[Greggo]

Just for fun...

Richard Vandersteen, Soundstage!, August 1998...


"To see what was possible sonically without the secondary radiation products, we mounted drivers naked in space, no enclosure or baffle at all. In the ‘70s, second- and third-order crossovers were by far the most common types in use and that is what I was working with. Experimentally, but almost by accident, we discovered that a tweeter in this free-air fixture took on a completely different sonic character depending on whether it was driven by a first-, second-, or third-order filter. It’s wasn’t just different because the 3dB-down points were different for each crossover or because of the slower roll-off in the lower-order crossovers. The tweeter took on a noticeable pinched, twangy sound with a second-order crossover, which was even more noticeable with a third-order crossover. Only with the first-order crossover did the tweeter sound natural.

And specifically discussing midrange and tweeter interaction...

"Our stagger is part of our minimum baffle design. The baffle is the flat surface the driver is mounted on. We try to make that surface as small as possible because our research proved and keeps proving as we revisit those tests that the smaller the baffle, the less surface there is around the driver, the better the driver sounds. Using foam or felt around the driver to attempt to reduce the effect of the baffle is better than nothing, but no baffle at all is much better. This is a direct result of learning about diffraction and how detrimental it is to the sound of loudspeakers by introducing large amounts of the secondary distortions we set out to eliminate in our speakers way back in the ‘70s. Small or no baffle produces no diffraction distortions. We put each driver in a separate enclosure so we can minimize the size of the baffle around the driver."

Regards,

Greg Jensen

[JohninCR]

Interesting stuff Greg.  Even though I no have fully flexible XO slopes and point with
my active solution, tuning by ear I've preferred the 1st order XO slopes even though
I can do phase correction too.  I thought this was just because I needed to break
down and start measuring.  It's comforting when I find out that real experts agree.

[notech]

You just demonstrated how little you know about Vandersteen's approach, which I am not going to get into, and coupled with your strident and condescending tone, I am now more interested in psychiatry.

It has been a few years since I've worked directly wirh Richard, but unless his "approach" has changed I'm not too far off base.

The old addage could not be more appropriate --- You can lead a horse to water but you can't make him drink it.

Guys - Good luck with your "OB Baffleless" projects.  I've done some poking around your site and it appears that you're in good company.   

[JLM]

This "design" concept of no baffle is silly, I agree with notech.

Yes, the Auggie can make bass with little or no baffle, but after all it is a 15 inch driver.  This could be compared to providing a 500 hp engine on a bicycle.  Imagine how much more bass can be produced from a properly designed cabinet with a 15 inch driver.  Now mount that 500 hp engine in a proper chasis.  That's the point here.

What Vandersteen is quoted to say about small baffles cannot be logically extrapolated to mean that no enclosure is better than having a "proper" enclosure.

[JohninCR]

NoTech,
Too bad everyone else pounced on you.  I was hoping you'd
try to make a valid point before you went scurrying away.


JLM,

My goal since I started on the OB trail 3 years ago has been
to build OB speakers with rich full natural bass in as small a
physical and visual package as possible.  I took the single
driver approach to OB as far as I could, and it just wasn't
small enough with enough bass. 

I'm not after maximum SPL just enough for my needs.  If I
wanted maximum bass spl, I'd put my JBL 15" in a ported box
and pump 5kw into it.

Now that I've added a 15" driver, I realize that a baffle isn't
even necessary, so these NoBaffles are just a test cab to
prove that it works.  Since it exceeded my expectations, I
want to take the idea to the limit in terms of being unique
visually, while retaining outstanding sound.  I'm getting so
much bass with minimal excursion that even a 12" might
work, especially with a 1.5" diffraction ring around it to retain
the 15" overall diameter.  Finding the right 12 may be difficult
though.

These speakers are smaller with more and argueably better
bass than your MLTL's.  To me what is silly is putting a
driver in a box, manipulating the rear wave and dumping
it into the room via a port or whatever, and then convincing
people that you've done something good.  Using that method
bass doesn't sound close to natural due to the manipulation.
In addition, you create time, phase, and room problems, which
combined are offensive to my ears.

If you don't like this idea, you really won't like the next one,
because they'll get even smaller.  My 20minute test cabs that
I'm listening to tonight are even better.  Any of my future baffles
will be just to show off some wood, act as support structures,
hide the backside of drivers, and/or to cure diffraction at the edges,
anything except the typical purpose of an OB baffle.

[Greggo]

Did I miss out on the Pedantic Parade invitation, or was it the Doubting Thomas Club, something else?  Whatever it was, clearly the agreed upon meeting place was this thread on this fine day.  Of course it is reasonable to extrapolate that, if given your own goals regarding power, SPL, drivers, dollars, and all such other things that may constrain a commercial company but not necessarily constrain a DIY effort, this type of investigation would at least be an interesting path worth pursuing.

Your logic about "imagine how much more bass..." and "properly designed cabinets" could be used to condemn virtually any dipole design, from Linkwitz on down the ranks, so why bother posting here on the Open Baffle forum?  If you are serious about exploring the potential of open baffle speakers, then everything between "infinite baffle" and "no baffle" is fair game and has the potential to inform us in different ways, point the direction to new variables and new results, and accomplish that very interesting feat known as open source, open minded thinking and new experiences.  500 hp engine on a bicycle?  Give me a break.  Maybe I have two 500 hp engines, one on a unicycle for 60hz and above, and one in a Caterpillar dump truck just to handle 20-60hz, and maybe to me it sounds better, or maybe just different, and a kind of difference that I just like for some reason and have fun building.  Are all these thoughts really that threatening to the "proper box" crowd?  If only every mangufacturer and every DIY builder and every potential inovator in this industry just stayed with "proper boxes", this hobby would be so much more fun!

Regards,

Greg Jensen

[Bob in St. Louis]

Wow, a few hours goes by and this thread explodes. Nothing like a little controversy between geeks.

notech.
#1 - You still haven't answered my first question to you.
       

Are you referring to OB speaker design? If so, I'd like some links.

#2 - What does a router have to do with anything.
       ...and speaking of routers, are you saying all speaker builders use routers?

#3 -

Other sites that I frequent have technical moderators

       Are you still a member of any of these forums?
       Have you been, "technically moderated" off the forums?
       Are you here looking for more technical moderation?

Most importantly
#4 - Have you heard OB? I'd like you to try it. Then give me an opinion.

Bob

[JDUBS]

Come on Dmason, you've seen guys like notech before!  A troll with nothing better to do but try to shoot down people's ideas!  He'll soon leave Audiocircle but will do so on his "own terms" as he doesn't want to waste his time with the likes of the Audiocircle regulars!  He's waaay too smart!! 

Its pretty funny actually...and sad...but more funny!! 

[JohninCR]

Nothing like a little controversy between geeks.

Geeks?  NoTech may be one of those measurements are everything, computer model every
detail, box geeks, but he didn't try to provide anything of substance to be able to tell. 
Otherwise, I don't see any geeks here.

[Dmason]

JDUBS

When someone comes howling out of the ether, all fire and brimstone, rage and machination, yes, my interest is in psychiatry. Trust me, it isn't speakers that brings his ilk....interesting stuff.

Oh well, onward with our naievete!   

[Bob in St. Louis]

Otherwise, I don't see any geeks here.

John, your my favorite geek. You can "geek speak" with the best of 'em!  

Bob - wannabe audio geek

Hey Trevor, I see you lurking there! Welcome. I didn't know that "you knew these parts".

[Russell Dawkins]

When someone comes howling out of the ether, all fire and brimstone, rage and machination, yes, my interest is in psychiatry.    

I imagine he's probably lonely. I wouldn't think he has many friends. 

[notech]

Sorry guys - you have this lonely, inept, semi-literate, pointless loser feeling blue.  I'm out. 

Good listening and keep up the good work.

-Audiomatica Design-

[JLM]

First, this is just a hobby, why get your shorts in a bind?  I like AC because its friendly.  The fanatical aspect of open baffle discussions is the biggest exception I've found to the AC premise.  Regardless of how big or how many words used, its gets very cold in these parts.

Second, where does this miniminalist approach end?  One driver, rarely done well but I'm with you.  Open baffles, I'm still interested in the concept.  Start with a single big driver and no baffle.     Hardly original and a slam of virtually every speaker designer that has lived.  Now a smaller driver can be used?  Why not just eliminate the drivers next?  In your madness and imagination I sure that it too can be rationalized.  Your island is getting smaller and more remote.

[Bob in St. Louis]

Your island is getting smaller and more remote.

TRYING to get away from the "undesirables".

Bob

[Dmason]

Bob, as always, the "moths" are attracted to the "flame." It seems to "empower" them. It never ceases to amaze me. Obscure, yes. Audio? No.

Let's get on with this discussion. It was stimulating until yesterday.

[Bob in St. Louis]

Let's get on with this discussion. It was stimulating until yesterday.

Fair enough sir... Let's get it on!
Ok, I'll restart the "Idea Train"......

How about a flexible tubing type product, maybe two inches in diameter, wrapped around the drivers mounting holes? Sounds to me like it would "fit the bill" for sound quality and appearance.
Whatchu guys think?

Bob

[JohninCR]

Dan,

I'm with you.  If there really is something inherently wrong with this approach
I'd like to hear about it.  I can't really proceed until I make some diffraction
rings (for lack of a better name), and do measurements.  I have the equipment
for measuring, but I want to take a few sets as far as I can with my usual
tune by ear approach before I figure out how to do measurements.  Then I
can compare.

I admit that the test mules don't sound as good as the same drivers with a
minimal baffle, but I blame this on 2 factors rather than a basic flaw in the
approach. 

1.  The primary audible problem is my construction.  It puts a reflective
surface within inches of 2 of the 6 rear openings in the basket. Those early
reflections of a big chunk of the rear wave are a real problem. 

2.  The circular shape of the baffle (the driver itself) causes the diffraction
effects to occur at the same frequencies, and the thin sharpe edge of the
frame causes very pronounced diffraction.  With usual rectangular boxes and
baffles these diffraction effects are spread accross a range of frequencies
so they aren't as noticeable.  While that approach is typical, it is significantly
flawed, because it doesn't eliminate the large ripples in response caused by
the shape of the baffle edge.  Olsen's work shows us how to shape the edges
of our baffles to eliminate diffraction as opposed to averaging it.  Again I
don't mean baffle step, I mean edge diffraction, even though they are commonly
lumped together because they occur in the same frequency range based on
the size and shape of your baffle. 

Edge diffraction is typically ignored, because it's much easier to build squared,
or near square edges than the large deep transitions from front to side that Olsen's
work demonstrates are required.  His work was with boxes, but with OB's I find
that edge diffraction is much more pronounced, but I've been unable to engage
anyone with more knowledge in that discussion.

Lastly, I've decided against building very massive speakers.  Instead I will
totally isolate the big bottom driver and its support structure from the main
driver support structure.

[JohninCR]

Let's get on with this discussion. It was stimulating until yesterday.

How about a flexible tubing type product, maybe two inches in diameter, wrapped around the drivers mounting holes? Sounds to me like it would "fit the bill" for sound quality and appearance.
Whatchu guys think?
Bob

It might work.  Keep in mind that you probably don't want anything to protrude forward past the front plane of the driver frame, and you want a smooth expansion of the rear wave too.

[Bob in St. Louis]

Keep in mind that you probably don't want anything to protrude forward past the front plane of the driver frame

Otherwise it would be like putting a bowl on the front of the driver, as I imagine it.
You know, if that were done correctly, it could be used to our advantage. No??? Maybe???

Bob