Filtered sound (no mid/high) and lower power output then back to normal (intermittently)

Portable PA
1

Hi all,

 

I hope you are all well. After weeks without having gigs due to covid we are fortunately going back on stage as we live in Andorra and the sanitary situation is under controlled by applying stricts basic rules for public places (hotels and campings).

 

So, we use a L1S with B2 and T1 for our two bands, trio and quartet. Very simple setups.

In the trio situation, to the T1, 1 SM58btea for lead voice, 1 keyboard mono, 1 drum pad mono, 1 extra SM58 mic for hand percussion, and bass preamp from XLR to the line input of the base.

In the quartet situation, to the T1, 2 lead voice (SM58beta&SM58), 1 SE X1S (with Phantom) for the  acustic drums, 1 keyboard mono and bass preamp from XLR to the line input of the base. The guitarist use his amp directly without going through the T1. In some demanding places, we use the output mono to chain 2 self amplified speakers in the front of the band.

 

We own the gear since 2014 and we dis an average of 120 gigs a year without any issue.

 

The issue has happened in the trio situation.

First gig after 3 months stop.

 

At sound check we felt that the sound was not as usual (we played a lot in this venue so have a good reference on how it should sound): lower in overall power output and like if we were under water, lack of mids and high frequency. I had to tweak the EQ to try getting back and had to level up the volume as sound was not spreading as usual around the venue.

 

During the live, after playing 3 or 4 songs, the sound went back to normal in the middle of a song, big smile on faces but had to apologize to the audience for the increase of power output and reload the usual config from the T1. We were joking that the Bose has quit out his mask... and we thought it was because the Bose has not been played for a while and we hopped that would have been a one time only.

 

No, no... yesterday we had 2 gigs one in the afternoon, and again same issue but this was intermittent, started with the issue during the sound check and getting to normal at this time also, very worried again. During the show issue came back and disappeared 2 or 3 times during the concert. 

At night, we had again the issue of low power and filtered output since the beginning but stays bad untill the end... never went back to the normal sound.

 

We are desperate as we have 3 shows this week, we hope that we could do something/anyhing to get rid fo the issue. It's anoying for the public, the overall quality of the show and the our moods...

 

I search the forum, the internet, I read the FAQ and didn't found any similar issue described and/or maintenance steps to chack and solve that problem.

 

Many thanks in advance for any thoughts on this.

2

Hi mmilian,

 

If the anomoly is affecting all sound that is routed through the L1, check the speaker array connectors in the Model 1s base and the speaker and the extension. Check the B2 cable, make sure both ends are twisted and locked in place, and all four wires are secure inside the plug.

 

You might also check the cable connecting the T1 to the base by substituting a different Cat 5 cable.

 

If the anomaly is only on some of the T1 channels focus on the connections related to those inputs.

 

Intermittent issues can be very difficult to isolate, especially if they are internal to the T1 or Model 1s base. Hopefully yours will be a cable or connection that is easily repaired or replaced.

 

O..

3

Thank you O. for your answer.

 

The sound was globally affected, not only one particular channel.

I could also say it has affected also the Bass signal from the line IN entry in the base.

 

So if the L1 has bi-amp one for the sub one for the array, it could be the amp of the array connection, right?

Bad connections form the base to the extension, or from extension to the array and depending on vibrations it connects or not?

 

Is it possible there is a physical security, we did notice that even with the foot wide open there is a small balance than could affect contacts. Note that two of the 3 last shows we where in perfect flat surfaces.

 

Today I'll go to the local dealer and hopefully he has the same model in stock and we could try to interchange elements if the problem is still there and point to what is the origin.

 

Have a nice day!

4

Hi mmilian,

 

There have been a few instances over the years where one of the plastic connectors in the base or in a speaker section or extension have broken, lost a wire, or perhaps been pushed out of place, resulting in intermittent / partial speaker response. Should that be the case, a careful visual inspection should show the defect. 

 

Loose conections or broken wire in the bass module connections usually result in intermittent silencing of the system not a partial loss of volume, but, worth checking anyway.

 

If the instrument connected to the analog input of the power base was affected in the same way as the mics and instruments connected by the mixer to the digital input, that suggests the problem is not in the mixer or its cat 5 cable.

 

O..

 

 

 

 

5

So, went to the local shop.

We mount everything.

Problem was NOT replicated.

Inspection on the columns connections, white connectors, was OK, but I have a concern on the one in the base, on contrary of his opposite or connectors for top element (array), the one in the base is moving.

We did inspect the NL4 cable and found loose cables opening the connectors. Cut them and screw them again. I don't know if that was the issue but definitely will be better.

 

This week from Thursday, 3 concerts, so we will get the result.

Thank you,

6

Hi mmilian,

 

The connector in the power stand base is designed to have just a little movement. As the speaker , or extension, is put in place the receptor in that section collects the white connector and guides it into place.

 

Hopefully the repaired NL4 connector has a positive impact on your sound and the intermittent dropouts will be a thing of the past.

 

Let us know how this weeks gigs go.

 

O..

7

first concert yesterday, in exterior with ground inclination... and NO issue.

That really seems good!

8

 

 

That's good news, I've got my fingers crossed, hoping you have solved the problem.

 

O..

9

Hi O.

Unfortunately, sad/bad news. The problem persists and we faced the same issue last Saturday night.

 

Less volume, no mids/highs resulting in less bright. We felt directly that is wrong during the sound check.

After 3 or 4 songs (same as previous concerts) the full frequency range is recovered along with an  increased volume.

 

Fortunately a friend of us has the same equipment and will let us use it and we will be able to test element by element and determine where the failure comes from. This way we will send and service to the Bose tech support only the relevant element. IMO, it's the base or the array (as the LINE Input is affected).

 

My guess is a bad contact in the array of speakers, leading on some speakers not outputing some frequencies and this could change the impedance, and affect power driven from the amp, right?

 

Or, an electronic component (crossover) that react on temperature after a while?

 

10

Hi mmilian,

 

Well, as you have discovered intermittent problems can be difficult to diagnose.

 

There are any number of places in the signal chain where a component failure could cause a temporary loss of output, and I wouldn't want to start guessing now.

 

Question. Have the loss of output anomalies all been in the same venue? Compromised or overloaded electrical circuit might cause  a problem.

 

If possible set up with the friends equipment at home instead of waiting for a gig. 

 

I know it is frustrating to not be able to trust your equipment and I hope you identify the problem and  are able to make corrections or repairs very soon.

 

O..