[Dmason]

Mark

I would imagine if you plan to do your intent listening in the nearfield, and at very reasonable SPL's,  the Fosgate should do quite nicely. IME, the addition of even a hint of foundation puts the OB sound into accurate perspective; it seems to be a "different" kind of listening. Personally, I have never ever been into boom boom bass, which is one reason why I prefer dipole bass, ergo, the Fosgate H model I would automatically prefer over just about any "sub" woofer My guess is it will work really well. The H baffle is a well known implementation for success. I think you will have a whole new OB rig when your speakers return. As for the IKEA angle, I used the HAL enclosure for a W baffle with two Eminence 12LF very successfully. OUtstanding value, and makes things very easy. A great dipole bass enclosure from IKEA.

Right now I am looking at the slew of used wideband instrument speakers on eBay by JBL, Altec, Jensen, and comparing their specs with the JBL Heritage database. I can't believe the buckets and buckest of jewels in this thing; real audio treasure. Tone Tubby is coming out with a series of five retro fits. Imagine a 12 inch Alnico D series wideband guitar driver with new hemp cone might sound pretty phat on an OB.

[-Richard-]

Here is a very important review of the Visaton NoBox Open Baffle "system"...
from Enjoy the Music.com written by Dick Olsher...

Dick Olsher gives the necessary if cursory background to the beginnings of
OB's and unpacks the NoBox story very nicely...it is must read as it sets
a certain amount of confusion to rest...Dick also discuses dipole bass's unique
character and fleshes out some implementation possibilities...

My own experience flies in the face of Dick's assessment of needing 5 feet
from the back wall to create the optimal spatial illusion...my OB's are 1 foot away
and sound rather fabulous...

http://www.enjoythemusic.com/magazine/equipment/0606/visation_nobox_bb_loudspeaker.htm

If that link does not work, here is more information: Enjoy the Music.com
May 2006/The VISATON NoBox Loudspeaker Kit/Thinking outside the box!

Warm Regards -Richard-

[Dmason]

Richard

Thanks for the link; well written explorations by Dick Olsher, as usual. If I take anything from that review it is the inherent sonic inferiority passive components bring to the overall picture. Crossovers plain suck the life out of the party. There is absolutely nothing grainy about the B200 when it isnt 'occluded' by electrolytics, and I for one prefer its sound to the Lowther DX4. I do agree about it sounding more like the Fostex Sigmae, than anything else.

The best part is the B200/OB method gets some press.

[Vinnie R.]

Thanks for the link, Richard!  Nice find!

I can't help but wonder why can't they simply put a coil in front of the 15" bass driver (at a cutoff freq that will allow the 15" to slowly roll off at the higher bass freq's as the bass freq's of the B200 roll off in the opposite direction...thus flattening the bass response with a smooth filter and not a sharp one).  the and let the B200 play without the crossover junk in front of it.  

The good news is that the system response drops at a rate of only 6dB per octave below the open baffle's bass cutoff frequency down to the woofer's resonance frequency.

And one coil in front of the 15" (or 2nd B200) also drops at 6dB per octave....it just seems to make sense that this is the way to go.  The trick is to find the best cutoff freq (coil value).  I suspect that for best results, this will differ from room to room.  In my room, bass with my OBs (one B200 per OB) seems to be pretty solid down to around 80-90Hz.

The best part is the B200/OB method gets some press.

I agree, and there were plenty of good comments about it.  I also agree with dmason that the crossover components in front of the B200 were mucking things up (even with the Black Gates installed)  

The B200 cult is growing and many are having a lot of fun with this ear-opening experience, so it is all good!  

[-Richard-]

Dick Olsher's comment about the NoBox sounding "grainy" before changing the
stock capacitors certainly proves what Dmason has been saying all along
about passive filters sounding like junk in the signal path...

I think Vinnie has a good idea using a simple "choke" inductor coil for one of
the lower B200's or a bass drivers and let the B200 play full range...
however we need to pay attention to the DC Resistance...for example on the
Jantzen products an inductance of just 5.00 mH uses a 20 gauge wire...which
results in a Resistance of 2.32...that causes a load tolerance that could
compromise amplifier efficiency...a much thicker gauge wire would be needed
in that case...

We should come up with an inductor coil product that has a much thicker wire
and hence a greater Resistance value...has anyone come across a better coil
product that is not boutique?

Warm Regards -Richard-

[JoshK]

If you use a steel lam inductor it has lower DCR.

I see one fallacy in a conclusion drawn the review, and that is that passive components kill the sound.  The real conclusion that can be drawn IMHO is that electrolytics kill the sound.  If you replaced them with good quality film caps and then compared to without caps at all, then I might believe that conclusion.  

I think it has long been agreed upon that electrolytic (black gates included) have no business in a speaker crossover.

[Dmason]

I think it bears mention, and was earlier mentioned in this thread, that Visaton is a kit oriented outfit. In Germany, people build their set ups often from the ground up, same as Japan, and often obsess over its component parts. As such, I would say the main reason for the fairly complex Visaton circuit isthe fact that it is all part and parcel of what they sell; they are in the business of selling ALL the components, doodads being the "optional" bells and whistles. Even the woofer is nothing special at all, and there are far, far better choices domestically for far less dough. Look at some better examples of Mind-numbing Visaton XO inventions, look more like Bosch ignition wiring. I also believe in the German tendency toward complexity in engineering. If you do not believe me, look under the hood of a modern BMW, the car you only lease. THAT will convince anyone.

I like Vinnie's idea, as a passive approach. Shunt caps at the amp work too, but my guess is that overall running the main driver full range without sand storms or copper funnel clouds the issue less. Unfortunately the best way seems to be pro audio DSP, which ain't cheap, but works a treat.

[JoshK]

something like this would work well to see if Visaton's concept is a good one for very little dough...

47uf MKP

[opnly bafld]

UPS brought my inductors today.
Sledgehammer steel laminate 15ga from Madisound, 12mH .426DCR.
Rolloff should start at @80hz with 6 ohm drivers.

Of course, with just the lower drivers playing more mids than I would like.  
But with both drivers playing, sounds good so far.
I will do some more serious listening tomorrow(busy tonight) and try and get some numbers.

These OBs with 2 B200s just keep making me
Lin

[JoshK]

What the hell is that dip at 600hz?  Is that real or an artifact of measurement/baffle?  That would certainly be audible and could contribute to the "recessed mids".

ahhh...maybe its a c-t-c spacing issue.  What is the acoustic slope of the lowpass?

[-Richard-]

I placed a coil inductor with a cut-off at 100 Hz with a 6 db per octave augmentation
between my upper B200 driver and my bottom B200 driver...

The result is astounding bass...just as Dmason suggested...

I almost fell on the floor during certain passages when the lower frequencies
spilled into the room as if they were being poured from somewhere invisible from
within the space...

Does it sound different than running the 2 B200 together full range?
Yes...significantly...there is the lowered frequency range for one thing...building
a real foundation under the music...for another the upper frequencies no longer
present a mildly exaggerated rise on some musical passages...but there is a
surprise as well: much more articulation...much more!!!!

Before the musicians sounded as if they were playing in the room...
now they are in the room physically...I can even smell the sweat!!!
3-D textures that almost take on form...

The bass is not as articulate as it could be...yet!!!!

After all...my lower B 200's are not yet broken in...only 30 composite hours on them...
so I expect much more articulation in the not-to-distant future...

I am taking them down to Roger Modjesky tomorrow...he wants a listen...
"burn them in, burn them in"...was Roger's last words (there really was a sense of
urgency in his voice...he knows the difference!!!) on the phone...
sorry Roger...I am doing the best I can...I am very very interested in his
take on things...he will measure everything and I should have some information
I can share with everybody afterwards...if I can remember it all!!!!!

I know what opnly bafld is hearing...the lucky so-and-so...ahhhhh the fun of
it all...if those audio enthusiasts who spent over $10 grand for their speaker
ever heard this...they would fall into tears...

More to come...

Warm Regards -Richard-

[Wind Chaser]

One thing that no one is discussing regarding the addition of more drivers is the loss of pure single point source sound.  For me this is far more audible than a properly designed XO.  Since the B200 will make bass, my vote is for building baffles that take full advantage of the B200.  Then if you need more bass, add a sub, or stereo subs, or build them into your baffle, but keep them operating only in subwoofer territory and cross them steeper than 1st order, so you really can't hear that they are there.   ...

I'm in total agreement with this. The Horn Shoppe Horns were my first education on the wonders of a true crossoverless point source. Combined with a Decware SET, everything I thought knew about sound staging and imaging took on a whole new definition. The single driver is without equal in this regard.

Inspired by... http://www.diyaudio.com/forums/showthread.php?s=&threadid=68920&highlight= I initially bought two pairs of Visatons thinking I could attain deeper bass. But in the end I but sold one pair and bought a pair of drivers designed to go deep in OB. Even though this cost a little more, I think it's the better approach to attaining better bass.

[Sarchi]

Just dropping in, I'm the guy who's swapped speakers with mcgsxr for the last few weeks. Really enjoyed having the B200's, unfortunately Mark wants 'em back now..can't really blame him. I used to have Lowther DX2's in a pair of original corner acousta horns, the Visatons remind me of them but with few -if any- of the horn-associated room loading problems.

The small Omegas may suit my 9x11 room better, but I will almost certainly build a pair of these B200 OB's. They're addictive. No, I haven't read all 71 pages of this thread yet!

And a "hola" to John in CR!  Pura vida and saludos.  

[opnly bafld]

John,
What frequency and slope would you consider as sub territory?
Thanks,
Lin

[mcgsxr]

It is exactly this discussion of single vs multiple b200's, and the associated loss of point source with increased TONE etc, that I find interesting - and what I was referencing in my comments about how differing tangents are developing, as people go off on their own.

I love it.

Sarchi - glad to have borrowed your Omega's, and very glad to have introduced you to the b200's, they are a pile of fun.

I will continue to run my b200 full range, and bring in the single dipole sub beneath that, and experiment with how that all sounds etc.

I will continue to report what I find, and if I can buy an SPL meter, I will also report objective numbers, along with my subjective warm and fuzzies!

Interesting article (thanks Richard!) that made me think some, about how I have my baffles positioned today, and how they were in the past.  In my old room, they were within 3 feet of the rear wall, and one was within 2 feet of the side wall.  In my current setup, corner loaded, they are within 2 feet of the side wall, on the angle, and roughly 6 feet from the actual corner.

I have not tried them way out in the room, but may have to, just for fun, in this relatively large space, while it is still unfinished etc.

[-Richard-]

I am the least emphatically knowledgeable person contributing to this thread in terms
of science, math and other forms of computation and measurement strategies...

Some information is needed if one is to follow a particular creative thread and see
where it can lead...however even assuming that nothing is known...if one has a
reasonably "seasoned" ear you should be able to find out what you need as you
go along...that is the essence of the creative mind...it learns what it needs to in order
to solve problems...that is clear...

I am suggesting here that anyone who has not tried the B200 in OB yet but is very
interested...and is beginning to feel that all of this is a bit beyond them...there is after
all a lot of measurement prose being painted on the street level here...like road
markings that direct traffic on a modern city street...

I can only say don't let that kind of prose distract you from jumping-in and trying a
simple OB strategy of one B200 on a simple panel...or as I have done (and apparently
opnd bafld and Dmason) place 2 B200's on a simple panel as it has been suggested
earlier...

Remember that all the measurements in the world...and all the agonizing over
measurements that many of the more astringent among us insert into their speaker
building strategies is not the music we hear...it is not in and by itself the "sound"...

So go ahead a do a bit of experimentation knowing that you will come close to the
optimal performance of the B200 in Open Baffle configuration...with even a careless
placement of the driver in a simple hole in a simple baffle board...that is the "nature"
of how this driver works and the dipole room interaction...

Whatever the carefully controlled measurements and math is doing is just to gain
a bit more smoothness, or a bit more of something else...it is not an intrinsic
all-important consideration...

Coming within 90 percent of what is possible here is all I need...it sounds fabulous...
that is the important consideration here...

Audio took a strange turn when it started to think it could creep into that twilight
zone of perfection...perfection relative to what? to the absolute of the real?
Hardly!!!! That is an exercise in futility...there for those who want to give themselves
projects to keep busy with...I have nothing but projects to attend to besides trying
to "perfect" a sound that is artificial by any standard worth applying...

So go ahead and stick 2 B200's in a board that is 26" wide by 42" high...the top driver
7 inches from the top centered and the bottom driver 3" from the floor or measurements
that are roughly comparable...use a simple coil inductor that cuts off at 100 Hz for
the bottom driver...run them both on the same amp...let it all burn-in for a couple
of weeks...get acquainted with the sound...and see what it does for you...enjoy
the music and leave the ruler and math on the shelf...

I cannot begin to express the excitement this simple speaker design does for the
music...quite amazing!!!!

Warm Regards -Richard-

[JohninCR]

Richard,

I agree that people should just jump in and give it a try, however, I feel that your wonderful prose may lead to some unrealistic expectations.  What I want to people to have realistic expectations, so they aren't disappointed with their initial OB attempt.  Also, many feel more comfortable having some kind of numbers to use as a guideline.  Visaton gives us a graph of the IB response, which is the same as our OB response minus the effect of the rear wave and room.  Linkwitz gives us the rear wave effect on response with the formula for Fequal, which is nice and simple.  It's the only formula I use and I've built argueably the most complex OB's ever made with my OB-RLH's.  The only measurement tool I use, other than my ears, is a tone generator and that's so I can get a feel for what is happening at exactly what frequencies.

I don't think that arming people with a little knowledge hinders any artistic approach, and I'm sure there are a lot more people reading these forums who want to give it a try, but haven't because they are a little afraid of taking a blind shot in the dark.

[-Richard-]

The OB approach has no greater friends than you, JohninCR and Dmason...

I am always grateful for all of your contributions...always extremely interesting...

And I like your feisty persona, as Dmason suggests, you are most certainly the
Don Quixote of Open Baffle aesthetics...I hope you always feel comfortable
contributing your remarkable insights to this and any other thread that  
interests you...

Warmest Regards -Richard-

[opnly bafld]

What I am trying to stress, (and I think maybe, maybe, Richard and Dmason also) is that, if anyone following this thread is interested in experiencing/hearing what we are, all it takes is $250 for a pair of B200s and a piece of wood.
 
If a person is trying to wait until there is a "definitive answer" to their questions about how "exactly" to do it, they will probably never have one.
There are just too many ways to do it according to what each individual listens for/likes in music reproduction.

With some experimentation of what to do for low bass, (I felt that I had good success with a sub) I can't think of a $250 speaker that will come close to this sound, even without any expertise in how to build.
Lin

[Wind Chaser]

It is exactly this discussion of single vs multiple b200's, and the associated loss of point source with increased TONE etc, that I find interesting -

The thing about tone is there are so many more variables one can play with instead of just adding more drivers.  However a true point source of necessity requires a single driver, there are no other options here.  The way I see it is there’s no point in having a cake unless you can eat it too.  I’d rather not have to compromise one for the other, but if I did, I’d sacrifice a little tone for the virtues of the point source hands down.  As it is, one B200 in OB is a tone machine in it’s self.

As an example, Dave at Planet 10 has spent some time listening to the B200 with a phase plug, and guess what?  As a result of nullifying the soup can resonance’s that occur behind the dust cap there’s now not merely more tone, but better tone.    And as a bonus the driver now exhibits a wider HF dispersion.  This is exactly what he predicted would happen by the addition of the phase plug.  Arguably Dave has the most experience modifying drivers in this manner insomuch that he has built a business around providing phase plugs for various full range drivers.  Since he was so kind to do the time consuming delicate work on mine, I’ll let him enjoy them for another week or so before I ask him to ship them back.

John