VST RIAA and Inverse RIAA Plugin

[markrob]

Hi All,

I have written a set of VST plugins that do the RIAA and inverse RIAA curves in software and wanted to know if anybody is interested in checking them out. These will work on any PC based DAW that can host a VST plugin. They allow for adjustable turnover freq's but default to 50, 500, and 2122hz as per the spec. The adjustable turnovers are useful if you want to cut/playback 78's that match older curves pre-RIAA or cut half speed.

I wrote the RIAA plug several years ago before getting into cutting (I'm still a newbie at this). The RIAA plugin allows you to connect a turntable with a flat pre-amp and do the playback EQ in the DAW.

The plugs work at any host supported sample rate. In fact, they become more accurate at the high freq limit at higher sample rates. At 44.1khz, the error is about -3db from ideal at 20Khz. At 96Khz, this is reduced to about -.7db. I can supply info on the filter design calcs if anyone is interested. Being new here, I understand that there is no place to post files for others to download. I don't believe my Comcast web page will allow it either, so if somebody wants to be the host, that would be great.

In the next few days, I intend to make an additional version of the inverse plugin for heads like the Presto 1-D that have the 500hz turnover built-in via a series resistor. I'm debating if I should put a low freq pole-zero at 50 hz and say, 20hz to make the head match the curve at low freq's. Interested in any comments on that idea.

[Simon]

will it work with Audacity? if so happy to try it out.

[markrob]

Hi Simon,

I took a look at the Audacity web site and it looks like it should work if you use the VST Enabler.

[url]http://audacityteam.org/vst/[url/]

If you PM me with an email address, I'll send the plugins as attachments. They are small .dll files about 72Kb each

I think I saw you post that you have an Audax head. If it behaves like a Presto, the 500hz roll-off is engineered into the head. If this is the case, this plugin will cut the bass where it should not be. I hope to have a version with the 500 hz turnover removed later this weekend. Let me know if this is the version you want.

[Simon]

I could not get them to load in Audacity - but I got them to load in n-Track Studio - I will test them further later this week.

[JayDC]

can i try these?

[JuanPabloCuervo]

wanted to know if anybody is interested in checking them out. .

Yes.

[teas]

would like to check out, for playback

[markrob]

Hi,

Just PM me with your email and I'l be glad to send it out for you to try.

Mark

[JayDC]

I put this on one of my servers.

http://www.haze.fm/IRIAA.zip

As people come up with working presets, please post the files here so we may all have a look.

[SueDenim]

Nice one!

[petermontg]

any hope of one for OSX users

[markrob]

Hi,

I can supply you with the source for the x86 version. Cubase and VST have always been cross platform. I don't think it would be a big deal. If anybody is game, drop me a PM and I'll send it along.

Mark

[JuanPabloCuervo]

iRiaa but no Riaa

[markrob]

iRiaa but no Riaa

I have both. Most people here only need the recording version. If you PM me, I'll send you the playback version. To use it, you have to use a flat phono preamp terminated with the proper 47K ohm impedance and capacitance,if needed (or whatever you pickup manufacturer requires). I built a flat pre-amp with a gain of 40db (100X) and use that. Since the plugin turnovers are adjustable, you can easily change the plugin to work with disks that were recorded berfore the RIAA became a standard.

Mark

[JuanPabloCuervo]

http://jiiteepee.fortunecity.com/riaafilter/index.html

http://www.youtube.com/watch?v=JIJD2dbbFuE

[markrob]

Hi,

They did a much nicer job of making the filter accurate at the highest frequencies than I did with my plugin. At 44.1Khz, they are within 1.7DB, while my plugin is off by 3db. The advantage my plugin has it that the filter parameters are easily calulated on the fly as either sample rate and/or turnover frequencies are adjusted. This makes it useful for playback of non-RIAA disks. The error in my plugin can be reduced if you run at higher sample rates (at 96Khz, the error is reduced to .6db). Here is a link to the method I used to derive my filter.

http://home.comcast.net/~markrob1066/docs/RIAA_Plugin_Math.pdf

This is a static printout of a live Mathcad sheet done at 44.1Khz SR to show the error. I have a similar sheet for the IRIAA for cutting.

Mark

[Serif]

Must be because I have been a tape op, but I wish the those who say "inverse RIAA" for cutting eq, instead, said, "RIAA pre-emphasis," since "inverse" sounds like an undoing of something, rather than the doing of it. However, I don't mind saying, "inverse RIAA," for the same filter used for debugging RIAA de-emphasis preamps... (a la Lipschitz and Jung, e.g.)



Andrew



P.S., Mark, you do realize that all digital filters ignore the necessary phase shift... (j/k)

[markrob]

Hi Andrew,

I agree with your semantics about RIAA vs. IRIAA. I probably got this wrong coming at it from an end user perspective.

I don't belive that you are correct about the phase response. My filter design is an IIR type and is just a mapping of the S domain to the Z domain. I haven't tried to plot the phase response, but I'd bet it closely tracks the equivalent analog filter up to the point that you get close to the Nyquist limit.

Mark

[andybee]

nice, nice, NICE!!!

but, is it not that, what you want:
phase errors, distortion ?

[JuanPabloCuervo]

Must be because I have been a tape op, but I wish the those who say "inverse RIAA" for cutting eq, instead, said, "RIAA pre-emphasis," since "inverse" sounds like an undoing of something, rather than the doing of it. However, I don't mind saying, "inverse RIAA," for the same filter used for debugging RIAA de-emphasis preamps... (a la Lipschitz and Jung, e.g.)

Andrew
P.S., Mark, you do realize that all digital filters ignore the necessary phase shift... (j/k)

some people call it Inverse RiAA Filter
http://www.hagtech.com/iriaa.html

others RiAA Inverter
http://shop.adjustplus.biz/product_info.php?products_id=40&osCsid=ff6ad375bba40cdade379a4cba2cacd0

others Precon LP Level Converter...
http://www.elusivedisc.com/prodinfo.asp?number=KABPRECON

others Phono Burn-In Box
http://store.acousticsounds.com/d/16103/KAB-Pre_Con_LP_Phono_Burn-in_Box-Turntable_Set_Up_Tools

others... pre-emphasis, de-emphasis, passive and active circuits.
http://www.kabusa.com/riaa.htm
http://www.kabusa.com/eqs12rvw.htm