i see that you use titanium tweeters, since metal tweeters such as aluminum and titanium are known to reproduce "revealing" sounds rather than the "smooth" sounds of silk. but what are the advantages of an aluminum woofer, specifically over polypropylene, kevlar, and laminated paper? just curious as to your design theory.
We have been using in some of our models and doing design experiments on metal cones since 1985 and have a good depth of knowledge into their characteristics. To sum it up as briefly as possible, the main advantage is the cone rigidity, which stops the cone itself from distorting especially at higher output levels. The disadvantage can be resonance if the characteristics of the cone are not designed properly. We know how to do it properly and avoid any of the resonance issues. This means you can have smoothness and accuracy at all volume levels.
Ian Colquhoun
President & Chief Engineer
With all due respect to Ian, have you sought out the thoughts of speaker designers who use different material? I am sure, as with all things in the world, they would have reasons why they choose differing materials.
If you have, I would be most interested in hearing some thoughts.
Regards,
BBIBH
The conversation comes up about cone materials from time to time. Have had a few lengthy discussions about it in fact. For our own research we do a lot of testing with as many various cone materials as we can avail ourselves of. There are a number of factors to consider, not the least of which is price. Metal cones are more expensive than most of the materials available so we use a number of different cone materials ourselves in less expensive models. The cone material, assuming the other design factors about the speaker are equal, will normally have its greatest impact at higher volume levels. I am sure other designers have their own research into this subject but, as I am sure you can appreciate, we need to rely on ours.
Ian Colquhoun
President & Chief Engineer
Having been part of the audio landscape for some time, I can remember the numerous changes in materials from manufacturers. WIth regards to your older and newer lines, you once offered metal cone drivers in the best of the lines and subs. Now you offer in most models. What made you switch the AX3-M50/60 size model from the older material to metal? Is the performance that much greater?
Regards,
BBIBH
Yes, we started by using metal cones for all our upper end sub-woofer applications. The benefits are very high, especially at higher volume levels and lower frequencies. We worked for quite a period to get the metal cones operating perfectly through all frequencies and then introduced the Millennia line with all metal cones. The results are awesome in my opinion especially given the higher dynamic requirements that Home Theater requires.
Ian Colquhoun
President & Chief Engineer
In terms of my current AX3's I had replaced the drivers about 3-4 years ago because of problems. Would there be an advantage of moving to the new drivers? I would assume the drivers are not radically different in design.
If there was a problem with my current drivers, and I needed to have them replaced under warranty, would they be the newer drivers? I am not experiencing any problems...in case you are thinking the worst!
Regards,
BBIBH
Since the x-over, cabinet volume, and porting are all designed to be one with the components; I would not recommend changing your AX3 components. You could always upgrade the whole speaker to the M60s though.
Ian Colquhoun
President & Chief Engineer
Yes, I have looked at that. However, if I was to look at that option, I would likely aim higher.
Regards,
BBIBH
But aren't metal drivers a lot heavier than paper, kevlar, and polypropylene ones? Does this mean that metal cones aren't as quick and responsive as ones made of lighter materials above? I would think that this would make the bass sound mushy, especially in musical passages or theatrical scenes that require quick, responsive bass (i.e. trills and drum rolls in music; rapid-fire machine gun blasts in home theater). Please advise.
Good point, I am sure there is an answer
There are actually many factors that come into play when you are looking at the ability of the woofer to maintain control during bass reproduction at high volume. The mass of the cone is only one factor and in fact aluminum is not, in most instances, heavier than other cone materials, but it does have a better stiffness to mass ratio. Another very important factor to consider when trying to achieve clean reproduction of low frequencies at high volume is the motor control of the voice coil. Regardless of the cone material if the combination of the cone travel, voice coil length, and BL in the top plate gap are not sufficient to maintain control of the woofer the bass performance at higher volume levels will get very ugly. Thus in the design of the woofer itself we need to consider all of the factors surrounding bass distortion at high volume. This is an area where we have spent much time researching.
Ian Colquhoun
President & Chief Engineer