difference between 2 Vifa drivers for line array

[tomcat9]

Well, I have been looking at these 2 Vifa drivers for sometime. I cannot decide which one is better. Or, maybe they are so much alike that it does not matter which one I use. I want to use them for line arrays, 16 per side. The biggest difference I see is a foam surround vs a rubber. Does anyone else see any differences? Pros or cons?

http://www.partsexpress.com/pe/showd...number=299-432

http://www.partsexpress.com/pe/showd...number=299-495


Thanks for any help.

Tom

[rcavictim]

Foam works good in matresses but nt so good in speakers. I refuse to put my hard earned $$$$ into the pocket of any manufacturer that still makes foam surround drivers after it has been common knowledge for at least a decade that this is a bad idea. Foam rots away.

For me the choice would be easy.

[tomcat9]

Thanks rcavictim.

Yes, I agree about the foam. Like I said, that was the big difference I saw. Other than that, they seem to be almost the same speaker. Most of the specs are very close to the same for both drivers.

T

[wrenchone]

The JBL drivers have a rubber surround, not a foam surround. This is much less susceptible to rotting. Foam is used on the back of the trim ring as a sealer, and there's not much of it. I just finished using 32 of these drivers to redo my old closed box speakers, so I have first-hand experience with them. They sound pretty good. If you are looking at doing open baffle line arrays, the 69 cent 4" Poineer drivers have a Qts which is more appropriate for open baffle operation. The JBL drivers have a Qts of only 0.27, which is more suitable for a ported system. You can put a resistor in series with each speaker to correct this, but it puts a dent in the SPL. Another possibility is a buyout speaker featured in the latest Parts Express sale bulletin. It is a 5 1/4" PP driver with rubber surround and a Qts of 0.8, perfect for open baffle. The part number is 299-145. I can't vouch for how they sound, but the price is certainly right at $4.94 each.

[wrenchone]

I want to clarify a bit. The 4 ohm JBL driver has a real rubber surround. The 6 ohm driver appears to have some sort of foam surround - I don't know what "treated foam" is.... I won't buy foam surround drivers, either.

[BillFitzmaurice]

When talking about quality drivers from respected manufacturers it's not what you make it out of, it's how you make it. The treated foams used today are not the same as the stuff from the '70s. Rubber tends to highly dampen the cone and often that leads to less HF extension. Your best bet is to look at the respective plots for each driver and pick the one that best suits your needs sonically speaking. If that turns out to be the foam surround job be prepared to do a surround replacement - in twenty-five years or so.

www.billfitzmaurice.com

[rcavictim]

Well now we know that Bill is part of this conspiracy.

Bill,

There was something I read somewhere that explained that the compliance of foam surround drivers is not uniform in both directions of travel and that it is related to excursion. I am foggy on the details but do specifically remember reading apparently this fault does not occur in corrugated paper or real rubber surrounds. Do you know of what I am referring to?

[tomcat9]

wrenchone,

I did notice the 5.25 in driver, 299-145, at parts express. That may work better because I am planning a closed box for this project. I like the closed box because the bass will roll off at 12db, and will have a pair of 12 in or 15 in woofers for the low bass.

[BillFitzmaurice]

There was something I read somewhere that explained that the compliance of foam surround drivers is not uniform in both directions of travel and that it is related to excursion. I am foggy on the details but do specifically remember reading apparently this fault does not occur in corrugated paper or real rubber surrounds. Do you know of what I am referring to?

I've seen that too, though not specifically relating to foam surrounds. It is possible for the suspension to offer more resistance in one direction than the other, though by only a very small amount, and it usually only affects response when the driver is pushed hard, right to the XMax.

Foam surrounds have gotten a bad rap as those of the first generation have by now all pretty much rotted away. Well, 40 years ago who knew? Well, they know now and have addressed the problems with the material. Foam is generally found in less expensive drivers, but that's not an all encompassing fact. Some very good drivers use foam because it can allow a higher frequency extension than rubber with all other factors being equal. And on the other hand my 69 cent Parts Express wonders have rubber. Does that make them better than a $30 Vifa? I tend to think not.