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

abdo123

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are you talking about the Schroederfrequency?

mine is around 203Hz acordig to https://amcoustics.com/tools/amroc?l=408&w=293&h=243&r60=0.3

anyways

is around 800-1000Hz afaik

you're crossing your subwoofers way too high, I feel like I'm repeating myself for the tenth time but i will go ahead and repeat for the 11th.

above shroeder's sound becomes stochastic/chaotic and a measurement at one point in time/space is no longer representative of what you actually hear. if you move 1 cm up the phase will be different and the response will be different. same thing with time, every measurement becomes distinct and different from each other.

we use 'smoothing' to estimate the overall sound energy but that's not really reflective of the actual listening experience.

you have to integrate your subwoofer in the region where sound is 1+1=2. not in the region where watermelon juice is a sexy spaghetti meatballs.
 

dasdoing

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you're crossing your subwoofers way too high, I feel like I'm repeating myself for the tenth time but i will go ahead and repeat for the 11th.

above shroeder's sound becomes stochastic/chaotic and a measurement at one point in time/space is no longer representative of what you actually hear. if you move 1 cm up the phase will be different and the response will be different. same thing with time, every measurement becomes distinct and different from each other.

we use 'smoothing' to estimate the overall sound energy but that's not really reflective of the actual listening experience.

you have to integrate your subwoofer in the region where sound is 1+1=2. not in the region where watermelon juice is a sexy spaghetti meatballs.

I apretiate your help, but for now I will respectfully continue with the setup I am enjoying.
If one day I identify those artifacts I'll let you know.
have a nice weekend
 
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Spkrdctr

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I have no idea why you would cross over a sub at 200hz. You are asking for all kinds of trouble. Get it down to 80 to 100hz and it should clean right up. 160hz and my sub sounds terrible. at 80 to100hz it is fantastic. Once properly set up it is awesome.
 

dasdoing

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FeddyLost

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the topic is still waiting for a rational explaination of this kind of claim
This topic have mixed up two VERY different things:
1) dedicated subwoofer driver with TS parameters suitable for good LF performance in proper enclosure with linear input (i.e. Scan-Speak 32W/4878T00)
Most probably such driver will be not performing good even in midbass range, don't mention midrange itself.
2) subwoofer as (commercially available) active speaker with good LF performance.
Currently there are more possibilities to make one from driver with "wrong" TS parameters and (digital) correction at resonance frequency and below. If one have enough displacement and power, there's no downsides for end user.
For example, builder can take good powerful PA woofer and apply heavy correction below "natural" roll-off in sealed box. Such unit might play even some mids well until we push it under real stress.
 

sigbergaudio

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The most obvious differences are driver mass (much heavier in subwoofer drivers), and the different type of suspension used to provide the high xmax required at low frequencies. The design of the subwoofer drivers compared to drivers not designed for the lowest frequencies are simply different.

Consider most PA woofers, they have massive spl capacity, and can often play relatively high frequencies despite being 12 or even 15". But they don't have a suspension supporting very high xmax, and not very low fs.

A long throw, high mass subwoofer driver is not designed to perform well at higher frequencies.
 

headshake

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I have no idea why you would cross over a sub at 200hz.
I cross around 320 with a 10" sub to a 3" mid. The mid does not play low enough and I wanted a 1/4WL of the XO spacing for the mid and woofer.
You have chosen a good example with the Seas L26ROY.
This is available in two versions, the old, discontinued version (D1001-04 L26ROY) and the current one (XM004-04 L26RO4Y).

Would I use the current version in the frequency range above 150Hz?
Rather not, because the frequency response shows that the driver probably can't follow signals above 100Hz any longer correctly, the manufacturer's measurement shows a falling frequency response in half-space:
View attachment 143100
This is an indication that the magnet (and cone) is not strong enough to accelerate the high membrane mass accordingly.
Eigenmodes and break-up resonances then occur at higher frequencies.

The discontinued version showed a completely different frequency response and was more suitable for reproducing frequencies above 100 Hz:
View attachment 143101

In the new version the moving mass is 160g, in the discontinued version only 107g.
In the new version, magnet strength and diaphragm stiffness and high voice coil inductance (compare the blue arrows at the impedance curves) no longer seem sufficient for "correct" frequency reproduction above 100Hz.
So if a sub shows a loss of power at 100hz it is incorrect? Why can't EQ make it correct?

https://audioxpress.com/article/test-bench-the-l26roy-10-subwoofer-from-seas
From the article on the l26roy:
Given the location of the break-up mode at 3.6 kHz, an upper crossover frequency would likely be around 1.5 kHz or so, making this driver a good candidate for a three-way design.
That's higher than anyone here has suggested and his job is to review drivers.
 
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dasdoing

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what we need in this topic is someone making LP(!) meassurements of the same system crossed at 80Hz and 160Hz-ish.
only than the question can be realy answered.
and don't tell me the issue can't be meassured. if it is not in the FR, it is in the time domain...probably strong ringing caused by corner placement
 

sigbergaudio

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what we need in this topic is someone making LP(!) meassurements of the same system crossed at 80Hz and 160Hz-ish.
only than the question can be realy answered.
and don't tell me the issue can't be meassured. if it is not in the FR, it is in the time domain...probably strong ringing caused by corner placement

Many subwoofer drivers can play just fine to at least 200hz, including the mentioned scan-speak drivers, but wouldn't use them way higher than that. Some drivers fall apart above 100hz, and that will as you say probably be measurable.

We've measured up to 300hz with no measurable issue with the Scan-speak drivers we use in our subwoofers.
 

abdo123

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I cross around 320 with a 10" sub to a 3" mid. The mid does not play low enough and I wanted a 1/4WL of the XO spacing for the mid and woofer.

Are the speaker and subwoofer on-top of each other? or are they in different locations in the room?

it would be a really strange experience otherwise I think.
 

Vladimir Filevski

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my ears can't confirm the not localizable bass theory. I throw 30Hz at my sub and I clearly hear it form it's direction.
does the theory realy work for you guy in the real world test? Do you guys hear the soundwave emerging form all sides or something like that?
Your ears will happily confirm the non-localization of the sub with 30 Hz sinusoidal signal, if you can build strong enough subwoofer enclosure without parasitic resonances.

I also tested my setup steep-crossed at 200Hz for stuff like male voice. without the mains I can obviously hear it coming from the sub,
And that is exactly why the crossover frequency must be lower than 100 Hz.

If that theory was true, you could throw in a 30Hz in the living room, and if you hear it at the other side of the house you would think the source is there. it makes no sense.
Yes, I can not tell where it comes from - it make sense to me and to several millions other audiophiles.

the topic is still waiting for a rational explaination of this kind of claim
Besides several others, I also gave rational explanation (post #60), maybe you skip it.

I apretiate your help, but for now I will respectfully continue with the setup I am enjoying.
Positioning sub exactly between mains (as you do) is a good solution for very high (200 Hz) crossover frequency. Several manufacturers of sets of sub crossing at 150-200 Hz to two very small satellites also recommends this positioning.
 

Vladimir Filevski

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I cross around 320 with a 10" sub to a 3" mid. The mid does not play low enough and I wanted a 1/4WL of the XO spacing for the mid and woofer.
With such a small mid driver, 320 Hz is OK, if the 10" sub has cone break-up high enough in frequency.
I don't understand why it should be 1/4 wavelength spacing?

https://audioxpress.com/article/test-bench-the-l26roy-10-subwoofer-from-seas
From the article on the l26roy:
"Given the location of the break-up mode at 3.6 kHz, an upper crossover frequency would likely be around 1.5 kHz or so, making this driver a good candidate for a three-way design. "
That's higher than anyone here has suggested and his job is to review drivers.
That driver (XM001-04 L26ROY) has brake-up at 3.6 kHz, which is very, very high for a subwoofer driver - it resembles conventional midbass. The driver from post #1 (XM004-04 L26RO4Y) is completely different beast - just see the nightmare break-up at 800 and 900 Hz. It is much easier to tame the cone break-up at 3.600 Hz than at 800-900 Hz (with RLC trap). Also it would be much, much cheaper.
So yes, the XM001-04 L26ROY is good candidate for a three-way loudspeaker, not just for a subwoofer. Also note that "upper crossover frequency" is just that - upper limit. I would choose crossover frequency anywhere from 300 Hz to 800 Hz.
 
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EJ3

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The specs on the actual speakers in my subs say that the FR is 20-80 HZ. I wouldn't even think about crossing them over above 80 Hz. (2 subs both down firing), one under each speaker.
 
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Honken

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what we need in this topic is someone making LP(!) meassurements of the same system crossed at 80Hz and 160Hz-ish.
only than the question can be realy answered.
and don't tell me the issue can't be meassured. if it is not in the FR, it is in the time domain...probably strong ringing caused by corner placement
Well, I figured that I may just as well make some adjustments to my positioning that I have had in mind for a while when I was playing around with the subwoofers anyway. As a result I now cross at 120Hz instead of 160. The spekers are above the subwoofers.

I can't really tell where pure tones come from with both subs running, I can sort of make it out at 160 with only one sub though. Not sure if this was unexpected or not.

And as per your request, here are some very quick and dirty measurements at my LP of LR8 crossovers at various points. No room EQ added and there was quite a bit of background nice when I was running the sweeps, so thankfully it does look better in actuality. The filters were created with rePhase with 4096 taps (to keep the delay in check for REW).
 

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  • 120Hz.zip
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  • 200Hz.zip
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EJ3

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I forgot to mention about my speakers (with their internal crossover) that the close-miked woofer (and port) response was also considerably flatter than measured from most speakers, with a very small bass -resonance peak. At the system resonance of 60 Hz, the output is only about 2 dB above its average level in the upper part of the woofer's range, and even that minor output variation was spread over almost two octaves. When the bass curve was spliced to the room-response measurement, the resulting composite frequency response was flat within about ± 2 dB from 26 to 20,000 Hz. The horizontal directivity of the tweeter was only discernible in the room measurement above 10,000 Hz.
That also has a lot to do with choosing 80 Hz as the crossover point.
 

ctrl

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So if a sub shows a loss of power at 100hz it is incorrect? Why can't EQ make it correct?
https://audioxpress.com/article/test-bench-the-l26roy-10-subwoofer-from-seas
From the article on the l26roy:
That's higher than anyone here has suggested and his job is to review drivers.

If the driver can no longer follow the frequency signal due to its drive and the mass of the cone, then it should not be used with EQ for higher frequencies, as usually the decay behavior is no longer optimal.

The old version of the L26ROY (D1001-04) is definitely capable of handling the midrange. This was also said so:
There is a magazine review of the old version, which shows that use up to 1kHz is possible without problems (low harmonic distortion, good decay).

The new version of the L26ROY (XM001-04) has a higher moving mass with the same drive. Therefore, this version is no longer quite as suitable, which the manufacturer's frequency response measurement also shows. One would have to look at the decay below 1kHz in detail, which cannot be judged properly in the review of audioXpress.

Not at all suitable for the midrange, are the two versions with the 4-layer voice coil of the L26RO4Y (old and current version), these are pure subwoofers.
I had mixed that up a bit in Post#23 - there are a total of four versions of the L26 :eek:
 

dasdoing

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Well, I figured that I may just as well make some adjustments to my positioning that I have had in mind for a while when I was playing around with the subwoofers anyway. As a result I now cross at 120Hz instead of 160. The spekers are above the subwoofers.

I can't really tell where pure tones come from with both subs running, I can sort of make it out at 160 with only one sub though. Not sure if this was unexpected or not.

And as per your request, here are some very quick and dirty measurements at my LP of LR8 crossovers at various points. No room EQ added and there was quite a bit of background nice when I was running the sweeps, so thankfully it does look better in actuality. The filters were created with rePhase with 4096 taps (to keep the delay in check for REW).

sorry for late reply.
you didn't talk about how it sounds. you heard what was described when crossing at 200Hz?

your meassurements show the same that I see; crossing at 200Hz makes the time domain better:

80
a.jpg


200
b.jpg



group delay also looks better.

with that beeing said, I suspect that described phenomenon actualy happens above 200Hz.
you probably get into the resonance range of a cube shaped box
 

fineMen

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Don't want to interferre with Your discussion. Anyway, this might be of interest:


I wonder if the subjective impressions are backed up by measurements. I would even argue that without individual measurements the less satisfying outcome was to be expected. You may get away with adding a sub without, but not so when the x-over goes up to the lower mids. No mysteries here.
 

Tangband

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One has to remember that a subwoofer location often is at the floor. Thats the main reason you can not do crossover higher than 100 Hz . One has to see the whole loudspeaker as one, playing all frequencies at the same time with real instruments .
A cello has a register going from bass , midrange to treble.
Its sound is not located in the bass area.

A crossover at 500 Hz where a wavelength is 68 cm makes the sound bad if there is to much space between the subwoofer - main speakers.

Crossing at 100 Hz where the wavelength is 3,4 meters is much easier with long distances from subwoofer - mains.

If you put a 12 inch subwoofer close to the midrange in a three way loudspeaker, its much easier to crossover higher in frequency , and still get good sound.

Forget about crossing a freestanding subwoofer higher than 100 Hz, for the reasons above.
 

bigjacko

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If the driver can no longer follow the frequency signal due to its drive and the mass of the cone, then it should not be used with EQ for higher frequencies, as usually the decay behavior is no longer optimal.
Can I ask what things make decay behavior not optimal? I also want to ask if Qtc is higher than 0.707 does speaker ring at for longer at that frequency?
Not at all suitable for the midrange, are the two versions with the 4-layer voice coil of the L26RO4Y (old and current version), these are pure subwoofers.
Can you elaborate on why the 4 layer versions can only be used as subwoofer? Thank you very much.
 
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