# About Standard Reverb

**URL:** <https://qa.fmod.com/t/about-standard-reverb/13804>\
**Category:** FMOD Engine\
**Created:** [April 3, 2018, 7:02pm UTC](https://qa.fmod.com/t/about-standard-reverb/13804 "2018-04-03T19:02:26Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jiyongman](https://avatars.discourse-cdn.com/v4/letter/j/ebca7d/32.png) [@jiyongman](https://qa.fmod.com/u/jiyongman)\
**Post date:** [April 3, 2018, 7:02pm UTC](https://qa.fmod.com/t/about-standard-reverb/13804/1 "2018-04-03T19:02:26Z")

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I’m applying Standard Reverb using FMOD\_System\_SetReverbProperties() and have several questions.

A. What is the difference between passing 0 and FMOD\_PRESET\_OFF to the third argument?

The document says  
“Passing 0 or NULL to this function will delete the physical reverb”  
and  
“When using each instance for the first time, FMOD will create a physical SFX reverb DSP unit that takes up several hundred kilobytes of memory and some CPU”

‘deleting the physical reverb’ seams like ‘deleting the instance’…

B. Does this mean, when I apply NULL and then reapply something else again, the old physical SFX reverb DSP unit will be removed and newly created again?

C. Are both calling FMOD\_System\_SetReverbProperties() and FMOD\_System\_CreateDSPByType() with FMOD\_DSP\_TYPE\_SFXREVERB the same?

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**Author:** ![cameron-fmod](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/cameron-fmod/32/261_2.png) [@cameron-fmod](https://qa.fmod.com/u/cameron-fmod)\
**Post date:** [April 9, 2018, 4:18am UTC](https://qa.fmod.com/t/about-standard-reverb/13804/2 "2018-04-09T04:18:15Z")

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You are spot on with all the points you mentioned.

By passing in zero to SetReverbProperties, the DSP will be removed and then need to be created if needed at a later point. If you use FMOD\_PRESET\_OFF, the DSP will still be used and this can use CPU if it is not needed.

The DSP used is of type SFXREVERB, previously it could have used hardware reverb but they don’t exist anymore.

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**Author:** ![jiyongman](https://avatars.discourse-cdn.com/v4/letter/j/ebca7d/32.png) [@jiyongman](https://qa.fmod.com/u/jiyongman)\
**Post date:** [April 9, 2018, 12:22pm UTC](https://qa.fmod.com/t/about-standard-reverb/13804/3 "2018-04-09T12:22:15Z")

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> [@](#):
>
> You are spot on with all the points you mentioned.
> 
> By passing in zero to SetReverbProperties, the DSP will be removed and then need to be created if needed at a later point. If you use FMOD\_PRESET\_OFF, the DSP will still be used and this can use CPU if it is not needed.
> 
> The DSP used is of type SFXREVERB, previously it could have used hardware reverb but they don’t exist anymore.

Thanks!!