hi folks. This is a theoretical Question. IF I wanted to increase the Xmax in a given 12"woofer to increase its loudness how could I do that and still retain good response and quickness in its upper range.
Lets say I had the voice coil liquid or fan-cooled so heat dissipation wasn't an issue hence could use smaller voice coils if I so chose. Also lets say I had the best alnico or Neo magnets. For cone material I had beryllium,aerogel ,carbon fiber or even graphene at my disposal. and for coil wire had the best,copper clad square aluminium wire.
I'm thinking I would want a smaller voice coil to limit inductance and get good frequency range response and would want the lightest cone possible that could withstand breakup modes for excellent dampening,i.e, able to stop on a dime. Would this give me a direct radiator that could get louder than a conventional 12" off the shelf scandinavian woofer and not sacrifice its upper end frequency response. Thanks in advance.
Lets say I had the voice coil liquid or fan-cooled so heat dissipation wasn't an issue hence could use smaller voice coils if I so chose. Also lets say I had the best alnico or Neo magnets. For cone material I had beryllium,aerogel ,carbon fiber or even graphene at my disposal. and for coil wire had the best,copper clad square aluminium wire.
I'm thinking I would want a smaller voice coil to limit inductance and get good frequency range response and would want the lightest cone possible that could withstand breakup modes for excellent dampening,i.e, able to stop on a dime. Would this give me a direct radiator that could get louder than a conventional 12" off the shelf scandinavian woofer and not sacrifice its upper end frequency response. Thanks in advance.
It sounds like some of the issues that full range driver designers face. Many full range drivers have a smaller voice coil and trade some of their limited low end against efficiency. Many also use a well damped cone material (such as paper) to ease their way through the breakup region. It may cause issues but they can be dealt with to some degree.
Basically though, such drivers don't play both low and loud at the same time, and voice coil heat is reputed to affect sound.
In my opinion you will find the answers to what you seek elsewhere. Whether you re-evaluate your main needs, or decide to add another driver. Looking at your room and your speakers as a system, there might be a place that a crossover is less of a compromise than some of the changes you are proposing.
Basically though, such drivers don't play both low and loud at the same time, and voice coil heat is reputed to affect sound.
In my opinion you will find the answers to what you seek elsewhere. Whether you re-evaluate your main needs, or decide to add another driver. Looking at your room and your speakers as a system, there might be a place that a crossover is less of a compromise than some of the changes you are proposing.
The loudest 12" speakers I know of have a relatively small Xmax (and, of course, relatively limited bass response). It's keeping the voice coil in the magnetic field (mostly) that makes them loud.
Cooling isn't going to help at all with X max. X max is defined by voice coil geometry and is essntially limited to the voice coil overhang. That is, if you take the coil winding length and subtract the top plate thickness you will define how much excursion you will get before the coil starts to exit the gap (or the coil end starts to enter the top plate). At that point the motor drive drops dramatically and distortion skyrockets, so no greater excursion is available.
David S
David S
Thanks everyone for the responses. I should have said 12" conventional woofer and not a full ranger. I want a 12 or 15" that can do 20 herz louder than any off the shelf eton or scanspeak but very linear in all modes. How would I do that,money no object. What about an aluminium cone.Very light and pistonic throughout its range. It will ring somewhere but hopefully above crossover point. Would that be the way to go? the lightest and stiffest cone I could obtain with a long Xmax?
You know, there are very physical limits that govern how "loud" a driver can play given certain parameters, either having to do with the motor design or the loading of the driver in a "box" or "horn". You mentioned 20Hz, which is a pretty low frequency, so you are not likely to use a horn unless you are able to use a huge amount of space for it because the size of the horn mouth is related to how low in frequency the horn loading is effective. It could be done, however, it would be very large indeed.
So, the next best option is probably a large vented or passive radiator loaded design. If the tuning is around 23 Hz, there will be a minimum there in the driver excursion and you will get low excursion output to 20 Hz no problem.
The next thing you want to look at is the efficiency of the driver, the higher the better.
Finally, the driver Thiele Small parameters must be capable of being used to design a vented enclosure that is tuned to 23 Hz (for instance). You will need to look for a low Fs (e.g. around 20 Hz) and medium Q (e.g. around 0.4-0.5). There are several free speaker design programs that you can use to test out various scenarios.
Unless you want to spend tens of thousands having a high SPL driver designed for you, and then spend more getting a 100 pcs made for you, you are stuck with whatever you can purchase as a DIYer. Why are you obsessed with "better" performance than these brands that you mentioned... 😕
Here is a 12" driver you might consider:
http://www.creativesound.ca/pdf/CSS-Trio12-data-051009.pdf
It can probably do what you need, and is not expensive. It has a special design to the voice coil that makes the motor very linear. You will still have suspension non-linearities, though! Make sure to model the excursion...
Good luck with your high SPL goal!
-Charlie
Google "Maximum Efficiency of Direct Radiator Loudspeakers" (by Don Keele) and read it before doing anything.
Best of Luck!
Best of Luck!
If you really want to get serious about Xmax possibilities, maybe you need to talk to these people: www.makeitlouder.com
Frank
Frank
So they've found a driver that'll do 135dB at 5w input? Why, pray tell, aren't they being used in every PA system ever? You'd only need one or two.
Something's amiss there.
Chris
I'd definitely take a close look at the Rythmik Audio/GR Research Direct Servo Subwoofers:
SW-12-16FR
Rythmik Audio • Servo subwoofer products
You can't get the crowd inside the 3ft3 box. "Inbox" SPL is very high compared to whats radiated into a habitable space.
It's asking too much out of a single 12" woofer to do 20hz. You'll make some concessions with overall sensitivity. And you'll absolutly need passive radiators or a vent, reducing power handling near tuning where impedance and driver motion are both lowest.
What you probably want is a sealed box with its impedance peak around 20hz, and efficiency over 85db/w/m. Only then would I worry about volume displacement. AFAICT you need 18" or 21" woofers if you want ""meaningful"" 20hz sealed - or more than one 12" woofer. I believe the Exodus Maelstrom Gen 1 fit these criteria while also having very low inductance for smooth frequency response up high.
A driver that comes awful close to these criteria is the mach V UXL-18, but unfortunately its inductance reduces efficiency above 100hz. My understanding is that Mach V is working on a new 18" woofer with lower inductance. At that point the only issues I can see as a woofer are driver spacing/directivity, which may not matter much around a typical 3-way's crossover point near 250hz, and cone breakup.
A fifteen inch driver that may fit these criteria is the Dayton RSS390. That might be a driver that could really benefit from more throw. There are drivers with more throw but lack overall efficiency and low inductance(many subwoofers), and drivers with more sensitivity but not efficiency around 20hz (IE JBL W15GTI).
key phrase - "inside the box levels"
What you probably want is a sealed box with its impedance peak around 20hz, and efficiency over 85db/w/m. Only then would I worry about volume displacement. AFAICT you need 18" or 21" woofers if you want ""meaningful"" 20hz sealed - or more than one 12" woofer. I believe the Exodus Maelstrom Gen 1 fit these criteria while also having very low inductance for smooth frequency response up high.
A driver that comes awful close to these criteria is the mach V UXL-18, but unfortunately its inductance reduces efficiency above 100hz. My understanding is that Mach V is working on a new 18" woofer with lower inductance. At that point the only issues I can see as a woofer are driver spacing/directivity, which may not matter much around a typical 3-way's crossover point near 250hz, and cone breakup.
A fifteen inch driver that may fit these criteria is the Dayton RSS390. That might be a driver that could really benefit from more throw. There are drivers with more throw but lack overall efficiency and low inductance(many subwoofers), and drivers with more sensitivity but not efficiency around 20hz (IE JBL W15GTI).
key phrase - "inside the box levels"
Last edited:
- Status
- Not open for further replies.