Gravity Well Of A DarkStar

-Richard- · « **Reply #140 on:** 6 Jun 2005, 06:45 am »

Hi barfind,

I have a tubed pentoid single ended integrated amp with tone
controls...I recently retubed it and the sound with my Omega grand
8's...which use Fostex 207E drivers is incredible...the extension is
spectacular...the harmonics rich...detail galore and real pace and
rhythm...very musical...I LOVE TONE CONTROLS...nice to hear
someone else say so...they are intuitive and easy...I even like the
knobs!!!!

(I hope Freud is not reading this post...hummmmm)...

Warm regards -Richard-

ooheadsoo · « **Reply #141 on:** 6 Jun 2005, 07:07 am »

After thinking about it for a few moments, I was thinking that the high efficiency of the B200 makes it very easy to apply EQ without ever clipping an amp. It sounds like a better and better gamble by the day.

Dmason · « **Reply #142 on:** 6 Jun 2005, 07:15 am »

Tone controls are great, because it allows one to TUNE the sound to the room. It gives you choices. How bad can that be?

Forget all the audiophool bullshit out there; if it sounds good, it IS good, I say. I always thought tone controls on tube amps were cool, and sounded way better than those of primitive and evil sounding transistor amps. I am using digital EQ, because I dont have a tube amp with tone controls, and the WORST thing I can do is to physically kill the sound using ceramic prosthetics to tame poorly behaving, or poorly integrated drivers. Crossovers are exponentially worse than the idea of tone controls on tube amps... And then there is the Visaton. No need for tweeters here, and for quite a few, no need for a woofer, IF you have the ability to lift the FR on the lower end. It is well capable of making all kinds of bass, and really nice bass. I use a digital EQ because I use digital sources. Tone controls in digital. As it is, it sounds very like the Lowther PM6A, flatten it and it sounds more like the Fostex sound, but with added sparkle and coherency, far greater resolving power, likely the result of better build, stronger, larger magnet, plus, the magic ingredient of "manila" cone material.

Baffle resonances are as near as a non issue as could be with OB. Forget about poured concrete and such. I am using 3/8 Lexan and acrylan and with the driver mounted on a vertical yoke of 1" MDF ten inches wide, the acrylic baffle mounted to the yoke through the driver's mounting holes, the weight of the baffle, standing on the floor is enough to damp vibrations. Rebates are important for a flush fit of the baffle against the yoke. A very workable solution, and it hugely decreases the apparent size of the thing to not really noticeable at all.

powerbench · « **Reply #143 on:** 6 Jun 2005, 07:34 am »

it was just a thought if vibrations with plywood/mdf with the B200 was a worry...hey why not concrete.I remember seeing concrete baffles for some sort of speakers yrs ago....FYI i used to work construction and a concrete finnisher so whip up a batch with sealbond and sand would be no problem.As of weight i would not go crazy but would plan it to me easily moved.I am a past national powerlifting champion (2004) so moving stuff is not a big concern at my old age of 41

.(i know who cares)

what the heck Ill stick with plywood if i ever get to that pt...the mini me's should be here tomorrow....so i might not ever get that far

barfind · « **Reply #144 on:** 6 Jun 2005, 08:12 am »

Hey Powerbench, I may have eluded to vibrations being a problem, sorry. I was only thinking out loud. I dont really think its a real problem, and from the sound I have maybe no problem. I still may try the 2 piece baffle I mentioned a few posts ago. Anyway better to just try them first, you may find they dont need much.

Nigel

JLM · « **Reply #145 on:** 6 Jun 2005, 10:03 am »

powerbench,

The increased mass of the concrete would help, but it's reflective properties would probably do more harm than good. There's a few issues at work here:

1. The momentum of the cone movement must have something to react against, so the increased mass would dictate that the baffle would move very little.

2. All objects have a resonant frequency (the Earth's hums at about 1.5 Hz). The greater the mass and/or stiffer the object, the lower that frequency. For our purposes the lower the better because the greater the energy it takes to excite the object and because it's below the range we can hear. BTW the average speaker emminants more acoustical energy than the driver(s). So often what you hear is the box. The open baffle concept takes care of much of that.

2. In theory the baffle would flex under the strain from the energy of the moving cone. Most of the designs we've discussed are acting as plates that are supported primarily on the bottom, not a good structural design and one prone to flexure. But I say "in theory" because all the baffles specified so far would be quite stiff and compared to box speakers, open baffles have no pressure on them and therefore almost no strain.

3. After speakers, many if not most audiophiles would agree that the room plays the second biggest factor in what you hear. Large baffles would provide large surfaces to reflect sound in ways our ears are not accustomed to.

4. As sonotubes were mentioned, some poor soul a couple of years ago tried to put the tube and concrete ideas together to build speakers by using concrete pipe. You can guess what that sounded like and he abandoned the project. A Canadian as I recall.

I'm a licensed engineer, degreed in civil engineering, spent 8 years doing structural engineering, and am a past member of the American Concrete Institute. (But again, who much cares?)

Dmason · « **Reply #146 on:** 6 Jun 2005, 01:46 pm »

JLM

If the momentum of the cone is transferred to the baffle, in my case the mount, then one could get away with a thinner acrylic baffle? 3/8 is plenty thick, and you have to have your ear right on the surface to hear any reflections/resonances. Do you think using this method, which I guess "grounds" the vibrations, one could use a thinner baffle, say 1/4"?

While were at it with baffles, I also used 1/2" MDF and there were no acoustic problems. This would be the ideal material to try different sizes at home.

JoshK · « **Reply #147 on:** 6 Jun 2005, 01:50 pm »

OK, another question about the Visaton driver if you don't mind bearing with me. Again, I am awaiting a pair of fullrange single driver speaks to try myself, so I am just curious. Do the Visatons suffer from beaming above a certain freq like many fullrange drivers are reported to do? How wide is the sweet spot?

Dmason · « **Reply #148 on:** 6 Jun 2005, 04:20 pm »

hi Josh

The B200 beams like any wide range driver does when a wavelength is longer than the diameter of the cone. The 8" factor means theoretically, it should beam more, however, none of these things are carved in stone, and the B200 beams less in my experience, than the Fostex 207 for example, which no one complains too much about. I havent had an issue, none thus far with Mark M, and so goeth the pattern. I have mine sort of corner loaded, and they fill my luxury seaside pavilion (small condo) with glorious, dynamic sound that all can "see" right into. Mark and Nigel allude to this quality as well.

Anyone reading this thread, wanting to give this stuff a try but not ready to throw down 3 bills, I recommend the following drivers for excellent OB results

Ciare CH250 www.assistanceaudio.com
Beyma 8/agn www.spectrumaudio.de

Both of these drivers are value monsters, everyone who has heard the Beyma has been really impressed, and the Ciare company does themselves no favors in referring to the CH250 as a "car" speaker. The Beyma is a strange animal that also works in a modified D-37 MkII Nagaoka horn,

which shows that none of the so called speaker physics is truly carved into stone. -- A driver that works both on an open baffle, and is yet also a virtual legend in the "Veich" horn (German for beast)

The Ciares, once broken in are lovely drivers, and you will not be let down, I promise. They are 10 inchers and they beam some more, ameliorated to an extent by a big and cool looking whizzzer cone. Ciare also has their act together and makes, arguably the best coaxials around for less than the better known stuff, like Tannoy, Radian, Altec. There is a Ciare 12" that has a Q high enough to work well on OB, and this is likely my next target.

nodiak · « **Reply #149 on:** 6 Jun 2005, 04:50 pm »

As to beaming and sweet spot size I find using the same driver in a sealed enclosure vs. an OB gives very different results. When I use Fostex FE167E's in sealed enclosure (xo 70 hz to subs) I get a distinct and narrow sweet spot. When I put them in OB the rear wave fills out the dispersion so much that the sweet spot can be made 3 feet or more wide, dependent on toe in.
My ob's are 36" from wall behind them. The key for me for tuning their dispersion is to use material (blanket, dacron sheet, foam, etc.) on the backside of the ob, and the wall if needed. You can really dial in the way the sound is distributed in the room. More material cuts down on the rear wave, and so the drivers front wave becomes more pronounced, and the sweet spot narrower (according to the drivers typical characteristics). Less material and the sound really fills the rooms volume, and gives a larger sweet spot. So it can be done to taste to a large degree, very room dependent too. It's about delaying the rear wave so it hits us after the front wave enough so that it fills in (ambience) instead of competes with it (confuses the brain). Described as mimicing nature better, as that's how we locate sounds outside. Right now a blanket of dacron on the back of ob, covering the driver is doing well.
I have a large room now but can't bring the speakers out from the wall very far. If the OB's could be maybe 6 feet from any wall I bet the delay wouldn't need much help with materials.
The Decware Radials are my favorite speakers for dispersion characteristics, they're designed with that in mind.
http://www.decware.com/radials/radials.htm
Click on Features to see them without grills.
I'm finding that by dialing in the rear wave reflections of OB's I can get about the same effect. Happiness.
Don

nodiak · « **Reply #150 on:** 6 Jun 2005, 05:03 pm »

Material-wise, there's a gentleman on the Decware Speaker Builders forum that was using surfboard foam blanks to assemble horn cabinets. I think he planned on fiberglassing it too. The point was to avoid resonances, and be light weight and physically easier to build-no power tools, but dealing with fumes for sure.
Cut an old surfboard in half, cut the holes = (another odd) OB.

JLM · « **Reply #151 on:** 6 Jun 2005, 05:22 pm »

Dan,

If the driver is mounted apart from the baffle, then the cone momentum issue would go away.

Dmason · « **Reply #152 on:** 6 Jun 2005, 05:41 pm »

JLM

This would explain why with the baffle/driver mount yoke assembly like I have for the acrylic DarkStars, baffle vibration is a non issue, so this is a very good type of design, and neednt be only for acrylic baffles. You could use skin ply as well, and shape the baffle by bending it, and holding it in place using two eyelets and some string. With use of the wood baffles and cork lined backside, the sound is quite different, warmer, less ambience, the acrylic, drier, more literal sounding.

One guru thinks the B200 could work mounted in the end of an open pipe, that a radial hybrid a la Decware would also work. I still think OB is plus-forte killer for this thing, my room anyway.

I had heard about using board blanks which would work great, and the stringer makes them incredibly strong, and light. A glassed 9' longboard only weighs abit more than 10 pounds, so if you go to Clark Foam online, they will sell you blanks and have advice on glassing structures.

-Richard- · « **Reply #153 on:** 6 Jun 2005, 08:18 pm »

Hi nodiak,

In my minds eye I saw more or less exactly what you described as the
process for "dialing-in" the back wave...probably because of my experience
with the Maggie 1.6's in 3 very different rooms over a period of 4 years...
a similar kind of dynamic is at play with these speakers...but of course they
are not dynamic drivers and so the back wave on the Maggie's is probably
not as "active" as the B200's...just guessing here...

Thanks so much for your insights...beautifully and clearly described...and obviously
an important part of the equation...

I don't think that anyone who has never heard what a back wave can do to fill in the
music and help to create the illusion of "ambiance" can really understand how
compelling it can sound...

It places the music "into the air" so-to-speak and makes the need for surround
speakers a non-issue...please understand...I am not taking a stand against
surround sound...but a well implemented back wave creates the very
dynamics that surround sound is trying to do but without the cumbersome need
for all those drivers...and the magic of the back wave in the case of the single
driver speaker, like the B200, is that all that sound comes from one speaker...

And that brings up a question: Since the back wave is such an important part
of this OB experience, doesn't a large front baffle INTERFERE with the back
wave entering the room...what I mean is a large front baffle could actually set
up too much of a block for the back wave to integrate itself into the all-over
sound picture...and create yet another surface for the back wave to bounce off
creating a third back wave and so on...

Incidentally, JLM and powerbench...I for one find it very interesting to read about
your "professional" life and your professional experiences...we are all getting to
know each other here on AC...and our forums help us to form a kind of community...
not just a community...but a group of serious minded music lovers that are
realizing that we can actually rely on each other to be honest, effective and
helpful to each other to find and establish a direction into the often veiled and
overly hyped world of audio...so to answer your question "who cares"...I care...
and I deeply appreciate your sharing some part of your life with us...

Warm regards -Richard-

Dmason · « **Reply #154 on:** 6 Jun 2005, 11:22 pm »

Nicely crafted wording, Richard. I agree, and the thing I like at least as much as music is frolicking in the Fields of Humanity.

As to the baffle size question, it is a good question; every environment, room, material, mood, recording values, etc., seems to alter how things sound. The wider the baffle, the lower the Fb of the driver. On an infinite baffle, or 107L (Vas) enclosure, the B200 has impressive results at its Fs. Into the corners, more bass, more ambience. Cork covered back of wood baffle, very different from acrylic. This is the thing that fascinates me. The physics appear not to be carved in stone. My experience has been like playing with a Rubik's Cube.

powerbench · « **Reply #155 on:** 6 Jun 2005, 11:39 pm »

well the day has come that the Mini me has arrived(check my other posts).Now I may not be so as techno-educated as some audio enthusiasts but hey i know what i like.The Mini mes are frigging awesome and well suited for most of anything than techno/rap/heavy rock metal they breath and move fine.I am curently listening to some Elvis Costello and Blue Rodeo and I have to say the clarity and dynamics (recording dependant)is great.Not to say i will not play around with other things BUT the suprising thing is how clear vocals are and non complex recordings.For the money (788 bucks)you get an awesome setup.Real awesome....geez i spent more on my Kefs and yes they were weightier soundand a great speaker but this combo is brillant and fun.Good for everything in my collection so far other than rock ie Cult/Audioslave yada yadda
Oh yes its nice .to see people on this forum are so personable and yes we all have various lifes and careers.Nice to have appropiate feedback Ill skip the concrete and stick to wood LOL. iam currently listening to a mish mash of classical now and wow what detail and breathe to the music...cool very cool

-Richard- · « **Reply #156 on:** 6 Jun 2005, 11:51 pm »

Hi Dan,

What you point out has interesting implications...

Audio enthusiasts pay big bucks for ancillary gear that impacts on
the sound of their "main" system...cables, vibration absorbers and on and on...

What you are suggesting is that the same driver, the B200, can be applied
to a variety of different "styles" of baffles and placements and one would get
a very different sound picture...perhaps not totally different...but it would affect
the sound picture at least as much as changing an appliance...

Very interesting...you are encouraging all of us to enter the world of speaker
design...as an education...as a form of play...and there is no doubt in my
mind that our audio life will never be the same after this...and our understanding
of the inner life of how things work in "relationship" will never be the same after this...
you are helping us to strip away the curtain and peek inside the back of the
stage...nice!

Warm regards -Richard-

Dmason · « **Reply #157 on:** 7 Jun 2005, 12:08 am »

Richard,

I am saying same drivers, different baffles, different room, different everything, except this Ultra Verve, sonic planetarium effect of the combination of high resolution, crossoverless speakers actively powered by equally high resolution amplifiers, subtract noise. It can be sooooo good, I dont even miss the bass, if I dont have bass speakers on.

The room IS the speaker enclosure, and every room is different.

mcgsxr · « **Reply #158 on:** 7 Jun 2005, 02:23 am »

Josh asked a great question about beaming and sweet spot. When I first built up the WR125 as a single driver, I marvelled at how the sound refused to move around as I moved my head side to side, and even walked back and forth between the speakers. When I built out the balance of the KIT41, and added the tweeters, I found that magic was gone - now, when I moved from side to side, the sound would move from speaker, to center, to speaker.

With the Visatons in my baffles, in my room, I have them toed in to cross around a foot in front of me, but also tilted back, so that they are aimed about 3 feet above my head. Configured like this, the sound is centered - by this, I mean that I can sit in the sweet spot, and move my head 1 foot in either direction, but the image remains centered. More fun, I can stand behind the sweet spot, and walk all the way OUTSIDE the R speaker, and the sound is STILL centered... this freaks me out, and I am not equiped to explain how this works - I assume it has something to do with the dispersion patterns of the driver, and that no matter where I go in the room, one of the drivers is pointed at me...

As for the highs, well I experience no change in timbre, with all that moving around either, so for me, beaming does not seem to be an issue. I wonder if that has to do with the large surround on the driver - sure, it is an 8 inch, but the actual cone is more like 6, inside that folded paper surround.

As Dmason mentioned, there is something fascinating about the way these enormous panels disappear - Copperfield would be jealous! The music just appears in front of me, and blooms.

Sure, there is room for improvement - I still cannot get the room loaded with a 30Hz tone on these... but that is fine, there are ways to make that happen.

Great fun, next up might be playing with clamping on some lengths of mdf to act as "walls" on the top or sides of the baffle, to see how that changes things.

ooheadsoo · « **Reply #159 on:** 7 Jun 2005, 03:51 am »

You guys are starting to make me think that a simple triangular baffle mounted into a ceiling corner may be an adequate solution after all. There should be plenty of bass and imaging while stuck in a corner seems not to be an issue with at least a couple of implementations so far. DMason, thanks for the open baffle thread tip. I remember seeing it before in my sporadic perusals of diyaudio, but never delved deeply.