA phono preamp.
 
RIAA equalisation during playback, BOOSTS 20 Hz signals by 20 dB.

Hence Rumble pick up from the Turntable is also Boosted by 20 dB.

Add to that the problem of Room resonances at LF, and a LF filter makes a LOT of sense in typical audio setups...
 
Low Frequency signals in music typically have large amplitude / power. If these werer recorded directly into an LP, the LP Groove would not be wide enough and the Groove would rupture into the adjacent Grove.

As a solution, the RIAA ( Recording Industry Association of America ) created a standard where all signals below 500 Hz are gradually reduced before recording... The reduction / attenuation keeps increasing untill it is 20 dB of attenuation @ 50 Hz. Below 50 Hz it remains a constant attenuation of 20 dB.

To retain signal fidelity, during playback, the Phono stage Boosts by 20 dB signals between 20 Hz to 50 Hz.

From 50 Hz to 500 Hz, the boost is gradually reduced to no boost (Unity Gain) @ 500 Hz.


RIAA-EQ-Curve_rec_play.svg.png



At the High Frequency range... signal levels are typically low, accounting for 10% or less of the audio power. If these signals were recorded at their actual (miniscule) levels, they would be difficult to detect by the cartridge & reproduce faithfully. Also when tracking such low level HF signals, the phono cartridge rubbing against the vinly grain would create Noise / Hiss. Also the Phono stage noise would be added to this HF signal.

Hence the RIAA also specified that while recording HF Signals (above 2.122 KHz, the Signals would be Boosted... The amount of boost gradually increases till its 20 dB Boost (while recording) @ 20 KHz.

Replay requires the converse, ie a CUT of 20 dB @ 20 KHz.

This cut also cuts HF Noise / hiss when reproducing the HF signal.
 
Get the Wharfedale EVO 4.2 3-Way Standmount Speakers at a Special Offer Price.
Back
Top