Need Advice for Choosing Fostex Drivers

[ezkcdude]

I'm new to this full-range stuff, but it seems like a great thing to try - no need for crossovers, right? So, just giving a quick look at the Fostex range of drivers, the FE Sigma jump out at me as the ones to try. I'd like to try the 8" FE208EZ - but I'm worried about the high-end response. What is the collective wisdom around here as far as pros and cons between the FE168EZ (6.5" Sigma) and the above mentioned FE208EZ? Also, for whichever full-range driver I end up using - do I still follow the same equations for box volume as if I were building a regular 2-way or 3-way? I've built two sets of 2-ways in the past, one using the now-discontinued 8" Aerogels (below right) and the other using 7" Scan-Speaks (below left). Thanks!

[Scottmoose]

The FE208ESigma is a Wide Range rather than a Full Range driver and is all the better for it IMHO. Rather than trying to do everything, Fostex concentrated on getting the LF & midrange as good as they could, and left the HF for drivers intrinsically better able to deal with it, i.e. supertweeters.

Kill zone for FR drivers is the midband -there are numerous definitions; best is still Bell Labs classification as ~200Hz - 4Khz. If you can push crossovers above and below this region, they are a) less obvious, and b) can be much simpler. The 208 is best crossed over to a supertweeter at roughly 10KHz -just capped off, & dialled in with an Lpad is fine. Most people, if it's loaded right, will be happy with the LF performance; those who aren't can add subwoofers to deal with everything below 40Hz.

I wouldn't be sticking them in regular BR boxes though. You'll get better results from different types of cabinets.

[blumenco]

there is am old japanese design using the 168EZ which adds a super tweeter (t96) AND two woofers in a separate cabinet. reputed performance is extremely good. suitable for use as a studio monitor even I think.

the 208EZ works well with a ribbon crossed in lower, around 5k or horn supertweet at 10 or thereabouts. think BIB. I am...

others in this forum have more experience with such. though. contact daniel mason. dmason.

the fostex sigma drivers are a good place to start and end the search for single driver exstacy. performance, refinement beyond their means.

Good luck!

Clark

blumenstein-ultra-fi.com

[AMV8]

Go for the wide range and not the full range driver - I agree with Scottmouse.

In my experience full range is difficult to achieve to a good enough standard. Wide range covering mid and lower treble and upper base is very achievable and can providen a very clear midrange.

I use a 5" wide range mid driver with no crossover. I find 5" about the best size for providing detail in the music. I find some detail is lost as the mid speaker gets bigger than 5". I augment my midrange with a 10" base unit with a single phase crossover on the base unit only and I use a high tweeter with a single phase crossover on the treble unit onky. As said earlier no crossover on ther mid unit.

I use sealed boxes of about the size you would expect. However as the mid range is now so detailed and clear I find it important to make the mid box VERY rigid.

Let us know what you buy amd I hope you enjoy them.

Don

[ezkcdude]

Thanks, for the advice guys. This won't be a project I start for several months, while I am getting ready for a move. However, I like to start thinking about these things well in advance. I may end up going with the FE168EZ, based on your comments. I just need to figure out which tweeter. I'm not sure I can still get the Focals, which I really love.

[AMV8]

Hi

Ideally you need to match the natural role off of the tweeter with natural role of the mid range. Otherwise design a single phase filter ( check the role off on the mid range to decide the best filter angle but I think you will find it is a single phase ) to add to the tweeter to match the role of on the mid range. If the tweeter you like goes low enough use that with a filter and then add resistors to obtain the amount of treble augmentation you need - my guess is very little.

Don