Please list True Stereo Reverbs

[3ee]

PSP Springbox... you can chose several modes. (stereo input + you can have stereo springs too)
Great plug, use it all the time as a tone/coloring/imaging reverb.

[AC222]

I thought all the Exponential Audio reverbs were true stereo. Maybe Michael Carnes can weigh in. They sound fantastic. I just wish they weren't ILok.

[kelldammit]

artsacoustic verbs are as well.

[oneshotdeal]

Anyone know if the Toneboosters reverb is TS?

[CableChannel]

Melda Convolution Reverb (includes IR generator for calculated reverbs)

[codec_spurt]

Anyone know if the Toneboosters reverb is TS?

Well they all seem to have the one stereo input in the modular view in EnergyXT2, with the exception of Verbiage which has two stereo inputs - one for a sidechain I think. And then the one stereo output. None that I can see have two stereo outputs.

Even the other True stereo ones have just the one stereo input and one stereo output so it must be an internal thing - i.e. Ambience and Valhalla all have the one stereo input and output. As does MMultibandConvolution reverb. And that can load two different sources.

Still, Verbiage looks such an interesting reverb. It certainly sounds different. Giving a nice cut to drums. So that sidechain feature could be really worth exploring. Not too expensive either.

I was actually wondering about this stereo thing myself recently, as even Reverberate Le outputs 'true' stereo images in as much as they are different to each other and not the same. So I guess I don't know what the variable 'true' means in this context. I fired up Reverberate Le alongside my MMultibandConvolution, and started playing about. I even downloaded the FULL trial version of the Rerverberate program which DOES have the TRUE stereo capability. I just need to install it now and play some more. But that Reverberate Le sounds mighty fine I must say. I think I might go for that full version with the other extra features too when get a bit more cash. These are the sort of developers I want to be supporting from now on. And it obviously just doesn't do reverb with its IRs. I find the Mela one very confusing and there doesn't seem to be any decent help system.

Sorry for not adding anything to the debate - that's me admitting ignorance, btw, so anyone with a good definition of exactly what TRUE STEREO means in this context?

[Warp69]

Sorry for not adding anything to the debate - that's me admitting ignorance, btw, so anyone with a good definition of exactly what TRUE STEREO means in this context?

That's a rather good question. Most people would categorize a reverb as "True Stereo" if the reverb creates 4 different outputs for a stereo input - e.i. left input creates a pair of outputs (left and right) and the same is true for the right input. Those 4 outputs are different compared to each other and are mixed together to form a stardard stereo output (L->L + R->L, L->R + R->R).

Reverbs that only have a mono->stereo algorithm or reverbs that mix left and right inputs before going into the mono->stereo algorithm are not considered as "True Stereo". Lexicon PCM70, EMT250 and AMS RMX16 are mono->stereo reverbs and TC Electronic VSS3 mix the left and the right inputs before the mono->stereo algorithm, so they're are not "True Stereo" reverbs.

Some algorithms mix the left and the right inputs after some initial processing (which could be after the Early Reflection or diffusion engine) before going into a mono->stereo reverb tank - those reverbs would be defined as "True Stereo". In this category you find TC Electronic VSS4 and some Lexicon algorithms. Other algorithms waits even longer before mixing the left and right inputs (this happens in the actual reverb tank) - in this category you find the rest of the Lexicon algorithms (Lexicon 224(XL), 480L, 960L etc) and many others.
And lastly some reverbs have completely separated algorithms for left and right inputs/outputs - here you find Bricasti, Quantec etc.

[b4serenity]

Does anyone have or know of a demonstration of True Stereo vs. regular?

[mystran]

Personally, for Tila I used the "mix in the reverb tank" approach. It essentially amounts to treating the "tank" as a room, and then feeding the input as a stereo pair of monophonic sources (eg speakers). Whether or not that qualifies as "true stereo" is for someone else to decide.

For Abstract Chamber, I didn't use any of the mentioned methods as the plugin never separates stereo signals into mono channels at all (instead treating the stereo signal directly). It's still too limited for my taste though, so if I ever try to write another reverb, I'll probably try using spherical harmonics.

[aciddose]

Hi guys
I can only think of one that I know for sure is true stereo

Can you define "true stereo" ?

Do you mean independent stereo, as in two mono reverbs in parallel?

Do you mean reverbs which make an attempt to compute a true stereo field based upon coefficients of a human head?

I assume you mean the first, in which case my free Xhip Reverb is independent stereo.

Not by necessity but simply because I've never really found more complex results to actually sound better. Instead they tend to sound more mono on stereo or multi-channel sources, although they do sound a little better on mono sources.

[valhallasound]

I define "true stereo" as anything that doesn't mix to mono before being processed by a reverb network. By this definition, algorithms that have stereo early reflections, but mono input late reverbs, aren't true stereo.

I make this distinction not due to any physical, real world correlates, so much as the fact that mixing a stereo microphone signal to mono will create weird artifacts. If these artifacts are injected into a reverb, it adds coloration that can't be taken away. If the mixing happens inside the reverb network in some manner, the coloration doesn't happen.

My plugins have various ways of generating true stereo:

- ValhallaRoom can have independent processing for left and right channels, with controllable mixing time for energy moving between the left and right. I'm not sure how useful that is, but it's in there.
- ValhallaShimmer has the ping-pong thing going on for higher values of feedback, and independent processing for left and right with no feedback. Except for the mono input mode. Which is mono in, stereo out.
- ValhallaVintageVerb has fixed left/right mixing, where the speed depends on the algorithm used, the reverb size, and the decay time.
- ValhallaÜberMod has controls over the initial stereo image and the mixing over time. This does really interesting things with choruses and flangers, but is more subtle with reverb.

Generally speaking, I find the "dual mono" approach (independent processing for left and right w/no crosstalk) to be a little fake sounding. Real rooms always have a mix between left and right. The stereo reverb chambers at Capitol Studios had independent chambers for left and right, but with some coupling of the space at the top, so that the energy would spread through the whole chamber after a few hundred milliseconds. However, "fake" is not always a bad thing, and dual mono reverbs can sound really wide, while preserving the panning of the input mix.

Sean Costello

[Andrew Souter]

That's a rather good question. Most people would categorize a reverb as "True Stereo" if the reverb creates 4 different outputs for a stereo input - e.i. left input creates a pair of outputs (left and right) and the same is true for the right input. Those 4 outputs are different compared to each other and are mixed together to form a stardard stereo output (L->L + R->L, L->R + R->R).

agree...

Reverbs that only have a mono->stereo algorithm or reverbs that mix left and right inputs before going into the mono->stereo algorithm are not considered as "True Stereo". Lexicon PCM70, EMT250 and AMS RMX16 are mono->stereo reverbs and TC Electronic VSS3 mix the left and the right inputs before the mono->stereo algorithm, so they're are not "True Stereo" reverbs.

Some algorithms mix the left and the right inputs after some initial processing (which could be after the Early Reflection or diffusion engine) before going into a mono->stereo reverb tank - those reverbs would be defined as "True Stereo". In this category you find TC Electronic VSS4 and some Lexicon algorithms. Other algorithms waits even longer before mixing the left and right inputs (this happens in the actual reverb tank) - in this category you find the rest of the Lexicon algorithms (Lexicon 224(XL), 480L, 960L etc) and many others.
And lastly some reverbs have completely separated algorithms for left and right inputs/outputs - here you find Bricasti, Quantec etc.

B2 is capable of all of these behaviors for what it's worth...

Generally speaking, I find the "dual mono" approach (independent processing for left and right w/no crosstalk) to be a little fake sounding. Real rooms always have a mix between left and right. The stereo reverb chambers at Capitol Studios had independent chambers for left and right, but with some coupling of the space at the top, so that the energy would spread through the whole chamber after a few hundred milliseconds. However, "fake" is not always a bad thing, and dual mono reverbs can sound really wide, while preserving the panning of the input mix.

B2 (and Breeze and Aether) are also capable of Dual mono via setting Cross is 0.0. Dual mono can be quite useful on synths that have extreme panning things (and perhaps dynamic panning) happening. It's not particularly natural, but it can work well. There are no rules for synths/pads/FX etc.

[valhallasound]

Generally speaking, I find the "dual mono" approach (independent processing for left and right w/no crosstalk) to be a little fake sounding. Real rooms always have a mix between left and right. The stereo reverb chambers at Capitol Studios had independent chambers for left and right, but with some coupling of the space at the top, so that the energy would spread through the whole chamber after a few hundred milliseconds. However, "fake" is not always a bad thing, and dual mono reverbs can sound really wide, while preserving the panning of the input mix.

B2 (and Breeze and Aether) are also capable of Dual mono via setting Cross is 0.0. Dual mono can be quite useful on synths that have extreme panning things (and perhaps dynamic panning) happening. It's not particularly natural, but it can work well. There are no rules for synths/pads/FX etc.

I might be using the term "Dual Mono" incorrectly. IIRC, the SKNote Verbtone has a "dual mono" mode, where the left and right channels are not only processed separately, but also have the same reverb network for each channel (i.e. 100% correlated). I have the capability for independent left and right reverbs in a few of my plugins (Room, ÜberMod), but the left and right reverbs will be decorrelated. Most other reverbs with no crosstalk between left and right will have decorrelation between the channels.

Sean Costello

[stian]

I define "true stereo" as anything that doesn't mix to mono before being processed by a reverb network. By this definition, algorithms that have stereo early reflections, but mono input late reverbs, aren't true stereo

I definitely agree with you there, Sean. While experimenting with different reverb designs for Verberate, I was actually surprised to find out how important true stereo processing is also in the late reverberation in order to achieve a sense of space even if other techniques are used to de-correlate the outputs.

Stian

[Warp69]

I define "true stereo" as anything that doesn't mix to mono before being processed by a reverb network. By this definition, algorithms that have stereo early reflections, but mono input late reverbs, aren't true stereo

I definitely agree with you there, Sean. While experimenting with different reverb designs for Verberate, I was actually surprised to find out how important true stereo processing is also in the late reverberation in order to achieve a sense of space even if other techniques are used to de-correlate the outputs.

So this very simple setup would not produce "True Stereo"?



The ER engine could have any numbers of taps and/or allpass filters and/or something else. The above would create 4 completely different outputs which equals "True Stereo".