A question about reverberation effect

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iurie
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A question about reverberation effect

Post by iurie »

Hi! I know that there are a lot of free software (open source) reverb plugins, different types available,
and discussions on this subject. Some of them are based on the same core library, like freeverb or others.
Also, I know that the success of a good sound it depends the experience of how to apply reverberation,
and in general how to apply a effects.

Also, there depends of the style of music, for example, there are different requirements for ambient-like music,
orchestra music etc, for some what we have it works probably. Anyway, I believe that there is lack of a free software
good quality algorithmic reverb, and which probably is the mot important effect.

Just for the curiosity I have compared various free software (open source) reverb with the standard one
provided by the proprietary Bitwig DAW (I just tried the trial version of this DAW on GNU/Linux). I am not a specialist
in reverberation DSP, but I can say that the result from Bitwig sounds obvious better. What is the problem? Is in the complexity
of developing this effect to this quality? Or are there patents that prevent this? Or I am wrong about everything?

I am asking because I am composing music and still don't feel that for
most of the cases the existing free software reverbs works for my music, mostly is downtempo, chillout, ambient like music.
It maybe still due to experience, but trying that from Bitwig I see the difference, and I have an impression
that If I would try other DAWs with the standard reverb DSP the result will be better too.

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Michael Willis
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Re: A question about reverberation effect

Post by Michael Willis »

Like a lot of things in music and audio production, reverb is very subjective. I have had some people describe a reverb plugin as being amazing, while other people use derogatory expletives to describe the same reverb plugin.

Also, developing a reverb DSP is an art of wizardry. There are plenty of well-known DSP components that algorithmic reverbs tend to be built from: delay, feedback, diffusion, chorus, modulation, allpass, lowpass, highpass, etc. There are infinite ways to put these together to create a reverb effect, with both significant and subtle differences in the results.
iurie wrote:I can say that the result from Bitwig sounds obvious better.
You have answered your own question. You like the sound of the reverb provided by Bitwig, so use that.

merlyn
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Re: A question about reverberation effect

Post by merlyn »

@iurie : The first thing that comes to mind is did you compare like with like? Was the routing the same?

I would usually use a reverb as a send effect with the dry level at zero. Is that what you did with the plugins you were comparing?

If you have a dry signal present in the reverb path as a send you won't hear the reverb so much.

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bluebell
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Re: A question about reverberation effect

Post by bluebell »

iurie wrote: Just for the curiosity I have compared various free software (open source) reverb with the standard one
provided by the proprietary Bitwig DAW (I just tried the trial version of this DAW on GNU/Linux). I am not a specialist
in reverberation DSP, but I can say that the result from Bitwig sounds obvious better. What is the problem? Is in the complexity
of developing this effect to this quality? Or are there patents that prevent this? Or I am wrong about everything?
It's a matter of taste and with some reverbs (convolution reverbs like klangfalter or IR) the sound is dependent on the impulse response file that you load.

There is no lack of high quality Open Source reverb plugins.

However, if you like Bitwig's reverb then use it.
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iurie
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Re: A question about reverberation effect

Post by iurie »

merlyn wrote:@iurie : The first thing that comes to mind is did you compare like with like? Was the routing the same?
I see a difference in stereo wideness and the tail effect which lasts.
merlyn wrote: I would usually use a reverb as a send effect with the dry level at zero. Is that what you did with the plugins you were comparing?
.
Not dry level to zero, but small to simulate large space. Not very much tail, enough to make the tail last.

iurie
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Re: A question about reverberation effect

Post by iurie »

bluebell wrote:
iurie wrote: Here is no lack of high quality Open Source reverb plugins.
However, if you like Bitwig's reverb then use it.
Ok, Thank you. Than it means technically there shoudln't be any difference if to use it right. No, I am not going to use because I am using only free software for music composition, just wanted to know the status quo regarding free software reverbs.

merlyn
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Re: A question about reverberation effect

Post by merlyn »

It sounds like you're using these plugins as inserts.

What I was thinking is that the Bitwig built-in reverb loads up with settings that you prefer, rather than a fundamental difference in quality.

Anyway, as stated above, go with your ears.

iurie
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Re: A question about reverberation effect

Post by iurie »

merlyn wrote:It sounds like you're using these plugins as inserts.
What do you mean as inserts?

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ufug
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Re: A question about reverberation effect

Post by ufug »

Your commentary is interesting and thoughtful, but it's not clear what are you trying to achieve.

It doesn't make much sense to evaluate reverb plugins and say one is good or better than others. Reverb has one of two functions: to create a perception of instruments inside different locations in a physical space (to mimic reality if you don't have any natural reverb), or as a sonic effect for color. Sounds like you know that. But it's important to consider why you are choosing to use reverb, don't just automatically put it on everything.

To decide one reverb plugin is the best would make everything really boring. Sometimes really bad reverbs sound great. Context is everything. Sometimes a reverb (or any effect) will sound terrible when soloed, but fantastic in a mix. The inverse is also true. Sometimes you think you want a reverb but a timed delay works better. Sometimes a "bad" reverb just needs to be put on a bus and EQed separately and will give you an entirely different sound.

It's fine to have favorite "go-to" plugins, we all do. But why limit your palette with academic out-of-context evaluations?

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Re: A question about reverberation effect

Post by merlyn »

iurie wrote:What do you mean as inserts?
With an insert effect the whole track goes through it, so you need wet/dry balance.

With a send effect part of the track is siphoned off and sent to another track with the reverb on it. Sends are usually 100% wet. This Sound on Sound article goes into more detail :

https://www.soundonsound.com/sound-advi ... nd-effects

iurie
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Re: A question about reverberation effect

Post by iurie »

ufug wrote:Your commentary is interesting and thoughtful, but it's not clear what are you trying to achieve.
I
I'll be sincerely, I was thinking for to develop a free software reverb, to enter into this subject technically, but I wasn't sure if it makes sens if the problem is only in my experience in using the current ones, and not in the quality of implementation.

iurie
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Re: A question about reverberation effect

Post by iurie »

merlyn wrote:
iurie wrote:What do you mean as inserts?
With an insert effect the whole track goes through it, so you need wet/dry balance.

With a send effect part of the track is siphoned off and sent to another track with the reverb on it. Sends are usually 100% wet. This Sound on Sound article goes into more detail :

https://www.soundonsound.com/sound-advi ... nd-effects
It depends of the piece I am working on and the effect I want... often use a separate bus for 2-3 reverb types... or/and I use a reverb per instrument in order to adjust what I want. But my problem is that for me always sounds a litle centered averall, and somehow to realistic for a space... is sound like is recorded in real space/room...this works good for strings or orchestra. I don't know how can I acheve something wider... I don't mean about panning instruments and other technques to spread context... I feel is about reverb, but still don't know. I think I am now too subjective, don't know how to expain this.

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bluebell
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Re: A question about reverberation effect

Post by bluebell »

iurie wrote:
merlyn wrote:
iurie wrote:What do you mean as inserts?
It depends of the piece I am working on and the effect I want... often use a separate bus for 2-3 reverb types... or/and I use a reverb per instrument in order to adjust what I want. But my problem is that for me always sounds a litle centered averall, and somehow to realistic for a space... is sound like is recorded in real space/room...this works good for strings or orchestra. I don't know how can I acheve something wider... I don't mean about panning instruments and other technques to spread context... I feel is about reverb, but still don't know. I think I am now too subjective, don't know how to expain this.
Ah, you talk about a "larger than life" reverb to create a soundscape. To achieve that some plugins do some modulation of the reflections. You can get "snapshots" of such reverbs as impules repsonses. You need a convolution reverb plugin like Klangfalter or IR. The 4-channel IRs of the Bricasti M7 are good. Get the Wav files at
http://www.samplicity.com/bricasti-m7-i ... responses/

In my current project I use Klangfalter and Bricasti M7 IRs: http://marzen.de/tmp/klangfalter_bricasti_m7.mp3

Or use an algorithmic reverb like Dragonfly and play around with chorus effects and extra stereo in the wet path.

You can use CALF Multiband Enhancer to make the stereo image wider.
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Re: A question about reverberation effect

Post by sysrqer »

Michael Willis wrote: Also, developing a reverb DSP is an art of wizardry. There are plenty of well-known DSP components that algorithmic reverbs tend to be built from: delay, feedback, diffusion, chorus, modulation, allpass, lowpass, highpass, etc. There are infinite ways to put these together to create a reverb effect, with both significant and subtle differences in the results.
As a side note to this, would it be possible to port Plateau reverb from VCV Rack to a plugin (not you specifically but generally)? The source is available as far as I know:
https://github.com/ValleyAudio/ValleyRackFree
I'm not sure what this is using though. It's the lushest sounding reverb I think I've ever heard.

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Re: A question about reverberation effect

Post by CrocoDuck »

iurie wrote: Just for the curiosity I have compared various free software (open source) reverb with the standard one
provided by the proprietary Bitwig DAW (I just tried the trial version of this DAW on GNU/Linux). I am not a specialist
in reverberation DSP, but I can say that the result from Bitwig sounds obvious better. What is the problem? Is in the complexity
of developing this effect to this quality? Or are there patents that prevent this? Or I am wrong about everything?
Looks at this paper: About This Reverberation Business. As others have mentioned, there is a huge number of DSP algorithms for reverberation. Also as others have said, context is very important, but there are few important points. The paper is quite old (1985) but it covers those important points rather well.

In essence, humans have a strong preference for natural physical reverb, that is, that of physical spaces. Typically the reverb of a real space will be preferred to an artificial one, even if analog (plate or spring reverb).

I am not too familiar with realtime DSP algorithms, a part for Schroeder reverberation and convolution reverberation, but I am familiar with modelling techniques used for Acoustic simulation. Normally, we solve for the low frequency impulse response with wave based methods (BEM, FEM) and solve for the high frequency with geometric methods (for example Ray tracing). Then, we put all together*. This creates very realistic results. By the way, the last version of LSP plugins contains a Ray Tracing reverb, I bet you will be interested.

As for your question: you seem to think that open source reverb have lover quality than commercial ones. Based on what I know about psychoacoustics, it is quite hard to be able to really measure quality of something like this, so I cannot say whether that is true or not. But let's assume it is for the sake of argument. If that is the case, I do not think it is due to implementation. Open Source DSP algorithms are well written, perform well, and are efficient. Implementation is normally state of the art. I think companies might have the upper edge in:
  • Having the means to perform listening tests with trained subjects in order to refine implementation; and
  • Having talented sound engineers good at cooking real good presets (and provide real useful feedback on how the controls should operate)
*This has inspired me right now. What about passing your audio through a bank of filters, and applying a different reverb to each bank? If you tune an independent reverb on each band you might become able to mimic real spaces... As a rule of thumb, in real spaces, the higher the frequency the faster the decay.
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