Stereo Tool

A few listeners, 8 million (!) and they can't pay € 349,=? There it's crises too
Great you have found that post on that forum

...not shure if the last part of my post is good understandable:
It should work this way
There are 2 things causing a (target) band to reduce its gain:
1. target band sidechain’s gain control Signal
2.source band’s gain reduction signal as multiplied by the relevant Band Coupling control
The higher value of these should determine the target band´s gain reduction.

I think also weskeene would also agree with this cause the subsequent Optimods are using this method.

The Optimod 8100 used the method to add These 2 vaues. So when you turn the "Bass coupling" knob to 100%, the amount of the bass band´s gain reduction is (nearly) alway greater than the Master Band, except for the case that no energy below 200Hz is in the Audio...

The reason for using band coupling is to achieve a compromise between Maximum Sound consistency (low couplings at all) and a Sound nearer to the original.
You also Need the couplings if you are using more multiband drive (reducing Dynamics with less possible artifacts) to prevent certain bands (especially highest and lowest) to "run away" if there is a passage in the song with very less highs.

In a 5- band preset with the band 3 to 4 coupling control I can say how much highs AND upper mids are allowed to boost (assuming the band 4 to 5 coupling is set to a high amount) compared to the energy in the (main-)band 3.
So you can achieve good reasons when you set Band 4 to 5 coupling to - let´s say 70% and then "tune" the band 3 to 4 coupling so that all the music with less amount of highs is brightened up enough but so that you don´t hear process of buiding up highs in cases of short passages without highs - to not hear the Sound coloration.

And the case you described with band 1 to 5 coupling - there you Need the coupling method of your band coupling Matrix, cause you *want* to have the effect of adding both of the control values to make band 5´s gain reduction greater.

So the Norm- Switch in the Matrix should Change These 2 algorithms: Norm=off causes the System to *add* the 2 control values and feed the sum of These to the target band, Norm=on activates the comparision of These 2 values and feed this to the target band.

OK my suggestion with the norm Switch is not perfect, cause 1 band can be a source band for more than 1 bands and a target band can have more than 1 source band...
But perhaps this here is the solution:
When you make a table with 4 columns and several rows:
column1: source band (to fill in a numerical value)
column2: target band (to fill in a numerical value)
column3: algorithm (mode 1 or 2, what I described in my prior post about the norm switch)
column4: percentage slider

So you can determine the algorithm per coupling way instead of per band.

That's far too expensive for me and interferes with my personal use of it. So I don't use it at all, other than isolated lab environments that never see a transmitter. Both arms and both legs plus internal organs for someone like me. Nothing for the station that has 8 million listeners? I'm poor as heck here. No joke. I don't know about them guys though. Surely they could afford it.

RobertSack

Yes, I think your explanation of how the Optimod works is largely right, but a tad outdated. Yes, when coupling was specified as a percentage, you could end up with more gain in the coupled band than you probably should have. However, since they moved to specifying coupling as dB of max separation between the bands, this should no longer be possible. I've only been able to test this using their Optimod sound cards, but it did seem to be fixed.

It was considered a negative effect, and the manual provided a solution to get around (by dialing something slightly less than 100% for coupling, maybe 85%??).

I'm not sure I would change a single thing about what ST is doing starting with beta 17. Coupling among the top and bottom 3 bands sure seems like plenty. If someone needs more than that, it's probably time to consider a different crossover structure (read: fewer bands).

Even in the case of a 9 band structure, with all of the coupling engaged at 100%, you're reduced to a 5 band processor with benefits. I don't see any benefit in making this feature any more complicated than it already is.

In fact, Hans could make it *more* simply, by having the UI dynamically replace references like N - 1 > N with 4 > 5. After all, the UI knows how many bands the user is employing.

Pretty sure Bob Orban said the exact opposite in an interview he did a while back. I cant rememeber it word for word but he mentioned his multibands are all-pass (except for the 110x) and they all use quite steep crossover slopes.
Even their website states "The best results are obtained with steep crossover slopes allowing more consistency from various program sources. It can also give the "illusion" of an unprocessed "big" sound."

@RobertSack
6dB/octave sounds rather dubious to me, care to share how you came up with that value ? Is it something you read in any of the manuals ?

Can't be very steep:
http://www.orban.com/support/orban/tech ... b_bull.php

Granted, one half of it is 6dB, but probably fair to say the other half is well, about half, another 6dB.

In the actual Optimod 8600 the band coupling is determined in percent, wich doesn´t say something about *how* the bands are coupled. The percantage value determines the factor that is used as a Multiplier for the source band´s gain reduction. In the 2-band AGC it is done in dB, wich is also correct. Cause when you specify this in dB, the result is Independent from the Input Level. This is what you want to have in the AGC, cause different Input Levels should as less as possible have an influence to the outcoming Sound.
But when you are in the Multiban, it is better to do it in percent, cause the Level going into it is well controlled by the AGC. And if level is lower or higher caused by the AGC- Timing, than it is good that the absolute coupling value also changes according to this.

RobertSack -

I was unaware they hadn't converted to dB everywhere. In any case, the rationale makes sense for multiband, and I think I prefer it. But I like the "safer" approach ST employs where the coupled band never artificially gets more gain than the source band unless it actually needs it.

Thanks for the info.