Why is the Reverb input mono?

[Bodde]

Is there a reason why the reverb input is mono?
Say you have a dual delay or a pitch shifter (or any other block) with hard panned signal and put a reverb block at the end of the chain. When the other blocks go into the reverb you lose the stereo panning. Is that correct? If the reverb input was stereo that wouldn't be the case. Is there a workaround? Instead of using two reverb blocks.

And another question. Didn't want to start a separate topic for this.
When using the digital delay for long delay soundscapes and setting feedback to 100% and mix to 50% the repeats don't stay clean for the whole time. After some time the repeats eventually start degrading. They become more muffled. I would expect this with an analog or tape delay model but not with a digital delay. Why is this? (all settings are standard for the rest, no ducking or EQ on the repeats)

 

[FractalAudio]

Is there a reason why the reverb input is mono?
Say you have a dual delay or a pitch shifter (or any other block) with hard panned signal and put a reverb block at the end of the chain. When the other blocks go into the reverb you lose the stereo panning. Is that correct? If the reverb input was stereo that wouldn't be the case. Is there a workaround? Instead of using two reverb blocks.

And another question. Didn't want to start a separate topic for this.
When using the digital delay for long delay soundscapes and setting feedback to 100% and mix to 50% the repeats don't stay clean for the whole time. After some time the repeats eventually start degrading. They become more muffled. I would expect this with an analog or tape delay model but not with a digital delay. Why is this? (all settings are standard for the rest, no ducking or EQ on the repeats)

The input is stereo.

 

[Bodde]

The input is stereo.

Did it change in the Axe fx III? I am on Axe fx II. Forgive me for asking here.
the wiki says:

The signal at the input of the Reverb block (only the part for reverberation, not the passing-through signal) is summed to mono.

The Reverb's output is stereo (except Spring reverbs). You can make it mono by setting Stereo Width to 0%.

 

[FractalAudio]

Did it change in the Axe fx III? I am on Axe fx II. Forgive me for asking here.
the wiki says:

The signal at the input of the Reverb block (only the part for reverberation, not the passing-through signal) is summed to mono.

The Reverb's output is stereo (except Spring reverbs). You can make it mono by setting Stereo Width to 0%.

The wet signal is summed to mono. The input to the block is stereo. You don't lose the stereo image because the dry signal is stereo.

 

[IronSean]

So the Dry signal stays stereo, and the reverb effect is in stereo, but the reverb effects gets generated from a summed mono signal.

This would be pretty accurate to playing a stereo signal in a room and recording the room reverb, both sides create one room reverberation where elements from the left reverb in the right and vice versa.

But if you had a truly separate Left and Right channel you needed separate mono reverbs on, you'd be best splitting you path into two separate reverb blocks.

 

[Bodde]

The wet signal is summed to mono. The input to the block is stereo. You don't lose the stereo image because the dry signal is stereo.

ok thanks. Think I did something wrong in the chain elsewhere then. Can't remember having this problem before of losing the stereo panning of my delay block. I thought it was because of the reverb but I was wrong apparently.

Any ideas on my second question about the digital delays? I let the feedback ring for a while on 100% and then after some time the repeats start getting more blurry.

 

[GlennO]

So the Dry signal stays stereo, and the reverb effect is in stereo, but the reverb effects gets generated from a summed mono signal.

That's right. It's possible to devise a reverb effect that processes stereo input, but the juice usually isn't worth the squeeze. That's true of most effects that add stereo imaging to the signal, especially ones where you generally mix dry and wet...it usually works best to leave the dry signal stereo and then process summed mono.

 

[GlennO]

Any ideas on my second question about the digital delays? I let the feedback ring for a while on 100% and then after some time the repeats start getting more blurry.

That's true of any recursive processing in a digital system, for example delay feedback. But you'll generally have to let the delay go for a long time before it would be noticeable.

 

[Lumikut]

Is this an instance where looking at the block volumes on the grid would come in handy to see where you're losing the stereo image? I'm not sure; just curious myself

 

[Bodde]

That's true of any recursive processing in a digital system, for example delay feedback. But you'll generally have to let the delay go for a long time before it would be noticeable.

I agree it takes a bit long before you start noticing the downgrade of the repeats. But if you do long soundscapes you will hear it. i thought with a digital delay you won't hear any downgrades at all.

 

[GlennO]

I agree it takes a bit long before you start noticing the downgrade of the repeats. But if you do long soundscapes you will hear it. i thought with a digital delay you won't hear any downgrades at all.

The tiny imprecision artifacts that are inherent in digital recursion processing will accumulate and eventually become noticeable. But it's way smaller than the artifacts you get an with an analog BBD.

 

[DLC86]

The tiny imprecision artifacts that are inherent in digital recursion processing will accumulate and eventually become noticeable. But it's way smaller than the artifacts you get an with an analog BBD.

What kind of artifacts are generated in a digital delay feedback?
I'm pretty sure other digital delays I've used in the past don't exhibit such artifacts, or at least not as noticeable as the axe fx one

 

[Admin M@]

You can play with dual reverbs by placing two volume blocks in front of two reverbs.Not shown here: pan the reverbs left and right.
It's not the same thing as having a stereo source in a real space -- you may want to not hard pan the reverbs.

 

[GlennO]

What kind of artifacts are generated in a digital delay feedback?
I'm pretty sure other digital delays I've used in the past don't exhibit such artifacts, or at least not as noticeable as the axe fx one

There is an inevitable degradation due to precision limitations. That said, I'd have to agree that the AxeFX feedback degradation, while small, is more than one would expect to hear.

 

[Bodde]

What kind of artifacts are generated in a digital delay feedback?
I'm pretty sure other digital delays I've used in the past don't exhibit such artifacts, or at least not as noticeable as the axe fx one

I agree. Never noticed it on other digital delays. But maybe I didn't check it carefully enough at that time.

 

[DLC86]

I previously thought that degradation was caused by the high and low cut filters not defeating when set to 20 and 20000 kHz (as it happens in some other blocks, e.g. synth) but some months ago I checked and that wasn't the culprit.
Maybe some additional filtering in the feedback path which is not exposed to the user?

 

[markyd]

The digital delays degrading is my one wish for improvement in an otherwise perfect device! I have to use an external delay because of this.

 

[markyd]

That's true of any recursive processing in a digital system, for example delay feedback. But you'll generally have to let the delay go for a long time before it would be noticeable.

My external digital delay does not do this. Press the repeat hold, and the delays will be pristine indefinitely. In the AxeFX III it only takes about a minute for it to be noticeable.
Samples in this thread:
https://forum.fractalaudio.com/threads/delay-hold-degrades.160777/#post-1924845

 

[Chuck P]

In the AxeFX III it only takes about a minute for it to be noticeable.

The diversity of techniques and interests is part of what makes this forum so compelling. When you guys were talking about a "long time" w/r/t delays, I figured you were talking about like three seconds. I thought, "there's no way the delay degrades that fast...!"

 

[markyd]

The diversity of techniques and interests is part of what makes this forum so compelling. When you guys were talking about a "long time" w/r/t delays, I figured you were talking about like three seconds. I thought, "there's no way the delay degrades that fast...!"

I use it to add a drone/rhythm in a single guitar soundscape/jam/improv band. I can hold a delay wash for a section of the music, play over it, and then release the hold and the old sound gradually fades away with a new sound gradually replacing it. I then can fade it out and bring it back at a later part of the piece. Very different than using a looper. Very organic and interesting/evolving. A delay that is held can appear several minutes later to bring continuity to the piece. That is why it is important for it to not degrade.