DSP, EQ and other Plug-Ins

I am looking at this thread as being an ongoing list, and summary, of various DSP tools, Equalizers and other plug-ins for audio/music playback (or mastering/recording) - be they commercial/paid or free/open-source.

Note: Plug-ins require music-player software that can host them. There are some standard formats such things in Windows and on macOS. For macOS the most common is the “Audio Unit” (AU), and Windows is generally “VST3”). Players like JRiver Media Center and Audirvana can both host these plug-ins, and both are available on Windows and macOS.

Commentary, discussion and questions are welcome.

I expect that many posts here on specific plug-ins will spawn dedicated, linked, threads to cover them in more detail. But this is a starting point for cataloging and high-level commentary.


SPL TwinTube

This is a tube-emulation plug-in from SPL and is a software implementation of one of SPLs well-known, but now discontinued, hardware processors.

It is designed to let you add, and control, harmonic distortion and/or tube saturation effects in controllable amounts and some pre-determined points. Harmonics can be applied from one of four configurable center frequencies, with a controllable degree of intensity (up to +15 dB). And saturation effects can be controlled in terms of their level/intensity (up to +6 dB).

There’s an overload indicator so you can easily tell when your settings are causing distortion/clipping that is not intentional.

Like a lot of professional audio plug-ins, TwinTube adopts a skeuomorphic UX - the appearance and controls are represented as they’d look on a physical device:

If you’re not already audibly-familiar with how saturation or harmonics affect sound, it takes a bit of time experimenting to get a feel for. But the results become clearly audible, as you push the intensity up.

You can apply very subtle effects here, to the level it might take protracted listening to “get it”, and you can also introduce gross changes that result in significant and brutal distortions.

It’s something fun to play with if you’re interested in having some “tube flavor” without actually going down the tube-amplifier route.

It’s available via “Plugin Alliance” and has a 14-day free trial. Normally it runs $199, but periodically goes on sale for as low as $29.99.


PulseEffects on Linux provides a nice suite of effects in a centralized UI. Amongst other things, it includes some cool plugins from Calf Studio such as the Bass Enhancer, which is a nice way of using harmonics to add some fullness to the bass without changing tonal balance.


Another toy I’ve been enjoying is DDMF’s PluginDoctor. Basically it lets me analyze the frequency response, phase response, distortion, etc. from applying plugins, for example Audeze’s Reveal, Sonarworks Reference, etc. It’s a fun learning tool and also gives me the ability to reverse engineer stuff into EQ presets that’ll work in situations where those other tools aren’t available (e.g. on a DAP).


I’d managed to miss that one (“Plugin Doctor”). I can think of some interesting additional uses for that, especially if paired with DDMF’s “Metaplugin” (especially if it’s possible to run multiple instances of “Plugin Doctor” within “Metaplugin”).


thank you @Torq /Ian!

so if I run foobar 2000 with a Flac file, I can open this plugin and add some “tube like sounding”?

or do I have to use another music player software with this plugin?

so my DAC is fed thru this plugin with a colored sound of some kind and does no changes to this coloration, except his own filter?

sorry for this newbie questions!

To use this, and similar plug-ins with Foobar 2000 you’ll first need a “VST Wrapper” or “VST Adapter”. That’s actually a Foobar 2000 plug-in that can then load a VST plug-in. It’s a little fiddly to set up, and not something I can help much with since I haven’t had a Windows machine at home since 2008, but it’s not hard if you follow the steps and other’s here can probably help as well.

If you want a music player that can use such plug-ins directly, then JRiver Media Center and Audirvana 3.5 can both do it.

Once you have it setup …

The SPL TwinTube plug-in applies its processing to the sample data and that is then sent to your DAC. Your DAC just plays what it is sent and has no way to know whether the samples it receives are altered or not. It works the same way EQ tools do, but rather than simply changing frequency response, it adds different distortions.

As you adjust the settings in TwinTube you’ll be able to hear how they affect the sound in real-time. And when you turn up the intensity of those settings you’ll get effects that are MUCH more directly audible than most tube amplifiers. Which is not to say it sounds exactly like running a tube amplifier, and it doesn’t simulate specific tubes directly nor all of their behavior, but it’ll give you an idea and is quite enjoyable to play with.


thank you very much!

so it functions as I thought.

I will give it a try, this evening when I am back from office.
Already read about the need for VST Wrapper a few minutes back. Sounds manageable to me :slight_smile:


One I use for a bit of fun occasionally, and for certain mixing purposes, is Waves “NX”. This is designed to simulate a mixing room, spatially and dimensionally, with the ability to adjust speaker placement, adjust headphone response (preset EQ curves for a small list of common headphones found in mixing/tracking setups).

It can make listening on headphones feel a lot closer to using speakers, particularly if paired with a head-tracker, so that the position of the sound changes as you move your head.

With the RAAL-requisite SR1a the effect is even more convincing.


short update on the W10 64Bit PC running Foobar 2K with VST plugins

the VST Wrapper - did not work at all
the VST Adapter - did work but crashed the moment I had to activate the license for the TwinTube plugin

contacted the plugin alliance support and wait for feedback
send the foobar2k crash reports and added all infos

in the meantime I downloaded/installed J River Media Center and the TwinTube plugin crashed again

so I read about Audirvana 3.5(now new on PC) also supporting VST3 on PC - will give it a try, after office - have a good feeling that this should work finally
75€ would be ok for me, if it´s stable and makes no problems with any of my DACs drivers
I do like the new design


You could try loading the plug-in in a DAW just to accept the license and then see if it works in the player app.


Here’s another fun one, prompted by a different discussion (and that I haven’t used in a while).

iZotope’s “Vinyl” - which likely does exactly what you think it will based on it’s name - though probably with more control and believability than you might expect.

Oh, and it’s free … not just a free-trial.

1 Like

did exactly what you suggested and it worked with the DAW “cakewalk” by Bandlab :slight_smile:

listen now to “Hey Porter” by Johnny Cash and play around with the harmonics and the saturation
the presets help a bit with orientation


Audeze “Reveal+”

Audeze’s “Reveal” plug-in has been available for a while, and provides presets (with some adjustments) that bring most of Audeze’s line-up of headphones to a neutral tonal profile.

I’ve used it to good effect with the LCD-4 … to the point that I would rather not listen to them without using Reveal (fortunately the same “corrections” are built into the the DSP Presets for Audeze headphones in Roon, which is my preferred way to listen at home).

They’ve just released a new version: “Reveal+

This adds a custom HRTF profile, derived from pictures of your ears, to provide spatial cues to ones listening, in addition to the usual tonal corrections that the original “Reveal” plug-in provided. The idea here is that you get a better representation of speaker-based listening and the imaging and spatialization that goes with it.

Unlike “Reveal”, the new “Reveal+” is not free … it’s a $199.00 purchase.

I’m going to play with the trial. It doesn’t do me much good if it isn’t incorporated into Roon, so I’m unlikely to buy it unless it is a transformational thing.

I’m more concerned that this kills the (still downloadable) free “Reveal” plug-in.

And I’m hoping that Reveal+ proves to only need the paid version to get access to the HRTF/spatialization capabilities, and without that continues to provide the EQ presets of the original.

We’ll see …


I wound up taking advantage of the “Plugin Alliance” November off of $199 for a year-long subscription to their “Mega Bundle”.

Part of this was prompted by missing out on a $79.99 offer on “SPL Hawkeye” (which seems to be back in effect right now … but I have no idea for how long … normal price is $249).

Anyway, “Hawkeye” is a very comprehensive audio analyzer. I’ve got other such tools in my DAW/production tool chain, but they’re not that useful, nor as comprehensive, for just seeing what’s going on with the music files one is playing.

One of the more interesting metrics, for me, is the “Loudness Range” (LRA, top row, 2nd panel). In the attached shot it shows a dynamic/loudness range of under 2! The best tracks I have push this up to 20.

Lots of other interesting metrics/views here … and quite a fun little toy!


Old video I made about EqualizerAPO and Peace. Hopefully self promotion isn’t against forum rules. I was a noob and didn’t even know shelf filters existed at the time, but other than that I think it’s a fair overview. https://youtu.be/gFCXWMV5YfQ

Also this is not a “plugin” per se so feel free to move this to another thread if it doesn’t belong


This was a great introduction for me back when I got into it as well. I’m more of a “mild EQ” kind of guy, and I may do a video on how I approach it, but I think everything you’ve mentioned is still applicable.


Set a bookmark for tomorrow
Thank you @metal571
had seen it long time ago and was not ready
Now I don’t fear away from eq with the RME ADI 2
and could use APO and Peace for the other DAC (without eq)


I’m definitely a mild EQ guy too. That’s why I almost never use my HD 8 00 anymore lol


In my experience, none of the good EQ software or music softwares with good EQ are free. Here is a list of softwares, which I have personally used and think have decent or good Parametric EQ.

1. JRiver Media Center (Mac and Windows) - $50 - $80
An affordable cross-platform, favourite music player among audiophiles. Has a good Parametric EQ and also supports plugins, so that you could use Sonarworks Ref 4 and Audeze Reveal inside the software to EQ your headphones using the presets.

2. Audirvana (Mac) - $100
Audirvana doesn’t have a native PMEQ. But it does support AU/VST plugins. So you could use Apple’s own AU DSP/Filters, with which you can do Parametric EQ. Also supports Sonarworks Ref 4 and Reveal plugins to EQ your headphones.

3. Roon (Mac and Windows) - $700
I only tried the trial version of the Roon. Has a very good Parametric EQ. One thing I don’t like is, it doesn’t support AU/VST plugins.

4. SoundSource (Mac) - $35
This gives you system wide EQ on Mac. It gives you the option to apply separate EQ for different apps like Chrome, Safari, iTunes, VLC etc. Doesn’t have a native Parametric EQ. But it does support AU/VST plugins. So you could use Apples DSP/Filters for PMEQ and also have the option to implement Reveal system wide.

5. USB Auto Player Pro (Android) - $10
A very nice music player that also supports streaming services. Has a very good Parametric EQ. But you need a large screen device to get the best experience of the PMEQ.

5. Neutron Music Player (Android) - $10
Another great music player with a very good Parametric EQ for Android. It doesn’t support streaming. But the UI is optimised that the EQ is decently easy to work with even on a fairly small screen.

6. VOX Music Player (iOS) - $5/Month
The only music player for iOS with a decent Parametric EQ. It used to be free until 2 years back. Too bad they have started charging. If you are willing to pay $5/month, this is not a bad option. iOS users who need access to a good PMEQ have no other choice.

P.S: 2 other softwares that I have heard very good things about but have not got a chance to try are:

  1. Equalizer APO - (Windows) - Free
  2. Equilibrium by DMG Audio (Windows and Mac) - $200