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Software Based RIAA Equalization For Best Quality Vinyl Archival?

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Posted on May 10, 2007 at 10:41:08
NuMystic
Audiophile

Posts: 10
Location: Maui, NYC, Johannesburg
Joined: May 10, 2007
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!

 

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'Nother option, posted on May 10, 2007 at 10:50:50
lipmanl


 
DSP inverse RIAA is far from mature (as you implicitly pointed out), and once you've equalized and introduced anomalies, they're going to be difficult to get out.

I recommend storing with RIAA and equalizing later, perhaps on playback. That will let you have the digial files, and equalize them with many iterations of software.

 

I think the Behold gear which is digital until the amps does vinyl this way., posted on May 10, 2007 at 11:20:19
Norm
Reviewer

Posts: 31024
Joined: September 6, 2000
I would think if you are going to digitize your vinyl, doing the RIAA correction in the digital domain would be superior.

 

Ask over in vinyl. Many there are digitizing their vinyl. What does the vinyl playback system consist of?, posted on May 10, 2007 at 12:50:32
artemus
Audiophile

Posts: 15273
Joined: March 12, 2001
That may be a critical factor in determining the proper RIAA source. If you have a very good phono preamp, then use it. If not, then maybe the software will suffice. The system is no better than the weakest link in the chain. The quality of the recording will/should reflect the quality of the playback system
Life has lots of trials and lots of music to help us through them.

 

Re: Software Based RIAA Equalization For Best Quality Vinyl Archival?, posted on May 11, 2007 at 08:00:08
NuMystic
Audiophile

Posts: 10
Location: Maui, NYC, Johannesburg
Joined: May 10, 2007
Artemus... haven't settled on most of it yet. I already have 3 completely stock Technics SL-1200mkII tables on hand so I am probably going to take one and tweak it heavily with either KAB or Origin Live mods amongst others.

Which path (stock arm rewire + fluid damper vs rega replacement arm) will obviously directly impact stylus and phono stage choices. (The Creek OBH18 and Musical Surroundings Phonomena are both appealing in their respective price classes)

lipmanl... just had your sentiment echoed by a gentleman that heavily researched the same thing a while back. Tried both software packages I mentioned above along with a few other options. He says none compared to quality phono stage based RIAA correction. (with his Lyra Titan > SME 2/20 > Manley Steelhead > EMM Labs DSD system!!!)

 

undecided, posted on May 11, 2007 at 11:56:27
dwk
Audiophile

Posts: 235
Joined: September 4, 2000
I've been thinking about this technique off and on for a while, and still haven't come to a conclusion. I definately agree that theoretically it looks great - a simple differential balanced pre into a balanced pro card like the Emu 'should be' as transparent as you can get.
The aspect that I'm worried about is headroom. Without the attenuation of the RIAA stage at higher freqs, pops and clicks would seem very likely to induce digital clipping, and that's something that can't be fixed after the fact.

My thought is that a pre that incorporates only the first ~50Hz pole might be the way to go. It gives you the 6db/Oct attenuation to preserve headroom, but is still (maybe?) simple enough to retain very high quality at relatively low cost.

 

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