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Author Topic: Practical use of downward expansion help me understand  (Read 4833 times)

Scott Olewiler

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Practical use of downward expansion help me understand
« on: October 21, 2018, 09:32:49 AM »

Where does everyone find using downward expansion is better than using tradition gates and why? 
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John Roberts {JR}

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Re: Practical use of downward expansion help me understand
« Reply #1 on: October 21, 2018, 10:04:12 AM »

Where does everyone find using downward expansion is better than using tradition gates and why?
Downward expansion gives a more subtle fading down of the noise floor instead of the abrupt on/off of a noise gate. 

JR
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dave briar

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Re: Practical use of downward expansion help me understand
« Reply #2 on: October 21, 2018, 11:44:56 AM »

Downward expansion gives a more subtle fading down of the noise floor instead of the abrupt on/off of a noise gate. 

JR
I defer to those more knowledgeable but can't the same response be achieved via setting the attack, hold, and release values on the gate?
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Scott Olewiler

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Practical use of downward expansion help me understand
« Reply #3 on: October 21, 2018, 12:11:00 PM »

Downward expansion gives a more subtle fading down of the noise floor instead of the abrupt on/off of a noise gate. 

JR
John, Thanks but I already understand what it does.

I was more interested in what practical applications folks use it  over gates? Where do people find it more useful.
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Chris Hindle

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Re: Practical use of downward expansion help me understand
« Reply #4 on: October 21, 2018, 12:43:54 PM »

John, Thanks but I already understand what it does.

I was more interested in what practical applications folks use it  over gates? Where do people find it more useful.

Quiet Jazz, quiet hall, with a noisy band.
No, it makes no sense, but I got good results anyway.
Chris.
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Rick Powell

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Re: Practical use of downward expansion help me understand
« Reply #5 on: October 21, 2018, 10:31:09 PM »

John, Thanks but I already understand what it does.

I was more interested in what practical applications folks use it  over gates? Where do people find it more useful.

I use downward expansion more in recording where the abruptness of a gate causes issues that are more noticeable than with a live situation.
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Luke Geis

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Re: Practical use of downward expansion help me understand
« Reply #6 on: October 22, 2018, 02:05:27 PM »

It has a few upsides, most notably with things like drums, vocals or spoken word in noisy environments.

It is not like a gate although in principle that is what it is. A gate is more abrupt and doesn't have a ratio making it more like a switch with parameters to make it less noticeable or more controlled. An expander is more like a reverse compressor. It has a ratio, attack, release, and range ( db reduction amount ), and is much more subtle at opening and closing making it more natural and useful for things that are more sensitive to an on-off sound.

The Neve 5045 Primary Source Enhancer, in essence, is a glorified expander with fewer knobs. When most of us hear downward expansion we think more like a gate, but that is not what it is. Downward expansion should be thought of as more like downward compression, or decompression. As the signal gets quieter the output level is reduced more and more in relation to the ratio and threshold setting we use. The range sets the amount of db reduction and the attack and release times adjust the softness of the on-off nature of the compressor.

If used well you can get up to 10db more gain before feedback in touchy situations, but you have to be careful. The concept is simple. When the person is not talking the gain is reduced and feedback is staved, as soon as the person talks the expander opens up and you get full output again. If set up well, you can get a little more volume without feedback. For drums, you can use it to reduce background noise and tighten up the drum mix. With noisy stages and background vocals, you can use it to at the very least duck out some of the stage wash when the background singers are not on the mic.

Think of an expander as more of a compressor in reverse. It simply reduces the noise floor by compressing it into a smaller dynamic range. As the signal gets quieter it drags the signal down more quickly to the noise floor which you set. As the signal gets louder ( in relation to the noise floor ) the expander drags the noise floor up ( opens ) and the signal is released from the expander. There is a makeup gain feature as well. Again an expander is designed to act more like a compressor. The makeup gain increases the output as you can imagine by the set amount. This brings the noise floor up with it. The range sets where the noise floor is and the ratio and threshold settings set the db level where the expander starts to uncompress. This is what allows you to make the quiet things louder in relation to the noise floor, hence the term expander.
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Helge A Bentsen

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Re: Practical use of downward expansion help me understand
« Reply #7 on: October 22, 2018, 02:41:45 PM »

I use it sometimes on inconsistent drummers. First an expander, then a gentle compressor to keep the levels in check.

Works magic when you're doing a birthday gig or a corporate show where the customer brings his own "band".
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Doug Johnson

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Re: Practical use of downward expansion help me understand
« Reply #8 on: October 22, 2018, 04:07:02 PM »

I have found that downward expansion works really well on podium mics in windy conditions.
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John Roberts {JR}

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Re: Practical use of downward expansion help me understand
« Reply #9 on: October 22, 2018, 05:28:39 PM »

It has a few upsides, most notably with things like drums, vocals or spoken word in noisy environments.

It is not like a gate although in principle that is what it is. A gate is more abrupt and doesn't have a ratio making it more like a switch with parameters to make it less noticeable or more controlled. An expander is more like a reverse compressor. It has a ratio, attack, release, and range ( db reduction amount ), and is much more subtle at opening and closing making it more natural and useful for things that are more sensitive to an on-off sound.

The Neve 5045 Primary Source Enhancer, in essence, is a glorified expander with fewer knobs. When most of us hear downward expansion we think more like a gate, but that is not what it is. Downward expansion should be thought of as more like downward compression, or decompression.
The name expander is literal and accurate, it "expands" the dynamic range the reciprocal or inverse function of compression. 
Quote
As the signal gets quieter the output level is reduced more and more in relation to the ratio and threshold setting we use. The range sets the amount of db reduction and the attack and release times adjust the softness of the on-off nature of the compressor.
for people who remember dbx tape noise reduction, that was basically a 2:1 compressor before the tape path, and 1:2 expander after. The 1:2 expander made the loud louder, and the quiet, quieter while making the tape hiss quieter too. 
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If used well you can get up to 10db more gain before feedback in touchy situations, but you have to be careful. The concept is simple. When the person is not talking the gain is reduced and feedback is staved, as soon as the person talks the expander opens up and you get full output again. If set up well, you can get a little more volume without feedback.

I would advise caution about this or any dynamic gain ranging in a monitor system path (dynamically changing gain is often a recipe for instability).
Quote
For drums, you can use it to reduce background noise and tighten up the drum mix. With noisy stages and background vocals, you can use it to at the very least duck out some of the stage wash when the background singers are not on the mic.
more of a recording tool than live, but the OP asked.
Quote
Think of an expander as more of a compressor in reverse. It simply reduces the noise floor by compressing it into a smaller dynamic range. As the signal gets quieter it drags the signal down more quickly to the noise floor which you set. As the signal gets louder ( in relation to the noise floor ) the expander drags the noise floor up ( opens ) and the signal is released from the expander. There is a makeup gain feature as well.
??
Quote
Again an expander is designed to act more like a compressor.
inverse of a compressor
Quote
The makeup gain increases the output as you can imagine by the set amount. This brings the noise floor up with it. The range sets where the noise floor is and the ratio and threshold settings set the db level where the expander starts to uncompress. This is what allows you to make the quiet things louder in relation to the noise floor, hence the term expander.
The nomenclature comes from the simple fact that it "expands" the dynamic range.

Compression makes the quiet bits louder and easier to hear... unfortunately this also boosts up the noise floor, so downward expansion when used correctly can restore the noise floor to it's appropriate level wrt signal. Again more of a recording than live sound issue. 

I have actually built downward expansion into compressors to restore the noise floor down where it should be, but made it transparent to the operator hoping to KISS. What they don't know can help them. 8)

For live sound, SR gates are generally faster and easier to set up. The benefit of downward expansion is marginal compared to the extra time and effort. 

JR   
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Re: Practical use of downward expansion help me understand
« Reply #9 on: October 22, 2018, 05:28:39 PM »


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