Sure. Ignoring everything else, one example of how you might get different results can lie in different motor designs.
Heavily over-simplifying, all drive units have harmonic distortion from various causes. Since this is just an example, we'll assume they're a nice flat line at some level below the fundamental output. However, we'll also now say there is a key difference between the two drivers: A has a superior motor design to B, and as a result, its basic harmonic distortion levels are lower. Fair enough so far?
Now let's pull a number out of the air & say that the two drivers each have a big cone resonance at 6KHz. Other than the obvious (a big cone resonance at 6KHz 😉 ) that does a few other things. One of them is that you see amplification of the individual harmonic distortion levels lower down the range, where you may actually be using the driver. They lie on sub-multiples of that resonance, so if you looked at the distortion plots, they wouldn't look like a nice flat line any more: what you'd see is a spike in the 3rd order HD level at 2KHz, a spike in the 4th order at 1.5KHz, a spike in 5th order at 1.2KHz & so on, above their original baseline levels. It's sometimes called distortion amplification because of that. So you can probably see from this one reason why you might then get audible differences between the drivers. If Driver A's basic distortion levels are sufficiently low in level, then even when it's amplified at certain frequencies by the cone resonance, those spikes may still be buried far enough below the fundamental output to be inaudible. Driver B, by contrast, which has a higher baseline level of distortion for xyz reason, might start to run into trouble as the spikes in level may rise sufficiently high enough to become audible.
That's just one [over] simplified example of course, but it may give you a bit of an idea about how these things can relate to each other.
Heavily over-simplifying, all drive units have harmonic distortion from various causes. Since this is just an example, we'll assume they're a nice flat line at some level below the fundamental output. However, we'll also now say there is a key difference between the two drivers: A has a superior motor design to B, and as a result, its basic harmonic distortion levels are lower. Fair enough so far?
Now let's pull a number out of the air & say that the two drivers each have a big cone resonance at 6KHz. Other than the obvious (a big cone resonance at 6KHz 😉 ) that does a few other things. One of them is that you see amplification of the individual harmonic distortion levels lower down the range, where you may actually be using the driver. They lie on sub-multiples of that resonance, so if you looked at the distortion plots, they wouldn't look like a nice flat line any more: what you'd see is a spike in the 3rd order HD level at 2KHz, a spike in the 4th order at 1.5KHz, a spike in 5th order at 1.2KHz & so on, above their original baseline levels. It's sometimes called distortion amplification because of that. So you can probably see from this one reason why you might then get audible differences between the drivers. If Driver A's basic distortion levels are sufficiently low in level, then even when it's amplified at certain frequencies by the cone resonance, those spikes may still be buried far enough below the fundamental output to be inaudible. Driver B, by contrast, which has a higher baseline level of distortion for xyz reason, might start to run into trouble as the spikes in level may rise sufficiently high enough to become audible.
That's just one [over] simplified example of course, but it may give you a bit of an idea about how these things can relate to each other.
But then again the fun is: if you remove the linear distortion in the stop band of the driver, the nonlinear distortion in the pass band disappears like snow under the sun.
I remember those units. The same people at Celestion, Wharfedale & KEF were the ones doing the SCanned Laser Plot juju. Late 80s early 90s is about the right time too. It was Peter who started using the magnesium powder stuff but there were cheaper & easier alternatives which he came up with too 😊
Were you working or consulting for KEF? They used far more external consultants than the other major UK makers in those days.
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You can't separate the two. Matching the cone edge to the surround is the key. We were the first to look at this with FEA/BEA to confirm what we saw with the Laser juju in an attempt to formalise what we already knew from experience.
The L15 aluminium cone would probably start to 'breakup' at a much higher frequency. Have you got a frequency response, impedance curve & waterfall for this and its paper sister?
Nope, but an old friend was for a short time. Oops, now I gave it away 🤐
Easier than magnesium I can grasp. Cheaper, well today any boulder gear shop could deliver huge loads at fair prices.
Yes, I'm aware you can't separate the two in terms of engineering: I'm simply pointing out that the root cause is the lack of rigidity at the edge of the cone rather than the surround itself. The latter attempts to control it, to greater or lesser success 😉 but isn't usually the culprit per se. We see the same thing in most 'soft' cone drivers relative to sister models with rigid aluminum / alloy cones.
Oh, it does. Much, as you'd expect. That's simply the point I'm making: the cone, being rigid to a much higher frequency, doesn't have that edge resonance of the softer unit lurking around the [mean] 1KHz area, so it's not actually the surround that's the cause of the problem with softer cone materials: it's just trying its best to control the [relatively] flobbery periphery.
FR & impedance plots are available on the Seas site:
https://seas.no/index.php?option=co...5rly&catid=44:utv-prestige-woofers&Itemid=461
https://seas.no/index.php?option=com_content&view=article&id=56:h1141-08-l15rlyp&catid=25&Itemid=347
It's a shame Seas discontinued the L15 & its larger L18 stablemate -stonkingly good drivers for the money when used properly. Not that the ER15 & ER18 are bad units -also excellent, & as semi-rigid units, they're a reasonable compromise.
PIoneer/TAD used that as a regular part of they're transducer development, starting somewhere between 78-81.
Part of the doped surrrounds, "epoxied" cones, non round surround etc. That came with the release of the TL-1601a that was released for sale in 1982.
The pics are extracted from they're 1984 brochure.
Also found in the 82 versions from Pioneer etc.
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SEAS Excel W15 series has several nice cones of different materials. Sadly price is high...
Paper/Nextel https://seas.no/index.php?option=co...8s-w15ly001&catid=49:excel-woofers&Itemid=246
Mg https://seas.no/index.php?option=co...8s-w15cy001&catid=49:excel-woofers&Itemid=246
Paper/Nextel https://seas.no/index.php?option=co...8s-w15ly001&catid=49:excel-woofers&Itemid=246
Mg https://seas.no/index.php?option=co...8s-w15cy001&catid=49:excel-woofers&Itemid=246
Yes and motor structures and construction is still very basic compared to many manufacturers, which does not help to justify the price.
They're consistency and QC is great though.
And still produced in Norway meaning high wages, 20% government taxation to the company, and insanely high energy prices to manufacture. And a lot of special "red tape", fees and taxation most countries manage to avoid.
Wavecor came out with some new transducers this year with a woven kevlar/carbon mix that look well behaved especially for the price.
In fairness to Seas, they might not chuck in the most advanced motor designs, but the actual quality of what they produce is still excellent, and their party-piece is that they tend to remain consistent with drive level -more so than a lot, showing that how well it's designed can be as important as the features themselves. The value in recent years has dropped (the Millennium tweeter for e.g. has doubled in price, & IMO is too much for what you get), but they & Scan are still two of my go-to manufacturers of conventional hi-fi drivers for that & other reasons.
I am trying to design a passive, first order filtered, open baffle system for some time. The drivers should be a woofer, a mid bass and a tweeter with crossings at about 200 Hz and 2 kHz.
The biggest problem with this concept is finding a mid bass with fair behavior above the piston range, so it should have nice cone-breakup characteristics.
Right now I am looking at the 5FE125, a 5” mid bass from Faital.
Very important is a fair behavior up to about 10 kHz.
Who has other suggestions for such a mid bass ?
The biggest problem with this concept is finding a mid bass with fair behavior above the piston range, so it should have nice cone-breakup characteristics.
Right now I am looking at the 5FE125, a 5” mid bass from Faital.
Very important is a fair behavior up to about 10 kHz.
Who has other suggestions for such a mid bass ?
1" drivers are clean up to 10kHz. You likely want it bigger tho, to get any output at 200Hz. And since you plan to use it beyond "dipole null" alias baffle size, I'm not sure if there is any other way to get forward than use 200Hz sized baffle. So, pick any driver that is clean uo there, like some few inch fullrange drivers like tymphany tc9 and similar.
The Faital's good; depending on sensitivity requirements you might want to look at the Seas MCA15RCY, ER15RLY, CA15RLY, or Excel W15RLY001 if money isn't tight; they're all relatively well behaved out to 10KHz. From Scan, the Discovery 15/4424G00 is also well behaved, a pricer option being the Revelator 15w/8530K00. Some others of course, but those are ones that immediately come to mind.
Yes, and they should have ?
Look at Norwegian currency devaluation since 2020, inflation, and 700-3000% increase in cost for energy. Increased private and company taxation ontop etc.
And of course increased prices on shipping (corona, and red sea/houthis).
Having to find alternate suppliers due to red tape concerning some countries and sanctions and so on.
A piston is only 'good' up to sorta kr = 2. Above that, it beams too much. Of course, if you are happy with zillion way systems and zillion dB/8ve xovers ....
For 'good sounding unit' the impedance wriggle isn't a yucky resonance (like you have on a rigid cone). It's the start of the well behaved 'shrinking' regime at higher frequencies.
It's what allows some small 2 way systems to outperform MUCH larger and $$$ multi-way systems in DBLTs
You got a Scanning Laser Doppler system? 😲
Cudgelling Jurassic memories, I DO know something about this and also the JBL system. One of the JBL engineers came to see us about a job and was surprised at what we were doing with ours.
You don't need a Scanning Laser Doppler system to investigate hard cone breakup or surround wobblies. But it is very useful if you are interested in controlled 'breakup'.
I don't think anyone else has published stuff on this in the intervening 40 yrs or so even though the instruments are now available commercially. If anyone knows more and can post, please do ... and please send me secret illegal copies of AES papers 😊
I used to have some animated plots of how 'good sounding' plastic & paper cones behaved from our instrument but I've lost them in several HD crashes
I keep stressing 'good sounding' cos that's what we're after. Rigid pistons don't give you that ... going back to Arie Kaizer, Philips's stuff from the late 70s. He was the first to use FEA to predict cone behaviour. I think he's got more recent stuff. IIRC, much of our stuff was published by Julian Wright in conjunction with PAFEC. He was the first to develop & use BEA for dis stuff in conjunction with Patrick Macy IIRC.
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If you look closely at the impedance curve of L15 you'll see the tiny impedance fluctuation just before the HUGE 8kHz resonance.
Here the poor old surround is certainly unable to damp the cone when it breaks up. 😊
The impedance blip isn't an indication of how bad the resonance. It just signals the start of the 'controlled' breakup on a 'good sounding' unit. Of course on a bad sounding unit ....
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It is possible to design a 3-way system where all drivers are used in their pistonic range, and always below a Ka=2 frequency. It does not require a zillion ways, it does not even require a 4-way... 🙂
Thanks for all your suggestions for a good mid bass, it will take some time to look at them all.
The system I am working on now consists of an open baffle with:
The midtone is not high-pass filtered since this would cost a lot of large and expensive components. For this reason the mid can not be an small full- range driver since these drives can not handle a lot of bass when not filtered. Therefore the mid has to be a mid bass driver.
The system I am working on now consists of an open baffle with:
- BIANCO-120-B150-01 12” woofer
- 5FE125 5” mid bass
- D2004/602200 Dome tweeter
The midtone is not high-pass filtered since this would cost a lot of large and expensive components. For this reason the mid can not be an small full- range driver since these drives can not handle a lot of bass when not filtered. Therefore the mid has to be a mid bass driver.