mono plugin on a stereo track or bus


I constantly use barry’s satan maximizer on the drums stereo bus, I find it works beautifully and a slight touch of this plugin can make the snare ghost notes be heard really clear in the mix. But, I found out it’s a mono plugin with only 1 in & 1 out. Am I missing something? how come it just works? It might be paranoia but I’m wondering how can it work on a stereo track without even altering the stereo image of the drums…


@vervelover: for VST, LADSPA and LV2 plugins, Ardour will invisibly and silently replicate 1in/1out plugins for Nin/Nout tracks. Every instance of the plugin gets exactly the same parameters. We don’t do this for AU plugins, because the AU spec provides a mechanism for a single plugin to support multiple I/O configurations (though not all AU plugins do so).

A “normal” dynamics processor wouldn’t work - because the side-chains for the two instances would not be linked, and therefore the stereo image would shift as different amounts of level reduction were applied to the two sides of the stereo signal (which is why I provide stereo and mono versions of compressor plugins). The ‘satan maximizer’ is (as far as I remember) completely broken in terms of what would be considered ‘normal’ dynamics processing and most probably ‘seems’ to work in this configuration more by luck than design

@linuxdsp: right, this is why, if you’re stuck with an API like VST or LADSPA (and to some extent LV2), supplying multiple versions is the thing to do. a screenshot of the menu of all the Waves plugins with their M/S/Quad etc. variants is kind of hilarious, especially on OS X where AU makes such a thing mostly unnecessary (only mostly: the user may have special reason for trying to add the “wrong” version). however, the fact that AU lets the plugin totally reconfigure itself based on the I/O requirements its being asked to meet is just one of a number of nice features of that API. if you put an AU dynamics processor in a mono and a stereo track, there’s no particular requirement that the two instances would even share all the same controls.

Thanks for your exaustive answers!


is there a way to do what the satan maximixer does using your plugins?

There isn’t a way to do that with my plugins at the moment, the maximizer seems to be a kind of hard limiter with a very short attack and decay, so much so that I suspect it would be all but useless for any dynamics processing on anything except percussion. In fact, to quote from the SWH plugin docs:

Barry's Satan Maximiser (satanMaximiser, 1408) Formerly Stupid Compressor. Thanks to Matt Yee-King for the name.Compresses signals with a stupidly short attack and decay, infinite ratio and hard knee. Not really as a compressor, but good harsh (non-musical) distortion.

Note the ‘harsh (non-musical) distortion’ which is an expected side-effect of the short attack and decay - (and something I wouldn’t have expected to be very useful), although you have obviously found something that it seems suitable for.

The short attack and release would likely explain why two mono instances of the plugin seem to behave as a linked stereo instance should - because its most likely just a transient / distortion effect rather than something which is responding to the signal level averaged over a longer time (as a normal limiter / compressor would)


I have to chuckle, with the abundance of great LV2/LXVST Plugins now including linuxDSP’s unparalled contributions I use the Satan Maximizer across my Master Bus on pretty much everything I ever do with Ardour or Mixbus, it does do phenomenal things for drums and percussion but in my experience at conservative levels (ie 24 samples/-6db) it punches up a master mix very nicely with a nice warm analog quality and doesn’t get ‘pumpy’ like some other compressors and limiters do. It also works great in Video editors that support LADSPA (Cinelerra, Kdenlive) for post production on Audio tracks.

It may be evil, it may be broken, but I think it’s amazing!

Another amazing effect to dirt things up in a ‘nice’ way is linuxDSP’s DT-1 Distortion stompbox, If you have some keyboards or anything that sounds a bit sterile (pretty much anything lined in) it has amazingly smooth and predictable overdrive that sounds really natural on stuff like Wurlitzer or Rhodes Electric Pianos or Hammond organs, it’s a little wonder box!

@GMaq: I guess the maximizer is a good example of ‘whatever works’ - it may be a bit unconventional, but if it works then why not use it. Some great guitar sounds originated with amps that were (intentionally or otherwise) ‘broken’ in the conventional sense.

I’m glad the guitar distortion box is useful - as with all the guitar effects, they were designed for guitar but work great with other instruments too, once again, use whatever works.

@pmb: this description must be misleading. LADSPA plugins have no way to vary the number of channels that they use for input or output. they could try to look at the data arriving on their input ports, and guess whether or not they are connected or not. but LADSPA doesn’t allow a plugin to have 2 or 1 or 4 inputs (or outputs).

All LADSPA plugins adapt to the sampling rate, as do all plugins in any format - its not something that they control.

Hello Paul,

Ardour will invisibly and silently replicate 1in/1out plugins for Nin/Nout tracks. <

I have a problem with that kind of thing, so I happenend onto this thread.

I tried to apply a mono plugin (C* JVRev - Stanford-style reverb from STK) to a stereo track and Ardour won’t do it, because it’s mono, it wouldn’t make sense, and I would loose part of the signal.

I am using the standard installation within the latest Ubuntu Studio.

Is there somewhere where I can set this up? Or do you have any pointers for me where to start searching for a solution?


That isn’t a 1 in 1 out IIRC, it is a 1 in 2 out, which isn’t quite a simple matter to duplicate.

Hello seablade,

thanks for answering so quickly. :slight_smile:

In the meantime, I have been trying to find out something about the plugin. There is not much to be found, but here

it says:

description: LADSPA plugin notes: Automatically adapts to the number of channels and sampling rate of the consumer.

Well, maybe that’s where the problem is. Perhaps both Ardour and the plugin are trying to adapt to each other at the same time, and go into some kind of deadlock, which maybe Ardour resolves by refusing to use the plugin.

That would be a pity, certainly, because I don’t know much about reverb, and that plugin gives me a nice result at the default values (in Audacity, which I have used up to last week or so) …