Funny thing is I did not see any problems with ringing in the CSD in the 10-20Khz region with either the original or stretched ribbon configuration.
Both looked clean and free from any resonances, probably because the divergence in response was only 1dB at most and it was a very smooth and gradual change across a whole octave - there was no sharp response peak in either configuration, in both cases there was just a very smooth gentle curve just with a slightly different final trajectory. Very gradual changes like this will not cause measurable ringing as the effective Q of the resonance is so low.
But the tonal balance between <10Khz and >10Khz was wrong - the tweeter lost its "sparkle" with a 1dB loss in the top octave, so I started over and replaced the foil a second time.
One thing the experience really brought home to me is that if you are replacing foils on two ribbon tweeters at the same time you really have no reference for how much to stretch the foil unless the manufacturer provided good quality photos of the original configuration - only by counting the exact number of visible corrugations on the untouched one was I able to get it correct.
If I had been replacing both foils with no clue what they originally looked like (if I bought them second hand damaged for example) then I could have made them match each other but the chances of them matching their original brand new performance would be remote without a known good unit or photo to use as a reference.
"Funny thing is I did not see any problems with ringing in the CSD in the 10-20Khz"
Yes thats typical of ribbons whos width is small. They are easy to get right. Wider ribbons are far more finicky.
The "sparkle" as u say is an area that many struggle with. Getting that "air" without being overly bright. Just 1/2 db changes at 10k relative to the reference region can make a difference. Ive heard ribbons go from sounding just average to truly great with proper rake down in this area.
I was impressed by the objective approach of you until I read this! Seriously, you could pick out 1db difference between 10-20kHz????? Are you batman
I now realise that there are subjective objectivists and objective subjectivists, that goes for "lowmass" also! 0.5 db at 10kHz makes an average system go great...?
Yes, that's it, the distance from the speaker (assuming a point source here, but I presume this can be done separately for each driver's frequency range/height/directivity) to the floor to the ear is longer than the distance directly from the speaker to the ear, so there's an extra "copy" of the sound from the speaker reflected from the floor. The DSP also makes this copy by using a short delay.
It then inverts the polarity of the delayed copy it makes and adds it to the main signal, so that the DSP-generated copy and the floor-bounced copy sum together and cancel (presuming the correct amplitude and many other details) at the ear.
Yes, it's position dependent, if you stand up it won't work because the relative distances change, but it's an enhancement that works for the "sweet spot."
I was impressed by the objective approach of you until I read this! Seriously, you could pick out 1db difference between 10-20kHz????? Are you batman
I now realise that there are subjective objectivists and objective subjectivists, that goes for "lowmass" also! 0.5 db at 10kHz makes an average system go great...?
Im not sure its wise to respond here but yes. However a little context may help.
First off I would agree with you IF I did not spend so many hours going back and forth on this one area alone to prove even to my self as I found it hard to believe. AND im not certain why but I did not have the same experience with the same system with a dome tweeter.
The setup is an 8 inch cone working to 500hz. The ribbon is a six inch long free swing design working from 500 to 20k. With such a setup it is quite easy to adjust overall rake from 1khz on out and we ahve the advantage of one driver through this region. what I repeatedly found with this setup was that if the FR was set to flat it sounded, well for lack of a better term "HiFi'ish". It was good on some material but not great on most. Over time and against preconceived notions of "correct" I found that a smooth rake down of somewhere between 2-3 db by 10khz sounded much more convincing. From there I played back and forth from 2 db down to 3 db down at 10k and found on some material, mostly male voice, the difference was easily noticed.From there I went on a month long marathon just playing with this and in the end I realized there was something very important, at least with this setup, about the level difference between the 1-5k reference region and the level by the time we get to 10khz.
Im hardly a Bat as My ears are rolling off by 15 k but yes in the end 1 db at 10k was easily noticed on a fair amount of material and often took male voice from good to truly convincing. As well this level adjustment often seemed to make cymbols go from splashy bright (-1db) to somewhat dull(-2db) so I conclude that yes 1/2 db focused on this area can be that critical .
I have sense played with all this in other areas of the audio range and for sure 1 db means very little elsewhere.
BTW years ago I was developing my own swing of Apogee Duetta vs Apogee Diva platforms. My bass diaphragms were different than theirs BUT my MRT and Tweeter were very close to copy. I remember I ran into this same phenom here too but in my lack of experience didn't nail it down and eventually I realized the market for these designs was too limited and decided to work on a smaller closed back ribbon that could goto 500hz instead.
That's a bit harsh!
Just because the thread has drifted from the original topic in the title doesn't make all the interesting discussion that followed a turd.
There are lots of threads on this forum with amazingly insightful discussion that bear little resemblance to what the thread started out to discuss - should they all be pruned or labelled as turds as well ?
..the thing is, most posts never really answer the question. (..I think I did once, a while ago.)
The original post isn't about the merit of a low distortion driver, rather the question posed is about ACTUAL DRIVERS that meet some form of objective low-distortion, be it linear or non-linear.
It's a DRIVER THREAD.
I expect to see at least every page of this thread mentionng at LEAST one DRIVER that is low in distortion in some respect. (..and perhaps even debating its merits/detractions.)
This poor thread got derailed right from the start.
Now a thread that actually answers the reason for it's existence - with multiple pages (assuming it lasts that long) and then is later derailed, yeah that's acceptable (..where the topic has "run its course). That's not a turd.
This one is a turd.
(..and a spectacular one at that given its length.)(..that's not to say that it doesn't deviate to something interesting occasionally (though its also likely most of this is re-hashed and can be found on at least one other thread - if not many others), rather that the thread has utterly failed to meet its purpose.)
..and a load of crap I've helped "polish" on several occasions.
(..I never said I wasn't complicit in this thread's derailment.)
-and yeah, this is a PRIME example of a thread that should have been turned-into a different thread (of its own discussing perceptual distortion). OR just altering the title. (..particularly given that there is almost nothing to speak-of with respect to actual drivers.)
(..I never said I wasn't complicit in this thread's derailment.)
-and yeah, this is a PRIME example of a thread that should have been turned-into a different thread (of its own discussing perceptual distortion). OR just altering the title.
(..particularly given that there is almost nothing to speak-of with respect to actual drivers.)You can generate yet another copy, delayed twice the time of the original.
More elegantly, you can feed the first delayed copy back into the main signal that goes into the DSP (digitally within the DSP code so you don't get the D-to-A-to-D distortions and delays - in the digital domain this is simply an add instruction), so it gets processed again, and thus cancels the floor bounce of the first inverted copy, which then gets fed back again, ...
This presumes the floor bounce is at a lower level than the original sound direct from the speaker, which I presume it always is.
It's not just about linear or non-linear distortion.
A good example is taking nearly identical tweeters, with nearly the same distortion profiles (linear and non-linear), and the same dispersion, but having different materials and then using DSP to create exceedingly similar "flat" responses and the same eq. (that abreviates any substantive defect) and then listen to the difference.
Though the sound will be very similar initally, over-time you'll likely hear some differences - certain "characteristics", that become *material differences.
*pun intended.
A lot of what I've heard in this regard are with respect to diaphram profile vs shape, edge damping of the shape (by the surround) - which is particularly dependent on the materials used, and finally - how a rear-chamber is "pathed". I'll also usually pick-up on which drivers have higer force in their gap depending on the difference between drivers (..and this is assuming both are at a reference output - so that they are substantivly equal).
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A 1dB shelf over the entire top octave ? Sure. If you know what you're listening for it can be heard quite easily.I was impressed by the objective approach of you until I read this! Seriously, you could pick out 1db difference between 10-20kHz????? Are you batman
I now realise that there are subjective objectivists and objective subjectivists, that goes for "lowmass" also! 0.5 db at 10kHz makes an average system go great...?
Not so much as a shift in tonal balance but a change in imaging and "realism".
When talking about a frequency response error you have to consider how many octaves it covers - if it only covers a small fraction of an octave a change in 1dB might not be audible, but if it covers multiple octaves (like adjusting the L-Pad on a tweeter) then even a fraction of a dB can be very audible as a change in imaging and presentation.
When I was younger I could hear up to 17.5Khz very well, (with a sudden and complete cutoff above that) now I'm in my 40's I think my cutoff frequency has dropped to 16Khz, but I can still hear a 1dB shelf increase or decrease above 10Khz quite easily.
Like a lot of critical listening that you pick up with a lot of tinkering with speaker designs and crossover tweaking it takes some practice to learn what to listen for but once you do it's there.
I also find that the closer a speaker gets to flat the easier it is to discern relatively small changes in frequency response that would be lost in the weeds if the speaker was grossly un-flat or unbalanced. So you find yourself making some very subtle and small adjustments that you previously wouldn't have bothered with or found necessary. By that point the small changes are not about achieving perceived tonal balance but optimising imaging and realism.
While I haven't found a need to slope the response down by 2dB like you have, (possibly due to different directivity of our respective tweeters and the fact that I'm crossing to a full range driver at 3Khz) I otherwise agree with what you describe - the balance of the treble between 1-5Khz and the top end 10Khz and up is very critical.
When I first completed building my all-new crossovers based on measurements and a lot of work in Virtuixcad to get the flat response, phase tracking etc that I showed earlier I hooked them up and listened for the first time - and marvelled at how neutral, clean and balanced they seemed right from the get go, but something wasn't quite right with the imaging, and I just couldn't put my finger on it at first. It was good but didn't provide a convincing illusion.
In fact it took me a week of listening and a bit of tinkering with active EQ before I started to realise that the balance of the treble wasn't quite right, but I still wasn't sure in what way it was wrong.
The presence region seemed slightly recessed, and I initially tweaked the L-Pad's for the tweeters to give them a half dB increase, but that seemed to make it worse if anything, and resulted in over bright symbols etc as you describe.
I quickly reverted the change as it became unpleasant to listen to on some recordings that already had a lot of treble and sounded slightly "thin" overall. (Yes, from a half dB increase across just 2.5 octaves) It was quite a bit later that I thought to increase the first cap in the high pass filter slightly - not much, I changed it from 3.4uF to 3.6uF.
According to virtuixcad (confirmed by measurement) that would lift the bottom end of the treble from about 2-5Khz by 0.4dB gradually tapering off to no effect by 10Khz.
0.4dB doesn't sound like much does it... but that 0.4dB change in slope was what was missing. The presence region now sounds nicely balanced - alive with a good sense of realism but not over bright and never harsh or fatiguing even on "bad" recordings. The change in slope has made the top end of the tweeter sound a little bit more laid back and "natural", but still with air and sparkle.
As for other frequency ranges, I disagree a bit when you say they're not as fussy - there are specific ranges where I find there is a similar degree of fussiness - the low mid-range 200-400 region is one.
My cabinets are 39cm wide so have their baffle step rollover point at about 280Hz, my initial baffle step correction was based on a theoretical 6dB at 280Hz, however that also didn't seem quite right when I first started listening.
I realised fairly quickly that the values I'd chosen in the sim were based on free standing measurements, but I only have the speakers about 40-60cm from the front wall.
Also the simulated design was based on a driver measurement that spliced together a gated measurement and a near-field measurement of driver and ports - and I'd had some difficulty splicing them together accurately so there was a little bit of uncertainty about just how valid the spliced response was, so I realised there could be an error here.
It was just slightly on the "wooly" side so I increased the baffle step coil value quite a bit to reduce the lower mid-range response centred around 250Hz by about 1dB. Too much as it turned out! It improved the imaging but with the speakers 60cm out from the wall it actually sounded a bit over bright and pushy...
I eventually settled on a coil value that dropped the lower midrange by 0.5dB from the original calculated response and that after a few weeks listening seems to be spot on. So even in that frequency range I found there was a very obvious change in the imaging and presentation for a +/- 0.5dB shift over only one octave.
I'm still pretty happy with how close the original theoretical crossover design was though - I haven't touched the baffle step attenuation level (resistor value) or the L-Pad for the tweeter from the original starting point, I've only tweaked two component values slightly to lift the low treble by 0.4dB and drop the lower midrange by 0.5dB.
As I said earlier, attention to detail is key in getting that last mile...
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Driver thread? OK. I want a very high performance road car, anyone have any good examples?
Typical answer: You don’t need one. Save your money. Besides without something good to directly compare it too your perceptions can be met by an inferior vehicle. But if not, with active suspension we can make your steel wheeled schitt speader feel like an Indy car.
Grrrrr...
Barry.
I would think that a larger mass producing the same frequency as a lighter one (all things equal) would have more "authority" (there is more mass changing direction).
But still as far as I can glean from the discussion, there isn't any difference in the transients. Meaning the actual timing of the vibrations are identical. To actually produce the frequency correctly any device needs to have the same transient.
It would seem that magnet strength and damping and everything else only matter to the extent that they produce a flat frequency response (assuming a linear behavior), unless I am completely misunderstanding something.
..a substantivly higher mass driver results in a different pressure for a given input (assuming same motor ..Et al.). There are of course, other changes as well. So it's never truly all-else-equal.
There are always differences - its just that most of them are averaged-out with a typical graphed display. Look at a driver's raw impulse - never two are identical (though you can get close depending on how similar the drivers are) and sometimes the same driver isn't even identical (with the same test).
Again, a freq. response is a "fudged" graph.
-remember, drivers are far from perfect devices - more so than just about any other area within the equipment "audio chain". (..a record stylus can give them some competition, but that's about it.)
There are always differences - its just that most of them are averaged-out with a typical graphed display. Look at a driver's raw impulse - never two are identical (though you can get close depending on how similar the drivers are) and sometimes the same driver isn't even identical (with the same test).
Again, a freq. response is a "fudged" graph.
-remember, drivers are far from perfect devices - more so than just about any other area within the equipment "audio chain". (..a record stylus can give them some competition, but that's about it.)
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The new Tesla Roadster that was sent into space seems like a really nice option.
If I recall correctly, the Wireless World article which mentioned titanium cone seems to offer some explanation. Probably have to dig into each article to find.
Ted had experimented with lots of different ideas in his life, I have collected a few variations and looked into some aspects using modern measurements.
Mark audio had some technology transfer from Ted, but I doubt they will talk about it since no improvement has been made. To generalize, the general shape of cone is the first step, the function is a hyperbolic family function as explained in one of his articles; then the hard anodizing thickness is what fine tunes the characteristic; finally, the surround needs to match.