[KCHANG]

Hi all,

  Being urged by the good Doc, I am providing a link to two pictures of my main stereo system and my home threater system.

http://groups.msn.com/AudioNutPhilosopher/shoebox.msnw?Page=Last

Please be warned that they are quite ugly, as I have a chronic problem of not being able to finish up any speaker project I started.  It seems that I just could not move from the "make-them-sound-good" stage into the "make-them-look-good" stage.

Here is some informaion about the two systems, if you are interested.  The main system uses the B&G RD75 75" line-source drivers, and the eight 18" woofers are on simple open baffles.  The crossover point is at  180Hz LR4, so basically the system is a simple two-way using a widerange driver (the RD75) and multiple woofers for dipolar bass on each side.  The goal was to have a system that can do unaccompanied female voices (e.g., Anonymous 4) extremely well but at the same time is comfortable with the Japanese drum music.  IMHO, that goal was achieved reasonably well by this system.  The 18" drivers were made by Eminence.  I got them on a clearance sale, and I believe that model was discontinued.  Since they work quite well after some EQ (only 6dB max), I have not seen a compelling reason to replace them with some fancier drivers.  Nonetheless, if I am going to build another system like this I'd use the Dayton 15" IB woofer.  

  In the HT system, each of the three front speakers has an Audax PR170MO on an OB, augmented in the highs by a Fostex horn tweeter and in the bass by a JBL 4648 bass-reflex box each having two JBL 2426 15" woofers.  By the way, the baffle shape was intended to be that of an orchid, although I was quite amazed by what some people saw in that shape when their imagination ran wild.    I have painted the baffles red so they  now look slightly better.  

  The good Doc mentioned the Fostex FE206ESRs.  They are currently on two OB's with 15" woofers for initial listening.  I intend to build two fully-OB speakers, each with one FE206ESR and two or three 15" woofers.

Hope you find my sysetms interesting.  If you are in the Chicago area and would like to listen to these ugly systems, just let me know.

Best,

Kurt

[-Richard-]

Hi Kurt,

Ugly is a relative term of course...aesthetically speaking...actually I find your large
panels of the B&G system "exciting"...as in sculpturally and texturally innovative...

Scale is something one must learn to tolerate in ones reproduced musical life
in order for speaker solutions like the B&G to fold back into the musical
space...and not impose themselves physically on ones sense of what you
are actually hearing...

I applaud your experiments and your willingness to tolerate this kind of scale...
and for sharing your work with us...Thanks so much, Kurt, for this peek into your
"inner" audio world...there is something almost science fiction about it...

Whatever you learn from this kind of adventure will no doubt eventually find it
way to some sort of reductionist interpretation...the aging process mandates it...

Warm Regards -Richard-

[KCHANG]

Hi Richard,

there is something almost science fiction about it...

  I was a physicist for a good portion of my life, and I guess the mad scientist part of me manifested itselft through those speaker projects.  :)You can take the scientist out of the lab but you cannot take the lab out of the scientist.

Scale is something one must learn to tolerate in ones reproduced musical life in order for speaker solutions like the B&G to fold back into the musical space...and not impose themselves physically on ones sense of what you are actually hearing...

  Actually, the B&G system performs the disappearing act very well.  When you are in the sweet spot, the soundstage and the scale of the music will grab your attention such that you'll not really notice the presence of the two big speakers.  The two speakers are like two doors swung wide open to expose the inside of an acoustic venue, and you won't pay much attention to the doors when you are intensely watching/listening to what's happening in that acoustic space.  Many of my friends are particularly impressed by the soundstage, which is very deep and wide with nice instrument placement.  Imagine hearing a cello that sounds as if it were from the furnace located 12ft behind the speakers.  It might be largely a result of speaker placement though, as I have obtained similarly good results with some other OB speaker projects.


Best,

Kurt

[ALF]

Kurt, like Richard said, people's perceptions of "ugly" vary with the person - if everyone was afraid of 'ugly' there would be no great artists - And I reckon you are on the way Bro!    I love your pics, and I'd love to hear 'em.
People say I'm crazy having 2 X 15" speakers aside with my B200s in OB ... I'll direct them straight to your 4 X 18s ... it'll blow their minds!
Keep up the good work ... and enjoy
ALF

[Bemopti123]

Kurt, just saw your HT set up.  I say that the execution is overthetop and I am sure the sound will be the same.  The shape of the baffles really match well with the something "Space related" such as Dark Stars, Star Wars and other star stuff.  

I assume that you have dedicated crossovers for each component of the set up.  How do you power them?

[JiffyBoob]

Kurt,

WOW!! And I thought I was thinking "big" with four B200's, same idea. Someday, I swear I will build something like Kurt's rig, JUST to see what it sounds like. Who knows, it could be soooo grand that one decides one cannot live without that sound. As Dmason once wrote, the first rule of high end audio is: you don't know what you're missing.

Those drivers arrived today, and I pitched them in my trunk on the way home. Very excited to be part of the great experiment.

JohninCR,

A very interesting and innovative design. I as a newbie am constantly amazed at the level of intellectual curiosity, inventiveness, and technical know-how of you guys, and ALL in the "search of the lost chord." All that and Costa Rica too. Do you get around to Tamarindo? Playa Hermosa? That monster left there?

[opnly bafld]

This may be getting a little past k.i.s.s.
I was adjusting the x-over tonite and realized that between 150hz(or a little lower) and 200hz did not have much effect on overall sound.
And a lower x-over, like 100hz, did not allow the lower driver to contribute enough to the sound.
Looking at Nodiak's measurements it would seem a gradual slope is needed, not a cliff.
With a L-R 24db/oct I have more of a cliff.
Don't get me wrong it still sounds very good this way.
Then I remembered (Richard will love this ) that the preamp that I am using to drive the bass amp has TONE controls.
If I boost the bass a couple of dbs it will have no effect on the midrange because of the x-over.
But I should have the more gentle rise in bass that I need to flatten out the response.
Too late to find out if or how well this works tonite.
Of course what would probably work better is a 6db slope, but I have to work with what I have available now.

Lin

[mcgsxr]

KCHANG, welcome to AC, I have followed your posts over on AA with interest!

As for the look of those babies, other than being a little large, what could be better?

I am interested to read more, as several local explorers here, go off on their tangents with multiple b200's, and or other bass solutions.

Glad to see the renewed interest in this thread, I am really happy with my OB b200 creations, and look forward to making a final decision around implementation, so that I can loose the mdf panels, and get with some style!

[scorpion]

There is one experiment I really would like you, who are playing around with B200s on Open Baffles, to do. If you just have one B200 connect 6 ohms of resistance in series with the speaker, or if you have two parallell  B200s connect 3 ohms i series with them. This should raise Qts to about  1.5.

What happens to Bassrespons and SPL ?

/Erling

[scorpion]

I agree, Visaton's specs may be misleading. What I was driving at is a SPL reinforcement by the backwall for bass, specially from 40 to 80 Hz.
It would just be fun to know if there was an effect. Backwall and perhaps corner should be at about 1 meter away.

I run the Ciare CH-250 placed like that on a winged baffle measuring 100 x 60 cm in all and I get good bassrespone down to 60 Hz. Of course the Ciare already has a Qts of 1.4 about so it do not need any resistor support. Fs for CH-250 is 65 Hz.

/Erling

[opnly bafld]

Hi scorpion,
Currently running 2 B200s in a 1 and a 1/2 way config and am getting bass down to 40hz.
Baffles are 20"w - 3 ft from side wall and 5+ ft from front wall.
Lin

[Wind Chaser]

Lin,

How much bass down to 40Hz are you getting relative to 1K, and are you using any EQ / tone control to achieve those results?

John

[opnly bafld]

Hi John,
I need to order a test signal CD that has the full freq. range.
The only one I have is just bass freq.
For now I am setting levels by ear.
I can adjust the level of output from the selected X-over point down on the lower driver.  
I am using a separate amp and level control.
Top driver is running fullrange.
So how 40hz compares to 1k depends on where I set the level and 40hz output is very good compared to frequencies up to 100hz.
Think subwoofer crossed over between 150 and 170hz and the ability to adjust the level to the main speakers.
Can be set too loud, too soft or just right.
Hope this makes some sense.
Lin

[JohninCR]

Lin,

Just download the TTG Test Tone Generator by Timo Esser and make whatever tone CD's you want.  It's free for 30 days.  I have my computer connected to my system, so I don't even have to burn a CD.  It's the most used tool for speaker building that I own, other than my ears, of course.

[-Richard-]

Several days ago I placed another pair of new B200's in the lower area of
my simple OB panels...I cut the hole with a saber saw and bolted-in the drivers...
they are 3" from the floor/bottom of the panel...

My listening experiences confirm what everyone else is hearing...

The sound is extraordinarily rich...it still penetrates the room in the way we have
grown to expect with the B200's in OB...meaning there is no beamed wave as
one gets from a box of any kind or horn speaker design...instead the music simply
appears "in the air" as if generated by real instruments in a real space...which is to say
the space of the recording becomes the space of the room...

However, I wanted to share some further insights with everyone...

I am not using any filters right now...so both speakers are playing full range...this is
a very instructive experiment...on most musical material the speed of the B200's
and the dipole effect allow the richness of tone to sound perfectly natural...it does
not sound like 4 drivers playing (2 per panel) both rather sounds as if my amplifier
gained a tremendous power boost without any loss of the nuances that make the
B200 so extraordinarily resolving...

Most drivers that are new start out pumping out the frequencies that are easiest to
throw...so I expect that the bass will "fill-in" as the driver shakes itself loose...
the top end is slowly beginning to locate that silky shimmering higher frequency
tone...

I am now designing an OB for 3 B200's...I imagine the cut-off to be something like
this: lower driver 280 Hz, middle driver 2000 Hz, upper driver full range...perhaps using
a simple inductor with a gentle slope...

What does one B200 sound like in OB? think $10,000 Quads...only this sounds like
what the Quad wishes their speaker would sound like but fails to deliver...stunning
transparency and speed with the dynamics leaping into space like Nureyev...

2 B200's gives up a bit of the transparency for optimal warmth and other worldly
detail that fleshes out every hidden layer of sound that is otherwise trapped in the
microscopic holes of the CD...a musical bloom that fills and penetrates the room
so completely that it becomes impossible to believe that the 4 B200 drivers are
actually creating the sound...they do not appear to move...they lie still visually like the
sphinx...it is magic and illusion...

Voices are projected on a throbbing air that pulsates with fleshy intimacy...

Naturally I don't expect anyone to believe any of this...such is the nature of our
conditioning that we have been trained to believe that something as simple as a
driver mounted in a hole in a wooden panel cannot possibly sound even close to the
exuberant prose such as you are reading right now...

What Dmason has done here is to get me, and many of us here on AC, off the audio for
rich people hysteria, hyperbole and hypnotic somnambulistic sleep that the magazines,
glittering jeweled surfaces and high prices of audio have beguiled us into believing is
the real thing...well...they are not the real thing...the are the wrong thing!!!

When Roger Modjesky, bless his heart, saw me carry my simple OB's into his
laboratory he rolled his eyes...in the flash of that Diane Arbus snapshot I knew that
Roger was saying to himself..."oh god, yet another one...why me, oh lord?"
then we listened and he became a believer instantly...well...Roger was one of the
designers that perfected the sound of the Beveridge electrostatic speakers...

I think Vinnie's new Signature 30 amp will only take this to another level of
sophistication, heightened reality, tonal richness, speed and beguiling resolution...
the incredible cheap price of these drivers and their simple cheap implementation
begs for a sophisticated amplifier solution...think of the OB's and Vinnie's amp as
a package...that is what I am doing...putting my money where it counts...into
the Signature 30...oh yes...I use 18 gauge lamp wire for cabling...just like Roger...
it cost me $8 at Radio Shack...

Just sharing experiences and ideas here...

Warm Regards -Richard-

[opnly bafld]

Richard,
I highly recommend you try some kind of filter on the lower driver.
You will retain all the positives and get rid of the negatives of running both drivers fullrange.

Are you being literal when you say your drivers seem not to be moving?
My drivers are moving a lot, as much or more than most speakers I have seen at moderate listening levels.

Lin

[-Richard-]

Hi Opnly bafld,

There is no perceptible movement of my drivers...naturally if I gently touch the
surface of the cone I can feel it vibrate...but otherwise they enigmatically
appear in deep meditation...

"I highly recommend you try some kind of filter on the lower driver."

Vinnie, wrote me this morning suggesting the same thing, (Thanks Vinnie for all
your help!!!!) pointing out the rise that seems to be inherent in the B200's design...
and I admit that on some musical material there is an mild excess of upper
frequency information...it depends on the music...

I will try something like a Jantzen Air Core Inductor or Copper Foil Inductor (Again,
thanks, Vinnie) paying attention to where I think the roll-off would have the best effect...
a gentle slope of 6 db would seem to work best here...

The important thing to realize here (for those interested in the potential of what
this configuration can do but who are not yet ready to pounce) is the richness
that 2 B200's playing together on one panel brings to the music...this is not simply
about "hitting" the widest spread of the frequency gamut...it is about a richness of
TONE that is unprecedented in my experience...audio enthusiasts with deep pockets
willingly spend well of $10,000 for amplification that promises this kind of tone...
it almost never works because most speakers just do not have that kind of potential...

Thanks, opnly bafld for sharing your experience and certainty with us...I deeply
appreciate it...

Warm Regards -Richard-

[Russell Dawkins]

I would just like to alert experimenters here to a potential that should be auditioned if the opportunity presents itself.

Many (37) years ago an audiophile friend and I had an experience that has remained with me ever since. It relates potentially to what you are doing with the 2 - B200s a side configuration.

What we did then was: he had an old Lafayette or Fisher tube receiver and a pair of efficient old Wharfedale speakers in big reflex boxes that were probably 92 dB efficient. He had a friend with an identical pair who brought them over and we stacked them. These speakers had 12" drivers with whizzer cones, I think, and probably a single series cap in line to the cone tweeter, with the 12" main driver probably direct coupled to the amp.

Anyway, onto the player goes Janis Joplin. My back is to the speakers and the imaging was so realistic that I swung around by reflex.  It really sounded like she was standing between the speakers.

Since I value imaging capabilities highly, I have always had this at the back of my mind whenever the subject comes up, and have thought long and hard about it since - I spent 5 years designing speakers 30 years ago.

My current thinking is that this type of imaging is possible with two widely separated, not close, fullrange speakers or point sources.

So if I were, say, adding a second pair of B200s, even if the second pair had a low pass filter, I would try that sort of configuration, especially since it would seem not to be in conflict with other design considerations, such as putting the "bass" unit close to the floor as opposed to right next to the other drivers.

One caveat would be to ensure that the angle be such that the path distances from each driver to your ears be roughly the same.

[opnly bafld]

Russell,
The lower driver is 23 1/2" below the top driver, center to center, on my baffles.
The lower driver is @ 3" to 4" further from my ears than the top driver.
I used no scientific math when cutting the baffles. (maybe a little)
The top driver was placed with the center 32 1/2" off the floor so with a little back tilt it would fire to seated ear height.
The lower driver was placed near the floor for added bass.

Is this what you are referring to, the 23 1/2" between the drivers?
If I separated them much more the top driver would be firing over my head.
With my current configuration imaging is very good.
Lin

[Russell Dawkins]

no, that's the kind of separation I was talking about (2-3 feet).
Ideally, a right angle off the line between the drivers at the halfway point should point to the listening position.