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Author Topic: AES50 dropout during subharmonics/anything under sustained 50hz  (Read 2038 times)

Jason Branden

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Hey Folks,

First time poster here. Sorry in advance if somebody has touched on this topic before but I haven't been able to find a post that covers the exact issues I've run into and am looking to see if anyone has heard or otherwise run into this bizarre issue.

The issue:

I ran a stage at the Hyatt Hotel a number of months ago where I had ZERO dropouts throughout bands, guest speakers, people moving around on and over the cables, etc. All day, No issues.  Later that evening, there were four "DJ's" lined up. First 80's style set was fine. Second set were EDM style music events.  This is where I ran into massive issues. Every time there were (persistent) low end frequencies running though the PA I would lose AES50 sync and get dropouts. sometimes one right after the other  The only thing I could do is turn down the volume and/or cut the frequency at 40hz (and even then I would sometimes get a dropout at LEAST every 15mins)

Next day, everything was fine. -Until the DJ sets again.  Same issue. Wash, rinse, and repeat. lots of troubleshooting, no resolve.

Troubleshooting steps taken
* measured power at amp rack to check for voltage dip. None. Rock Solid.
* measured (mains) power at supply (150A 3 phase 208) -all phases during event. -Perfect
* measured power going directly TO the DL32 -rock solid
* checked ground bonding between everything in the rack. -completely fine.
* checked the integrity of the shielded cat5 line (every line and the shield for continuity)  -even replaced with a spare. -all was fine.
* moved FOH power to and from house power (checked voltage AND ground differential between the two supplies) -All looked fine.
* monitored voltage differential between DL32 AND M32 during event -Nothing stood out.
* strapped extra grounding between amp racks and FOH for grin giggles. -no difference.
* pulled DL32 out of amp rack in am attempt to limit electromagnetic interference -no change
* moved from AES50 "A" to AES "B" on both the snake and console. -No change
* put the DL32 on its own power supply outside of the rack mounted PDU in the amp rack. (right to mains power) -No change.
(loss was observed by readout on the console going "red" then "green" during these outages so for sure was a AES50 dropout)

I'd be at a complete loss except I've had some time to reflect on this a little bit and have a few thoughts as to what might have been happening, but still don't feel warm and fuzzy with my assumptions.

Before I get into that, I'm curious as to what everyone is doing with their DL32's/DL16's.  Are you guys putting them in the back of your amp racks or otherwise near amplifiers and speakers?  I can say that I've run the X32 board and S16 in this same same rig without issue whatsoever, same event previous year, same music, etc. That said, I upgraded this rig to a Midas M32 along with its DL32 counterpart last year and that's when the issues started. (same configuration, new board and snake) As you can imagine, I am a little dismayed by my upgrade.



relevant equipment;

FOH:
Midas M32

AMP RACK 1:
MIDAS DL32
Driverack Venue 360 (running in analog NOT AES input mode)
Driverack 260 (hot spare)
Powersoft Digium 5000 amp (driving four labsubs)
Six PAS TOC RSLA's being driven by 2000 watt"ish" (peak) amps.
three phase power distro rack (3P 208v 30A {90A total power @120v})

AMP RACK 2:
<same as above except no dl32 or driverack>

I can only come to the conclusion here that the DL32 does not have as good of shielding as the S16 snake does. The fact that it was near four labsubs, a Digium powersoft amp, along with other magnetic inducing equipment is the reason why I was losing sync during the EDM events. Its when the system is working its hardest. The amps and driving tons of power, subs are producing massive amounts of magnetic output, TONS of SPL. Etc, etc. All of this sustained due to the type of music it is. Just... Really low, really long low end sound. Its the only thing I've got at the moment. And still, why this all worked with the s16 and x32 is confusing.  (as mentioned above, I did at one point take the snake out of the rack but had the same issues)

All of that said, I am planing on moving the DL32 to the rack that houses all of the wireless mic receivers and an in-ear system stuff.  This rack is usually further from the business end of the PA power system(s) and closer to the stage anyway, which is good. I am also purchasing a pair of KLARK TEKNIK DN9620 which will support fiber optic connectivity alongside a tactical/armored optical snake. (both AES50 "A" and "B" get sent down that pipe, W/ shielded cat5 as a backup at the push of a button, so bonus) After the misery last year I never want to deal with dropouts again. I'm not convinced that THIS issue was cat5 related, though, with all the other things I've been reading, seems like a good idea to just optically isolate the snake and board all together.

Aside from those upgrades, in hindsight, it does seem foolish the keep the DL32 in the back of the stage left amp rack, considering its a high speed network device, being subjected to all sorts of potential noise (both electrically and physically being beat up)  but I'd still like to know if anyone has had issues quite like this? Any distance issues to consider? (how far should the DL32 be from sources of magnetic fields, etc)

-Any take would be greatly appreciated! I still can't decide if my new DL32 is defective (loose connections or IC pads actually vibrating around creating issues) or if this is just normal and par for the coarse with me making stupid life choices in regard to where I'm placing equipment. ;)

Thanks for the read and any advise anyone might have. I know this is somewhat of a wall-o-text post, but I wanted to be as concise as possible.

-Jason


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Dave Garoutte

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Re: AES50 dropout during subharmonics/anything under sustained 50hz
« Reply #1 on: May 15, 2018, 12:52:11 pm »

My first thought is that you have a vibration issue; a physical problem not an electronic one.
Something in the chain doesn't like shaking at 50 hz.
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Jason Branden

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Re: AES50 dropout during subharmonics/anything under sustained 50hz
« Reply #2 on: May 15, 2018, 01:38:10 pm »

My first thought is that you have a vibration issue; a physical problem not an electronic one.
Something in the chain doesn't like shaking at 50 hz.

Normally I'd completely agree however I could almost, with precision, estimate when a drop would occur depending on how much current was being drawn by the PA. (which I suppose could correlate to "shake" threshold) On the other hand the 80's sets and bands with WAY louder and punchier than the EDM sets were.  -That's my only hesitation in this instance.   I'm hoping to try and replicate the problem this summer/spring before any big events, I'm just having a location problem.  -Never a convenient place to setup the entire rig and pound on it like that without some kind of complaint or issue ;)

If there is something going on with the DL32, I'm not sure how I'd even get them to warranty/test something like that.  I feel really stuck at the moment.
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Geert Friedhof

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Re: AES50 dropout during subharmonics/anything under sustained 50hz
« Reply #3 on: May 15, 2018, 02:48:20 pm »

Quick one to check: is the shield from the cat5 connected to the shells of both ethercons?  What's the lenght of the cat5?

My DL32/16's have never skipped a beat. Last weekend one lived 4 days between racks of d&b D12, D20 and 1200's, and some dimmers, with EDM.
« Last Edit: May 15, 2018, 03:12:11 pm by Geert Friedhof »
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Lee Buckalew

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Re: AES50 dropout during subharmonics/anything under sustained 50hz
« Reply #4 on: May 15, 2018, 03:31:50 pm »

Normally I'd completely agree however I could almost, with precision, estimate when a drop would occur depending on how much current was being drawn by the PA. (which I suppose could correlate to "shake" threshold) On the other hand the 80's sets and bands with WAY louder and punchier than the EDM sets were.  -That's my only hesitation in this instance.   I'm hoping to try and replicate the problem this summer/spring before any big events, I'm just having a location problem.  -Never a convenient place to setup the entire rig and pound on it like that without some kind of complaint or issue ;)

If there is something going on with the DL32, I'm not sure how I'd even get them to warranty/test something like that.  I feel really stuck at the moment.

Is it possible that voltage sag was causing the issue?

Lee
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Lee Buckalew
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Art Welter

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Re: AES50 dropout during subharmonics/anything under sustained 50hz
« Reply #5 on: May 15, 2018, 03:37:55 pm »

Normally I'd completely agree however I could almost, with precision, estimate when a drop would occur depending on how much current was being drawn by the PA. (which I suppose could correlate to "shake" threshold) On the other hand the 80's sets and bands with WAY louder and punchier than the EDM sets were.  -That's my only hesitation in this instance.   I'm hoping to try and replicate the problem this summer/spring before any big events, I'm just having a location problem.  -Never a convenient place to setup the entire rig and pound on it like that without some kind of complaint or issue ;)

If there is something going on with the DL32, I'm not sure how I'd even get them to warranty/test something like that.  I feel really stuck at the moment.
The LABSub has an impedance minimum right around 40Hz, so the most current would be drawn on sustained notes at that frequency. EDM often has sustained continuous LF content, a surface resonance may be shaking the DL32 enough for the cord to loose continuity, while short "louder and punchier" peaks evidently aren't exciting the resonance enough to become problematic.

You could get an equivalent SPL of four with just one LAB Sub if you remove the grill and place the DL32 inside the mouth, do a slow sine sweep right around 40 Hz and see if the problem occurs, and determine at what specific frequency and SPL.

If it does occur, you should be able to eliminate the problem by applying pressure around the connector to dampen the resonance.


Good luck!

Art
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Art Welter

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Re: AES50 dropout during subharmonics/anything under sustained 50hz
« Reply #6 on: May 15, 2018, 03:40:16 pm »

Is it possible that voltage sag was causing the issue?

Lee
OP stated:
Troubleshooting steps taken
* measured power at amp rack to check for voltage dip. None. Rock Solid.
* measured (mains) power at supply (150A 3 phase 208) -all phases during event. -Perfect
* measured power going directly TO the DL32 -rock solid


So low voltage is not the problem.
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Lee Buckalew

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Re: AES50 dropout during subharmonics/anything under sustained 50hz
« Reply #7 on: May 15, 2018, 03:41:56 pm »

OP stated:
Troubleshooting steps taken
* measured power at amp rack to check for voltage dip. None. Rock Solid.
* measured (mains) power at supply (150A 3 phase 208) -all phases during event. -Perfect
* measured power going directly TO the DL32 -rock solid


So low voltage is not the problem.

Oops, Thanks Art, I missed that.

That's what I get for reading and replying at work while I'm doing other things.  :-)

Lee
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Jason Branden

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Re: AES50 dropout during subharmonics/anything under sustained 50hz
« Reply #8 on: May 15, 2018, 03:47:50 pm »

Is it possible that voltage sag was causing the issue?

Lee

I never saw any voltage sag whatsoever. (never dipped more then two volts at any given time during the dropout)
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Jason Branden

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Re: AES50 dropout during subharmonics/anything under sustained 50hz
« Reply #9 on: May 15, 2018, 03:49:09 pm »

Quick one to check: is the shield from the cat5 connected to the shells of both ethercons?  What's the lenght of the cat5?

My DL32/16's have never skipped a beat. Last weekend one lived 4 days between racks of d&b D12, D20 and 1200's, and some dimmers, with EDM.

It was 150 feet including patch cables. Ground tested on every cable. (barrel to barrel)

-J
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