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Software Based RIAA Equalization For Best Quality Vinyl Archival?

Posted by NuMystic (A) on May 10, 2007 at 10:41:08

I'm about to begin archiving my collection of 3000+ records into 24 bit / 96kHz files for preservation, digital playback on very large pro audio systems (yes, some are apalling, but quite a few are truly outstanding), and studio production work.

I've come across one or two references to sidestepping the phono stage EQ and doing the RIAA equaliztion on the computer to achieve a more transparent recording.

This is a software package designed expressly for that purpose:

Pure Vinyl

And this is a second company that sells software as well as phono preamps without RIAA conversion for this purpose:

The New Way For Vinyl Recording

A few quotes I've found relating to the idea and methodology (the links above are far more detailed) ...

> The RIAA playback equalization curve functions much like an integrator with a 75
> microsecond time constant. This is also known as a pulse stretcher, and you will notice
> that your click waveforms have tails on them.

> You might try plugging your turntable directly into the iMic to record a track, and then
> do your declicking right away. Then you can feed the declicked file to the Griffin
> software for RIAA equalization. This will avoid the phenomon of pulse-stretching of
> clicks by the RIAA playback curve.

> Doing the RIAA equalization in the Griffin software will have the effect of amplifying the
> quantization noise and distortion increasingly below 500 Hz. But the human ear has
> decreasing sensitivity to low-level sound with decreasing frequency, so this may not be
> a problem. I do not own an iMic nor use the Griffin software, so you might try a transfer
> both ways, and see which you prefer. The RIAA curve can be done more accurately in the
> digital domain, in most cases, compared to the analog domain.

Right off the bat I'm very dubious about the above person's advice as the Griffin iMic and software is FAR from pro studio quality. (the iMic is a cheap A/D converter for macs that plugs into the mic input)

But then I found one other person talking about the same thing:

> Software RIAA equalization can take a bit more effort (at this time) than a "conventional"
> phono pre setup (more work on the hook-up side), but there are many advantages to
> doing it this way. For instance, a balanced input mic pre and low output moving coil cart
> will provide zero audible hum (if the TT is wired correctly, that is). No capacitors in the
> signal chain (at least not the ones required in a phono preamp); just clean, straight-wire
> gain. Perfect channel phase and RIAA amplitude match (no analog component tolerances
> to deal with). I've noticed some information going around that suggests that using
> software RIAA EQ throws away resolution from your audio interface, but this isn't a
> factor in a real-world situation, if the EQ is done properly.

Problem is the two people above are the ONLY ones I've ever heard making mention of this and I've spent days searching here and elsewhere and haven't seen any other first hand experiences with it.

So my question is, with all else being equal (quality turntable, tonearm, stylus, proper isolation, interconnects, top notch A/D converter) would going this route truly provide the most transparent and "authentic" recording?

There's no doubt that many audiophile phono stages are prized as much for their unique "coloring" of the sound as they are for their low noise floor. Since I am looking for the most transparent archiving possible taking one piece of hardware out of the signal chain makes sense to me (at least in theory).

Many thanks in advance for any light you can shed on this subject. I'm an absolute newcomer to the high end audio domain and while the theories put forth on the websites above are compelling, I don't have enough real world experience to separate the hype from the facts. (they are after all selling software/hardware)

Since this is going to involve literally hundreds of hours of effort and I would prefer to do it only once!

This post is made possible by the generous support of people like you and our sponsors:

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