[AJinFLA]

AJ,

Why do you post responses basically attacking what others have posted?

MJ,

Why do consider my post an "attack"? It's my response. Why do you chose to attack it?

Other than attacking what the poster says are you providing any added value in your response in the way of discussions or explanations.

Other than attacking my post, why don't you provide some value to your response by dissecting what I said or posted questions to and point out all the errors in what I have stated or provided links to information for?

So there is nothing in between complete measurement and using Beranek's law?  What is Beranak's law?  I guess I am not familiar with that expression.

You don't know what Beraneks law is, but ask if there is nothing between it and complete measurement?
BTW, what is "complete measurement"? Where did I make any such statement in my post?
My point (that you missed) is that it is important to measure. There are those who decry any measurements. Beranek stated it this way http://users.ece.gatech.edu/~mleach/beraneklaw.html

I think your statement is way to restrictive, there are people who build very good speaker systems without complete measurement capabilities

So my "some measurements is better than none" has been translated by you into "complete measurement" because this is what you want to see in my post?

there are also many examples of the opposite case.

Of what opposite? The opposite of what I said, which is no measurements, or the opposite of what you said, which was some measurements?
If it is no measurements like I said, could you cite me an example? Could you define "very good" under such circumstances, when no measurements are utilized? Isn't this already partially covered under Beranek?

Probably the most difficult part of speaker building is producing valid measurements and being able to understand and interpret what they are telling you and what they are not showing you.

I thought I had said as such, without using the exact words.

Do you consider yourself an expert in the art of measuring speaker systems and all of the acoustics and digital math that takes place to produce the picture on the screen that you then still need to interpret?

That's what I have to be, to understand that measuring is better than not measuring? Since I do measure as much as I can, I should quit and not measure at all, because I am not an expert in the art of measuring speaker systems and all of the acoustics and digital math? Under these circumstances MJ, how does one ever become an expert without first being one? That's terribly logical.

Other then referencing other people's work, do you have anything original to offer?

  Originality is a prerequisite for posting? I didn't realize that was a rule. When did you make it up? Did you invent Mathcad? Or do you simply use it and reference it? Where is the originality there?

I will admit that I am not intimately familiar with all of the sites you have quoted

Good, then I hope you found something of worth when you read them. If you didn't, that won't stop me from posting them as valuable references for the speakerbuilder. Others may find value where you don't.

does that mean I should not be able to design and build speakers.

That's a question (or statement as you made it) that I will let you answer yourself, since I didn't state any such thing.
Anyone can design and build a speaker. No one can design and build a great measuring and sounding speaker without ever measuring. If someone can, please link me to it.

The sites you have provided represent positions and not necessarily absolute truths.  There are some people who disagree with some of what is presented by your references.

Other than making statements, do you have anything to offer yourself debunking all that was said on my references?
Can you provide your own absolute truths to counter these positions? Could you provide the disagreement to my references or reference me to positions of the alternative viewpoints? Could you cite me some examples of great loudspeakers built with nary a measurement? Thanks.

AJ

[AJinFLA]

Beranek's law isn't even applicable to his arguments.  It simply says that, to you, "The best sounding speaker is the one that you just built."

Wrong. He mentions something you won't recognize.

Beranek's Law
It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.

L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.


Frequency response. It's something you have to measure.

cheers,

AJ

[MJK]

AJ

I am tired of you AJ.  One of us has to go, I am done here.

Martin

[AJinFLA]

You are going to leave because you disagree with my viewpoint(s), or how I present them?
Then what is the point of a message board?
Only viewpoints that coincide with yours Martin? No dissention or alternative? There seems to be far more here that would agree with your measurements are evil views, so I'll bow out myself if you wish to stay and discuss things with only those that agree with you and pat you on the back saying so.
I love the fact that I don't see a single rebuttal of anything I posted, just cut and run when you have no viable answer. Thanks for all you answers Martin. I was hoping I might learn something from them, but alas, there are none.

AJ

[JohnR]

I'll bow out myself

That's a good idea, why don't you do that.

[JohninCR]

I'll bow out myself

That's a good idea, why don't you do that.

Ditto!


btw I prefer Dr. Bruce Edgar's interpretation of Beranek's Law than Leach's excerpt from
a book taken out of context.  I've specifically found Dr. Edgar's interpretation to hold true
and that it takes a while before we start to hear the flaws.

Also, I emphatically disagree that measurements are required to judge the frequency response
of a speaker.  With practice and simple tools like a tone generator, our ears can be quite sensitive
instruments for speaker building.  Plus they are able to detect characteristics that are yet to be
quantified by any mechanical measure.  Since you've already stated that you have trouble hearing
you must rely more on machines, but since you don't hear so well, why even bother?

Go ahead and only copy the work of others if you want, but your frivolous points are really nothing
more than an inconvenience.  Try finding something meaningful to debate.  No one said measurements
were a bad thing.

[corloc]

As for measuring, (Hmm, I'm speaking as a novice), is very usefull.

It is mandatory, to end up with an Orion or a NaO or an R909. Otherwise, the DIYer simply ends up obeying Beraneks law.

Why should my work end up sounding like these systems?  There is a flip side to Beraneks law as you have posted it.  If you end up with a system that measures perfect, and you don't like the sound than what is the point of listening?  People build their speakers looking for the love of music.  Their system should reflect there hearing and means. 

To design and tweeking systems, but you have to define what your end goal is.

The end goal of all such speakers is superb sound. I wasn't aware there were any other goals to something like an Orion. Is there?

No the end goal is to enjoy the music.  I don't know why you feel the Orion is the end goal of OB.  If that were true, I would just go build a pair and be happy.

I've heard speakers, and rigs that were supposedly flat

Supposedly flat where? How are you defining "flat"?

I didn't define flat, The owner of the system did, and I have no why of verifying it, but the respect of the man how designed it.

I've heard systems with a higher distorion and not ruler flat speakers sound more like the music was live.

Hmmm. Lets assume you mean frequency response, without stating as measured from where (critical). By this rational, could I increase the the "livens" of my system by inserting a CD player with +/- 15db variation (not ruler flat) and high levels of distortion? Or does this only apply to speakers? Does your CD player or amplifier do this?

What? Actually I was thinking of Class A tube amps.  That often have higher harmonic distorion, but people dearly love.  O' before you get on the class A.  I use AB ultra linear.

These are generalizations not the rule, but you have to take into context what you are measuring and how it is being used.

I would certainly hope the people who measure are aware of this.

Thank you for your wisdom, but not all do.

If my memory serves, in the early days of using feedback.  Engineering used as much feedback as they could, because it measured well for distorion, but ended up sounding like ,well, not so good.

Is this a generalization or a rule? Do you disagree with Bob's papers? http://www.cordellaudio.com/papers/another_view_of_tim.pdf
http://www.cordellaudio.com/papers/another_view_of_tim_II.pdf

Thank you for the links. I will read them when I get a chance.

In the realm of digital pictures, I listen to a article on PBS about digital images look more natural to human eyes with a little distorion.  If you cleaned it up it looked worse and if you added more it looked worse.  I have wondered if the same thing goes on with hearing.  Human ears may not be designed to like for pure tone.

This is well known in psychoacoustics. Something that Linkwitz, Toole and Geddes, etc. are well aware of. Thats why Geddes is partnered with Lidia Lee. Are you familiar with her work http://www.gedlee.com/lidia_bio.htm ? Are the folks who aren't measuring as familiar with psychoacoustics?
Have you read all of Geddes papers, like this http://www.gedlee.com/distortion_perception.htm ?
Certainly, as a OB fan, you have read this http://www..com/reproduction.htm

What I was talking about was not psychoacoustics.  I will post a link tomarrow.

My point is, What is the benchmark for measuring?

An understanding of what you are measuring. And what to do with it's significance.

Ruler flat across frequency spectrum or sounds great to your ears.

Both.
If you correctly define "ruler flat" and its significance amongst a thousand other variables.
Since you keep mentioning "Flat", here you go http://www.harman.com/wp/pdf/Loudspeakers&RoomsPt2.pdf
I always hope that everyone who builds their own speakers are already intimately familiar with all the sites I have linked to, but its still worth reading a 2nd or 3rd time.

Intresting, I'll have a look.

No. I'm OB all the way. I like the "pretty pictures" as much as the next guy, but the information contained in non-OB stuff just confuses me since it doesn't relate (usually) to OB.

I am OB "all the way" as well . As in OB loudspeakers. I found a tremendous amount of useful information about loudspeakers in the JBL link, even though he does not use open baffles. I'm sorry that you found nothing useful but the pretty pics. Here's one for you. At least I think its pretty



cheers,

AJ

[Bob in St. Louis]

I'll bow out myself

That's a good idea, why don't you do that.

Ditto!

--From what I've seen so far, I'd like Martin to stay. Unfortunately it's always the intelligent one's who are chased away.

No one can design and build a great measuring and sounding speaker without ever measuring. If someone can, please link me to it......Could you cite me some examples of great loudspeakers built with nary a measurement?

Check my signature AJ. I designed and built them. No, Beraneks Law doesn't come into play since others have echoed my feelings that these are damn good sounding! 
If you'd like, I'll walk you through the build process.
Then you too can be cool like me.     Well not AS cool, almost as cool.

Have a nice day

Bob

[fine]

Come one guys....
Some new people...like myself....want some quality info ....

What do you think about BGS 40 from Visaton...for ob?

http://www.visaton.com/en/chassis_zubehoer/tiefton/bgs40_8.html

@JohnCR
Do you think...if I go with a simple active filter the open baffle should be larger than your ob?
Also...I have an 8" driver...Supravox 215rtf bicone and I want to combine with an woofer in ob but I don't know what is the most suitable woofer for that Supra.

The cross will be on 200hz.
Also the Augie is in my list of option...but also Alpha 15A.
From that 3 mentioned drivers ...what is more suitable for ob in 18m2.

Thx.
What do you think?

[Bob in St. Louis]

Come one guys....
Some new people...like myself....want some quality info ....

I feel the same way, however sometimes watching 2 boxers going at it in the ring, the temptation to poke one in the ribs with a stick is kinda fun.
Some folks don't seem to realize/remember that this is a hobby, it's supposed to be fun.

Bob

[JohninCR]

Come one guys....
Some new people...like myself....want some quality info ....

What do you think about BGS 40 from Visaton...for ob?

http://www.visaton.com/en/chassis_zubehoer/tiefton/bgs40_8.html

@JohnCR
Do you think...if I go with a simple active filter the open baffle should be larger than your ob?
Also...I have an 8" driver...Supravox 215rtf bicone and I want to combine with an woofer in ob but I don't know what is the most suitable woofer for that Supra.

The cross will be on 200hz.
Also the Augie is in my list of option...but also Alpha 15A.
From that 3 mentioned drivers ...what is more suitable for ob in 18m2.

Thx.
What do you think?

Fine,

Yes you are right.  AJ does have a lot of knowledge, but he prefers to debate about
nothing rather than share constructively.

You really have to set your performance goals and baffle size in order to choose a driver.
Realistically, none of those drivers will work for you if you want high dynamics and deep
bass.  Visaton is up to it's familiar spec hiding with the BGS40, since its Xmax is only
2mm (winding 12mm - pole plate height 8mm = max point to point with VC fully in the
gap 4mm =  Xmax 2mm).  The Augie with it's 7mm Xmax will make the most bass, but crossing
at 200hz won't work because it is too heavy coned (to get the Fs lower).  The Alpha is
probably your best bet, but it takes 2 to equal an Augie at the bottom end, since it has
half the Xmax.

Welcome to the world of frustrating OB driver selection.

[rick57]

> it takes 2 to equal an Augie at the bottom end

But isn't the Alpha 15A less than half the price, and as MJK points out http://www.quarter-wave.com/Project07/Project07.html, with a high Q, doesn't need EQ?

it seems it an obvious choice

Cheers

[JohninCR]

Rick,

With OB there is never an obvious choice.  You have to start
with your performance goals combined with the construction
you are willing to accept.  Also, unless you can live with a big
baffle like MJK's, EQ in some form is mandatory if a flattish
response is one of your goals.  Effective EQ can take many forms
including traditional EQ or bass boost, additional drivers, or special
construction.

This Knight driver is probably an even more obvious choice with a cast
frame combined with sensitivity, Xmax (may be point-to-point though),
and price.
http://www.musicsupplycenter.com/ProductDetails.asp?ProductCode=813%2D013

[fine]

why not try something like that:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=82116&perpage=10&pagenumber=4

The 4 woofers was Peerless and I'm convinced 100% is SLS drivers.
Calvin...the owner said that achieve 25hz and match well with AER full range driver.

The entire design is well suited in some of medium rooms.
Any thoughts?

[rick57]

Xmax would be one of the top criteria.
http://www.musicsupplycenter.com/ProductDetails.asp?ProductCode=813%2D013
Is that the Knight that has Xmax of 0?

[JohninCR]

That's 0.25 inches or 6mm.  My concern is whether or not that is point-to-point,
since 3mm is typical of that size and efficiency pro-woofer.  Xmech is a concern for
anyone going for high dynamics, so the occasional very deep and strong note doesn't
damage the driver or cause that nasty banging sound.

[tminus]

hum4god, here is a driver that should do great bass on OB:

http://www.soundsplinter.com/rls_supreme_series_LMT_12_inch_and_15_inch_diy_subwoofer_drivers.html

I bought it for OB, but haven't mounted them yet.  It is a "cost-no-object" solution, however.  I'm scouring the net now, looking for mounting ideas.  Maybe some of the gifted folks here could offer some pointers??

In reality, the hawthorne Audio Auggies make allot of bass for OB, and I don't think in my case any more was warranted.  I just go to the fringe sometimes.

From what I've read, to make low bass on OB, you need two things - displacement and displacement.  You can get that by conal area multiplied by Xmax.  It has to be a driver that can operate efficiently in free air.  Look for big-cone, high qts drivers.  Pro drivers will probably bottom out bad, as JohninCR pointed out.  You have no spongy air behind the driver to damp the excursion of the motor.  Big conal area is key because (if I understand correctly) the OB driver is not loaded by the room, so you need to move allot of air to get the same chest-thump that you may be used to from sealed or vented enclosures.  Amplifier selection then is key too, I think.  It must have total control of the motor.  High damping can do this.  So can low watt high current amps, like "Firstwatt".  I don't know if a low watt amp would work with this particular driver recommendation, though.

[mcgsxr]

I own a set of these, and find them very good with 1 voice coil run open, and one connected.  This doubles the effective QTS to roughly 0.54.  I run them in series through my BASH 300w sub amp, and find them very good on OB, and quite affordable, if you are in North America.  If you are in Canada, they are a no brainer, they were less than $130 shipped to my door...

I know that you want a high sensitivity driver, but if you are biamping, then it becomes less relevant, else, sorry for the tangent.

http://www.mach5audio.com/product_info.php?products_id=41&osCsid=86290b555986cedce02e0ee8df710038

[JohninCR]

Mark,

How are those MAW-12's on noise of operation at healthy excursions?  If they're quiet, those
are probably the best 12's I've seen for OB bass.  $53 for cast frames and 13mm xmax with Fs in
the 20's is a real bargain.

[mcgsxr]

When I unplug my main amp, and run just the 12's on the baffle (thus only producing 80Hz and down, with a built in 12Db/octave Xover in the sub amp) it is the baffles themselves I hear vibrating, I don't hear any chuffing or slapping etc.

Just the baffles setting up standing waves at various frequencies.

They seem excellent value, and Mark in Western Canada was excellent to deal with.