ProSoundWeb Community

Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB: The Classic Live Audio Board => Topic started by: doug johnson2 on June 21, 2021, 01:02:43 PM

Title: limiter question
Post by: doug johnson2 on June 21, 2021, 01:02:43 PM
I am setting up a different processor as backup for a EAW UX8800 and I am trying to set up the limiters.  On my high frequency band pass the UX uses .05 ms attack time.  The shortest attack time on the other processor is .10ms.  Is there anything I should do to account for this, i.e. lower the threshold, etc.?
Title: Re: limiter question
Post by: Ivan Beaver on June 21, 2021, 02:45:30 PM
I am setting up a different processor as backup for a EAW UX8800 and I am trying to set up the limiters.  On my high frequency band pass the UX uses .05 ms attack time.  The shortest attack time on the other processor is .10ms.  Is there anything I should do to account for this, i.e. lower the threshold, etc.?
The attack time is based on the HP freq.  The lower the HP filter freq, the longer the attack time will be.

The threshold generally has nothing to do with the attack time, just where it starts to limit.  The attack time is how long it takes to limit.

Depending on which ratio they subscribe to, the 0.05ms would relate to a HIGH PASS filter of around 10K-20K.  0.5ms would be closer to 1-2Khz

Of course, if using as a backup, you could reduce the threshold maybe 3dB or so (a wild guess) to make it kick in at a lower level.  At that point in the show, you should be happy just to make it through.  It's better than blowing the HF.
Title: Re: limiter question
Post by: doug johnson2 on June 21, 2021, 04:13:16 PM
The high pass frequency is 1400hz.  The .05ms is what the EAW UX8800 Output Limiter Wizard Excell sheet spits out.  I guess I need to contact EAW to see if there is an issue with the sheet.  I was thinking that lowering the threshold might be a option to help protect.  I had a Ux8800 go down on me, I have a replacement but, they are getting long in the tooth and will feel better with a back up in place.
Title: Re: limiter question
Post by: Tim McCulloch on June 22, 2021, 12:27:15 AM
The high pass frequency is 1400hz.  The .05ms is what the EAW UX8800 Output Limiter Wizard Excell sheet spits out.  I guess I need to contact EAW to see if there is an issue with the sheet.  I was thinking that lowering the threshold might be a option to help protect.  I had a Ux8800 go down on me, I have a replacement but, they are getting long in the tooth and will feel better with a back up in place.

You missed Ivan's point - think of the frequency that 0.05ms represents. In this case, it means that the limiter is effective on much higher frequencies.  A slower attack time will let multiple cycles of higher frequencies through before the attack engages.