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HX Reverbs Sum To Mono?

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When using the new HX reverbs in Helix I noticed that if I have say, a ping pong delay before any of the HX verbs if I turn the wet mix to 100% the ping pong delay gets summed to mono.

Why is L6 doing this again? This was one of the reasons I hated Pod HD stuff.

Anybody else getting this?

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To clatify, it appears the inputs of HX verbs are summed to mono but the outputs are stereo. So if you have a ping pong delay going into a new verb with the verb mix at 100% wet you will lose the ping ponging of the delay though the verb will be stereo.

Not to sound bitchy but if this is the truth...it sucks.

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Hmmm, what exactly do you mean by "HX reverbs". If you mean the ones that are new in 2.50, I haven't gotten it installed yet so no comment.

 

But I really doubt that's true of the prior rev ones. Pretty much all of my patches have a stereo verb last in the chain, and I really doubt I failed to notice that that collapsed everything before then to mono. I bet most everyone's patches have a verb last, somebody would *have* to notice.

 

If the new ones are like that, agree, not cool. Wouldn't be at all surprised if the input the the verb itself was mono summed, but it really shouldn't do that to the dry signal.

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They're definitely maintaining stereo separation... Try putting something with a very obvious stereo split in front of the reverb like the Tremolo/Autopan block, and you hear right away that the stereo image is maintained. I hear it even pretty obviously with the Ping Pong delay. Double check that you're not using the mono version of the reverb.

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No mistake about it, using the STEREO panner, hard square wave before the STEREO glitz verb w/ the reverb mix set to 100%, there is absolutely NO stereo panning going on.
In fact if i play a note without the verb engaged the sound is hard bounced back n forth BUT, when i engage the glitz as stated above the panning effect is nulled, completely bypassed.
 

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No mistake about it, using the STEREO panner, hard square wave before the STEREO glitz verb w/ the reverb mix set to 100%, there is absolutely NO stereo panning going on.

In fact if i play a note without the verb engaged the sound is hard bounced back n forth BUT, when i engage the glitz as stated above the panning effect is nulled, completely bypassed.

 

Ugh. Please report this to Line 6 as a bug.

 

Verb input > mono, sure, maybe, but not the dry signal.

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No mistake about it, using the STEREO panner, hard square wave before the STEREO glitz verb w/ the reverb mix set to 100%, there is absolutely NO stereo panning going on.

In fact if i play a note without the verb engaged the sound is hard bounced back n forth BUT, when i engage the glitz as stated above the panning effect is nulled, completely bypassed.

 

 

It seems to me this is working as it should. If the the mix (wet/dry balance) on the reverb is at 100%, there is no dry signal and therefore no panning. If you decrease the mix towards 50%, the panning slowly reappears.

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It seems to me this is working as it should. If the the mix (wet/dry balance) on the reverb is at 100%, there is no dry signal and therefore no panning. If you decrease the mix towards 50%, the panning slowly reappears.

But the reverb should process the input, whatever is at the input should be reflected at the output,even if the mix is at 100%. If what you're saying is true then full wet = summed to mono at verb input.

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But the reverb should process the input, whatever is at the input should be reflected at the output,even if the mix is at 100%. If what you're saying is true then full wet = summed to mono at verb input.

 

That makes sense. I'm with taking zooey's advice then and report it as bug. But If it is summing the input to mono, that's probably intentional. I wonder why they would do that?

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It seems to me this is working as it should. If the the mix (wet/dry balance) on the reverb is at 100%, there is no dry signal and therefore no panning. If you decrease the mix towards 50%, the panning slowly reappears.

 

 

But the reverb should process the input, whatever is at the input should be reflected at the output,even if the mix is at 100%. If what you're saying is true then full wet = summed to mono at verb input.

 

I think I follow what both of you are getting at. Shouldn't a stereo effect that has stereo inputs and stereo outputs retain stereo separation whether it is 100% wet or not? In my head at least, wet versus dry just refers to the amount of direct signal being mixed with effected signal. It seems that even if only the effected signal is being passed out of the block to the output(100% Mix) shouldn't it still maintain stereo separation all the way from the block's input thru to output?

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That makes sense. I'm with taking zooey's advice then and report it as bug. But If it is summing the input to mono, that's probably intentional. I wonder why they would do that?

 

You wouldn't think it would be intentional as the manual points out which blocks are mono such that ostensibly you can maintain your stereo path elsewhere. But you're right, there's always the chance it could be by design.

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I think I follow what both of you are getting at. Shouldn't a stereo effect that has stereo inputs and stereo outputs retain stereo separation whether it is 100% wet or not? In my head at least, wet versus dry just refers to the amount of direct signal being mixed with effected signal. It seems that even if only the effected signal is being passed through the block(100% Mix) shouldn't it still maintain stereo separation all the way from the block's input thru to output?

That's exactly the way it should be to my thinking as well. A stereo reverb shouldn't nullify a stereo image at the output. But I have a feeling this is intentional, It was the same way with the old PodHD STUFF TOO. 

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Wait, you’re saying that having the mix at 100% defeats the stereo image? That’s probably expected. I thought you were saying you had the mix of the Ping Pong delay at 100%. The dry signal going into the effect is maintained, but the stereo signal from the wet portion of the effect isn’t completely separated. It’s not two completely independent mono effects.

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:huh: :huh: :huh: Huh?....I guess at this point I'm supposed to say " Oh well, at least it was a free update".

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If the HX stereo reverbs do indeed sum to mono at the input, then they are lose a lot of usability for anything other than guitar, especially synths. Honestly, they lose a good bit of usability for guitar specific signal chains as well.

 

I'm not at my Helix atm, but if this is the case (bug, or by design) it needs to be changed. Stereo reverbs are to be stereo in, stereo out. I have no problem with mono to stereo reverbs, but put them in a separate category, and keep the stereo reverbs stereo in, and stereo out.

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If the HX stereo reverbs do indeed sum to mono at the input, then they are lose a lot of usability for anything other than guitar, especially synths. Honestly, they lose a good bit of usability for guitar specific signal chains as well.

 

I'm not at my Helix atm, but if this is the case (bug, or by design) it needs to be changed. Stereo reverbs are to be stereo in, stereo out. I have no problem with mono to stereo reverbs, but put them in a separate category, and keep the stereo reverbs stereo in, and stereo out.

 

They don't sum the dry signal to mono. They maintain stereo separation of what's coming in. This is easy enough to prove to yourself. Just put a stereo effect in front, and you'll hear the stereo field correctly. What happens, though, is the wet signal isn't two discrete mono paths. It's a blended stereo path. That's to say that there's left and right processing being done on each side of the stereo field. So if you set the mix to 100, all you're hearing is the wet signal that's being generated by the effect block itself, and none of the original stereo dry signal. This is pretty typical of how stereo effects work in general.

 

If you want discrete processing of the left and right signals, the proper way to do that would be to split them into two mono signals and apply mono effects on each. I think, though, for reverbs, it would sound a little weird to have the wet reverb effect isolated on each respective side of the stereo field.

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Well then that does make me feel a bit better. Looks like the HX stereo reverbs are still fine for stereo processing of things like strings/synths/pads.

 

Like I said, am not at my helix, but I was reading this thread, and it had me a little worried.

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putting aside the rather petulant tone of this thread for one moment...

 

If you have a genuine reverb environment, say a nice mid sized auditorium, then you might have 2 speakers to feed the stereo signal in, and out in the room , 2 microphones to collect the reverb.  It should be obvious that both microphones are going to hear both speakers at similar volumes. What will differ is the mix of early and late reflections and the overall arrival times.  The result is that hard panned sounds will come out sounding like they are in the middle.
This is exactly the behaviour that the HX reverb should be exhibiting...and does.
 

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They don't sum the dry signal to mono. They maintain stereo separation of what's coming in. This is easy enough to prove to yourself. Just put a stereo effect in front, and you'll hear the stereo field correctly. What happens, though, is the wet signal isn't two discrete mono paths. It's a blended stereo path. That's to say that there's left and right processing being done on each side of the stereo field. So if you set the mix to 100, all you're hearing is the wet signal that's being generated by the effect block itself, and none of the original stereo dry signal. This is pretty typical of how stereo effects work in general.

 

If you want discrete processing of the left and right signals, the proper way to do that would be to split them into two mono signals and apply mono effects on each. I think, though, for reverbs, it would sound a little weird to have the wet reverb effect isolated on each respective side of the stereo field.

 

I think phil_m makes an important point(assuming I understand him correctly) that "Stereo" is not necessarily the same thing as "dual mono".

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I think phil_m makes an important point that "Stereo" is not necessarily the same thing as "dual mono".

So, is the ping-pong delay a dual mono effect?Using this logic any stereo effect placed before a ping pong delay set at full wet would sum to mono, Yet this is not the case,only the reverbs do this... Frankly I don't understand his aurgument at all. I have an eventide H9 (Not dual mono) when I run direct out of Helix stereo L/R using a Ping pong delay into the stereo inputs of the H9 set to a reverb algorithm full wet, I still clearly and fully and hear with crystal clarity the back and forth delay. 

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So, is the ping-pong delay a dual mono effect? Frankly I don't understand his aurgument at all. I havw an eventide H9 (Not dual mono) when I run direct out of Helix stereo L/R

 

I think someone else can better answer this question as I generally run a mono path. 

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So, is the ping-pong delay a dual mono effect?Using this logic any stereo effect placed before a ping pong delay set at full wet would sum to mono, Yet this is not the case,only the reverbs do this... Frankly I don't understand his aurgument at all. I have an eventide H9 (Not dual mono) when I run direct out of Helix stereo L/R using a Ping pong delay into the stereo inputs of the H9 set to a reverb algorithm full wet, I still clearly and fully and hear with crystal clarity the back and forth delay. 

 

I suspect even with H9 in the scenario you describe, there is significant crosstalk in the wet signal from one side to the other. Different manufacturers handle it differently, but I've never encountered a stereo reverb that would treat the wet signal as two discrete paths that track the separation from the input. The example above of having two mics in a space is a good explanation of what I'm talking about. I also imagine that with the Line 6 reverbs, the left and right sides of the wet signal at 100% wet are not identical.

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Why model a silly limitation? If you have a L/R Input on an effect, whatever is at those L/R inputs should come out of the L/R outputs whether the mix is 5% or 100%. Why would you even have stereo anything if reverb (which, 99% of the time is going to the last thing in the chain before the output block) isn't capable of passing that stereo signal at ANY mix level? If this is accurate, its something that could easily be fixed, and should be.

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Why model a silly limitation? If you have a L/R Input on an effect, whatever is at those L/R inputs should come out of the L/R outputs whether the mix is 5% or 100%. Why would you even have stereo anything if reverb (which, 99% of the time is going to the last thing in the chain before the output block) isn't capable of passing that stereo signal at ANY mix level? If this is accurate, its something that could easily be fixed, and should be.

Well, if you have the mix level at 100%, there is no dry signal by definition, so what's at the inputs is kind of a moot point. All you're hearing is the wet signal, and its stereo image is going to be whatever it is. It's not uncommon for the stereo image/spread of a stereo effect to be different than that of the input. I don't think it's modeling a limitation as much as it's making a sound design decision about how you want the stereo spread of the wet signal to behave.

 

What's being described here is what I've seen with most reverb plug-ins, fwiw. If you send a signal that's panned hard left into a reverb mix buss, you'll hear the wet signal from the reverb on both the left and right sides. It might favor the left side more, but you still hear reverb on the right side.

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You're feeding it two input channels. You're only getting one output channel apparently. The only way to get "expected" behavior would be a parallel path, but if you're stereo signal from one path is now basically a mono signal in the other path, who know what kind of phase issues it could cause. Seems stupid to me. I understand it theoretically, but it still seems stupid.

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You're feeding it two input channels. You're only getting one output channel apparently. The only way to get "expected" behavior would be a parallel path, but if you're stereo signal from one path is now basically a mono signal in the other path, who know what kind of phase issues it could cause. Seems stupid to me. I understand it theoretically, but it still seems stupid.

 

There are still two output channels. They probably have a more "mono-ized" quality to them at some settings, but on the new models, you can hear each channel doing its own thing. The stereo processing is really apparent on the Searchlights model, for instance.

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1. Dry signal (stereo) > split paths

2. Path1 > stereo to mix ctrl

3. Path2 > sum to mono > stereo processing > mix ctrl

4. Mix ctrl blends 2 stereo signals

 

Edit: I hope this is clear. Tried to draw an alphanumeric diagram, failed miserably...

 

Reason for sum to mono before stereo effect:

Reverbs are meant to replicate reflections in a certain space. If you are in the middle of the space and facing a stereo sound source, the left direct (dry) sound reaches your right ear earlier, and vice versa = fully stereo.

 

Now, to simplify things, we'll use a ping pong model.

1st reflection: The left source hits the left wall and reaches the left ear first.

2nd reflection: The reflection from the left wall carries on to bounce off the right wall before reaching the right ear first this time > inverted stereo image.

 

The result is a diluted stereo image of the source. Add more complex reflections and the stereo field of the source is lost after a few reflections.

 

Now explain the stereo processing:

Say the left wall is a soft material that attenuates some of the higher frequencies, while the right wall is hard and attenuates less. The direct signal interacts with both surfaces just as much, since they bounce left to right to left (i.e. the walls impart their "flavor" to both left and right signals)

 

However, each new reflection off the left wall will reach the left ear first, whether it is the 1st reflection from the left source, the 2nd reflection from the right source, etc. I.e. the left wall is constantly applying "processing" and the latest iteration of this processing always hit the left ear first.

 

Therefore, at 100% mix, even though the original stereo image is lost, the stereo image of the reverb effects are still clear. Those effects are constantly "refreshed" with each reverb iteration.

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lets try another way of explaining things.

Lets assume stereo input to a stereo reverb with stereo monitoring.

 

At mix say 25%

 

If you put a click into the left input you will hear a click from the left output, plus the reverb of the click from both left and right outputs.  Not the same signal as the reflections will be different.

 

If you put a click into the right input you will hear a click from the right output, plus the reverb of the click from both left and right outputs.  Not the same signal as the reflections will be different.

 

If you increase the mix to 100%:

 

If you put a click into the left input you will not hear a click from either output, but you will hear  the reverb of the click from both left and right outputs.  Not the same signal as the reflections will be different.

 

If you put a click into the right input you will not hear a click from eithe routput, but you will hear  the reverb of the click from both left and right outputs.  Not the same signal as the reflections will be different.

 

This is the exact correct action that should happen.

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I know nothing of studio recording and am less than amateur at live sound so this post comes with a truckload of salt that you have to swallow before you are allowed to read it.

It seems to me that when we talk about stereo effects there are two types of stereo we are talking about:

  1. Effects that emulate the feeling of having two ears in a room, listening to a sound source.  By sound source I mean an instrument, hand clap, cough, sneeze, NOT two speakers on opposite sides of the room!).
  2. Effects that simply exploit the existence of two audio channels.

Reverbs are (probably) always in the first group.  Delays could be in the first group or the second group.  If a pingpong delay is used to emulate the way a sound echoes in a room, it is in the first group.  If a pingpong delay is used for rhythmic effect it is in the second group. Autpan might emulate a sound source moving from left to right.  Add some phase or flange and it is now moving front to back as well, moving in a circle around you.

 

I think the error here is expecting reverb to happen in the ear after the sound has entered our ear.  If I clap my hands in a room, I expect to hear the dry clap and then the reverberations from the clap.  If my ears are plugged the instant the clap happens and unplugged the instant the clap ends, I will hear the reverberations with BOTH ears and I will not be able to tell if the clap happened to my left or right.

 

The OP wants to be a wall between two rooms.  He wants to be wall that has an ear on each side.  A sound in the left room would reverberate into the left room ear and a sound in the right room would reverberate into the right room ear.  But Line 6 knows we aren't walls.  We are people blessed by our creator with two ears on each side of our head.

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