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BASSBOSS Questions

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Reply with quote  #1 
Hello,

I'm having a problem with my subs. I'm not really sure what's going on. A lot of time my tops will just produce most of the bass. The subs will produce the lower frequency but not the higher ones. Seems like the subs are missing some beats.

I noticed it on the songs "Single Ladies" by Beyoncé and "Cha Cha Slide" by Platinum Band.

Thanks,
JP
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Reply with quote  #2 
Hi JP,

You may have checked some of these things already so bear with me because this is a weird situation that I have not encountered before.

The first step is to eliminate any potential external sources of problems. This means eliminating all outboard signal processing from the signal path. It’s recommended that you run the signal directly from the source, whether an iPod or a DJ mixer, directly to the speakers. Digital boards with builtt-in processing or external analog or digital processing should be bypassed to eliminate them as potential causes of the problem. They are not necessary with BASSBOSS equipment.

With that done, the first thing to do on the subwoofers is make sure the crossover, EQ and delay settings are identical. Check the knobs first by turning them all the way to one direction and make sure the pointers are pointing the same way. Next turn the gain all the way down on one of the subs. Play something familiar, or a song that you've noticed an issue with before on one sub. Check the sound in various locations about the room to ensure it's not an effect in one particular spot. (Ideally this would be done outside but if both boxes are against the middle of a wall the reflections should be consistent.) Turn up the second box and note whether the overall sound improves or whether the particular note/frequency loses level.

If the note/frequency loses level when the second box is added, there is a problem with the DSP programming and something must have saved incorrectly or there is a problem with one of the pots (knobs) and it isn't reading the setting correctly.

If the sound is consistently improved when the second box is added, then there isn't a problem with the amp or the box. The problem may be with the placement in the room or it may be that the target frequency you're wanting is outside the operating range of the subwoofers. I did a spectrum analysis of the single ladies song and also ran it through a parametric EQ and I think the frequency of that kick is about 125Hz. The one in cha cha slide seemed to be about the same. You can try using a parametric filter with a narrow Q, boosting it 10dB then sweep the filter frequency until it really accentuates the beat you're looking for. That should tell you what frequency the beat is centered on, and from there you'll know whether the beat is in subwoofer territory or in woofer territory. If it's up above the subwoofers' range, the other subs may have been set to operate in a higher band and would have been louder in this range.

Another consideration is that the phase alignment of the tops to the subs is off in this mid-bass range.  Ideally, when the boxes are close to each other, their phase traces will overlap through the crossover region. If they don't, there will be a hole in the frequency response in the crossover region. The center frequency of the hole will shift about with placement but there will be a hole somewhere if the alignment isn't right. If the phase alignment is right when the boxes are physically aligned, there may be a ripple or a slight peak when their physical relationship is changed but not a bad hole until the tops are about 5' to 6' away from the subs. This is a more difficult thing for you to analyze but there is a relatively simple way to check it. Place a top on a sub.  Turn everything on but leave the gain of the sub all the way down. Play the reference track without the sub then add the sub. Does the referenced beat frequency get louder or softer when the sub is added? If it gets louder, things look good. If it gets softer, there may be an issue.

The procedure to go deeper than this little experiment would be to put the two speakers next to each other with a measurement mic in front of the pair so that the mic is the same distance from the fronts of both speakers. Both have to be powered on. Measure and capture the response and phase of one and then the other. Then measure the combined response of both. The summed response should be higher at all frequencies where they overlap. This will be the case if the separately measured phase traces overlay. If they don't, either a crossover filter or a delay setting needs to be adjusted until they do and the summed response is entirely positive. On the plus side, once you have the two aligned, you can compensate for physical offset with a tape measure and a delay setting. Unfortunately, until you know your starting point is correct, deriving a delay setting from physical offset is not guaranteed to result in a re-alignment.

Confirming the ideal filter and delay setting for every other top box on the market is an impossible task, and most of the time it isn't necessary because the majority of powered boxes use a DSP with similar latencies and similar filter types. This may not be the cause of your problem, either. I mention it mostly to be thorough and to give you the opportunity to evaluate the possibilities. If all the other possible causes are exhausted, checking this alignment may come into play.

Once it's determined whether you're having an equipment problem, a phase problem, a placement problem or an operational range problem, we will know what needs to be done to sort it out.

I look forward to hearing what you find.
David Lee
BASSBOSS Questions

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Reply with quote  #3 
Hi David,

I have tried all the tests except for the measurement. I have tracked down the culprit of all these. It was the Mono LCR channel of my X32 rack. I rerouted the signal to the left channel and viola, it got the full spectrum. Once again thank you for the support!

Regards,
JP
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