Hmm... no feedback yet ?

As an addon:

As mentioned, this filter is for 44.1kHz samplerate/data only. What it means is that the mathematical model is matched for amount of this much samples per second (sample accurate processing). Biquad method used in this filter uses three samples to get the new output value calculated (current sample and two previous samples). What happens if you set samplerate to 48kHz, as for an example, ... samples becomes processed wrong --> quality becomes bad.

BTW, as I think this is quite good resulting method for RIAA EQ reproduction, if Stereophile 'testing grew' has not tested equal method yet and is interested to test this filter in action and maybe even compare against your ordinary reference phono pre-amp system (I suppose you have some HQ soundcards there (and maybe using ordinary card as well (SoundBalaster X-Fi, onboard sound)), I could e-mail you the VST plug-in version as a plain RIAA stage only (no additional filters included, only the output level control). This VST version is based on biquad method too, it has four filters (44.1, 48, 88.2 and 96kHz) and it selects the filter automatically by the host software samplerate settings. So, practically, it is a fully working 'RIAA stage' already now.

With certain VST host software, it's possible to record (rip) the LP so that the resulting audio file is processed already ... so, it's not for playback only as the evaluation version is.

jiitee

I have now improved the VST version a bit . Changed from biquad to 3rd/4th order filters. Some specs from calculations:

Maximum 'curve' error (0 Hz - 20kHz): 0.0005780dB (44.1kHz) - 0.0000046dB (96kHz)
Maximum Phase error (0Hz - 20kHz): ~+/- 21

No feedback/results yet??

Allright, maybe it is/was too hard to use or too limited to get your attention so, ... I prepared another evaluation version ... now it's fixed for 48kHz instead of 44.1kHz, it can be used without preamplifier too (in most cases) and it's possible to record the output to a 16-/24-/32-/32f-bit wav file (though, this needs another plugin being installed, see below).

I also added a "reset to defaults" button so It's possible to get everything working much easier. Subsonic filter is not improved ... it still cuts only 6dB/oct instead of 'required' 36dB/oct.

'bout recording the output:
You need to install Voxengo Recorder VST plugin into the same directory where to this RIAA Filter is placed to, to get the recorder working. Actually, you could use any plugin but it needs to be renamed equally to the voxengo recorder .dll. Set the "MME Device" to "Sound Mapper" .. otherwise you may hear some unwanted noises (those are not added into recorded file). Set the "Output To " -> "File". Name the file before recording. Set the bit-depth.

Here are links for the new version.
RIAA Filter (optimized for 48kHz) DEMO.rar
Mirror 1
Mirror 2

Hmm... still waiting some feedback/comments ...

jiitee

Everything should work well under w2k too but, I didn't get the Max/MSP Runtime installed for w2k. I know some has got XP only software installed/working w/ w2k even I have not managed to do so ... so you need to try if it's possible in your system. It's maybe just the installer that prevents installation for other than XP.

jiitee