So ...... if the manufacturer stretched the truth a little and stated fs about 10 Hz below the real value, how would you simulation change?
MJK said:
I think Martin has a point. I have also experienced Fs differences. Some are very significant, enough that you can feel it by hand.
There are no major changes setting the Fr to 120 or 130Hz but a little less SPL and a 5Hz higher fall-of. Even making the Qts higher (0.7 instead of 0.59) doesn't make a huge difference.
I suspect room interactions to modify the FR but these differences seem quite big
I have broken in this speaker for 8 hours now so I'm still searching for the cause of this difference.
Concerning your Fe164 MLTQWT, do you REALLY obtain this amazingly low 35Hz, and a so similar FR compared to the simulation ?
I suspect room interactions to modify the FR but these differences seem quite big
I have broken in this speaker for 8 hours now so I'm still searching for the cause of this difference.
Concerning your Fe164 MLTQWT, do you REALLY obtain this amazingly low 35Hz, and a so similar FR compared to the simulation ?
It looks like you are using pink noise. Is there any particular reason? Are you doing far field measurements or near field?
Yes, I use pink noise in order to have a flat FR signal.
The measurements are made at 1.2 meters (aprox.) from the speakers.
I use the "average" function to cumulate measurements during ~ 1 minute so I'm sure I get the true FR.
I've run my speaker quite loud this afternoon for 3 hours in my main room to have more acoustic space and made measurements again. The measurements show an improvement in the bass response although it's still under the expected level. Maybe I should run the driver longer and longer to get more bass and then the FR will just suffer of baffle step diffraction.
The measurements are made at 1.2 meters (aprox.) from the speakers.
I use the "average" function to cumulate measurements during ~ 1 minute so I'm sure I get the true FR.
I've run my speaker quite loud this afternoon for 3 hours in my main room to have more acoustic space and made measurements again. The measurements show an improvement in the bass response although it's still under the expected level. Maybe I should run the driver longer and longer to get more bass and then the FR will just suffer of baffle step diffraction.
Attachments
The comparison between the simulation and the measurements were done in the near field and shown in the ML TQWT article. I have described how I did the measurements and how I post-processed the results. The correlation was very good as can be seen in the plots.
In the baffle step correction article, the measurements were done at 1 m in my large basement. Again, I tried to describe how the measurements were performed and the LAUD settings are included in the screen capture. The FE-164 driver in the ML TQWT enclosure with a BSC circuit produced a reasonably flat response to about 40 Hz where it rolled off at 24 dB/octave.
The deep base can be clearly heard when listening to them upstairs in my audio room. The bass is not chest thumping like a large 15" sub but the low end is definitely present down to 40 Hz. The 6 1/2" driver in the ML TQWT can only move so much air. My 8" full range drivers do a better job at the very bottom but are still not like a dedicated woofer.
Is there something in the plots that troubles you? Those plots are screen captures and I tried to include raw data and also the octave smoothed data.
I was thinking about your results and have some questions.
Have you tried to change the scales on your two measurements so they are the same and lay one over the other?
Do they have the same low frequency roll-off?
What is the low frequency content of your source signal?
Does the signal go low enough to give you meaningful low bass measurements?
One nice thing LAUD that does is divid the response by the input to give a normalized SPL result. If your input signal is not completely flat down to say 20 Hz, then the absolute SPL response at a given frequency will be determined by the magnitude of the input signal and not by how linear your speaker behaves.
Have you tried to change the scales on your two measurements so they are the same and lay one over the other?
Do they have the same low frequency roll-off?
What is the low frequency content of your source signal?
Does the signal go low enough to give you meaningful low bass measurements?
One nice thing LAUD that does is divid the response by the input to give a normalized SPL result. If your input signal is not completely flat down to say 20 Hz, then the absolute SPL response at a given frequency will be determined by the magnitude of the input signal and not by how linear your speaker behaves.
youyoung21147 said:
I wonder whether it's possible to get good data if you are not in a really large room. Even with MLS signal it's necessary to have a 5M+ by 4M+ to get good data down to 200Hz you probably need 100 times the area to go down to 20Hz. Most people do outdoor testing.
I agree. But what is funny about the measurements is the lack of bass. What I have found is that the very bottom end is over predicted by room effects and backgound noise not under predicted. Any noise, like a furnace running inside or an airplane in the distance outside, causes a huge amount of low frequency problems in my measurements. If you look at my curves they start to roll off at 40 Hz and decrease at 24 dB/octave. But not far below the knee the curves get all messed up by low frequency outside noise. Since his curves were rolling off so high I am beginning to wonder if the source is filtered so as not to send huge amounts of deep bass that would ruin a speaker under test.
MJK said:
One other thing is that the W3 is a 3 inch driver, I don't think you will get much low end out of that.
Also, since pink noise is used, pink noise is a weighted noise spectrum, I'm not used to doing it that way, but I gave it a try and got high roll-off in frequency response.
I made the measurements in the widest room of my house : it's 4m*10 and the ceiling is made of two parts : one under the 1st floor and the 2d under the roof so there are not so many parallel surfaces. It makes a good auditorium anyway 🙂
I choosed RTA3 because the pink noise it delivers is perfectly linear from 5 to 44000Hz. Anyway, it detects well my subwoofer low frequencies.
On the measurements, the very low part is a bit stronger, there was probably something generating ultralow frequencies, like a plane or simply the fan of the computer ?
Moreover, the measurements cannot be wrong as my hears really feel there is not enough bass !
I tried a simulation with the TQWT of a friend that I measured with the same mic and the same soft and there is a good results correlation so your mathcad sheets seem to work great.
I should break in the speaker a little more, though it'll be difficult with my parents who only listen to classical music. It's the only way to know why the results are not similar.
I choosed RTA3 because the pink noise it delivers is perfectly linear from 5 to 44000Hz. Anyway, it detects well my subwoofer low frequencies.
On the measurements, the very low part is a bit stronger, there was probably something generating ultralow frequencies, like a plane or simply the fan of the computer ?
Moreover, the measurements cannot be wrong as my hears really feel there is not enough bass !
I tried a simulation with the TQWT of a friend that I measured with the same mic and the same soft and there is a good results correlation so your mathcad sheets seem to work great.
I should break in the speaker a little more, though it'll be difficult with my parents who only listen to classical music. It's the only way to know why the results are not similar.
Hi youyoung21147,
If I only knew how to help you 😉
The needle was constructed in a more traditional way: About 1/2 Sd for the throat, about 3Sd for the mouth. About 175 cm lenght, which corresponds with a quarterwave of 50 Hz. In my experience, if you tune a TQWP lower than Fs, it is wise to make the contour slimmer.
This measurement was performed on the brick (which bases on the same contour as the needle). The speaker was placed in the middle of our living room to minimize room influence. A notch filter was used to flatten the upper mids, no baffle step compensation.
You see a nice bass extension down to 60 Hz, if placed near a wall, it goes even lower.
Nice greetings, Berndt
If I only knew how to help you 😉
The needle was constructed in a more traditional way: About 1/2 Sd for the throat, about 3Sd for the mouth. About 175 cm lenght, which corresponds with a quarterwave of 50 Hz. In my experience, if you tune a TQWP lower than Fs, it is wise to make the contour slimmer.
This measurement was performed on the brick (which bases on the same contour as the needle). The speaker was placed in the middle of our living room to minimize room influence. A notch filter was used to flatten the upper mids, no baffle step compensation.
You see a nice bass extension down to 60 Hz, if placed near a wall, it goes even lower.
An externally hosted image should be here but it was not working when we last tested it.
Nice greetings, Berndt
youyoung21147 said:I made the measurements in the widest room of my house : it's 4m*10 and the ceiling is made of two parts : one under the 1st floor and the 2d under the roof so there are not so many parallel surfaces. It makes a good auditorium anyway 🙂
I choosed RTA3 because the pink noise it delivers is perfectly linear from 5 to 44000Hz. Anyway, it detects well my subwoofer low frequencies.
On the measurements, the very low part is a bit stronger, there was probably something generating ultralow frequencies, like a plane or simply the fan of the computer ?
Moreover, the measurements cannot be wrong as my hears really feel there is not enough bass !
I tried a simulation with the TQWT of a friend that I measured with the same mic and the same soft and there is a good results correlation so your mathcad sheets seem to work great.
I should break in the speaker a little more, though it'll be difficult with my parents who only listen to classical music. It's the only way to know why the results are not similar.
Get a CD with warble tones less than 50Hz to break in the drivers. This will cause them to travel max distance without annoying sounds.
Did you do an impedance measurment on the drivers to verify that they truly have resonace at the spec frequency? I had some instances where it was more than twice the spec frequency. I take it that you are using the same drivers in different box?
Hi soongsc,
the W3-871S are from break-in point of view quite harmless. They don't change over the time too much. A few days of normal playing should be sufficient.
I know other drivers, which need months to break in, for example the Beyma 8AG/N or the MAM137.
Nice greetings, Berndt
the W3-871S are from break-in point of view quite harmless. They don't change over the time too much. A few days of normal playing should be sufficient.
I know other drivers, which need months to break in, for example the Beyma 8AG/N or the MAM137.
Nice greetings, Berndt
Cyburgs said:
I was just recommending a less annoying was of breaking in speakers since youyoung21147 seemed to be disturbing his parents.
It's amazing that such small drivers can go so low. Is it a pure far field measurement or spliced near and far. What signal type did you use?
Hi soongsc,
the measurement was performed with MLS (using the DLSA- measurement system) in 1 meter distance, microphone pointing to the driver.
It is really amazing, how deep the tiny drivers go in this enclosure. The maximal volume level is limited of course, but nice room level is possible.
Your tip with the low frequencies to burn-in the drivers is good, although I prefer just normal music. Takes a little bit longer, but sounds better 😀
The reason for my posting was to tell youyoung21147, that burn-in of the drivers will probably not solve the lack of deep-bass.
Nice greetings, Berndt
the measurement was performed with MLS (using the DLSA- measurement system) in 1 meter distance, microphone pointing to the driver.
It is really amazing, how deep the tiny drivers go in this enclosure. The maximal volume level is limited of course, but nice room level is possible.
Your tip with the low frequencies to burn-in the drivers is good, although I prefer just normal music. Takes a little bit longer, but sounds better 😀
The reason for my posting was to tell youyoung21147, that burn-in of the drivers will probably not solve the lack of deep-bass.
Nice greetings, Berndt
I ran my speakers while I were at school with various musics to break in the driver, and my ears feel a little more bass, and by the way the suspension is a very little softer than this morning.
I made measurements again but the difference is not so high, so I suppose I cannot make the suspension softer, though the sound quality of the driver, that cannot be measured, is still improving. There is a strange dip between 92 and 100Hz, I don't know the cause of it because when generating the same frequencies with the sinus wave generator, no dip can be heard and the SPL is exactly the same.
The last thing I should do is finalize the cabinet, put more screws, glue all the edges and, mainly, make a connector so as the driver's wires don't go out through the port 😀
Cyburgs : I had already seen your cabinet on the Internet, and I'm sure it performs very well, as you obtain 60hz at -6dB
Unfortunately, my parents would'nt like to see an enclosure that they would consider 'enormous" in their living room : I promised to make small cabinets and the one I built is almost too big, but it was easy to convince them it was a good thing because they find the sound great 😉
In fact even if my speakers don't go lower than 75hz -3dB, it's enough because then the awful subwoofer of the home theater does the bass job, but without polluting the 80Hz and more with bass reflex resonances.
If I have time I'll do another simulation to get something better but otherwise, the bass response is theorically enough for this purpose. Anyway, this enclosure makes a great center speaker !
I made measurements again but the difference is not so high, so I suppose I cannot make the suspension softer, though the sound quality of the driver, that cannot be measured, is still improving. There is a strange dip between 92 and 100Hz, I don't know the cause of it because when generating the same frequencies with the sinus wave generator, no dip can be heard and the SPL is exactly the same.
The last thing I should do is finalize the cabinet, put more screws, glue all the edges and, mainly, make a connector so as the driver's wires don't go out through the port 😀
Cyburgs : I had already seen your cabinet on the Internet, and I'm sure it performs very well, as you obtain 60hz at -6dB
Unfortunately, my parents would'nt like to see an enclosure that they would consider 'enormous" in their living room : I promised to make small cabinets and the one I built is almost too big, but it was easy to convince them it was a good thing because they find the sound great 😉
In fact even if my speakers don't go lower than 75hz -3dB, it's enough because then the awful subwoofer of the home theater does the bass job, but without polluting the 80Hz and more with bass reflex resonances.
If I have time I'll do another simulation to get something better but otherwise, the bass response is theorically enough for this purpose. Anyway, this enclosure makes a great center speaker !
Attachments
If you want to break in your speakers [1] without annoying your parents, try facing the cabinets to each other, running them out of phase, then throwing a thick blanket over the lot to catch whatever reflections make it out. The emitted audio should be down quite a bit, 10 or 20 dB at a guess.
[1] I'm still agnostic on this one. Haven't noticed much difference one way or the other, but that doesn't mean it doesn't exist for drivers I haven't tried.
Cheers,
Francois.
[1] I'm still agnostic on this one. Haven't noticed much difference one way or the other, but that doesn't mean it doesn't exist for drivers I haven't tried.
Cheers,
Francois.
Yes I kwow a little about this solution but the problem is I have only one cabinet, because it's built for test purposes 
Anyway the speaker is almost completely broken in as I don't get better results anymore concerning bass.
I have to finalize the cabinet this afternoon because it looks quite ugly right now. What do you thin about black paint 😉 ?
But first I have to adjust the damping and make a real connector for 4mm connection.
I'll try maybe another simulation to build other speakers, and set this one as center speaker.
Anyway the speaker is almost completely broken in as I don't get better results anymore concerning bass.
I have to finalize the cabinet this afternoon because it looks quite ugly right now. What do you thin about black paint 😉 ?
But first I have to adjust the damping and make a real connector for 4mm connection.
I'll try maybe another simulation to build other speakers, and set this one as center speaker.
I'm back on this post 😱
Since I had very much work this month, I hadn't time to spend on my speakers.
I finalized the cabinet, with glue, screws, internal damping... 4 weeks ago and made measurements this afternoon. Th bass extends down to 70Hz -3dB which approximately correlates with the simulation. ( http://youyoung21147.site.voila.fr/W3_871S_centrale.PNG )
I tried it on the Home theater installation and it makes a nice center speaker !
Because I need more bass for the future front speakers (left + right), I ran again some simulations which led me to this ( http://youyoung21147.site.voila.fr/data_satW3_871S.PNG ). Though the frequency response seems not good at all, it compensates the losses I observed when comparing my center speaker FR and the simulation, so it should give an approximatley flat FR and compensate baffle step issues.
My problem is : after having ran the ML-TQWT sheet to get the parameters of the TL, I ran the ported box sheet to get the port height and improve smoothly the geometry.
But when I saw the frequency response, I was surprised to see it looked really different from the ML-TQWT simulation ! (see picture)
I ran other simulations like that, including the center speaker's, but never obtained such amazing differences
Could anyone tell me which worksheet should I rather believe concerning the expected FR ?
Since I had very much work this month, I hadn't time to spend on my speakers.
I finalized the cabinet, with glue, screws, internal damping... 4 weeks ago and made measurements this afternoon. Th bass extends down to 70Hz -3dB which approximately correlates with the simulation. ( http://youyoung21147.site.voila.fr/W3_871S_centrale.PNG )
I tried it on the Home theater installation and it makes a nice center speaker !
Because I need more bass for the future front speakers (left + right), I ran again some simulations which led me to this ( http://youyoung21147.site.voila.fr/data_satW3_871S.PNG ). Though the frequency response seems not good at all, it compensates the losses I observed when comparing my center speaker FR and the simulation, so it should give an approximatley flat FR and compensate baffle step issues.
My problem is : after having ran the ML-TQWT sheet to get the parameters of the TL, I ran the ported box sheet to get the port height and improve smoothly the geometry.
But when I saw the frequency response, I was surprised to see it looked really different from the ML-TQWT simulation ! (see picture)
I ran other simulations like that, including the center speaker's, but never obtained such amazing differences
Could anyone tell me which worksheet should I rather believe concerning the expected FR ?
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