Convenient Features of the JBL EON700 Series, PRX ONE, and EON ONE MKII: Auto Feedback Suppression

What is AFS (Auto Feedback Suppression) anyway? I think this is what it’s all about.
“Feedback” here refers to ‘audio feedback’ in PA terminology. This feedback is a phenomenon in which a loop of microphone, speaker, microphone, speaker, and so on creates an unpleasant sound like a “squeal” or “whirr”. This can not only ruin a live performance, but it can also be bad for your ears and cause damage to the speakers.

To avoid this, there are three things to keep in mind!

○ Pay attention to the position of the microphone and speakers.
Do not place the microphone near or in front of the speaker.

○ Do not raise the microphone gain or overall volume too high.
Using a band as an example, there is a pattern where the volume of the guitar and bass amps is too loud, the stage monitor volume is turned up, and then there is feedback. In this case, lower the volume of the guitar and bass amps and increase the volume of the stage monitors in front of the guitar and bass. It is easier to monitor and perform better when the sound on stage is reduced and clear.

○ Use an equalizer to find the frequencies that cause feedback and cut (attenuate) them.
In most cases, PAs use a 31-band graphic equalizer because a 3-band parametric equalizer attached to a mixer has a large impact on sound quality if one of the bands is cut too sharply. Experienced PAs can listen to the sound by ear and respond with, “This is about right,” but I think there are more people who do not.

This is where the AFS (Auto Feedback Suppression) comes in.
This function automatically detects the frequencies that cause feedback and cuts a narrow, pinpoint bandwidth to minimize the effect on the sound quality.

The JBL EON700 series PA speakers, the EON ONE MK2, and the PRX ONE are equipped with this AFS!

This is seriously amazing.
The AFS224, the famous dbx AFS, was succeeded by the AFS2, and now the popular feedback suppressor is built into the speaker.... I am so impressed (tears).

Now, let's take a look at this built-in AFS by dbx driverack.

This is a screen shot of the EON ONE MK2 and the JBL PRO CONNECT app on my iPhone.

Please see below for usage and the contents of each item.

AFS by dbx On/Off
Turns the AFS processor on or off.

Live AFS On/Off
Turns the Live (automatic) AFS filter on and off. The Live filter is ideal for catching feedback from microphones moving around the stage. Live AFS is the fastest and easiest way to start using AFS processing.

Reset Live Filters
Resets all live filters.

Fixed AFS On/Off
Toggles the Fixed AFS filter on and off. Fixed filters are ideal for catching feedback from non-moving microphones like guitar amp mics or drum mics.

Learn Fixed On/Off (Start Discovery: ON, Stop Discovery: OFF in app)
Starts auto-discovery and setting of the fixed AFS filter frequency.
Before going live, turn “Learn Fixed” ON with the microphone connected and speakers turned on. At this time, turn off Live AFS.
Then, approach the nearest microphone and speak loudly to induce feedback. If no feedback is seen, slowly turn up the main volume until feedback is heard and suppressed by the fixed AFS filter. Each time the speaker's AFS system detects a frequency of feedback, it automatically applies a fixed AFS filter to that frequency. Continue speaking loudly into the microphone by moving around the performer with the handheld microphone.
When all fixed AFS filters are filled, “Learn AFS” will automatically turn off and the fixed AFS filters will be retained. If frequency assignments for all fixed AFS filters are not completed, the user can manually exit “Learn AFS” by clicking the “Learn Fixed” setting again. When “Learn AFS” is turned off, the setting will automatically remain on.
Once the “Learn Fixed” setting is complete, turn on “Live AFS” to configure the feedback suppression settings for live events.

Reset Fixed (Clear Fixed filters in app)
Reset Fixed AFS filters.

Remember Fixed on Reboot On/Off
Speakers are sometimes used for extended periods of time with the same settings. In such cases, the speaker may be turned on and off many times. Turning “Remember Fixed on Reboot” on will set the fixed AFS filter settings to keep settings during reboot.
It is generally better to leave this setting on in case the power is accidentally turned off between the time the fixed AFS filter is set in Soundcheck and the time you attend an event. For PA systems that are moved around a lot, it may be better to turn this feature off. This is because different locations have different feedback issues, which the previous fixed filter cannot address.

In addition, I contacted JBL support for more information and received an immediate response. Quick response support is very reassuring, isn't it?

1. What is the maximum number of filters?
- 24

2. What is the bandwidth (/oct)?
- Q = 16 (1/11.1 octave)

3. How many dB can be cut?
-3dB-12dB

4. How long is the auto-applied filter retained?
- All are kept until overwritten by new feedback or reset by the user.
- For the PRX ONE/EON ONE MK2, the filters are divided into two groups: fixed (12 filters) and live (12 filters).
If the AFS parameter “Remember Fixed on Reboot” is set to ON, the fixed filters will be preserved when the unit is rebooted.
Otherwise, if it is OFF, the fixed filters will be reset when the monitoring system is rebooted. This can also be cleared by the user using the “Reset Fixed” parameter.
For the live filters, they are cleared when the monitoring system is turned off or restarted.
- In the case of the EON700, all 24 filters are saved even if the unit is rebooted. This can be cleared by the user using the “Reset AFS Filter” parameter.

5. What happens if a new feedback is detected when the maximum number of filters have already been applied?
Is the oldest filter immediately removed or does nothing change?
- In the PRX ONE/EON ONE MK2, when 12 filters have reached the fixed filter setting, the oldest filter with the closest frequency suppressed will be replaced.
In the live filter setting, when 12 filters have been reached, it replaces the oldest filter.
- In the case of the EON700, when 24 filters have been reached, the oldest filter with the closest frequency suppressed will replace the oldest filter.

Note that with the PRX ONE/EON ONE MK2/EON700, the gain before feedback can be increased by up to 3 dB when AFS is used.

What do you think? In short, it has almost the same level of built-in processing as an external AFS processor!

I wanted to try it out myself and let it howl.

I stood in front of the PRX ONE with a microphone in my hand and let out a strange voice that seemed to be prone to feedback, so I intentionally caused the howling. After that, the same strange voice did not cause any more feedback (haha).

I think it is very easy to use for PAs at events because there is really no need for difficult settings, just turn on the AFS. However, please note that when new feedback occurs during the performance, it takes a few seconds for the automatic AFS filter to detect it and cut it off.

Although the basic premise is “please adjust the placement and volume so that feedback does not occur,” the AFS is there to help you out in case of an emergency.

JBL PA speakers not only have great sound quality, but also these conveniences have been considerably enhanced for the user.

When in doubt about PA speakers, go with JBL.

This was my PA speaker as the person in charge of this department at Sound House.