I hope this is the right sub-forum to place this thread into (as this is related to PC audio as well).
Maybe you're familiar already w/ the "new method" described @ EnhancedAudio.com pages.
Well, after many tries w/ not so good results in using various EQ plugins and standalone EQ software for RIAA compensation, I have now started implementing a solution of my own (similiar w/ the enhancedaudio's) ... a RIAA reproduction filter to be used when turntable is connected into soundcard without hardware RIAA stage in signal path .. but just through a flat pre-amp. I've seen there some commercial solutions available and one 'open source' solution for Soundblaster/kX users (link given below).
All I can say so far, is that the results I get here are really qood (especially w/ 88.2kHz and 96kHz filters) but, since I have only one set of hardware to evaluate this software, I would like you to evaluate this too. This version of filter,
( .. Sorry 'bout the visual outlook but ... don't laugh, it should work well)
which I have linked below, is prepared only for this evaluation purpose. It's optimized for 44.1 kHz audio (any bit depth can be used), it's for output only and it can be used through Cycling74 Max/MSP runtime enviroment only. ASIO, MME, DS, etc. are supported as well as Windows XP and MAC OS/X 10.3.9-> (there is a runtime for both systems available). For this "evaluation" version, I have included a rumble filter (Subsonic) w/ ability to set the cutoff frequency (5-30Hz) and Q (0.1-1.41). It's allways switched "ON" and not very well implemented (see below).
Here are listed the needed software:
RIAA Filter (for 44.1kHz) DEMO.rar (~16kB)
-- 3 files included (2 pictures and the filter .pat file)
NOTE: Filename may become changed by the file service providers system.
Setting it up (Windows):
- connect your turntable output through some flat pre-amp (no RIAA stage in signal path) into PC through soundcard line input(s)
- connect your output device (amp/active speakers/headphones) into soundcard output(s)
- install the Max/MSP runtime enviroment
- extract the "RIAA Filter (for 44.1kHz) DEMO.rar" to your harddisk
Start the RIAA Filter program either by
- starting the runtime enviroment and Open the "RIAA Filter (for 44.1kHz).pat" or
- double-clicking the "RIAA Filter (for 44.1kHz).pat" (through Windows Explorer -> .pat extention should be associated to Max/MSP runtime then)
In "RIAA Filter (for 44.1kHz)" screen (important):
- set I/O devices; ASIO recommended (if no sound, remember check settings in your mixer software)
- adjust the Subsonic filter by dragging w/ mouse (Hz = 25Hz and Q = 0.71 are good to start from) (see below)
- adjust Gain to somewhere near the 0dB mark (128)
- press the Play/Stop button to enable the playback through filter
NOTE: If you can hear audio when Play/Stop is set "OFF" (there should be total silence) then you need to set something in your mixer software (maybe monitoring OFF, mute something, etc.) otherwise the unfiltered signal is summed into playback --> brighten sound.
It's low order highpass filter so the cut is not very sharp/steep ... you can use 25-30Hz as cutoff frequency w/o loosing much from above the 20Hz frequencies.
You see the RIAA de-emphasis curve for this filter as a background image for Filter screen. The original filter coefficients (15 decimal accuracy) gives quite accurate de-emphasis curve (error: