Korg Forums

Chuck · Posted: Wed Aug 31, 2016 12:08 am Post subject: Sound reduction not fixed

I posted an issue about the sound on the PA4 fluctuating while in style and play mode. At first I thought it was the PA system (Bose L1 Model 11). Got on the phone with the Bose techs and we ran the PA system through several processes and determined it was not the PA. Also checked the cables (TRS) that connect the PA4 to the mixer., no problem with cables also.
The sound will start to decrease in sound about a minute after turning on the keyboard. It will not go completely off but it is very noticeable. I turn off the keyboard and reboot it seems to be okay. Just don't know when this will happen and how often. But definitely not good during a live performance. One more thing. I am using the latest OS also. Any constructive thoughts will be appreciated. Thanks.

Chuck
Ohio, USA
_________________
PA4X & PA900
Bose L1 Model II w/ToneMatch
Neumann KBS 105 Mic
Old fingers

AntonySharmman · Posted: Wed Aug 31, 2016 1:38 am Post subject:

Chuck , as first when this happens , try to completely disable to OFF Maxx Audio module and remark changes.
Then make sure that Master knob works fine , varying it's value during that issue and disconnect any volume /
expression pedal ,even midi connections you might use.
If this insists then you probably face hardware issue , mostly focused at sound module of board and you have
to visit service center !
_________________
Music Conductor - Sound Engineer & Developer - Automotive SMPS/RF R&D - Electronics Engineer
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Keyboards : Steinway-D, Kronos X, Pa5X 76, Pa4X 76, Montage M7 , Roland-XV88, Emu3,Emax II,Synclavier II,Yamaha DX Series, ΟΒ-8V

Chuck · Posted: Wed Aug 31, 2016 1:44 am Post subject:

Thanks, I'll give your suggestions a go. I do not use expression or midi connected instruments. It seems to happen sporadically but it is getting more and more persistent.
_________________
PA4X & PA900
Bose L1 Model II w/ToneMatch
Neumann KBS 105 Mic
Old fingers

Jonyblues · Posted: Wed Aug 31, 2016 5:40 am Post subject:

Hi Chuck, I haven't read all of the back story to your tests but have a couple of questions/comments.

1. Have you managed to duplicate the reduction in sound using an alternative amp/pa system? If yes, it is probably an issue with the kbd (settings/hardware fault etc.). If no, I think it could be related to my next comment.
2. A friend of mine had a Bose unit and in order to try to improve her vocal sound, I bought her a vocal harmonizer/multi fx unit. I set it up for her as she wasn't really a techie and the sound was great. She did a few gigs and then started saying that the sound levels kept dropping and her vocals levels kept cutting in and out. I assumed that she'd set it up wrong or had a dodgy cable. After changing all of the cables and ensuring that all was wired up correctly, I actually heard this intermittent sound reduction problem too at two gigs.

Having done a lot of reading about the Bose unit I came to the conclusion that the first mistake I made was plugging into the mic socket not the line input (I had assumed that the mic input should have been fine for a vocal fx unit!). I also discovered that it was probably also caused by the inbuilt vocal fx in the Bose unit clashing with my external fx unit. Thirdly, and what was likely to be the most significant, was that the Bose unit had a built in limiter which kicked in when signals reached a certain level. And it appeared that sometimes the signal was allowed to pass and other times it got reduced. I found other people had had similar problem via Google.

So, in summary, am not sure if your sound dropping problem is anything to do with this but I just wanted to mention that my friend had an identical sound reduction problem which had nothing to do with a kbd.

Hope this helps.
Best wishes,
Jon
_________________
Korg PA4x, HX3 (B3 Sim module), Korg PA3x, Korg i2, Korg i40m, Roland AX-7, Roland FC300.

Jonyblues · Posted: Wed Aug 31, 2016 5:59 am Post subject:

Chuck, as a follow up to my previous comments, I've just found (and pasted) below part of the email that I sent the girl who was having the sound reduction problems with her Bose unit.

"....In short, I've discovered that the channel one control knob is only a trim control (not a volume control), which means that the amp in the Bose is always set to 100%. Secondly, both channels have limiters built into them which will clip (cut out) the signal if they get overloaded (and that there is a light indicator which turns red on the channel when this happens). Thirdly, there are Bose signal processors built into channel 1 which are designed only for a mic signal (i.e. they can't properly process non pure mic sounds). Therefore, I'm pretty certain that one or more of these issues has been causing the problems.

Interestingly, the 1/4 inch balanced jack input on channel 2 can handle any type of signal as long as it is ONLY MONO (no stereo signals accepted) AND that the switch on channel 2 is set to 'Line' NOT 'M'. And FYI, there are limiters on that channel too."....

Hope this helps Chuck.
Best wishes,
Jon
_________________
Korg PA4x, HX3 (B3 Sim module), Korg PA3x, Korg i2, Korg i40m, Roland AX-7, Roland FC300.

BR · Posted: Wed Aug 31, 2016 6:03 am Post subject:

Hi Chuck,
I was in the same situation sometimes ago (see my reply on your other post: http://www.korgforums.com/forum/phpbb2/viewtopic.php?t=105857).
My problem was solved by using the TS cables (Unbalanced). I don't know if you tried with TS cables but anyway I just copy/paste my suggestion from your other post:

broker22 · Joined: 10 Aug 2015 Posts: 27

ORGANGRINDER · Posted: Thu Sep 01, 2016 11:14 am Post subject: volume drop

if you look at bose sheet it says using ts cable will result in a weaker signal
so that might be a cure for hitting the limiter. adding a mic on channel one
probably adds to the total signal level so maybe a ts instead of a trs jack
will do the trick. try it. nothing to lose

mel
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KORG PA 1000, KORG PA900. BOSE COMPACTS 2 BOSE S1 PROS 2 YAMAHA STAGEPAS 500, ROLAND VP7.

Chuck · Posted: Thu Sep 08, 2016 1:38 am Post subject:

Sorry I've not gotten back this sooner, I've been out of the loop so to speak.
Since the sound fluctuation started I've been doing a lot of quality control processing on both the Bose PA and the PA4X. I had another situation with the PA4 the other day. All of a sudden the on board harmonizer stopped working. So I disconnected everything and hooked up my trusty Digitech EX Workstation Vocal Harmonizer (12 years old). Everything seems to be working including the sound fluctuation issue has not reoccurred.
My experience with issues like this are vast and most of the the time it is something simple so I'm laying back for a while to see what happens next. FYI...I have a Korg PA900 bought new when they first came out. I've never had any sound flux or harmonizer issues with it. I REALLY APPRECIATE all of your notes and expertise. At this point I ready to take the PA4 to a repair shop for their diagnoses. More later. Chuck
_________________
PA4X & PA900
Bose L1 Model II w/ToneMatch
Neumann KBS 105 Mic
Old fingers