[scorpion]

JohninCR,

The reason Visaton claim 3.5 mm X-max comes from this measurement with Laser and DC.
The link is here to the Visaton forum: http://www.visaton-lautsprecher.de/vb/showthread.php?s=29f85ea11e226cfb5931c8dec803a7ed&threadid=6320&perpage=15&pagenumber=2

/Erling

[Polarbear]

John

I'm trying to visualize your description. Is it like this:





BJørn

[JohninCR]

I wish I could read German.  I'm sure it would be interesting.  They don't call it
Xmax though, but instead "Maximum linear displacement".  The standard convention
for comparing drivers is Xmax, which would be 2mm.  Just as typical pro drivers can
be driven past Xmax, so can the B200.  I've seen mine flopping around far more than
the 2mm, but once the VC begins to go past the magnetic gap in an underhung
design, it is less than optimum since it is under less control.  At least I haven't heard
mine banging against the back plate like a cheap driver would in the same circumstances.
It still takes only a "handful" of watts to get there, whether you call it 2mm or 3.5mm.

[JohninCR]

John
I'm trying to visualize your description. Is it like this:



BJørn

Bjorn,

Here's a crude top view drawing of the transformation of mine.  The top one sounded
terrible, so I filled in the inside corner and rounded the front corner.  I retained the
narrow front profile, hid the back of the driver, retained the effective width of a 19"
wide flat baffle in a 10" visual width. 

The transformation went through numerous stages, and I started with the back to get
the "open sound" of a flat baffle.  That even included an ultra widening of the driver
cutout on the back side, because the FE108EZ's have a very shallow opening for the
rear driver radiation.

Then once I obtained the large radius front corner rounding, imaging improved markedly.
It's the first time I've clearly heard an audible difference related to edge diffraction.  It
took quite a bit of research to figure out why.

[Wind Chaser]

John,
I don't know what you're laughing about.  You added an extra driver
to help with the bass, and you'll be adding more later too, once you're
on to your next greatest thing since sliced bread.

Yes I did add a second driver - on the small flat baffle shaped like a trapezoid.  More on that to follow.

BUT on the first baffle I made with wings using one driver, there was certainly no need / desire for more bass.  I clearly stated that I was getting plenty of bass, almost to the extent of it being excessive.  Had I been able to live with the compromised soundstage resulting from the wings, I’d be very content with the bottom end output of just one B200 in OB.

However, with the small flat baffle shaped like a trapezoid I use a second B200 crossed over at about 70Hz using very little gain to fill in the bass.  Obviously a smaller baffle isn’t going to produce as much bass as a bigger baffle.  The reason I prefer the smaller flat baffle shaped like a trapezoid is because it produces a vastly superior soundstage with much better imaging.  The differences in this respect are night and day!

One thing I can’t stand is fat bloated bass.  Most audio enthusiasts rarely, if ever at all listen to live music without amplification.  Hence they are clueless as to what REAL or NATURAL bass sounds like…  To each is own.


John

[BrassEar]

Thanks Richard for such a detailed and informative explanation.

You have motivated me to investigate this path of musical satisfaction - a path I have pursued for over 30 years now. With Tripath amps, tubes, and NOS battery-powered DACs I am very close, maybe the B200 in OB will push me over the edge!

The journey thus begins. Any tips on cutting through the chase? In other words, is there a site to get up to speed on the B200 OB latest thinking as opposed to reading through 118 pages of posts here?

Thanks again for leading the pack with Dr. Mason.  You guys blow away most paid advertising audio publications and you are sharing the love of your hobby for free.  Keep it up please! 

[JeffB]

My B200s arrived yesterday.
Where can I find a good connector to connect to the positive and negative terminals on the B200?
Does this connector have a name and size?

e-speakers.com included a very nice Visaton brochure detailing the whole line of Visaton products.

I found these, but they seem less than ideal to me.
http://www.wiringproducts.com/?target=dept_44.html

[mcgsxr]

I used the push on terminals, for some Cat5e that I use from driver to binding posts.

Not elegant to be sure, but it works.

I think most would solder, but I am a fraidy cat...

[JohninCR]

Until you're sure of final form, I'd recommend against soldering, because
you're likely to have them in and out a number of times.  I use Cat5 and
Cat6 and I just give the bare wire a quick wrap around the terminal with
a small stiff alligator clip for added security.  I find it easier than the push
on connectors, which inevitably get too tight or too loose.

Tnuts are the way to go for mounting the driver.  You can only dodge the
screwdriver through the driver bullet for so long, and an allen wrench feels,
and is, so much safer.

[markC]

I'm Corked. Finished a full veneer front and back of 4 mil cork. Not what I had hoped for... Very smooth sounding, but still has the sting in the upper mid's-obviously now, higher in frequency than I initially thought. Next up is to varnish the cork, which hopefully brings a more pronounced lower mid and protects the cork. If that is unsatisfactory, I will scrap the cork baffles and go with Russian birch ply. Not that the ob's sound bad, just not quite "there" yet.
This is my take and my opinion...if you are about to begin the journey with the b200, don't expect to find the Holy Grail. It does so much right...as in open sound and extreme dynamics and 3-d presentation, but there are also areas that need attention. I, personally,could not be happy without bass reinforcement. The bottom end is there, but well down in extension, If, however, you add some bottom end that can blend with the reduced output of the b200, the result is very good. Mids are very realistic and open, allowing a vision into the recording. Highs are well extended, and on quality recordings I am not left wanting more. I probably can't hear above 18k and I assume most of us are in the same boat. Spacial cues and so forth may come into play here, but to me they image quite well. These drivers seem to be able to handle a lot of power and I have yet to bottom them out. At high volume, they are intoxicating. At nominal levels, they are better than my previous speaks. No one asked for a review, but ya'all got one anyway. (Being Canadian, I'm not sure if the "ya'all" is correct or not). The journey continues...

[corloc]

John
I'm trying to visualize your description. Is it like this:



BJørn

Bjorn,

Here's a crude top view drawing of the transformation of mine.  The top one sounded
terrible, so I filled in the inside corner and rounded the front corner.  I retained the
narrow front profile, hid the back of the driver, retained the effective width of a 19"
wide flat baffle in a 10" visual width. 

The transformation went through numerous stages, and I started with the back to get
the "open sound" of a flat baffle.  That even included an ultra widening of the driver
cutout on the back side, because the FE108EZ's have a very shallow opening for the
rear driver radiation.

Then once I obtained the large radius front corner rounding, imaging improved markedly.
It's the first time I've clearly heard an audible difference related to edge diffraction.  It
took quite a bit of research to figure out why.

Very cool,  I have been tinkering around with doing that myself.  Its good to know it works.  I'm also thinking of adding wings verticaly at 60 deg.  It would look like a mouth of a horn. 

The internal baffle would be a normal U, but with a 1 1/8" center baffle, and 3/4" wings.  I would then use bending plywood to create the front of the baffle.  I'm trying for 4" rad. I remember reading  AudioXpress artical on diffraction that said it would be optimum.  Fill the empy champers with sand, also mybe a t-amp in the bottom.  I havn't done it yet, because I wasn't sure difraction would be that big of a issue.

Chris

[-Richard-]

Hi Brass Ear ~

You are exceedingly kind and generous in your affectionate sharing of your thoughts
with Dmason and myself... I am touched by your sincerity ~

Obviously you will read a great deal of information on this thread... some of which may
seem to be contradictory... or at least it is clear that some of this information is inconsistent ~

Let's part the tall grasses and look into the jungle of information to get a clear view of what
is going on... my baffle size is 25" X 42" with the B200's placed 7" from the top, centered
in each baffle, the baffles are made from 3/4" maple plywood and are held up by a foot
in the back... this baffle was created based on information that Dmason furnished for me
quite some time ago, based on the then current understanding of a somewhat generic
optimal size ~

Since I built this simple flat baffle Dmason seems to have reduced the width of his "working"
baffle significantly... I don't remember his exact measurement but I believe at some
point he was recommending a 12" width as sounding just as good as the 25" width in his
space and with his amplification ~

There are several contributors to this thread who have taken upon themselves to experiment
with the Open Baffle concept... JohninCR, for example ideally wants to solve all the B200's
apparent anomalies, such as peaks in the upper frequencies and the roll off in the bottom end,
with the least amount of invasive electronics... to that end he has devised several strategies
that he feels addresses these (to him) less than ideal performance issues by using (among other
things) information provided by such luminaries as Linkwitz and by his own creative solutions
based on trail and error ~

Dmason uses an EQ device made by Rane that he feels also addresses the B200's frequency
anomalies without any injury to the signal... he feels very positive that EQ'ing "perfects"
any rises or roll-offs that might be troublesome under certain room conditions ~

I am not using any EQ'ing device at the moment beyond a pair of Bipoles that are "crossed-over"
with a simple coiled copper inductor at 150 Hz that diminishes 6db's per octave above that...
and I still use a simple flat baffle ~

So there is the "spread" of current thinking at the moment: you can shape your OB's
to "solve" the B200's less than perfect flat response across the listening spectrum, or you
can use EQ devices very effectively, or you can experiment a bit, but not as much as say
needing to absorb Linkwitz's formulae's and still manage to get incredible performance by a
more simplified trail and error observation like I am doing, and Wind Chaser and Opnly Bafld
seem to be doing at this time as well~

Here is what I would do if I was in your place at this moment: I would build as simple a
baffle as possible... knowing that what you will be hearing will have some things about it
that are not "ideal"... there may be a rise in the upper mid-range that you hear... there may
be a roll-off below 200Hz that you feel robs the music of its foundation in certain musical
performances... but at least you will have something to start with... and you can begin to
"hear" what the B200 sounds like in the Open Baffle paradigm and start your explorations
from there ~

One more thing, Brass Ear... there are quite a few members who contribute to this forum
who know much more than I do about speaker drivers and the physics and math that
are used to quantify this or that application of various design considerations... I bow
respectfully to their knowledge... but I do not let it interfere with my own experiments!!!
Why? Because I trust my own ears, and Deborah's for that matter ~

I have no idea what the other very knowledgeable members of AC are hearing...
or what their experience with live music is... which is to say their frames of reference beyond
the ruler and principles that define their functional or operational pathways ~

So I am still learning and reading everyone who contributes to this thread very carefully...
the beauty of this thread is that one can pick and choose among our shared information
design solutions that fit my (or any else's who reads this thread) own design inclinations
and intuitions ~

Let me say again... I already have sound that is so extraordinary that I could leave things
exactly as they are and be entirely thrilled with it... but I am still open to suggestions ~

Here is a distinction worth noting, Brass Ear: do not be put-off by those contributors that
would like to pour their sour milk on our simple explorations by throwing mathematical
formulas around like saw dust in a carpenters studio... insecurity breeds aggression and
over-compensations of all kinds... steer clear of those types, at least at the beginning, until
you have some experience under-your-belt, and proceed with your own simple experiments...
I may have more to say about this later ~

Perhaps Dmason would like to share some insights with you as well, Brass Ear ~

Go ahead and jump in... you will have one-hell-of-a-time and learn a great deal as well!!!!!!

Warm Regards ~ Richard ~

[Polarbear]

Very interesting John. But would not this shape make a horn at the back, adding more sound backwards than foreward?

Bjørn

[JohninCR]

Very interesting John. But would not this shape make a horn at the back, adding more sound backwards than foreward?

Bjørn

That's why I haven't tried wings above and below the driver like Corloc mentioned.
I want to avoid horn loading and instead have the structure act only as a wave guide.

[scorpion]

JohninCR,




I would name such an OB either 'The Boomerang' or perhaps even better 'Asterix'

Will there be any advantage over a similarly sized flat baffle ?

/Erling

[scorpion]

MarkC,

Your remarks above just hit the nail's head !

/Erling

[Brad]

Richard - very nice summary of the thread so far......

Let's see if we can get to 200 pages!
I am finally going to get to start experimenting with OB in the next coupla weeks.

[-Richard-]

Hi Brad ~

Great to hear that you will soon be jumping-in!!!!!!!!

I have always found your contributions, observations and resourcefulness
highly stimulating... I think you will find a wealth of fascinating insights about audio
as a result of your upcoming OB explorations... please keep us informed of your
findings!!!

Warm Regards ~ Richard ~

[BrassEar]

Thanks again Richard, your summary was exactly what I was looking for. I feel a bit like I am cutting the line here.  So many on this thread are sharing their trial and error experiences and I can truly leverage those experiments.

THANKS TO EVERYONE FOR POSTING YOUR OBSERVATIONS.

With your summary, I will be off and running very soon.

Regarding EQ, I actually have a tube-based, 4 band parametric (Behringer T1951) that I have modded with Ei tubes and Black Gate caps. I think it sounds very good. Not as clean as a Rane ala Dr. Mason, but certainly worth trying out. Are the EQ points based on room, baffle size, cancellation effects, or ?  I wish Dr. Mason would weigh in here but I would understand if he bows out given some of the recent bashing on this thread. This hobby can be rewarding, positive, and FUN, l wish we would all keep it that way.

[-Richard-]

Hi Brass Ear ~

"I wish Dr. Mason would weigh in here but I would understand if he bows out given some of the recent bashing on this thread. This hobby can be rewarding, positive, and FUN, l wish we would all keep it that way."

You are quite right... there is at least one contributor to this thread that has the most
unfortunate attitude toward Dmason and anyone else whose ideas do not fit his
delusional sense of self-importance... most unfortunate... I am doing everything I can to
help keep this thread as clean as possible... I also hope that Dmason can ultimately
feel sufficiently comfortable to re-enter the thread that he started and inspired with
his considerable gifts for research, observation and speculation... I also miss Dmasons
highly energetic prose which bristle with intelligence, information and insights ~

Warm Regards ~ Richard ~