Digital RIAA

Is there an easy way of applying the RIAA Eq curve to a 24 bit file recorded direct from an LP cart. without any Eq ?

I am new to this, so a fairly detailed explanation would be appreciated.

Speaking as someone who has actually done it, as opposed to theorizing...

The Scarlett i2 will give you somewhere around enough gain (at completely the wrong input impedance to match the pickup) so you can probably rig something up with it if you are desperate

I fiddled around...

You would probably need to - see above

Singnal/noise on your 24bit recording should plenty good enough so you don't have to worry about applying the eq on the way in rather than inside the digital domain...

That’s not really the issue - I think its a given that you need at least some form of gain in the analogue domain, which your interface provides, irrespective of equalisation / compensation, so its not really about EQing in the digital vs analogue domain - my point was (speaking as someone who has, as I mentioned before, extensive practical experience of a huge amount of ‘this kind of stuff…’) that if you are compensating digitally to get better / more precise (RIAA curve) matching, its kind of redundant unless you have the correct pre-amp, and, you are unlikely to find a pre-amp designed to match the pickup correctly whcih doesn’t have RIAA built in, or, if you build / hack that yourself, then why not also build in the some good quality RIAA stuff too.

What your experiment proves is that you can hack this if you are desperate / not too bothered by the quality / or just lucky with the combination of hardware you have, but I still wouldn’t recommend it as the preferred solution. The best option is to do it properly with a decent phono pre-amp that correctly matches the pickup. That might be expensive, but this kind of thing generally is if you want good results.

Speaking as someone who has actually done it, as opposed to theorizing, I found it works quite well.
I have an old Revox A78 amp with RIAA eq-ing input built-in but it’s a bit broken and crackles and hums all over the place. Desperate for a result I plugged my record deck straight into the Scarlett i2 and recorded.
Here’s what the standard says you should do (i know it’s wikipedia but in this case i have reason to believe it’s factually correct)

I fiddled around with ardours off-the-shelf parametric eq plugin to re-model the curve but it didn’t sound quite right, I think i adjusted the filters (you need 2) to be much less intense than the 20dB mandated by the standard.
Singnal/noise on your 24bit recording should plenty good enough so you don’t have to worry about applying the eq on the way in rather than inside the digital domain. I plan to convert many more vinyl records “one day” but hey it’s one of those things I’ll probably never find the time for.

As someone with a vinyl collection, I will chime in to say the experience of listening to an album is its biggest draw, personally speaking. Obviously, the sound quality of digital recordings is superior, but that misses the point for me. When I get together with friends, and we take turns selecting albums to put on the player, that is a very different experience than someone queueing up music on their phone. Also, there are many records that are only available on vinyl because they were never released digitally, so you sometimes find interesting pieces of history. Essentially, there is more to vinyl than the audio quality, which I agree is inferior; there is the physical album itself with artwork and liner notes, which is absent from the digital download. There is a feeling that one is experiencing art versus just consuming a product.

(On a loosely related topic, I’m slightly perplexed by the current vinyl ‘revival’ - coming from a time when that was the only option we had, for too many years I desperately wanted something better… now it seems people are not content with near perfect quality digital media, that doesn’t degrade - and want to wind the clock back… :slight_smile:
I don’t subscribe to any unsubstantiated audio “voodoo” theories, but, I’d be the first to admit that vinyl does sound different, however, normally that’s because of some difference in EQ, somewhere between the master (tapes) and the listener’s ears - be that specific mastering EQ choices made for vinyl (it’s complicated) or just subtle - or not so subtle ‘RIAA’ (mis)matching - so its very difficult to actually compare like with like)

@mike: I think I do agree with you, for almost every case, just using an analog(ue) phono amp is going to be the best way to go. I think it is probably a case of if you have to ask, it’s not for you. If you are willing to build a custom flat response phono preamp, you are probably capable of tracking down the required EQ software on your own.

@ccaudle: I guess my thinking was (and having had a keen interest in almost all aspects of recorded music since well before we had affordable high quality digital alternatives, I’ve built analogue pre-amps for just about any kind of pickup you can think of at one time or another, including tube based with passive RIAA compensation etc) -
If a phono pre-amp is not available, then just using some kind of generic gain stage (or mic pre etc) is unlikely to correctly match the pickup - which can cause some problems as you correctly mention - which would in turn render using some kind of extra precise digital RIAA filter kind of pointless. If the OP has the skills to make a custom designed flat gain stage with the correct matching and appropriate analogue performance, then why not add some analogue RIAA equalisation too. There are some truly awful analogue phono pre-amps, but there are also some very good ones for not too much cost, and in this particular case I personally would favour an analogue phono pre-amp.

I am going to disagree with Mike on this question. You may end up needing custom hardware, because cartridges require specific impedance values (resistance and capacitance) to keep the frequency response flat. Too high an impedance and inductance of the cartridge causes a big peak, too low an impedance (like straight into a microphone amp) and there will be a big droop in the high frequency response.
But, if you can get the analog interface sorted out, matching gain between channels is much easier than matching frequency response of analog filters (mostly due to tolerance of available capacitors), and matching the specified frequency response curve is basically trivial. I would trust that the pre-emphasis amplifiers at the various mastering houses probably matched the specified curve fairly closely, but phono playback amps are hit or miss, especially for low priced phono amps. Either the manufacturer has to pay for close tolerance capacitors, or has to trim the resistor values to match the specific capacitor values in the circuit, so either the component cost goes up or the labor cost goes up, either way a truly accurate pre-amp is no longer low-cost.
If you have clean analog conversion, you can use digital RIAA filters and have the frequency response match the specified curve and also exactly matched between channels.

One advantage not really encompassed by the term “RIAA” is that prior to standardization of the emphasis/de-emphasis curve there were several different emphasis curves in use, so recordings made prior to 1955 give or take a few years would need different playback equalization than recordings released from say 1960 or later. There are some specialty phono amps made for archivists and record collectors that have different presets for pre-RIAA recordings and sometimes even variable equalizers, but doing that with digital is much easier to tweak.

SoX has RIAA filters available, and there are VST plugins available with RIAA. has a plugin available for Windows and Mac, ZamAudio contributed one to Calf Plugins (I think called Calf Emphasis now instead of Calf RIAA).
If you want to batch convert a number of files already recorded, SoX is probably what you want. If you want to listen while recording, or want to make your own modifications (EQ changes, mix with other material, compression, etc.) then you will want a plugin.

For many reasons, if at all possible, you would almost certainly do better to use a proper analogue phono pre-amp designed to match the pickup / cartridge you have - rather than recording direct and EQing / compensating for it digitally after the fact.