• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

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

FeddyLost

Addicted to Fun and Learning
Joined
May 24, 2020
Messages
752
Likes
542
What in the specs or measurements tell you to not use this driver at, say, 500hz?
I have no science confirmation for following statement, but afaik diy community looks at combination of Mms and BL (force factor).
They define "speed" of driver or maximum acceleration possible.
So, if you add more powerful magnet for this voice coil and diaphragm, you'll rise BL and will have faster woofer. Most probably new magnet system will alter TS parameters and make it NOT subwoofer anymore.
 

ctrl

Major Contributor
Forum Donor
Joined
Jan 24, 2020
Messages
1,616
Likes
6,086
Location
.de, DE, DEU
What in the specs or measurements tell you to not use this driver at, say, 500hz?
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:
1627036605081.png

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:
1627036625365.png


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.
 

ppataki

Major Contributor
Joined
Aug 7, 2019
Messages
1,216
Likes
1,356
Location
Budapest
Those are two different measurements
That one is listening position with crossover and Dirac, this one is at 1cm, with no filters or processing showing the response of the sub alone
 

dasdoing

Major Contributor
Joined
May 20, 2020
Messages
4,209
Likes
2,674
Location
Salvador-Bahia-Brasil
Those are two different measurements
That one is listening position with crossover and Dirac, this one is at 1cm, with no filters or processing showing the response of the sub alone

ok, a LP meassurement for the subs would be more usefull in order to answer the topic
 

ernestcarl

Major Contributor
Joined
Sep 4, 2019
Messages
3,106
Likes
2,313
Location
Canada
Those are two different measurements
That one is listening position with crossover and Dirac, this one is at 1cm, with no filters or processing showing the response of the sub alone

I agree with @dasdoing that we need to look at the response at the listening position itself -- the mid and higher frequencies from those subs may be more uneven and erratic than what the nearfield measurements would lead one to believe.
 

fieldcar

Addicted to Fun and Learning
Joined
Sep 27, 2019
Messages
821
Likes
1,258
Location
Milwaukee, Wisconsin, USA
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.
Ah. so OP was correct with the model number of L26RO4Y. Man, it does look like it starts to break up around 800Hz unlike the L26ROY. The only question I have is that, if you've got a good FR, and crossover before all of the peaks and dips, wouldn't it still be competent as a mid-bass driver? I guess this is where a graph showing 1-3rd order harmonics would be helpful.
 

ctrl

Major Contributor
Forum Donor
Joined
Jan 24, 2020
Messages
1,616
Likes
6,086
Location
.de, DE, DEU
I have is that, if you've got a good FR, and crossover before all of the peaks and dips, wouldn't it still be competent as a mid-bass driver? I guess this is where a graph showing 1-3rd order harmonics would be helpful.
You have already answered the question yourself.
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).

With the new version I would not recommend a use up to 1kHz, because all signs (FR downward slope, high voice coil inductance, 800Hz resonance) point to significantly worse measurements.
 

Tom C

Major Contributor
Joined
Jun 16, 2019
Messages
1,501
Likes
1,370
Location
Wisconsin, USA
What about cone breakup? Above a certain frequency, the diaphragm of any driver will stop behaving pistonically, right? Isn’t that a real physical limitation that has to be accounted for in any speaker, cabinet and crossover design?
 

FeddyLost

Addicted to Fun and Learning
Joined
May 24, 2020
Messages
752
Likes
542
What about cone breakup?
If we talk about properly designed subwoofer driver, we assume it very stiff and working pistonically.
Otherwise it will not withstand pressure rise inside the cabinet and will bend at required spl and frequency.
It might not be 100% correct for all subwoofers, but for dedicated subwoofer driver from reputable company it shall be applicable, i think.
 

Tangband

Major Contributor
Joined
Sep 3, 2019
Messages
2,994
Likes
2,789
Location
Sweden
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.
 
Last edited:

aarons915

Addicted to Fun and Learning
Forum Donor
Joined
Oct 20, 2019
Messages
685
Likes
1,140
Location
Chicago, IL
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?

Good discussion. Using the LS50 for a few years I have a need for higher crossovers so I have experimented quite a bit and have looked up research on subwoofer localization. The research I've found has shown 120Hz being about the highest crossover frequency that no one can localize but many people couldn't localize the subs up to 150Hz and having multiple subs helps as well. In my experience, the setup is critical and you have to measure the response each time you analyze a higher crossover point. My sub tends to have a rising response after 100hz so it will sound as you describe if I don't EQ anything and use a higher crossover.

When I ensure a flat response, I've gone up to 200Hz just to test it out and I was surprised that there still wasn't much localization happening. The bigger issue with higher crossover points to me is when the vocals start coming through the sub it just doesn't sound natural. Vocals more than anything should be coming from a point source in my opinion, that's why I think 2 way speakers in general sound more natural than 3 ways. I think 120Hz is a high enough crossover to allow most speakers to play loud with low distortion and shouldn't have any localization issues or vocals coming from the sub. Since most receivers use a 2nd order high pass and 4th order low pass even a 120Hz crossover should effectively be lower in your room, mine is closer to 100hz acoustically. A 150Hz 2nd order high pass and 4th order low pass should still acoustically be close to 120Hz and should still be safe from localization but I don't think I'd go higher than that.
 

Chromatischism

Major Contributor
Forum Donor
Joined
Jun 5, 2020
Messages
4,767
Likes
3,703
While slightly off-topic to why subs themselves tend to sound bad above the midbass range, yet related:

For years I've had issues crossing higher than 80 Hz unless I added extra filtering to the sub side. After reading the research, it turns out it wasn't just me.

I summarized that research here. It is mostly about localizability of bass frequencies in rooms, but it also talks about crossover points.

https://www.avsforum.com/threads/localizability-of-bass-frequencies-in-rooms.3205312/
 
Last edited:
Top Bottom