Excellent point and I believe very important.
I believe that minimising cone travel brings a LOT of advantages and this is best achieved by increasing Sd ie Use a larger single driver or multiple small drivers wherever possible.
Multiple small drivers enable you to greatly increase the dynamics, efficiency and SPL capability, PLUS you greatly reduce distortion.
It's just costly to do so. And modern long throw chassis can do stuff older ones couldn't even with lower excursion. The SB Acoustics 12" does 95dBSpl with 0,2% THD ... many older designs (like SB29NRX75-6) can't even deliver 0,2% THD regardles the level.
So chose the right chassis and just use a lot of them in a low Q housing (= closed) - that works ;-)
(I also use closed subwoofer for home cinema. When you scale it for the needed level at 20Hz you have IMENSE max level at 60Hz and very low membrane movement and THD for music. Membranes move when dinos jump around but music is a cake.)
So chose the right chassis and just use a lot of them in a low Q housing (= closed) - that works ;-)
(I also use closed subwoofer for home cinema. When you scale it for the needed level at 20Hz you have IMENSE max level at 60Hz and very low membrane movement and THD for music. Membranes move when dinos jump around but music is a cake.)
The audibility of harmonic distortion is debateable in the bass range, IMO. For example Klippel set the limit of HD at 20% for subwoofers.
Anyway, the SB29NRX75-6 have nowhere near that low harmonic distortion. At least according to the following test:
https://www.dibirama.altervista.org...ics-sb29nrx75-6-woofer-10-6-ohm-400-wmax.html
As I wrote.
https://www.diyaudio.com/community/...rxl75-8-vs-sb29nrx75-6-vs-sb29nrx75-8.402671/
And never trust a linear THD scale ... who is doing that?
(not enough resolution for modern drivers, 0,1-2% is the interesting range)
I don't take THD to serious in terms of being audible but it's a great indicator if everything is working well in a chassis. Like in my link above - the SB Acoustics 10" I tested are not good for lowmids, the 12" is one of the best you can buy.
Some H3 even sounds good in a subwoofer, precise and dry. But we are quickly at 10% anyways at low frequencies - and I don't mind that at all. Just interesting to know where the chassis reaches it's borders.
https://www.diyaudio.com/community/...rxl75-8-vs-sb29nrx75-6-vs-sb29nrx75-8.402671/
And never trust a linear THD scale ... who is doing that?
(not enough resolution for modern drivers, 0,1-2% is the interesting range)I don't take THD to serious in terms of being audible but it's a great indicator if everything is working well in a chassis. Like in my link above - the SB Acoustics 10" I tested are not good for lowmids, the 12" is one of the best you can buy.
Some H3 even sounds good in a subwoofer, precise and dry. But we are quickly at 10% anyways at low frequencies - and I don't mind that at all. Just interesting to know where the chassis reaches it's borders.
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The point you start noticing low frequency HD is when the signal to play back is complex with multiple tones ie. IMD and when the motor starts contributing its own noises and artifacts. Things like the cone deforming under higher air loads aren't that noticeable, but a dust cap snapping in and back out or a surround deforming sound awful, mainly in the lower mids. This is why i like smaller dust caps.
yes. When I look at driver distortion measurements, I ignore 2nd HD. I do pay attention to HD3, HD4, and HD5.
Me too ! A further benefit is that the cavity resonance behind the dustcap is higher up in frequency. Unfortunately large dustcaps can't be avoided when a driver has to have a large x-damage.
Regards
Charles
I've pasted this excerpt from a Klippel paper a couple of times recently, but it's worth repeating I think:
So here we've basically got a source of mid-range IMD. As bass frequencies move the cone, the impedance and current at higher frequencies is modulated. They focus on cone displacement, but there are other sources of similar effects, like the current itself, even if the cone is moving a lot less or the motion is out of phase with current.
A 1st order passive crossover can help fix this because the modulated impedance becomes a smaller fraction of the total impedance. Hence my suggestion of a hybrid design that uses a minimalistic air-cored passive coil, combined with active filters.
So here we've basically got a source of mid-range IMD. As bass frequencies move the cone, the impedance and current at higher frequencies is modulated. They focus on cone displacement, but there are other sources of similar effects, like the current itself, even if the cone is moving a lot less or the motion is out of phase with current.
A 1st order passive crossover can help fix this because the modulated impedance becomes a smaller fraction of the total impedance. Hence my suggestion of a hybrid design that uses a minimalistic air-cored passive coil, combined with active filters.
Hey there kouiky, I recommend you contact SB audience and ask about an upcoming 15" neo driver. I have been asked to keep quiet regarding the specs but I will say I believe it may be perfect for the use case. If the motor design of the 12" Nero is anything to go off performance will be very good, and their prices are very nice too.
I wish you the best of luck with your search, I know sometimes the perfect driver for the job seems impossible to find!
I wish you the best of luck with your search, I know sometimes the perfect driver for the job seems impossible to find!
Yes. John Krutke observed this more than 15 years ago and documented it here:
http://zaphaudio.com/Le(x)/
It actually is a quick and easy test to compare woofers. I encourage people to try it for themselves, particularly if they have a Woofer Testers or DATs or even the impedance test jig they build themselves for ARTA or REW.
Do you know when the release date may be? Are we talking Q4 or 2024?
There’s a 21” neo designed for OB use too.
Meanwhile, the 18” Nero (ferrite) subwoofer is in mass production and on its way to Australia…
https://www.sbaudience.com/index.php/products/subwoofers/nero-18sw1900d/
I'm afraid I don't know the exact date, I would assume it to be pretty soon as I enquired about it a few months back now.
And yes my mate has bought four from Wagner already, we've been keeping our eyes peeled for them as they're quite impressive for the price.
I'm curious to see the 21" OB driver. I don't have the space for OB myself but can see it being very useful for some. Would likely suit IB applications as well with some eq to tame the rising low end response...
I'm afraid so... 😅
And yes I urged him to get onto it as I figured there would be a few like minded souls about. They are on preorder though I believe as opposed to in stock so hopefully they will bring in a larger quantity as a result. We'll see.
We'll be testing them in some basic 35hz tuned cabs so will be interested to see how they go. Long term I've suggested tapped horns to make the most of the excessive power handling and excursion, but will wait to see them in person to judge the physical build.
And yes I urged him to get onto it as I figured there would be a few like minded souls about. They are on preorder though I believe as opposed to in stock so hopefully they will bring in a larger quantity as a result. We'll see.
We'll be testing them in some basic 35hz tuned cabs so will be interested to see how they go. Long term I've suggested tapped horns to make the most of the excessive power handling and excursion, but will wait to see them in person to judge the physical build.
Btw. this could be one reason why some people say they hear absolute polarity of speaker? Depending whether a transducer goes in or out initially with transient it affects high frequency content of the same transducer as well. Also, the louder the system is the more there ought to be difference, and so on.
Perhaps there is physiological reasons why high or low initial pressure peak would sound/feel different, but hearing difference changing absolute polarity could indicate the speakers aren't as good as they could
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For fun some GIF:s to illustrate what happens to "frequency response" with parameters changing per voice coil position. Not sure if this is legit but a demonstration nevertheless to help reason about the stuff:
Looked klippel data here https://audioxpress.com/article/tes...-8582t00-15-ellipticor-oval-voice-coil-woofer and fed datasheet numbers to VCAD enclosure tool, then increased Le with 0.13mH, "... swing from Xmax in to Xmax out is a very small 0.13mH, which is very good inductive performance."
And result to the woofer frequency response of Le varying 0.13mH is something like this as the woofer goes from xmax to other. It's easy to reason that as the woofer is sent to high excursion by low frequency content the whole passband gets ruined, or perhaps not ruined but performance of midrange depends on low frequency content.
Here is also Bl(x) somewhat mixed in, not quite accurate but it seems to vary between about 14-20 with the driver so used those extreme values for this. Also Le varies the same 0.13mH between extremes.
I bet the GIF would be quite funky if all properties were varied
So, it makes sense to limit passband by using multiple ways on a speaker system. It also pays to make the system wee bit bigger than it's really necessary so that xmax is never touched. It also pays back to select good drivers, especially if the system is small, or the less there are ways in it so that any effects are maximized.
Looked klippel data here https://audioxpress.com/article/tes...-8582t00-15-ellipticor-oval-voice-coil-woofer and fed datasheet numbers to VCAD enclosure tool, then increased Le with 0.13mH, "... swing from Xmax in to Xmax out is a very small 0.13mH, which is very good inductive performance."
And result to the woofer frequency response of Le varying 0.13mH is something like this as the woofer goes from xmax to other. It's easy to reason that as the woofer is sent to high excursion by low frequency content the whole passband gets ruined, or perhaps not ruined but performance of midrange depends on low frequency content.
Here is also Bl(x) somewhat mixed in, not quite accurate but it seems to vary between about 14-20 with the driver so used those extreme values for this. Also Le varies the same 0.13mH between extremes.
I bet the GIF would be quite funky if all properties were varied
So, it makes sense to limit passband by using multiple ways on a speaker system. It also pays to make the system wee bit bigger than it's really necessary so that xmax is never touched. It also pays back to select good drivers, especially if the system is small, or the less there are ways in it so that any effects are maximized.
This is a very interesting and detailed comparison of "serious bass" from a very well qualified musician (he is a very good bass player) and qualified engineer and skilled cabinet and crossover designer.... I am not jealous at all....!!! https://www.humblehomemadehifi.com/download/Humble Homemade Hifi_Serious Sub.pdf
I found his conclusion that open baffle bass sounded best in a limited sweet spot interesting... Maybe with todays (the article is 15 years old) more affordable/higher power room measurement/correction open baffle could be the best choice for the whole sofa/family rather than just the dreaded audiphile-itis "Critical Listening" seat?
https://www.humblehomemadehifi.com/download/Humble Homemade Hifi_Serious Sub.pdfI found his conclusion that open baffle bass sounded best in a limited sweet spot interesting... Maybe with todays (the article is 15 years old) more affordable/higher power room measurement/correction open baffle could be the best choice for the whole sofa/family rather than just the dreaded audiphile-itis "Critical Listening" seat?