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Behringer B2031A Measurement (broken sample?)

amirm

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Hey you all. Just finished measuring the Behringer B2031A. This is the spin:

Behringer B2031A frequency response broken sample.png


Even in-room measurements without NFS scan showed the same massive trough. Before I contact them, is there some config option that could cause this? I left all the filters at 0 (as shipped).

Near-field tweeter response shows the cause:
Behringer B2031A Tweeter frequency response broken sample.png


What is going on?
 

dfuller

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Looks like you got a defective unit, probably a bad op-amp in the crossover for the tweeter.
 

Ingenieur

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Where is the 'mute high' switch set?
Disables tweeter for service
A7764422-E0E6-4847-825B-0B8A3F698885.jpeg
 

Thomas_A

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Odd. Have no idea what could be wrong. Bad IC, broken solder joint?
 

Rick Sykora

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Looks a lot like an inverse null, but not exactly at the crossover frequency.

But if you can reverse polarity on the tweeter and remeasure, should be useful data. :)
 
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amirm

amirm

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Where is the 'mute high' switch set?
Disables tweeter for service
It is in off setting as shipped. I guess I could toggle it and see if makes a difference but the tweeter is definitely spitting out signal. Just rolling off at the low end too much.
 

Ingenieur

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It is in off setting as shipped. I guess I could toggle it and see if makes a difference but the tweeter is definitely spitting out signal. Just rolling off at the low end too much.
The crossover is at 2000 Hz
Defective likely


D3E98A59-074D-4F9E-A9F6-95732B8ED1DA.jpeg
 

Rick Sykora

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Probably not it. It’s much to broad and nearfield should then show somewhat normal response.

The nearfield may not be all that out of line, but agree the spin is dropping off way more in comparison.

I forgot the same crossover (or lack thereof) is in place in both cases.

EDIT: still can have a null occur when drivers are out of phase in far field that will not be prominent in nearfield
 
Last edited:

Rick Sykora

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Hey you all. Just finished measuring the Behringer B2031A. This is the spin:

View attachment 192457

Even in-room measurements without NFS scan showed the same massive trough. Before I contact them, is there some config option that could cause this? I left all the filters at 0 (as shipped).

Near-field tweeter response shows the cause:
View attachment 192459

What is going on?

Spent a good part of my day getting kinks out of my new test rig…

Have you put a known good speaker in place? As much as it seems unlikely, the gross difference between near and far measurements could mean test setup is messed.
 

LTig

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Looks like you got a defective unit, probably a bad op-amp in the crossover for the tweeter.
I'd rather say a wrong component (C or R) in the high pass filter of the tweeter (if the crossover is analog), leading to a much too high corner frequeny.
 
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amirm

amirm

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Have you put a known good speaker in place?
I had just measured the Focal using identical setup. So I am pretty sure it is the speaker.

Used the back switches to disable woofer. Tweeter barely plays the highs -- just like what the measurements show. Woofer is fine.
 

Ingenieur

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If you are set-up just for the heck of try a run with mute high on.
 

RobL

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Dang it…was looking forward to this one!
 
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amirm

amirm

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If you are set-up just for the heck of try a run with mute high on.
I tried it. Muting shuts it off completely. Leaving it on only pays the highest frequencies.
 

Rick Sykora

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I had just measured the Focal using identical setup. So I am pretty sure it is the speaker.

Used the back switches to disable woofer. Tweeter barely plays the highs -- just like what the measurements show. Woofer is fine.

Am leaning more towards a bad tweeter…
 
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