IRIAA VST3 Plugin PC Only

[markrob]

Hi,

Some years ago, I developed a 32 bit VST2 PC only IRIAA plugin and made it available here. In that time, the VST standard moved from 32 to 64 bit and from VST2 to VST3. I decided to update the plugin to modern standards and also improved it by adding 2X oversampling and an option for half speed mastering. The move to oversampling improved the accuracy at the high frequencies. I am using the same matched Z transform method used in the original plugin design to map the poles and zeros of the analog filter to the digital domain. This provides in good low frequency gain and phase accuracy, but is off by up to -3db at 20Khz at a 48Khz samplerate. By using oversampling, the error is now less than 1db at 20Khz at 48Khz samplerate. I have provided a pdf of my Mathcad calculations so you can see the derivation and the accuracy plots. Feel free to use it and let me know if it works for you or if you have any issues. I tested in Cubase 13 here. The plugin is very basic, just a switch to select half speed. This just shifts all of the turnover frequencies down one octave. The plugin gain is normalized to unity at 1Khz at full speed and 500hz for half speed. Enjoy.

Mark

IRIAA.pdf

IRIAA (64).zip

[farmersplow]

ÄÄÄHHHH - WOW! That was quite a lot of work. I will need some time to study these formulas, but I will do it! And as soon as I've finished my PCB and my lathe is turning again, I'll test the plug-in. I'm also looking forward to seeing how the half-speed mastering works. I'll report back here.
Thanks in any case!

[Semar]

Merci !

[Thelatheofus]

Thanks a lot ! Sadly it's not showing up in my Ableton 12. I've had quite a few vsts not showing up so it's probably on my end, but just letting you know. It shows up in audacity though.

[zdenek]

Thanks for sharing, but my program does not open this file.
I use Audacity for half speed, but this program distorts something because if I input the signal for rendering at 50% lower speed, it changes the frequency from, for example, 1kHz to 500Hz, i.e. one octave down and it seems to be ok, but unfortunately it is not ok, because after recording a vinyl record and playing it back at double speed, i.e. returning to the 1kHz frequency The sound has a lot of different harmonics that were not present in the standard signal before computer processing. My conclusion is that the computer with this program distorts the 1kHz signal and results in nonsense. This is only theoretically nice, but in practice it is bad. If I use an analog tape recorder and double speed, the first studio speed and I reduce the speed by half when recording vinyl, then when playing at double speed, i.e. not 16/2.3, but 33.33 is the recording, it is correct and there are no strange harmonics and it is ok. What is wrong with the Auda City program?

[markrob]

Hi,

For completeness, here is the playback RIAA plugin. To use it, you would need to have a phono preamp that is flat (no RIAA in the signal path) and the pickup would need to be a magnetic type (velocity responding).

RIAA (64).zip

Mark

[markrob]

Thanks for sharing, but my program does not open this file.
I use Audacity for half speed, but this program distorts something because if I input the signal for rendering at 50% lower speed, it changes the frequency from, for example, 1kHz to 500Hz, i.e. one octave down and it seems to be ok, but unfortunately it is not ok, because after recording a vinyl record and playing it back at double speed, i.e. returning to the 1kHz frequency The sound has a lot of different harmonics that were not present in the standard signal before computer processing. My conclusion is that the computer with this program distorts the 1kHz signal and results in nonsense. This is only theoretically nice, but in practice it is bad. If I use an analog tape recorder and double speed, the first studio speed and I reduce the speed by half when recording vinyl, then when playing at double speed, i.e. not 16/2.3, but 33.33 is the recording, it is correct and there are no strange harmonics and it is ok. What is wrong with the Auda City program?

Hi,

I just downloaded and installed Audacity and it seems to work fine for me. I took a 44.1 Khz wav file and used the "Change Speed and Pitch" effect with a speed multiplier of .5. Then I used the same effect on the result but with a speed multiplier of 2 and the result sounds the same to me.

I also tried the following experiment using my plugins:

1. Load in a wav file of program material and do a change speed using a multiplier of .5
2. Apply my IRIAA plugin with the switch set to half speed. It will appear to be clipped, but it is not as Audacity internally uses 32 bit floats for processing.
3. Use speed a multiplier of 2 to bring the pitch back to normal speed.
4. Apply my RIAA plugin set to full speed to remove the IRIAA half speed EQ

The end result sounds fine to me, but my 68 year old ears are not golden. I did notice that if I looked at an FFT spectrum of an exported half speed file, I could see the the brick wall post filter has some low level information above 10Khz. In an ideal world, this would not be there, but no filter is perfect.

If you want to use the IRIAA plugins for cutting, you need to have your cutter head equalized for flat velocity response. If your head EQ has the IRIAA cooked in, you will not get proper results. The typical open loop DIY head cal that most of us are doing involves capturing cuts with a standard phono preamp that has the RIAA playback curve and EQ'ing for flat overall response. You would need either need to use a playback preamp that is flat or use my IRIAA plugin after capture to remove the RIAA from the captured file when doing you head EQ. Hope this makes sense.

Mark

[zdenek]

It seems to me that Audacity cuts, quantizes, or otherwise does something like MP3, it ignores the timbre of the sound and what remains is a raw file with many harmonics without any order or structure. Thanks, but I gave up on digital half-speed, it just doesn't work it doesn't make sense, it seems to me that I don't want to get nervous, or my computer is too old... I'm on tape and I don't care about my ass either breaks off....Besides, to reach 15kHz at half speed, I need to have a 30kHz signal source, and that's what a mid-range tape recorder with a good tape can reach. In my PC, steep filters cut off sharply at 19.5kHz, so I won't get very far with such equipment. .. Regards