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What measurements/parameters tell you to NOT use a subwoofer for mid range frequencies?

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#1
I tried crossing several subwoofers "too high" and they all sounded very bad.
However I cannot see anything in the measurements or specs that suggests so, the FR looks flat but it still sounds terrible. it's not just beaming, it sounds "boomy" and "slow" and "muddy" in every direction.
e.g. this Seas L26RO4AY has usable FR up to 800hz per the manufacturer, and is even recommended up to 1Khz. yet it sounds really bad starting as low as 200hz.
I had the similar impression with peerless XLS12 and Dayton UM15, and saw similar impressions by other builders.
What in the specs or measurements tell you to not use this driver at, say, 500hz?
 

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escape2

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#2
use a subwoofer for mid range frequencies
Maybe I'm taking your question too literally, but why would you use a subwoofer for mid range frequencies???

As the name implies, subwoofer is best suited to handle sub bass. Ideally, you would not want it to play higher than about 80-100 Hz and let your main speakers handle the rest.
 
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fieldcar

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#4
"boomy" and "slow" and "muddy" in every direction.
Oddly enough, it looks competent when used as a woofer, so my guess is that you've got room modes or port resonance if it's ported. If you're into DIY, you may want to get a measurement mic and play around with Room EQ Wizard with the speaker outdoors, then bring it back inside to try and find if your room is the culprit. You'll see large peaks for room modes and resonance*. (EDIT: I meant Cabinet resonance.)

https://audioxpress.com/article/test-bench-the-l26roy-10-subwoofer-from-seas

1626896527740.png
 
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OP
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Thread Starter #5
you seem to be referencing the driver and not the actual subwoofer?

Anyway above ~120Hz or so it becomes increasingly difficult to maintain phase coherence between a subwoofer and a speaker, which is 'measurable'.
1. In this example I am referencing the driver, I have it in a dipole W enclosure. I got similar results with sealed subs.
2. What data shows the phase coherence problem? (other than building and measuring the complete speaker)
 

abdo123

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#6
2. What data shows the phase coherence problem? (other than building and measuring the complete speaker)
I'm talking here about two drivers in different enclosures in different locations in the room.

the 'Phase' tab in REW should show the phase of any measured driver.
 

Chromatischism

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#7
I tried crossing several subwoofers "too high" and they all sounded very bad.
However I cannot see anything in the measurements or specs that suggests so, the FR looks flat but it still sounds terrible. it's not just beaming, it sounds "boomy" and "slow" and "muddy" in every direction.
e.g. this Seas L26RO4AY has usable FR up to 800hz per the manufacturer, and is even recommended up to 1Khz. yet it sounds really bad starting as low as 200hz.
I had the similar impression with peerless XLS12 and Dayton UM15, and saw similar impressions by other builders.
What in the specs or measurements tell you to not use this driver at, say, 500hz?
I am not sure about specs, other than a large driver will be very beamy with midrange frequencies.
 
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Thread Starter #8
Oddly enough, it looks competent when used as a woofer, so my guess is that you've got room modes or port resonance if it's ported.
It's currently in a dipole W enclosure, and I reproduced the same problem with sealed 12" subs. However when playing the same frequencies (40-300hz) from a 8" woofer driver (dipole, in the same room and using the same amp) it sounds good.

Are you saying the L26RO4Y is really usable up to 800hz?
 

fieldcar

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#9
It's currently in a dipole W enclosure, and I reproduced the same problem with sealed 12" subs. However when playing the same frequencies (40-300hz) from a 8" woofer driver (dipole, in the same room and using the same amp) it sounds good.
dipole-W Like this? (see speaker pic)
I know very little about these open baffle designs. I assume that you could have out of phase sounds reflecting off your wall causing issues with mid to high frequencies.
If you have the same problem with sealed subs, it's very likely the room that needs better sub placement or bass traps.

1626899615853.png

Are you saying the L26RO4Y is really usable up to 800hz?
I'm sure you mean the L26ROY. From what I see in that article I posted, this speaker should work very well up to 800Hz.
1626898971849.png

It's not really surprising. My JBL 590's use the top 8" woofer as the midrange with great results, and it goes down to ~35Hz. The real challenge may be amplification and crossover. Again, if the problem is the room, this woofer's linearity wont save you. I think it's worthwhile to research how to fix your room modes if that's the issue. I hope that helps.

Good article.
https://www.audioholics.com/room-acoustics/bass-traps-not-just-for-fisherman
 

ppataki

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#10
I tried crossing several subwoofers "too high" and they all sounded very bad.
However I cannot see anything in the measurements or specs that suggests so, the FR looks flat but it still sounds terrible. it's not just beaming, it sounds "boomy" and "slow" and "muddy" in every direction.
e.g. this Seas L26RO4AY has usable FR up to 800hz per the manufacturer, and is even recommended up to 1Khz. yet it sounds really bad starting as low as 200hz.
I had the similar impression with peerless XLS12 and Dayton UM15, and saw similar impressions by other builders.
What in the specs or measurements tell you to not use this driver at, say, 500hz?
I have the same experience. I have a pair of Dayton Audio Reference HF 12" subs and I cannot use them above 100Hz, they just sound horrible
I was also unable to find any indication of that in my REW measurements...
Frequency response, phase, etc. all look fine...
 

headshake

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#11
How do you know it is not the eclosure?

Ever measure the decay/waterfall?

How did you come up with where to cross and what slopes?

I rock the l26roy... flab and boom are not something I would say about it. I use a PE sub box. They have 1.5" thick fronts and 1" walls with lots of bracing.

Good luck finding the issue(s).
 

ppataki

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#12
Here are my measurements of the Dayton Reference 12" from 1cm (no filters or correction applied)

Frequency response with Phase and Excess Phase

1626935555638.png


There shall be no issues till 1kHz at least

Group Delay and Excess Group Delay

1626935650341.png


I see no issues

Step response

1626935703139.png


Impulse response

1626935812092.png



Waterfall

1626935974347.png


As mentioned above it sounds horrible above 100-150Hz, which is not a problem for me since I cross them at 80Hz 24dB/octave anyway but still it is strange. Probably they shall be used as their name suggests: for the sub domain
 
OP
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Thread Starter #13
There shall be no issues till 1kHz at least

[...]

As mentioned above it sounds horrible above 100-150Hz, which is not a problem for me since I cross them at 80Hz 24dB/octave anyway but still it is strange. Probably they shall be used as their name suggests: for the sub domain
Isn't that a major flaw in the way we do audio science? so many measurements and we still miss such a fundamental trait ("sounds horrible").
 

amirm

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#14
Isn't that a major flaw in the way we do audio science?
I hope you are not including me in that. :) I have not tried to tackle subs yet and am not generally happy with the science behind their measurements.
 

Blumlein 88

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#16

YSC

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#17
I am no expert in interpreting any of these graphs, but what I can guess can be:

1) beaming at mid frequency with large drivers
2) port/cabinet resonanaces
3) phase as your sub won't be placed at same spot as the main speaker
4) localization, AFAIK above something like 100-120hz you can start identifying where the sound comes from, so I imagine your brain would tell you "hey something is wrong here" and make that awful sense of something wrong
 

fieldcar

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#18
I hope you are not including me in that. :) I have not tried to tackle subs yet and am not generally happy with the science behind their measurements.
So what's your take on this subwoofer that measures linear, but can't pull double duty and act like a mid-bass driver? I assume it's part of how a subwoofer would be reaching x-max at high volumes, and that would result in decapitated full range performance.
 
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