[Kevin Haskins]

Kevin,

Are you saying that the response at the sweet spot should be roughly flat because the rising response counters the off-axis drop-off at the angle towards the listening position?

So I started looking around for similar drivers hoping to find a flatter response and I am not seeing them.
This has led me to the thought that large wide-range drivers simply have a flaw in their response that requires correction on an open-baffle.

I am hopeful that a countour filter will fix the problems that I am hearing with this driver.

On the other hand, I love the open baffle bass I am getting out of a cheap Warrior 15".

In a typical room what you hear at the listening position is dominated by room reflections.   The off-axis response of a system has a profound effect on what you hear.    The on-axis measurements are useful only for design, and even then, you have to understand that its just a limited set of data.   You need much more information to categorize the "sound" of a loudspeaker.   You would need to look at the total power response and then distortion levels (and composition) all at different power levels & frequency ranges.   

To make it even more complicated, you then have to understand how people hear and what factors are most "audible".   Its a real can of worms to say the least.   

Filters are great.... they allow you to play around with the response but they are just a tool.    Their limitations are such that they can only control things like linear distortion (frequency response/phase) but they don't allow you to directly control non-linear problems (although you can avoid exciting a driver by notch filters and such).   They also cannot change the physical properties of the driver being used.   They cannot make a large driver have a wide dispersion pattern up high.   They cannot make a tweeter woof nor a woofer tweet.   

Anyway... I'm rambling.   The answer to your question is "I don't know".    There are too many variables involved for me to know what your hearing.    I've listened to a pair of the B200s at the last DIY event and they sounded pretty smooth.   Of course we where outdoors and amplification & source material can really change our perception of the "sound".

   

 

[miklorsmith]

Hey Jim, thoughtful ideas.  Considering that Roger's previous generation didn't have near the functionality that the new one does, I'd be surprised if he couldn't make that expanded range an option even on the current offering.

Since I just replaced my "hot" Fostex 206Es with 1st gen. Omega hemps which are smooth customers, I don't know how "great" my observations will be with the EQ in a Box.  I will do my best though.

Hopefully Roger will chime in with his thoughts about starting the curve higher up - I think this is a fantastic idea and increased flexibility could only make it better.

[jrebman]

Mike,

I am building a small FE-127 based speaker (actually the speaker is built) and will be installing some modified FE-127s in them as soon as they arrive from another planet .  The speaker design incorporates a parallel R-L  compensation network in series with the positive lead of the driver, but because I eventually want to use a 1.5 watt amp, I'm doing away with the filter and am going with a passive line-level filter on the input of the amp to accomplish the same thing.  This particular speaker also will have the speaker wires crimped and soldered directly to the speaker terminals bypassing the binding posts, for an even more pure connection.

Paul Joppa of bottlehead fame had an article on passive line level filters which is pretty easy to find, and which is the basis for my filter.  Add a pot to that circuit and you have something you can adjustsome parameters with.  Once you find the best spot for your situation, carefully disconnect the pot(s) and measure the resistance, get a couple of resistors of that value, hard wire them in, and you have the right filter for your speaker.  That's the theory, it will be interesting to see how it pans out in the real world.

-- Jim

[miklorsmith]

Nice!  My bass reflex boxes have the speaker cable soldered directly to the driver as well.

[markC]

JeffB,
Do try the LR circuit-I think that you will be pleasantly surprised. Don't forget to also add a zobel behind the LR. I think that once you try the B200's with this circuit in place, like me, you won't want to remove it.
I use a .68 mH and a 6.8ohm set-up with a 13uf and 6.2 ohm zobel.
Then again, I've also added a tweeter and a x-over aa

[planet10]

Paul Joppa of bottlehead fame had an article on passive line level filters which is pretty easy to find, and which is the basis for my filter.

http://www.t-linespeakers.org/tech/bafflestep/passive-BSC.html

dave