Hi Teh, excellent post. 
Here's my reply :
- High BL (most important)
- Stiff diaphragm
- Underhung motor
- Low Rms
- Xmax not too big
- High BL/Mms (in order to match the Accuton)
- High Cms (less important)
As you can see, no Fs (well, let's say Fs <40Hz, but that's all)
Yet the main problem for us isn't just to be able to reproduce 250Hz "well". The problem is to be able to reproduce 250Hz "well enough" to match the extraordinary characteristics of the C90-T6. If you put a good bass driver with a good mid, you'll feel everything is consistent. But if you put a good bass driver with an excellent mid, you'll feel something's wrong. We need a bass driver capable of totally awesome performance at 250Hz (we're talking "fidelity", not SPL of course). That's the key point for us.
OK, long story short... take a look at our final shortlist (as of today) with most of the T/S parameters (it's in french but you'll understand). Drivers are split up in 4 categories :
- Upper drivers : our current favourites (BD15, TADs)
- Light grey drivers : they look good but they are too expensive (1500AL) or we simply can't find them (Iconic).
- Dark grey drivers : looks like they aren't manufactured or sold anymore.
- Light green drivers : other relevant choices
There you have it folks : the best of the best for us (as of today). You guessed it, my personal favourite is the BD15, but nothing's decided yet.
PS : if Mms is so very important, then the TADs are not so good (look at their Mms compared to all the others...). But of course Mms is not everything. The TADs are more woofer-oriented than the other drivers : that's why their Mms are higher and their Fs are lower.
Here's my reply :Yep.
Ideally, yes. If there's a single speaker good enough at both 20Hz AND 250Hz to match the Accuton at Fx, then I'll take it. Otherwise, what I'm trying to say is that if that speaker doesn't exist, THEN we will make concessions at 20Hz (and not at 250Hz), and put a real mono subwoofer below 40Hz for instance.
It's not that simple IMHO. Beyond theory, the truth is a 18" can rarely go to more than 150Hz before fragmentation begins. A 15" should be capable of going up to 250Hz without problems. So since we're looking for the largest speaker capable of doing just that, the 15"'s look like the perfect choice. We are also open to 12" (mostly because of their ability to have higher compliances (Cms) than 15"), but in that case that would mean 2x12" to reduce excursion. So to put it simple the possibilities would be : 1x15" or 2x12".
Why care about Xdam ? We don't intend to even attain Xmax.
Yes, there will be a lot of digital eq. The problem here is not the sound level @ 30Hz or below (most speakers can do 105dB even with a very strong eq, no problem), but the excursion (most of them go quickly over Xmax). Of course a low Fs can help solve this problem.
I do agree, Mms and stiffness are VERY important for us. But what about BL ? You don't seem to take it into account, and for us it's an ESSENTIAL parameter.
VAS is quite proportional to Cms, and we are also aiming at high Cms (or at least not too low - this is not an essential parameter, it's just the icing on the cake). We are also aiming at low Rms.
Yes of course. That's why we are considering 2x12", not just one.
Again, yes, no doubt about it.
I don't think so. For us, the parameters importance for our application would be as follows :
- High BL (most important)
- Stiff diaphragm
- Underhung motor
- Low Rms
- Xmax not too big
- High BL/Mms (in order to match the Accuton)
- High Cms (less important)
As you can see, no Fs (well, let's say Fs <40Hz, but that's all)
Yes, efficiency is important, but all of the drivers we're considering are well above 95dB.
I must admit that I don't know. I'll take your word for it.
Enclosure size is not a problem at all. Performance is the only goal. Sealed enclosures allow for better group delays / better impulse response than BR enclosures. The price to pay for this is higher excursions below 50Hz, i.e. more distorsion don't you think ? To sum it up, can we really say that sealed enclosures are best regardless of the driver ? Some people think that we need to choose the driver first, THEN the right enclosure for it.
These are real subwoofers indeed ! OK, let's forget the 6174 (much too expensive !).The 1602 costs $625 and... yes, it's already on our final shortlist.
I think you get most of the picture.
Yet the main problem for us isn't just to be able to reproduce 250Hz "well". The problem is to be able to reproduce 250Hz "well enough" to match the extraordinary characteristics of the C90-T6. If you put a good bass driver with a good mid, you'll feel everything is consistent. But if you put a good bass driver with an excellent mid, you'll feel something's wrong. We need a bass driver capable of totally awesome performance at 250Hz (we're talking "fidelity", not SPL of course). That's the key point for us.OK, long story short... take a look at our final shortlist (as of today) with most of the T/S parameters (it's in french but you'll understand). Drivers are split up in 4 categories :
- Upper drivers : our current favourites (BD15, TADs)
- Light grey drivers : they look good but they are too expensive (1500AL) or we simply can't find them (Iconic).
- Dark grey drivers : looks like they aren't manufactured or sold anymore.
- Light green drivers : other relevant choices
There you have it folks : the best of the best for us (as of today).
You guessed it, my personal favourite is the BD15, but nothing's decided yet.PS : if Mms is so very important, then the TADs are not so good (look at their Mms compared to all the others...). But of course Mms is not everything. The TADs are more woofer-oriented than the other drivers : that's why their Mms are higher and their Fs are lower.
Ok, all distortion figures are calculated at maximum attainable power levels, correct?
If we can agree on that, then, if it takes 30% less power to achieve the same output for a 15" vs a 12" then is this not equivalent to comparing apples and oranges?
This is like a big man lifting 300lbs verses a small man. From a physics standpoint it is just much less effort for the big man, True?
If this can be agreed upon then nobody can say that a 12" can produce like an equally built 15", that is at low frequencies, right?
All the parameters in the world cannot overcome the limitations that physics presents us. Then we want to know why some 15's can produce better at higher frequencies than others and this cannot be a function beyond it's ability for speed (light weight, stiff) combined with the stiffness of the diaphram, right, not right? So, if you want low frequency response combined with higher frequency response, in leui of IM distortion, then it only makes sense this can only happen with the lightest, stiffest, reasonable membranes, right?
The length of the coil, the circumference of the coil, the size of the gap, nor the motor design can overcome this problem, can it?
You know, taken to extreme, the point can be made; can a 15" diagram accurately reproduce frequencies of over 5k? Of course it cannot so where is the limit? What creates this limit? How ugly is it to push this limit, what is the actual "limit"? So it is that what we're speaking of has it's extremes, so what extremes are we fighting and what extremes can we get by with? Isn't that the basis of this topic?
People love to speak of a driver's distortion capabilities (and observe the "graphs") yet, if you're pushing it that far, do you really think you've done the design process justice?
The point is, pick a driver that can easily perform within your requested perameters. Know what it is you're trying to achieve. When you look to go outside of those parameters you are inviting problems and you are inviting a troublesome problem to solve distortion characteristics relative to any driver's physical constraints. So, the issue is that size does indeed matter. Why fight it?
If you want a driver to cover the bottom octaves then, by golly, get one that does it! That means a low Fs and adequate X-max. If you want it to reach farther up the octave scale you had better know that it must do this with speed and, therefore, diaphram stiffness is of absolute significance, therefore MMs and the material matters. Paper is generally unable to be made stiff enough for higher frequencies. Cabon fiber reinforcement is seriously stiff and can "reach" farther than others. PP is soft a and loosy material and Aluminum rings (including other metals). So, your choices really, really become terribly diminished.
I've read many that say no other diaphrams are as "Tactile" as Carbon fiber and I would agree. Light weight, fast and dynamic is their forte. For this kind of application there are likely no others that can do it as well.
There is only one driver in the world that is a 15" carbon fiber, Low MMs, low Fs, high X-dam, high motor strength, superior surround like the TAD TL-1602. For this application, regardless of price, there is no other that can actually do what is being asked of it. On top of that you have the Alnico motor, still considered the finest driver magnet system in the world for drivers of this size.
Much of this stuff is opinion and suggesting options but when you start peeling away the detriments of other drivers (deductive reasoning) eventually you are left with only one. It just depends on what you're trying to accomplish.
Based upon Jose's parameters I see only one that can make the grade.
As always, just an opinion and far from always right?
If we can agree on that, then, if it takes 30% less power to achieve the same output for a 15" vs a 12" then is this not equivalent to comparing apples and oranges?
This is like a big man lifting 300lbs verses a small man. From a physics standpoint it is just much less effort for the big man, True?
If this can be agreed upon then nobody can say that a 12" can produce like an equally built 15", that is at low frequencies, right?
All the parameters in the world cannot overcome the limitations that physics presents us. Then we want to know why some 15's can produce better at higher frequencies than others and this cannot be a function beyond it's ability for speed (light weight, stiff) combined with the stiffness of the diaphram, right, not right? So, if you want low frequency response combined with higher frequency response, in leui of IM distortion, then it only makes sense this can only happen with the lightest, stiffest, reasonable membranes, right?
The length of the coil, the circumference of the coil, the size of the gap, nor the motor design can overcome this problem, can it?
You know, taken to extreme, the point can be made; can a 15" diagram accurately reproduce frequencies of over 5k? Of course it cannot so where is the limit? What creates this limit? How ugly is it to push this limit, what is the actual "limit"? So it is that what we're speaking of has it's extremes, so what extremes are we fighting and what extremes can we get by with? Isn't that the basis of this topic?
People love to speak of a driver's distortion capabilities (and observe the "graphs") yet, if you're pushing it that far, do you really think you've done the design process justice?
The point is, pick a driver that can easily perform within your requested perameters. Know what it is you're trying to achieve. When you look to go outside of those parameters you are inviting problems and you are inviting a troublesome problem to solve distortion characteristics relative to any driver's physical constraints. So, the issue is that size does indeed matter. Why fight it?
If you want a driver to cover the bottom octaves then, by golly, get one that does it! That means a low Fs and adequate X-max. If you want it to reach farther up the octave scale you had better know that it must do this with speed and, therefore, diaphram stiffness is of absolute significance, therefore MMs and the material matters. Paper is generally unable to be made stiff enough for higher frequencies. Cabon fiber reinforcement is seriously stiff and can "reach" farther than others. PP is soft a and loosy material and Aluminum rings (including other metals). So, your choices really, really become terribly diminished.
I've read many that say no other diaphrams are as "Tactile" as Carbon fiber and I would agree. Light weight, fast and dynamic is their forte. For this kind of application there are likely no others that can do it as well.
There is only one driver in the world that is a 15" carbon fiber, Low MMs, low Fs, high X-dam, high motor strength, superior surround like the TAD TL-1602. For this application, regardless of price, there is no other that can actually do what is being asked of it. On top of that you have the Alnico motor, still considered the finest driver magnet system in the world for drivers of this size.
Much of this stuff is opinion and suggesting options but when you start peeling away the detriments of other drivers (deductive reasoning) eventually you are left with only one. It just depends on what you're trying to accomplish.
Based upon Jose's parameters I see only one that can make the grade.
As always, just an opinion and far from always right?
@Richard :
--------------------------------------------------------------------
@Teh : here's an answer from Hub, a friend of mine who is an active team member. Like I've already said, he's a lot more experienced than myself. I consider him as a true, non-professional, impartial and quite cartesian electro-acoustics expert. His opinion is very valuable to me, and it will surely count a lot for the final driver choice.
--------------------------------------------------------------------------
With an enormous Mms and a tiny little BL ? No way !richard_majer said:
--------------------------------------------------------------------
@Teh : here's an answer from Hub, a friend of mine who is an active team member. Like I've already said, he's a lot more experienced than myself. I consider him as a true, non-professional, impartial and quite cartesian electro-acoustics expert. His opinion is very valuable to me, and it will surely count a lot for the final driver choice.
Ok, all distortion figures are calculated at maximum attainable power levels, correct? Not always, depends on the given measurement of the manufacturer, tester...but let's say OK for what follows.
If we can agree on that, then, if it takes 30% less power to achieve the same output for a 15" vs a 12" then is this not equivalent to comparing apples and oranges? OK
This is like a big man lifting 300lbs verses a small man. From a physics standpoint it is just much less effort for the big man, True? Let's say true.
If this can be agreed upon then nobody can say that a 12" can produce like an equally built 15", that is at low frequencies, right? Right, because the 15" moves more air vs the 12" for what you means "effort".
All the parameters in the world cannot overcome the limitations that physics presents us. Sure. Then we want to know why some 15's can produce better at higher frequencies than others and this cannot be a function beyond it's ability for speed (light weight, stiff) combined with the stiffness of the diaphram, right, not right? So, if you want low frequency response combined with higher frequency response, in leui of IM distortion, then it only makes sense this can only happen with the lightest, stiffest, reasonable membranes, right? A stiff membrane is one key of this problem; the other is a high BL/mms ratio; mms in itself isn't of any importance in this matter, except about higher stored energy in heavier membranes if fx is chosed out of the pistonic range of the driver.
The length of the coil, the circumference of the coil, the size of the gap, nor the motor design can overcome this problem, can it? Overcoming this problem, no...but regarding that VC/motor designs are part of BL value, they have indeed an influence.
You know, taken to extreme, the point can be made; can a 15" diagram accurately reproduce frequencies of over 5k? Of course it cannot so where is the limit? What creates this limit? How ugly is it to push this limit, what is the actual "limit"? Physically speaking, the only one is the directivity of such a large cone. So it is that what we're speaking of has it's extremes, so what extremes are we fighting and what extremes can we get by with? Isn't that the basis of this topic?
People love to speak of a driver's distortion capabilities (and observe the "graphs") yet, if you're pushing it that far, do you really think you've done the design process justice?
The point is, pick a driver that can easily perform within your requested perameters. Know what it is you're trying to achieve. When you look to go outside of those parameters you are inviting problems and you are inviting a troublesome problem to solve distortion characteristics relative to any driver's physical constraints. So, the issue is that size does indeed matter. Why fight it?
If you want a driver to cover the bottom octaves then, by golly, get one that does it! That means a low Fs and adequate X-max. If you want it to reach farther up the octave scale you had better know that it must do this with speed and, therefore, diaphram stiffness is of absolute significance Yes, therefore MMs No and the material matters Yes, about stiffness. Paper is generally unable to be made stiff enough for higher frequencies Correct . Cabon fiber reinforcement is seriously stiff Yes and can "reach" farther than others. PP is soft a and loosy material Yes and Aluminum rings (including other metals) Yes, indeed, but far higher than 250Hz . So, your choices really, really become terribly diminished.
I've read many that say no other diaphrams are as "Tactile" as Carbon fiber and I would agree. Light weight, fast and dynamic is their forte. For this kind of application there are likely no others that can do it as well, except metal, ceramic and some kevlar/nomex sandwiches ones.
Based upon Jose's parameters I see only one that can make the grade. Ben voyons (in french in the text, haha)
--------------------------------------------------------------------------
Then I simply ask : why ? what are your precise criteria for choosing or excluding a driver for a sealed enclosure ? Thanks.tinitus said:So lets push it even further and demand the same in a closed box .... leaves out another few
Thats very simple
I can understand using a big driver in a 3way, that needs some bottom end help from a BR, to be able to choose a driver with good midrange, but still enough lowend without a sub
But having a midbass driver that needs BR help to get down to 40hz, and still in need of a sub .... in high power PA, yes ... but in home hifi ... I dont think that should be necessary and would consider it a flawed design
I think we very often are messing around a bit
There are special designs that have compromises necessary to use small tube amps, and thats fine
I would think the Iconic may be one of those
But some of the compromises in such designs may not be necessary or even wanted when strong solid state amps are in use .... different design criteria, different compromises
I can understand using a big driver in a 3way, that needs some bottom end help from a BR, to be able to choose a driver with good midrange, but still enough lowend without a sub
But having a midbass driver that needs BR help to get down to 40hz, and still in need of a sub .... in high power PA, yes ... but in home hifi ... I dont think that should be necessary and would consider it a flawed design
I think we very often are messing around a bit
There are special designs that have compromises necessary to use small tube amps, and thats fine
I would think the Iconic may be one of those
But some of the compromises in such designs may not be necessary or even wanted when strong solid state amps are in use .... different design criteria, different compromises
I think you didn't understand me. I have no problem with sealed boxes ! All I was asking is : if you base yourself on my shortlist, and since you say "leaves out another few", then what drivers would you leave out just because you consider them to be incompatible with a sealed enclosure, and WHY exactly ? (based on precise criteria if possible). Thanks.
All I was asking is : if you base yourself on my shortlist, and since you say "leaves out another few", then what drivers would you leave out just because you consider them to be incompatible with a sealed enclosure, and WHY exactly ? (based on precise criteria if possible). Thanks.Sorry, stupid comment on my part
Still, I think I have tried to explain in above answer - nothing against BR
But confusion is still there - you dont seem to have decided on your design criteria .... well you know which parameters you want, but that driver may not be of this world .... well maybe the Fertin with electromagnet
BTW .... it could be interesting with the 6" Thiel in a fronthorn .... then it might even couple nice to a 18" (or TAD in BR)
But where to place the tweeter ... between bass and mid ?
But very expencive horns .... make one ??
http://www.aer-loudspeakers.com/eng/horn-e.htm
Yes a good compromise might be a TAD in BR, and nothing further and maybe xo a bit higher than 200hz, and it would give you a nice 93db sensitivity, with BSC
Still, I think I have tried to explain in above answer - nothing against BR
But confusion is still there - you dont seem to have decided on your design criteria .... well you know which parameters you want, but that driver may not be of this world .... well maybe the Fertin with electromagnet
BTW .... it could be interesting with the 6" Thiel in a fronthorn .... then it might even couple nice to a 18" (or TAD in BR)
But where to place the tweeter ... between bass and mid ?
But very expencive horns .... make one ??
http://www.aer-loudspeakers.com/eng/horn-e.htm
Yes a good compromise might be a TAD in BR, and nothing further
and maybe xo a bit higher than 200hz, and it would give you a nice 93db sensitivity, with BSC
tinitus said:
Iconic is continuing the manufacture of one of the most popular 15 inch drivers of all time: the Altec 515 series. I agree that it is a special design, but not for the reason you give. It was originally designed at a time when tubes were the only choice, but it was not built to cater to small tube amp users. It was built for the demanding movie theatre market. It may not be best suited to Jose's application, but it isn't a compromised design.
I can certainly understand why Jose wishes to use a driver similar to this in his application despite everyone's criticisms of his choices. The on-paper specs just don't tell the whole story. A 6 or 8 inch driver makes the 100-200Hz region sound miniaturised and anemic by comparison.
But my own feelings about TAD drivers .... I would never buy used drivers
Why .... I am am not quite confident with alnico drivers used with high power amps .... on "overdrive" you can destroy the motor/magnet assembly
Shure, it can be magnetized again .... but fore high power designs I might prefer NEO magnets
http://www.precisiondevices.co.uk/showdetails.asp?id=77
Why .... I am am not quite confident with alnico drivers used with high power amps .... on "overdrive" you can destroy the motor/magnet assembly
Shure, it can be magnetized again .... but fore high power designs I might prefer NEO magnets
http://www.precisiondevices.co.uk/showdetails.asp?id=77
Hi,
If your looking for 15" underhung speakers Altec 416-8B and
Altec 515-B and G and also the famous Altec Duplex 604
model 604 8H-II are being manufactured by Great Plains Audio.
http://www.greatplainsaudio.com/
These are brand new . If you go on their site you will find HF
compression drivers also.
..............................................................................
If your looking for 15" underhung speakers Altec 416-8B and
Altec 515-B and G and also the famous Altec Duplex 604
model 604 8H-II are being manufactured by Great Plains Audio.
http://www.greatplainsaudio.com/
These are brand new . If you go on their site you will find HF
compression drivers also.
..............................................................................
Attachments
Anybody know what this is ... says SLS-400 ????
http://www.bmm-electronics.com/Product.asp?Product_ID=4295
http://www.bmm-electronics.com/Product.asp?Product_ID=4295
)This Beyma 12G40 looks pretty good and affordable as a midbass
http://profesional.beyma.com/ENGLISH/producto.php
http://www.bmm-electronics.com/Product.asp?Product_ID=3603
http://profesional.beyma.com/ENGLISH/producto.php
http://www.bmm-electronics.com/Product.asp?Product_ID=3603
tinitus said:
This Beyma would have an overhung voice coil and not a underhung one . The reason is simple the X MAX is 6mm or .25"
Altec makes these through GPA in the 3000 series as direct radiators. They are excellent speakers but as HI FI speaker not Dynamic as the older ALTEC models with underhung voice coils.
.............................................
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.