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Pulsing sound from channel 17/18 on AR16

Posted: Mon Nov 05, 2018 6:57 am
by johnbarr1
I've been successfully using a StudioLive AR16 USB connected to an iMac for over a year. Yesterday it worked ok, this morning I have a problem.

With nothing connected to the mixed except speakers and power cord, and all sliders at their lowest level - then with MAIN moved beyond unity there is a faint pulsing sound - at about 8 beats per second.

With the MAIN level low (e.g. 30) the pulsing cannot be heard, but if the level for ST17/18 is advance to 30 the pulsing can be heard much louder than before. No other channels make any difference.

When the pulsing can be heard loud, changing USB/SD Card from USB to "SD Card" appears to make the pulsing go away, but if you then increase MAIN towards maximum the pulsing returns, but much more quietly.

If the mixer is turned on while attached by USB to the iMac, the computer does not recognise it.

Has anyone seen this behaviour before? Is there an easy fix?

Re: Pulsing sound from channel 17/18 on AR16

Posted: Mon Nov 05, 2018 8:17 am
by johnbarr1
Also, I can play through other channels. As long as the MAIN volume is not very high the pulsing is not audible.

But the existence of the pulsing at higher volumes, and the fact that the mixer won't connect to my computer remain significant problems.

Re: Pulsing sound from channel 17/18 on AR16

Posted: Sat Aug 31, 2019 9:45 am
by tommasovercesi
Hi
I have exactly same issue playing from SD card (channel 7/8 on my AR8)
Recording on SD card is clean, checked separately. Issue is on playing, not recording.
All other channels muted
Any suggestion is welcome.

Re: Pulsing sound from channel 17/18 on AR16

Posted: Wed Jul 08, 2020 10:05 am
by soaringspider
I have had the same problem on my AR16, which I describe as popping in the control room output. It is only there when 17/18 is on and the USB/SD button is set to select USB. It does not need to be connected to USB for the popping to be present. Audio from other channels still passes to control room as it should. Mixer was purchased December 2017 and the problem developed suddenly in January of 2019. Mixer was sent to Sweetwater (dealer) in February. They sent it to PreSonus and PreSonus was unable to fix it. Under their two year warranty Sweetwater replaced the unit. It has been fin since then, until this morning (7/8/20) when the original problem suddenly came back. I will be contacting Sweetwater this evening and if they can't help I'll be purchasing a new mixer, made by someone else.

Re: Pulsing sound from channel 17/18 on AR16

Posted: Thu Jul 09, 2020 10:30 am
by SwitchBack
I have a theory which can explain how a problem like that can develop over time, then to return even after equipment was replaced. It has to do with setup routines and wall warts or ESD (or both).

Depending on your setup routine and location not all gear is grounded before it's connected together. Gear powered from external power supplies (e.g. laptops) may not have a ground connection at all. Due to static electricity and the way ground isolated power supplies work the the various units can be at different voltage levels before the cables between them are connected. On occasion I've even seen small sparks fly when making connections.

This is still not a problem when it happens occasionally. Inputs and outputs are fitted with capacitors to protect the electronics from damage. The capacitors take the hit and, slightly worse for wear, live on to fight another day. Capacitors on audio inputs/outputs can easily outlive the unit this way.

But on data ports the protective capacitors have to be smaller or they filter out the high frequency data signals too. These capacitors can take hits but not as many as the caps on audio sockets. And once the capacitors go the electronics are next…

So with this in mind check your setup routines: Do you set up in a particular order every time? And in the same venue? Have a critical look at anything repetitive, with ESD (rubber soles and carpets!) and ‘floating’ equipment in mind. And take extra care of the data connectors as they are out of necessity the weakest point.

Re: Pulsing sound from channel 17/18 on AR16

Posted: Fri Jul 10, 2020 1:23 pm
by soaringspider
Thanks for that information. Unfortunately it doesn't help my situation. My AR16 is in my home studio and is always left attached to the other equipment in the studio. The AR 16 does not have a wall wart, it has a power supply (I suspect it is a switching supply) built into the unit. It is connected to AC mains via a standard three conductor AC power cord.

Re: Pulsing sound from channel 17/18 on AR16

Posted: Sun Sep 27, 2020 1:36 pm
by elliottrennie
*Sigh* 😔
I came looking for a solution to the problem, and we have nothing in two years from anyone at presonus. It seems this is a common problem when there is a USB line connected. I haven’t checked the revers yet, does the clicking/popping occurs when recording from the mixer to the capture software? I’ll have to give it a try in the morning.
My set up is home studio with a Windows 10 (AMD threadripper) connected to the USB and main out through 31 channel equaliser to the left and right Amp

Re: Pulsing sound from channel 17/18 on AR16

Posted: Tue Mar 30, 2021 11:05 pm
by paulzeman
Why is there no answer on this?

It is 2021 and I have this same problem on a new Studiolive AR12c.

Re: Pulsing sound from channel 17/18 on AR16

Posted: Sat Aug 28, 2021 6:33 am
by Geislinn
Same issue here on AR12.

Re: Pulsing sound from channel 17/18 on AR16

Posted: Sat Jan 01, 2022 9:55 am
by chaddbeverlin
Same here. they fixed once and now its happening again. Starting to think Presonus is a rip off

Re: Pulsing sound from channel 17/18 on AR16

Posted: Thu Jun 16, 2022 12:33 pm
by dodo6
Hi
I had the same problem this year - StudioLive AR16 USB .Pulsing (crackling) sound from channel 17/18 and 15/16 when the usb buttons have been turned ON, turn OFF USB buttons the sound disappeared.
It was easy to fix.I did it myself.The problem was in the power supply 5V section (digital section) bad capacitor C112 - 100uf/25V .
Replacement capacitor solved the problem no pulsing (crackling) sound and computer sees AR16 again .
Maybe it help someone.

Re: Pulsing sound from channel 17/18 on AR16

Posted: Wed Mar 20, 2024 3:00 pm
by KiloherzzAudioservices
@dodo6 thanks for that post! It really helped me to find the issue on an AR12c...

So idk if that is board revisions or because you have an AR16 but when I removed the PSU board I figured that this is an entirely different PCB revision and your instructions cannot be applied 1:1 - BUT it was still feasible to be repaired as follows:

My PCB revision is from 2019 and sports 2 capacitors 1000uF and 10V (see attached pic). I exchanged both for the sake of not knowing which one was faulty, and it seems to have helped. I chose 16V type to have a bit more headroom here.

Maybe someone from Presonus support should not this, it seems all those PSU boards from 3rd parties have capacitor issues after a few years - Its not acceptable that after 5yrs such a problem manifests in such a way.