I have no strong expectations of bass from speakers capable of such delicate finesse. I would like to try not using a sub so I don't have to high-pass the other drivers because I believe this would introduce phase shifts which would defeat the purpose of a full-range driver, although I'm otherwise willing to experiment. However, I have several choices in subwoofers along with various amps to power them, and an analog and two digital dsp crossovers and a grab bag chock full of caps and coils for whenever I need them.
On the other subjects - I've been wrong before and I have no problem if someone has an opinion that differs from my current understanding.
But as best as I can tell so far, there is no such thing as "fast" bass. If something is happening quickly, it's happening in a band that is at a higher frequency, period.
Now, that is not to say that when the ear is listening to everything happening all at once, there are characteristics which can cause bass to seem slow, or sloppy, or boomy, or honky. I know that when a large air mass is excited and has the means to voice itself outside the speaker, it can modify the qualities of the bass significantly.
And for that reason, in my own experience, my preferences lean to sealed boxes for woofers. I like to grab the rear wave and bury, disperse, dissipate, and silence it so it won't interfere with what's happening on the speaker's face.
I have a partially clear understanding that bass quality in the context of the rest of the spectrum is related to impulse response, group delay, and phase. I think I'm right in believing that the closer you can get to a theoretically perfect impulse response, and synchronized group delay the closer the various wavefronts at different bands remain coherent and give the illusion of 3-dimensionality and soundstage in the music. Using a bunch of caps and coils will unavoidably cause these things to shift all over the place, and though some find this inaudible others (like myself) identify another attribute in the sound which tarnishes the illusion and the mind perceives the sound coming from the speakers instead of the atmosphere around you.
As far as anything but sealed, I think one needs a driver with a Qts higher than those in the 0.3 range, more like 0.5 or 0.6. I have listened to some open baffle speakers, and (again with my current understanding) lower Qts drivers need the reaction of the air volume behind it to help control its movement. So in short, I know lots of enclosure styles have been tried; I'm wondering where the Mark audio drivers would feel most comfortable.
I think my first box will be a large-ish sealed, but I have plenty of time and materials to build some ported, transmission-line, folded horn, etc styles also.
Some of the Mark Audio drivers use metal cones, and some use paper. They have some expensive models that use a fancy process treatment on the cones, and if anyone has first hand experience with these, I'm all ears - pun intended. The quality of sound I consider most important in this project would be that it sounds natural and non-fatiguing. In other words, if the metal drivers have the typical issues with ringing and breakup modes I'd lean away from them. I look at waterfall plots, and when I see a mess I'm discouraged. Are the paper drivers very good in this regard? Should I spend more and get those fancy metal cones they say sound good anyway?
So many considerations...
On the other subjects - I've been wrong before and I have no problem if someone has an opinion that differs from my current understanding.
But as best as I can tell so far, there is no such thing as "fast" bass. If something is happening quickly, it's happening in a band that is at a higher frequency, period.
Now, that is not to say that when the ear is listening to everything happening all at once, there are characteristics which can cause bass to seem slow, or sloppy, or boomy, or honky. I know that when a large air mass is excited and has the means to voice itself outside the speaker, it can modify the qualities of the bass significantly.
And for that reason, in my own experience, my preferences lean to sealed boxes for woofers. I like to grab the rear wave and bury, disperse, dissipate, and silence it so it won't interfere with what's happening on the speaker's face.
I have a partially clear understanding that bass quality in the context of the rest of the spectrum is related to impulse response, group delay, and phase. I think I'm right in believing that the closer you can get to a theoretically perfect impulse response, and synchronized group delay the closer the various wavefronts at different bands remain coherent and give the illusion of 3-dimensionality and soundstage in the music. Using a bunch of caps and coils will unavoidably cause these things to shift all over the place, and though some find this inaudible others (like myself) identify another attribute in the sound which tarnishes the illusion and the mind perceives the sound coming from the speakers instead of the atmosphere around you.
As far as anything but sealed, I think one needs a driver with a Qts higher than those in the 0.3 range, more like 0.5 or 0.6. I have listened to some open baffle speakers, and (again with my current understanding) lower Qts drivers need the reaction of the air volume behind it to help control its movement. So in short, I know lots of enclosure styles have been tried; I'm wondering where the Mark audio drivers would feel most comfortable.
I think my first box will be a large-ish sealed, but I have plenty of time and materials to build some ported, transmission-line, folded horn, etc styles also.
Some of the Mark Audio drivers use metal cones, and some use paper. They have some expensive models that use a fancy process treatment on the cones, and if anyone has first hand experience with these, I'm all ears - pun intended. The quality of sound I consider most important in this project would be that it sounds natural and non-fatiguing. In other words, if the metal drivers have the typical issues with ringing and breakup modes I'd lean away from them. I look at waterfall plots, and when I see a mess I'm discouraged. Are the paper drivers very good in this regard? Should I spend more and get those fancy metal cones they say sound good anyway?
So many considerations...
Last edited:
In a reflex the production of the helmholtz resonance assumes the shape of the enclosure is close to a sphere/cube.
If a rectangualr box start to have 1 dimension becomes much larger than the others, a quarter-wave resonance starts to become significant.
If we take a well-tuned 6-sided reflex and start changing the dimensions so that one becomes dominant. The reflex tuning is no longer low enuff. A reflex becomes an ML-TL. The designe can warp the parameters and the shapes thru a much larger space of designs.
If we take designb space and stray further & further from the vector going thru it that represents sealed and the percentage of possible bad designs increases compared to the numbwer of useful designs. It taksa good designer to navigate this space, or recepes to follow. Speaker design space has become much richer & more navigatable since the advent of models like MJK’s and now hornResp
dave
If a rectangualr box start to have 1 dimension becomes much larger than the others, a quarter-wave resonance starts to become significant.
If we take a well-tuned 6-sided reflex and start changing the dimensions so that one becomes dominant. The reflex tuning is no longer low enuff. A reflex becomes an ML-TL. The designe can warp the parameters and the shapes thru a much larger space of designs.
If we take designb space and stray further & further from the vector going thru it that represents sealed and the percentage of possible bad designs increases compared to the numbwer of useful designs. It taksa good designer to navigate this space, or recepes to follow. Speaker design space has become much richer & more navigatable since the advent of models like MJK’s and now hornResp
dave
planet10 -
What I remember reading long ago is that the ideal "box" is either two spheres touching each other (roughly approximated by string instruments like a violin or guitar) or a series of rectangles whose dimensions are the golden ratio such that they favor no particular resonance modes too strongly over another. 0.6180339 to 1.0 to 1.6180339...
I have usually built my enclosures so the internal dimensions match these ratios, or if I need a tall, narrow box I'll take the first box and double or triple the height.
Is this advice still valid?
What I remember reading long ago is that the ideal "box" is either two spheres touching each other (roughly approximated by string instruments like a violin or guitar) or a series of rectangles whose dimensions are the golden ratio such that they favor no particular resonance modes too strongly over another. 0.6180339 to 1.0 to 1.6180339...
I have usually built my enclosures so the internal dimensions match these ratios, or if I need a tall, narrow box I'll take the first box and double or triple the height.
Is this advice still valid?
Box dimensional wavelength may or may not be a problem. If it is a bass reflex floorstander, then yes. But bass reflex is typically small size. In my case, the largest dimension is 17", which corresponds to quarter-wavelength of about 200 Hz. The woofer is crossed 2nd order at 170 Hz. With 1/3 off the bottom stuffed, the 200 Hz standing wave is not a problem. The picture was taken during construction before side panel gluing on.
Correct, only under/over damped, i.e. either stops short of the signal's peak ('fast') or extends it (slow/'rings').
This is backwards, i.e. the low Qt motor is so strong it needs a proportionally smaller air mass spring and vise versa for higher Qt.
While the 'sweet spot' (mean) is a ~0.4412 Qts', a 'close enough' simple guideline is:
~0.403, Vb = Vas, Fb = Fs (constant tapered MLTL)
~ <0.403, Vb = < Vas, Fb = > Fs (inverse tapered MLTQWT)
~ >0.403, Vb = > Vas, Fb = < Fs (expanding taper MLTQWT/MLhorn)
(Qts'): (Qts) + any added series resistance (Rs)
Keeping in mind that one has to factor in the (huge) impact thermal power, inductive distortion can have on effective Qts, the dominant vented box alignment factor.
The sonics of the metals are all similar, Mark has his own allloy (mechnical engineern at the higest levels with a lot of experience), and he has done a good job with the shapes. A7/A7.3>P7HD, A10.2/3>CHR-90, and the A6.2m. A5.2/3, A7/11ms are aimed at getting maximum DDR, A5..3 is very well balanced, larger ones we will whether the 1 suspension is durable or repeatable enuff (requires very tighttolerances) is still a question that only time will tell.
The paper cone drivers are a special Taiwanese paper formulation and similar cone shapes. There aren't nearly as many of these. The under appreciated A6p and the A10p. The A7p was an outlier. A10p > CHP-90, and it is nice to see small aper cheapies, haven’’t heard any of those.
The original paper cheaper driver was CHP70/EL70, second gen has a butchered top end. Cheaper metals were the original CHR-70 Now Get 3.
And the cheap stamped metal basket drivers. TheCHN-110an d CHN-50 are really quite good and are cheap.
The higher end metals have higher DDR and more “accuracy” (for whatever that means) at the expense of some HF ringing. This can be ignored or minimized in a number of ways. The paper cones (A6/10p) have a more controlled top end, smoother, more rolled off — vintage. A sweeter, more romantic midrange
CHN-50/110, which i have, give up some DDR for very good response and little to no ringing. See @waxx ’s comments on his CHN-0110 ML-TL vrs his A10.3/big woofer WAW.
A MAOP is where they take a higher end cone (A7x/A10x, P11) and bombard the cone withelectrons turning the top few layers of molecules to a ceramic-like material, taking the comne control to thenext level. Expensive process, poor yield > higher prices — but still dirt cheap compared to many higher end drivers.
And then there are the oddballs.
dave
Last edited:
I have experience with Pluvia Seven HD and MAOP-7. The Pluvia is excellent FR driver that exceeded my expectations. It works well in all types of enclosures: bass reflex, acoustic suspension, OB, and even without any enclosure! I was breaking-in my drivers by hooking them naked to my favorite receiver tuned to local FM station. The radio played 14 hours a day for about a month, with volume gradually increasing, and the progress was amazing. In a couple of weeks some bass appeared, and the tone was such that I started liking the kind of music that I previously didn't care about. Often I would set aside what I was doing to enjoy a song.
MAOP-7 is same as the Pluvia except cone treatment. Long story short, the MAOP is BIG improvement over the Pluvia. We all dream of speakers that perform at the same level as good headphones. Well, the MAOPs bested my Grado SR-325 and Sennheiser HD650 with all kinds of music, from pop to classical. They also need long gradual break-in.
Micro Arc Oxidation Process creates a layer of very hard alumina (4 times harder than the one created by anodizing, the process used e.g. by SB Acoustics in their ceramic drivers) tightly bound to metal substrate. The way it works, in my opinion, is by making a sandwich in which different layers have different speed of sound. This disrupts standing waves on the cone resulting from border reflections. MAOPs are so good that it would be a misdemeanor to make them play bass alongside with mids and highs.
Attachments
Last edited:
BTW, there is a youtube video comparing 4" full range drivers, among them three from Markaudio. The guy used HD recording in a studio setting, so with good headphones the differences are apparent. Pluvia Seven was a clear winner among the 8 drivers.
4" FR comparison
4" FR comparison
This is a non-issue in a properly designed enclosure (it's actually a functional aspect of most vented boxes as well, since some form of damping is almost always required) as can be seen in GD, step & impulse response plots. You can empirically determine your preferred damping level with those, just like Helmholtz based, via the old click test.
Mine are supported by 2 x 7” SDX7eN sealed. Earlier picture with A7.3eN (which comes pretty close to MAOP but not quite).
dave
I am still wondering what is the gain here in going into trouble of constructing a complicated labyrinth enclosure as opposed to making a simple and compact vented box?
To highpass or not highpass…
For the latter one would typically use a FR in sealed butterworth alignment, with woofers brought in below that. I call this REL-style since they are its greatest proponents. Plus: one acoustic hi-pass filter with nothing between speaker and source>power amp, minus: FR has to be capable of reaching the low frequencies asked of it without significantly mucking up what happens higher up.
dave
Last edited:
It is not really complete.
Considering the oiutside a sphere (as shown by Olson) or the evolution of that shape into the teardrops or elipsoids (represented by B&W Nautilius miodPod, and Fujitsu 10 loudspeakers). This produces the least ripple from the 2∏ to 4” baffle transition.
Inside a sphere is not all that good. The evolved shapes help with that. Here a thread with ideas at complexifying the inside resonant behaviour: https://www.diyaudio.com/community/threads/loudspeaker-chaos-theory-inside-diffuser.418563/
With a rectangular box you want ratios with irrational numbers. The golden number, √2 (only use it once), √3, and so forth. Note that once one dimension starts to become significantly larger than the other 2 you are dealing with a quarter-wave resonance.
dave
Well, I design all types of enclosures, so I have no particular bias one way or another, other than 'whatever achieves the goals'.
Regarding labyrinths / TLs -for a start, they are not necessarily complicated enclosures. Some can be, some are very simple -the desktop / standmount labyrinths Dave & I do for instance have two internal panels which also serve as bracing for the enclosure, which for similar rigidity would be necessary and (ironically enough) physically more complex to form with a sealed or Helmholtz based box. And that's just labyrinths -an MLTL for instance has no more internal panels than a Helmholtz type vented, unless you happen to fold it.
For the rest -quarter-wave type enclosures allow you to achieve different goals or realise different results which are not achievable with a regular vented enclosure, since you have greater freedom over the operating BW, alignment, control over impedance etc. There are a whole range of possibilities with QW / HW designs running from aperiodic lines e.g. an Augspurger type, which offers similar alignment results to a sealed with a little more extension & a flatter impedance load, out to highly resonant pipes, and (closing the circle) horns of varying types with their greater acoustic efficiency and enhanced coupling. There are other uses too: the enclosure Dave pictures above has the mid-tweet loaded by a midrange TL to damp out the back-wave of the driver for the purposes of impedance flattening & making the crossover simpler -it also reduces distortion in the process. So there are lots of very good reasons why quarter (and half) wave enclosures can be useful types to have up your sleeve as a designer.
Ported enclosure is also quite flexible. Using box tune frequency, stuffing, and variable acoustic damping, the same goals can be achieved as with more complex enclosure.
Dave - I am not well-versed in speaker-building terminology. Am I correct interpreting your post as placing FR driver into a sealed box, in which it will be acoustically rolled-off 2nd order at the frequency determined by box volume? If so, this is to me a high-pass, not low-pass filter.
This is perfect solution indeed - no crossover, single point source, limited cone excursion,, acoustic suspension (linear) dominating mechanical cone suspension (not so linear).
As I posted above, my MAOP-7 is in a 1L sealed box, which gives 170 Hz XO point. I have separate binding posts for MAOP and bass driver for bi-amping the latter with a Class D amp, which has a low-pass 170 Hz 2nd order XO at the input. As an option for a single amp, the woofer can be connected through 170 Hz Butterworth XO. I like the class D option though for its flexibility.
That a 'slight exaggeration' 😉 I'm afraid. It's certainly true that there's a larger amount of adjustablity in vented boxes than is often realised, but unfortunately there's also a limit to how far that can be taken, and you can't achieve all (or even a majority) of what can be done with the much broader field of quarter-wave types. That's just the laws of physics in action unfortunately. Try as I might, I've yet to be able to beat them. Which doesn't stop me constantly having another go, obviously.
