A/B Mix Explanation?

[Fox Uncle]

Hi Eventide Community (who has been immensely helpful to me in the past),

Could some generous and knowledgeable person share how “A/B Mix” settings are defined? For example, what does “A10+B10” actually translate to? It’s channel A and channel B, I assume, but what do the numbers denote? Lastly, and almost as importantly, what do the the little arrows surrounding the virtual dial, in the control app, correspond to: stereo spread? See image for what I am referring to. In the image, I have made them as “wide” as possible.

Thanks in advance. The H90 and control app for Mac have been such a great artistic tool for me.

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[brock]

To be clear, by channel would normally be the left half A side and the right half B side of a dual-effect algorithm.  You tagged DualVerb, so that is the Reverb A & Reverb B parameters.  It could be a ‘balance-type Mix for Delay A & B or Pitch A & B in other algorithms.

You picked a unique one, because it can be routed a little differently.  But the numbers with those letters indicate the relative levels, or strength of effect compared to its ‘sister’ effect.

The widest will alway be straight up at 12 o’clock.  A10+B10.  A10-B0 would be all A effect, and vice-versa.

I’ll link the pertinent DualVerb section, if you haven’t seen it.

https://cdn.eventideaudio.com/manuals/h90/1.8.5/content/algorithms/reverb.html#dualverb

I’ll also link an unrelated Delay section, because it dives into what the differences are between mono and stereo use.

https://cdn.eventideaudio.com/manuals/h90/1.8.5/content/algorithms/delay.html#digital-delay

[brock]

Oh, more importantly, I forgot to mention  those ‘little arrows’.  That means the parameter is also controlled by some  external device.  It could be a HotKnob, expression pedal, aux switch, MIDI.

Each arrow itself marks a point in the range of the external device’s control.  A start or end point of its influence, and those start & end points can be inverted for a reversed response.  The range itself being the colored band around the circumference.

[Fox Uncle]

Thanks Brock! That’s helpful. I did read the manual section, but I was confused by one thing. Here’s the excerpt that confused me with an explanation as to why I was confused, below:

<span style=”font-size: inherit;”>With stereo outputs, you may turn [A/B Mix] parameter fully clockwise for dual mono reverbs (A on left, B on right). A mono input will be sent to each reverb, while a stereo input will send input 1 to reverb A, and input 2 to reverb B.

</span>

What confused me about that is that my source is mono but dual mono actually sounds less wide or “less stereo” than A/B Mix settings more toward 12 O’Clock. It sounds like it’s dividing the signal reverb between the two channels more when it’s not in dual mono, with a mono source.

[brock]

I was hoping this would summon the Oracle Of Reverb @ndeshpande, for the inner workings of the algorithm.  You’ll have to settle for my experimental Program, and some speculation.  I held off  on blurting anything out before I had a chance to look deeper into it.

If a bit cryptic, I think the description below is accurate.  The part that may be ‘missing’ is that A/B Mix at A10+B10 is getting distributed equally to Reverb A & Reverb B (same mono signal for each), and then it gets split to a stereo image.

With stereo outputs, you may turn [A/B Mix] parameter fully clockwise for dual mono reverbs (A on left, B on right). A mono input will be sent to each reverb, while a stereo input will send input 1 to reverb A, and input 2 to reverb B.

With a strong center focus, but definitely information spread across the stereo field. Whether that’s by frequency, some (but not all) all-pass filters, black magic … I don’t know.

In the Dual Mono parameter setting, your input (mono) goes exclusively to the left / Reverb A, and effectively that same mono signal goes to the right Reverb B.  Panned reverbs, yes, but not exactly the same as two reverbs mixed together and spread to a stereo output.  On to lab testing …

 

[brock]

Dual Mono Dual-DualVerb

https://www.dropbox.com/scl/fi/bvnbqmw8epdt67c21hffu/Dual-Mono-Dual-DualVerb.pgm90?rlkey=fbyn0wbgwbsu8elirmvbd6rzx&raw=1

Insert Mode Program with two DualVerb instances side-by-side in Parallel.

• Preset (A) – A/B Mix at A10+B10 (Active default)
• Preset (B) – A/B Mix at Dual Mono (Bypass default)
• Switch between Act/Byp for either Preset (or both Active).

To better hear the separated reverbs, I used 450 & 900 ms Pre Delays in both instances.

• Defeat all Pre Delay with HS1.

I exaggerated the Tone A / B differences in each DualVerb instance to differentiate between reverbs.

• Adjust Tone A / Tone B with (A) & (B) HotKnob.
• HS2 sets all Tone controls to flat.

HS3 flips the Pre Delays in DualVerb-1, also setting it to Dual Mono.  Four 50 second reverbs to audition the wide separation.

(P) HotKnob adjusts Decay A & Decay B in both instances, from 0 ms – 50 S + INFINITE & FREEZE.

• EXP1 is mapped to the (P) HotKnob above.
• EXP2 is mapped to A/B Mix in both DualVerbs (saved at A10+B10).

[brock]

brock wrote:

• EXP2 is mapped to A/B Mix in both DualVerbs (saved at A10+B10).

I let a mistake slip in [EXP2 in Preset B inadvertently mapped to A/B Size] but that’s a minor use case.  You get the idea.

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