JBL PRX series auto-off disable?

Ben Lawrence

Senior
Mar 2, 2011
1,029
19
38
Vermont
vtaudiovisual.com
Re: JBL PRX series auto-off disable?

From a little quick research looks like no. I did find that it was supposed to be fixed in the 700 series. I have a bunch of these and am yet to notice the issue. I think I am usually running decent level into them. Do you have the 600 series or 700? Is it causing issues in acoustic / spoken word stuff. I am going to have to do some research in my own speakers to see if this is an issue. Is it a pretty obvious on/off gate pumping?
 
Re: JBL PRX series auto-off disable?

Thanks, Ben;
If you're running low level background music they can shut off or they can turn off when using them as monitors if you don't have them loud. The way they fade in with the delay is a problem, but it's a bigger problem that JBL thinks this is a "feature" anyone wanted or needed!
Just ridiculous that they don't have a recessed disable button.
I'll be ripping these apart I guess. Know where I can find a schematic?


Sent from my iPhone
 
Last edited:

Steve Garris

Freshman
Mar 29, 2012
46
0
0
Seattle, WA
Re: JBL PRX series auto-off disable?

From a little quick research looks like no. I did find that it was supposed to be fixed in the 700 series. I have a bunch of these and am yet to notice the issue. I think I am usually running decent level into them. Do you have the 600 series or 700? Is it causing issues in acoustic / spoken word stuff. I am going to have to do some research in my own speakers to see if this is an issue. Is it a pretty obvious on/off gate pumping?
The 700 series is were this feature was introduced. It is not on the 600 series (thankfully).
 

Sean Zurbrick

Freshman
Jan 15, 2011
57
0
0
Columbus, OH
Re: JBL PRX series auto-off disable?

Which PRX do you have? The 600 have a gate that exhibits this issues. The 700 has a "power saving" thing going on but once the signal is detected it stays "on" for a minute or so before it cuts out. So it wouldn't be an "on/off" problem. If you have this happening.
 

Sean Zurbrick

Freshman
Jan 15, 2011
57
0
0
Columbus, OH
Re: JBL PRX series auto-off disable?

PRX712 specifically.

JBL says it's not defeatable, they don't have a service manual or schematic and never will. The product is designed and made in China.

Not the JBL I grew up with, clearly.

Same boxes I use for monitors. I've not experienced this. They don't toggle on and off quickly. Once they sense signal they stay on for a minute or two before going to standby.
 
Re: JBL PRX series auto-off disable?

Same boxes I use for monitors. I've not experienced this. They don't toggle on and off quickly. Once they sense signal they stay on for a minute or two before going to standby.
If you use them in a quiet setting, they turn off and require a certain amount of level before they turn back on. Sure, 90% of people use them in loud situations where they'll never run into this problem. But for us 10% it's a deal breaker. ESPECIALLY since they're solving a problem that was never a problem to begin with. I've never heard anyone say "gee, I wish my speakers would go into power-save when they don't have signal". Ridiculous.
 

Sean Zurbrick

Freshman
Jan 15, 2011
57
0
0
Columbus, OH
Re: JBL PRX series auto-off disable?

If you use them in a quiet setting, they turn off and require a certain amount of level before they turn back on. Sure, 90% of people use them in loud situations where they'll never run into this problem. But for us 10% it's a deal breaker. ESPECIALLY since they're solving a problem that was never a problem to begin with. I've never heard anyone say "gee, I wish my speakers would go into power-save when they don't have signal". Ridiculous.

You aren't, by chance, running the speakers at full volume and barely putting signal through them are you? That would be a situation that would cause this. You should be able to put a nice healthy signal into the box and use the volume on the box to regulate the volume. I have to think the cutoff on signal is on the "input" side and not the output.
 
Re: JBL PRX series auto-off disable?

You aren't, by chance, running the speakers at full volume and barely putting signal through them are you? That would be a situation that would cause this. You should be able to put a nice healthy signal into the box and use the volume on the box to regulate the volume. I have to think the cutoff on signal is on the "input" side and not the output.
What's the dynamic range of the gate? I can think of a few scenarios where you'd want both very low levels and full output from the same setup.
 

Sean Zurbrick

Freshman
Jan 15, 2011
57
0
0
Columbus, OH
Re: JBL PRX series auto-off disable?

What's the dynamic range of the gate? I can think of a few scenarios where you'd want both very low levels and full output from the same setup.
The 700 series isn't really a gate that goes on and off. Think of it more like a motion sensor light that stays on for 5 minutes once it detects motion. I'm proposing that maybe the gain staging isn't ideal for low volumes. The powered speaker has an attenuation control. If it's all the way up and the desire is for low volume then you have to control it from the incoming signal, which would be very low.
 
Re: JBL PRX series auto-off disable?

The 700 series isn't really a gate that goes on and off. Think of it more like a motion sensor light that stays on for 5 minutes once it detects motion. I'm proposing that maybe the gain staging isn't ideal for low volumes. The powered speaker has an attenuation control. If it's all the way up and the desire is for low volume then you have to control it from the incoming signal, which would be very low.
Yes, I'm aware of how the device works (and the net effect is that of a gate with a very long hold time), and the need for proper gain structure. But there are applications where you need both low volumes and high volumes from the same setup, where reducing the loudspeaker isn't an option. Think loudspeakers being used for environmental effects in a theatrical setting. One scene may have a thunderclap sound effect (requiring close to full output from the loudspeaker), while another may have ambient noise like crickets at just above the background noise in the theater. Changing the gain at the loudspeaker between scenes simply isn't going to happen.
 
Re: JBL PRX series auto-off disable?

Like I say, it's a completely unnecessary, unneeded "feature" that nobody asked for, ever.
And it's a problem. Especially now that I know that JBL just rebrands Chinese crap without any design, involvement or thought it seems.
 

TJ Cornish

Graduate
Jan 13, 2011
1,263
0
0
St. Paul, MN
Re: JBL PRX series auto-off disable?

Like I say, it's a completely unnecessary, unneeded "feature" that nobody asked for, ever.
And it's a problem. Especially now that I know that JBL just rebrands Chinese crap without any design, involvement or thought it seems.
JBL has had a few head scratchers. I agree on the gate, which BTW has been around since at least the PRX 500 series - I was shopping 7 years ago or so, and hated the "feature" then. I ended up buying QSC HPR instead.

More recently in the fantastic sounding SRX-800P series, the default gain is 26dB rather than the more common 32dB, so the forums are filled with people saying the speakers are "underpowered" as they have to turn the gain knob higher than comparable products. Yes I know they did this to match the ITech defaults, but I don't like it on the ITechs either. BTW, there is a gate on by default in the SRX-800P series, but it's fast enough that I haven't been bothered by it, and I believe you can disable the "power saving mode" that turns it on.
 

Brian jojade

Senior
Jan 15, 2011
718
9
0
Wausau, WI
www.happymacshop.com
Re: JBL PRX series auto-off disable?

Like I say, it's a completely unnecessary, unneeded "feature" that nobody asked for, ever.
And it's a problem. Especially now that I know that JBL just rebrands Chinese crap without any design, involvement or thought it seems.
For speakers installed permanently, the auto off allows the speakers to remain plugged in and powered 24X7. Eg, if they are installed in a club, you wire them up, and leave them on. When music starts flowing, they turn on. Perfect scenario for that. It would be nice, however, to have an auto defeat switch available.

JBL has had a few head scratchers.
To this I will agree. Take a look at the EON 600 series. They have 2 channels of input, each with independent gain, and a mix output. One would think the mix output would be after the gain pots for each channel so you could use it as a mini mixer to control multiple speakers. Nope, the mix is tapped BEFORE the gain pots of each channel as a 50% mix. No adjustments on the mix at all. WTF were they thinking there???
 
Re: JBL PRX series auto-off disable?

For speakers installed permanently, the auto off allows the speakers to remain plugged in and powered 24X7. Eg, if they are installed in a club, you wire them up, and leave them on. When music starts flowing, they turn on. Perfect scenario for that.
That makes no sense at all.

First, who would install small MI-grade powered speakers permanently? Much more effective from a control and maintenance standpoint to use unpowered speakers and put the amps in an amp room where you can easily control the speakers.

Second, the switching power supplies in modern amplifiers would draw almost nothing when the speakers aren't producing sound. If they are using some sort of inefficient power supply that draws significant power even when the speaker isn't being used, then that's just poor design.

Third, in a permanent install, if you're going to all the trouble of running signal and power to each speaker, it's nothing to wire the AC to be sourced from a breaker or switch that can kill the power to the speakers if for some reason that's important to you.

Fourth, why would you want power to your speakers all the time? What if someone unplugs something at the source end? What if there's a problem with the wiring and a nice 60 cycle hum starts blasting through the speakers? What if one of the speakers' amps fail and it starts putting out noise or a buzz, or amp starts smoking?

None of what you suggest is a really a good reason for this terrible "feature", ESPECIALLY since it's not defeatable.



Sent from my iPhone
 

Max Warasila

Graduate
Feb 20, 2013
1,131
34
48
Richmond, VA
Re: JBL PRX series auto-off disable?

That makes no sense at all.

First, who would install small MI-grade powered speakers permanently? Much more effective from a control and maintenance standpoint to use unpowered speakers and put the amps in an amp room where you can easily control the speakers.

Second, the switching power supplies in modern amplifiers would draw almost nothing when the speakers aren't producing sound. If they are using some sort of inefficient power supply that draws significant power even when the speaker isn't being used, then that's just poor design.

Third, in a permanent install, if you're going to all the trouble of running signal and power to each speaker, it's nothing to wire the AC to be sourced from a breaker or switch that can kill the power to the speakers if for some reason that's important to you.

Fourth, why would you want power to your speakers all the time? What if someone unplugs something at the source end? What if there's a problem with the wiring and a nice 60 cycle hum starts blasting through the speakers? What if one of the speakers' amps fail and it starts putting out noise or a buzz, or amp starts smoking?

None of what you suggest is a really a good reason for this terrible "feature", ESPECIALLY since it's not defeatable.



Sent from my iPhone
He didn't say it would be his first choice, or what he would do - just that it happens. Remember that these are marketed to people who may not be as aware as the rest of use and did a DIY with gear from Guitar Center install (tm). He's suggesting that it's a neat failsafe for when people are being silly. We all agree that we don't want/need it in the pro world.

Who knows, maybe it gives them an Energy Star rating or something like that which they get a tax credit for.
 

Brian jojade

Senior
Jan 15, 2011
718
9
0
Wausau, WI
www.happymacshop.com
Re: JBL PRX series auto-off disable?

That makes no sense at all.

First, who would install small MI-grade powered speakers permanently? Much more effective from a control and maintenance standpoint to use unpowered speakers and put the amps in an amp room where you can easily control the speakers.

Second, the switching power supplies in modern amplifiers would draw almost nothing when the speakers aren't producing sound. If they are using some sort of inefficient power supply that draws significant power even when the speaker isn't being used, then that's just poor design.

Third, in a permanent install, if you're going to all the trouble of running signal and power to each speaker, it's nothing to wire the AC to be sourced from a breaker or switch that can kill the power to the speakers if for some reason that's important to you.

Fourth, why would you want power to your speakers all the time? What if someone unplugs something at the source end? What if there's a problem with the wiring and a nice 60 cycle hum starts blasting through the speakers? What if one of the speakers' amps fail and it starts putting out noise or a buzz, or amp starts smoking?

None of what you suggest is a really a good reason for this terrible "feature", ESPECIALLY since it's not defeatable.



Sent from my iPhone
1. There are many of these speakers installed permanently. They are one of many choices to install. It's quite common to install powered speakers versus having a separate amp location, especially if there is no convenient space for an amp. Your argument that you have better control of the speakers by having separate amps together could be used as an argument for your portable situation as well. If so, then why are YOU using powered speakers? Running a separate audio cord and power cord for a portable situation is more of a pain than running signal and power once for a permanent install.

2. At idle, a powered speaker probably draws 25-30 watts. While not much, that works out to about $30 in electrical consumption per year if the speaker sits idle 24X7. It adds up if you have multiple speakers in a room.

3. Yes, in an ideal world, you could put all of the speakers on a switch or a breaker. However, now you need to teach people how to find that breaker and turn on the speakers when they are needed. Believe it or not, in many situations, that's more difficult than it seems. If you can just pick up the mic and talk, that is much easier for many to understand. It's quite common in the install world to leave stuff powered on 24X7 because of this.

4.The reason to keep things on 24X7 is answered in question 3. The same problems you describe, of people plugging things in, or amp failures, etc. could happen if you have an amp in a rack.

The final reason that the auto power off is a good thing is that it makes the speakers completely quiet when there is no signal. So, if you set up the speakers in a quiet situation, you won't have any speaker hiss at all until there is signal and they power up. Yes, it would be nice if you could defeat the option, but that extra option would increase the cost of the speaker.
 

mackerr

Junior
Jan 29, 2011
374
6
0
Re: JBL PRX series auto-off disable?

1. There are many of these speakers installed permanently. They are one of many choices to install. It's quite common to install powered speakers versus having a separate amp location, especially if there is no convenient space for an amp. Your argument that you have better control of the speakers by having separate amps together could be used as an argument for your portable situation as well. If so, then why are YOU using powered speakers? Running a separate audio cord and power cord for a portable situation is more of a pain than running signal and power once for a permanent install.

2. At idle, a powered speaker probably draws 25-30 watts. While not much, that works out to about $30 in electrical consumption per year if the speaker sits idle 24X7. It adds up if you have multiple speakers in a room.

3. Yes, in an ideal world, you could put all of the speakers on a switch or a breaker. However, now you need to teach people how to find that breaker and turn on the speakers when they are needed. Believe it or not, in many situations, that's more difficult than it seems. If you can just pick up the mic and talk, that is much easier for many to understand. It's quite common in the install world to leave stuff powered on 24X7 because of this.

4.The reason to keep things on 24X7 is answered in question 3. The same problems you describe, of people plugging things in, or amp failures, etc. could happen if you have an amp in a rack.

The final reason that the auto power off is a good thing is that it makes the speakers completely quiet when there is no signal. So, if you set up the speakers in a quiet situation, you won't have any speaker hiss at all until there is signal and they power up. Yes, it would be nice if you could defeat the option, but that extra option would increase the cost of the speaker.
I'm with Andrew on this.

You can rationalize why it's a good idea to have the speakers turn off, but every one of your reasons would be fine with a 20min or 60min timer. You want them to turn off at the end of the day, ok, but they should not turn off during a show.

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