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Author Topic: JBL PRX800W MIX OUT design flaw? (complaint/rant post)  (Read 564 times)

Thomas Le

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JBL PRX800W MIX OUT design flaw? (complaint/rant post)
« on: April 23, 2021, 11:36:18 pm »

I picked up 4 new PRX812W's for remote delay fills today at GC of all places (there was one near my house that I did not know about that look to recently open) but I got them on "discount". Tested at home and I'm experiencing the issue that the MIX OUT is either too quiet or too distorted depending on how the 50/50 button is configured. I don't recall having this issue with my PRX710's that have a complete analog path for the THRU output. I'm guessing this is hard coded in the DSP maybe? And Yes I've done a hard reset on all 4 speakers.
I guess I'm making this post as an FYI for any PRX800W users out there that are experiencing the same issue. What I'm thinking to fix this is to do/make a simple Y splitter at the mixer out and split from there, granted there will be more XLR cables to run but I can't rely on that MIX OUT to have adequate levels.
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Steve Garris

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Re: JBL PRX800W MIX OUT design flaw? (complaint/rant post)
« Reply #1 on: April 24, 2021, 12:00:19 pm »

That sucks. Glad most of my boxes are the older style with simple knobs and switches. I love my PRX 6xx system so much I refinished the grills a couple years ago, still looks like new.
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Russell Ault

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Re: JBL PRX800W MIX OUT design flaw? (complaint/rant post)
« Reply #2 on: April 24, 2021, 05:06:41 pm »

What I'm thinking to fix this is to do/make a simple Y splitter at the mixer out and split from there, granted there will be more XLR cables to run but I can't rely on that MIX OUT to have adequate levels.

Why not use Y-splitters at the speakers and save yourself the extra cable?

-Russ
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Steve-White

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Re: JBL PRX800W MIX OUT design flaw? (complaint/rant post)
« Reply #3 on: April 24, 2021, 05:59:59 pm »

Interesting.  One would think a simple L+R summing done with toggle switch and resistors.  Could go through a gain stage for isolation and such - in which case there could be a problem there.

Do all 4 of them behave the same?

I looked for a schematic and can't locate anything.
« Last Edit: April 25, 2021, 11:39:17 am by Steve-White »
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Keith Broughton

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Re: JBL PRX800W MIX OUT design flaw? (complaint/rant post)
« Reply #4 on: April 25, 2021, 06:59:04 am »

MIX OUT is either too quiet or too distorted depending on how the 50/50 button is configured.
When it's too quiet, what are the settings of the input gains on ch 1 and 2? Mix out is post level controls.
When distorted, what are you running the mix out into?
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Thomas Le

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Re: JBL PRX800W MIX OUT design flaw? (complaint/rant post)
« Reply #5 on: April 25, 2021, 04:24:38 pm »

Why not use Y-splitters at the speakers and save yourself the extra cable?

-Russ
For this particular application, I have to run cables either way, I'm trying to do a wide coverage outside.
Interesting.  One would think a simple L+R summing done with toggle switch and resistors.  Could go through a gain stage for isolation and such - in which case there could be a problem there.

Do all 4 of them behave the same?

I looked for a schematic and can't locate anything.
Yep all 4 have the same issue.

When it's too quiet, what are the settings of the input gains on ch 1 and 2? Mix out is post level controls.
When distorted, what are you running the mix out into?
1. I'm running from a mixer line level XLR out to the initial speaker line level XLR in. I have the volume level just about noon level for the outside application, I have not hit the limit LED.
2. I'm daisy chaining to another PRX812W.


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Keith Broughton

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Re: JBL PRX800W MIX OUT design flaw? (complaint/rant post)
« Reply #6 on: April 26, 2021, 06:10:13 am »

For this particular application, I have to run cables either way, I'm trying to do a wide coverage outside.Yep all 4 have the same issue.
1. I'm running from a mixer line level XLR out to the initial speaker line level XLR in. I have the volume level just about noon level for the outside application, I have not hit the limit LED.
2. I'm daisy chaining to another PRX812W.
Some speakers have a link that is a direct connection to the main input and, as in your case, the link or mix out is level dependent.
If the level control of the first speaker is not at full, the mix out will not be at the same level as the input signal to the first speaker.
I have dealt with this before with Turbo Milan speakers and found you have to raise the gain on the second speaker to get equal level if the first speaker is not at full.
Y cables were my solution.
As to why the 50/50 distorts, I don't have an answer.
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scottstephens

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Re: JBL PRX800W MIX OUT design flaw? (complaint/rant post)
« Reply #7 on: April 27, 2021, 11:28:51 am »

Thomas,

Yep that sucks. About 2 years ago, I purchased 2 of the PRX 812's and I noticed that one of them was slightly lower in volume.  I remedied that by merely exercising the volume pot. It took a few minutes but since then, all has been good.  I still have a little piece of tape on the back of the one that was softer in case something happens later.  Good luck, they can sound pretty good and get  pretty loud in smaller settings.

Scott
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John L Nobile

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Re: JBL PRX800W MIX OUT design flaw? (complaint/rant post)
« Reply #8 on: April 27, 2021, 12:18:07 pm »


I have dealt with this before with Turbo Milan speakers and found you have to raise the gain on the second speaker to get equal level if the first speaker is not at full.
Y cables were my solution.


I found the same problem and solution with those speakers. Thought it was a problem with that speaker but now I see that it's "designed" that way.
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ProSoundWeb Community

Re: JBL PRX800W MIX OUT design flaw? (complaint/rant post)
« Reply #8 on: April 27, 2021, 12:18:07 pm »


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