Interesting... lets say I would go for the Fostex bass and the audax midrange, I would have a very efficient combination. The Fostex in particular is quite amazing in that regard, albeit a vey ugly looking driver. 🙂
How do you think the Fostex would compare to a pair of Satori MW16P? Withtjese drivers in parallel I could reach 93dB efficiency with low excursion due to dual drivers. Mms is also low, at least looking at the single driver.
Unfortunately I think the WAF would be a problem for the otherwise great 10” Ss classic woofer.
How do you think the Fostex would compare to a pair of Satori MW16P? Withtjese drivers in parallel I could reach 93dB efficiency with low excursion due to dual drivers. Mms is also low, at least looking at the single driver.
Unfortunately I think the WAF would be a problem for the otherwise great 10” Ss classic woofer.
Beware: that Fostex, while excellent in its own right, is NOT a bass driver, and it would perform very poorly in your intended application.
As Marco said - the Fostex isn't exactly a woofer. Excursion is pitiful (pretty much requiring low(ish) spl-use and resonant augmentation.. like a back-horn or at the very least a decent bass reflex design. It's also got high 2nd order distortion below 200 Hz and high 3rd order below 45 Hz (..if its like the FE206En).
I'll look around for a possible candidate for the Audax.
The Satori in parallel wouldn't have much in the way of "dynamics" at low spl.
This is going to seem odd, but I'd do this with the Audax mid.:
2 Eminence Delta Pro-8B in parallel.
There is so much gain with these in parallel that you can get respectable bass from them with the right bass reflex design and the right filter relative to a 93 db mid as your average. You won't be able to go terribly loud with them at low freq.s.
Note: with a design like this you'll want a filter for the in-box resonance (..to flatten impedance). Try to keep resistance LOW with your inductors for this filter (..I usually go to Erse for this sort of thing at a lower cost.) It dramatically improves transient bass and clarity.
I'd target something around 30 Hz for the vent tuning.
2 Eminence Delta Pro-8B in parallel.
There is so much gain with these in parallel that you can get respectable bass from them with the right bass reflex design and the right filter relative to a 93 db mid as your average. You won't be able to go terribly loud with them at low freq.s.
Note: with a design like this you'll want a filter for the in-box resonance (..to flatten impedance). Try to keep resistance LOW with your inductors for this filter (..I usually go to Erse for this sort of thing at a lower cost.) It dramatically improves transient bass and clarity.
I'd target something around 30 Hz for the vent tuning.
With the Audax mid I'd use this tweeter:
Viawave
new ribbon tweeter ? - Techtalk Speaker Building, Audio, Video Discussion Forum
Viawave
new ribbon tweeter ? - Techtalk Speaker Building, Audio, Video Discussion Forum
Yes, I realize that the Fostex is a fullranger 😱 and that it would need an additional woofer to reach the low end. There are by the way some really funky looking designs published on the web using this driver, check it out on google images.
You guys seem to agree that a sensitive speaker performs better at low volume than a less sensitive speaker. I can't help but think that what you are suggesting is that as power drops towards zero, a highly damped speaker actually looses some of its linear behaviour, somehow accentuating the Equal Loudness Countour of the human ear? Has anyone attempted to measure this effect?
By the way, does anyone know if the dispersion of a speaker changes significantly with volume?
You guys seem to agree that a sensitive speaker performs better at low volume than a less sensitive speaker. I can't help but think that what you are suggesting is that as power drops towards zero, a highly damped speaker actually looses some of its linear behaviour, somehow accentuating the Equal Loudness Countour of the human ear? Has anyone attempted to measure this effect?
By the way, does anyone know if the dispersion of a speaker changes significantly with volume?
It seems to me they are implying even more, that an efficient speaker compensates for it at low volume
If you are high-passing the Fostex at around 100 Hz (..200 for the FE), then it's a probably a great driver (for the upper midbass) provided you've dealt with reflections penetrating the rear of the diaphragm. That still leaves you with another driver to select (and implement) for the low end that is similar in character. ..look at the permanent magnet 12 and 15 bass drivers from EMSpeakers.
The higher sensitivity designs have more force in the gap acting on the vc/former/cone with lower inertia (and hopefully less resistance from the surround and spider - at least at the start of its stroke). It reacts a bit more quickly to its input and requires less current to do that.
Dispersion is a function of the driver's diameter and physical structure (..really nothing to do with output). Changing Inductance with power input can alter linearity however.
Here is a driver for the low-end:
Beyma Speakers - Beyma 15P80FeN speaker - Beyma 15P80Fe Water Resistant Speaker, 1,600 watt 15" woofer for all mid-bass applications. Beyma 15P80FeN and other Beyma 15" speakers here. Great for indoor or outdoor use.
..requires lots of volume though. 😱
(..can be placed on cabinet side for help with a narrower baffle and upper freq. "roll-off" to make the low-pass filter easier.)
Beyma Speakers - Beyma 15P80FeN speaker - Beyma 15P80Fe Water Resistant Speaker, 1,600 watt 15" woofer for all mid-bass applications. Beyma 15P80FeN and other Beyma 15" speakers here. Great for indoor or outdoor use.
..requires lots of volume though. 😱
(..can be placed on cabinet side for help with a narrower baffle and upper freq. "roll-off" to make the low-pass filter easier.)
that's a cool little Beyma 15 - oughta work with MMJ's Super Planar - here it is simmed in a little 4.5 cubic foot bulk K https://i.imgur.com/VmaICc6.jpg
it should be also nice in Klipsch heritage horns
it should be also nice in Klipsch heritage horns
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Explanation of what I meant by "static friction"
Have a look at this little video and see if it makes sense to you, in the context of selecting a woofer "for good performance at low volume".
The gist is that in a real (as opposed to ideal) speaker unit, an additional amount of force needs to be applied for it to budge from its rest position, because of the non-linearity of its mechanical resistance.
When the applied electrical signal drops to very low levels, this effect becomes more noticeable since the initial departure from the rest position is now a larger % of the total required travel. As a result, per unit of applied electrical force the speaker unit will move less than theoretically expected, resulting in acoustic compression and loss of low-level detail.
Incidentally, given that this effect is more prominent in Woofers than in Mid-ranges or Tweeters (due to their comparatively larger moving mass which requires more robust suspensions, etc.), this is also one of the reasons (if not the main reason) why the Woofer appears to gradually 'switch itself off' as the volume is turned down, resulting in a perceived loss of dynamics in the bass and a brighter tonal balance at low volumes.
I find that the extent to which this undesired phenomenon manifests itself in a Woofer is proportional to its overall mechanical damping at resonance, which is measured as (Rms/Mms) = 2*Pi*(Fs/Qms).
So when seeking a woofer that performs well at low volume, I would recommend selecting those with the lowest possible (Fs/Qms) first, and then, among the suitable candidates, choosing one with a suitable amount of electrical damping, i.e.: (Fs/Qes) = EBP, for the required application (closed box, bass reflex, etc.) and low frequency extension (*).
(*) In first approximation, the achievable low-frequency extension depends on the total damping at resonance (less total damping = more low-frequency extension), and it bears reminding that mechanical and electrical damping are additive, so the total damping at resonance is (Fs/Qts) = (Fs/Qms) + (Fs/Qes).
Have a look at this little video and see if it makes sense to you, in the context of selecting a woofer "for good performance at low volume".
The gist is that in a real (as opposed to ideal) speaker unit, an additional amount of force needs to be applied for it to budge from its rest position, because of the non-linearity of its mechanical resistance.
When the applied electrical signal drops to very low levels, this effect becomes more noticeable since the initial departure from the rest position is now a larger % of the total required travel. As a result, per unit of applied electrical force the speaker unit will move less than theoretically expected, resulting in acoustic compression and loss of low-level detail.
Incidentally, given that this effect is more prominent in Woofers than in Mid-ranges or Tweeters (due to their comparatively larger moving mass which requires more robust suspensions, etc.), this is also one of the reasons (if not the main reason) why the Woofer appears to gradually 'switch itself off' as the volume is turned down, resulting in a perceived loss of dynamics in the bass and a brighter tonal balance at low volumes.
I find that the extent to which this undesired phenomenon manifests itself in a Woofer is proportional to its overall mechanical damping at resonance, which is measured as (Rms/Mms) = 2*Pi*(Fs/Qms).
So when seeking a woofer that performs well at low volume, I would recommend selecting those with the lowest possible (Fs/Qms) first, and then, among the suitable candidates, choosing one with a suitable amount of electrical damping, i.e.: (Fs/Qes) = EBP, for the required application (closed box, bass reflex, etc.) and low frequency extension (*).
(*) In first approximation, the achievable low-frequency extension depends on the total damping at resonance (less total damping = more low-frequency extension), and it bears reminding that mechanical and electrical damping are additive, so the total damping at resonance is (Fs/Qts) = (Fs/Qms) + (Fs/Qes).
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I don't know whether static friction can be applied within a material (within the suspension). It would show itself as a shift in fs at low drive levels and huge harmonic distortion. Does anyone know whether fs increases and Qms decreases when fs is measured at a low level?
It could also be related to loudness: Equal-loudness contour - Wikipedia
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I also believe the ears non linear LF sensitivity is the root cause of speakers not sounding good at low levels.
If static friction were the issue I'd imagine the cone on a large woofer would grab-release-grab when pushed. It would also suggest a large high X-Max woofer with very low Qms would rest at different locations after being pushed inward or outward. I have never witnessed this.
That said, I do appreciate that a moderately high Qms is beneficial in other ways.
I've struggled with this issue as well but if you can find 1 design that sounds good at low level AND at high level, can you then exclude the equal-loudness curve as the sole issue?
I don't have enough experience with loudspeaker design/ear acoustics to give a definitive answer but I have heard a few designs that sound great at high and low volume so I'm convinced it can be done. At least for me this puts the equal-loudness curve in the "not as critical" column of the speaker design for the OPs type of design requirement.
Since I do not have access to such technology as Dolby Volume I've turned to other design aspects that allow for great sound at low volume. I have no proof but have found to my ears larger drivers and higher sensitivity make this easier to achieve. Also open baffle bass seems to make this easier and relaxes the in depth TS parameter investigations for a trade off in Open baffle design. Since more eq is required in the low end for an open baffle design perhaps that hints at marcos suggestions or is it room loading?
I long to find the magic TS parameters that allow for this type of reproduction in a sealed enclosure. For reference I have a vifa NE265W-08 subwoofer and is sounds dead at low volume compared to my 15TBX100 driver. The Vifa has according to the datasheet.
NE-265W-08
FS - 23 Hz
QMS- 10.33
MMs - 74.1 grams
Question to marco. Does the above driver satisfy your (Rms/Mms) = 2*Pi*(Fs/Qms) ratio for the OP application? Looking forward to more information on this subject as I'm very interested in the discussion.
Thanks!
Let me define Low Level and High Level. In my limited experience small drivers with low sensitivity need be played loud. Larger drivers with higher sensitivity can be played at "Low"/lower volume relatively but there is a level that my ears give up and nothing sounds good, this is probably the equal-loudness curve coming into effect.
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