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Buddha
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Speaker cabinet diffraction...

Hola,

After reading Art plotz for the Audio Notes speakers, and everyone else swooning for the Harbeth line, it made me wonder about a topic that doesn't seem to come when discussing those speaker lines...diffraction.

Some manufacturers seem to design speakers trying to minimize this phenomenon, others like Audio Note and Harbeth don't seem to 'care.'

If a listener can hear diffraction artifacts from one cabinet, then not hear them from a similar cabinet made by another manufacturer, what 'tricks' does the maker of the box know to eliminate this assumed barrier to better sound?

Are the Audio Notes and Harbeth's still diffracting, but sound so good that we forgive them? Or, is diffraction not the monster it's cracked up to be?

If real, I wonder how Audio Note and Harbeth work around it, 'cause their stuff sounds pretty good!

linden518
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Re: Speaker cabinet diffraction...

Before I got my Super HL5s, I did some research, and Alan Shaw of Harbeth IS mindful of diffraction, as any speaker designer would be. I remember reading something about Harbeth processing the edge of a front baffle in such a way to reduce diffraction. I also read somewhere in the Harbeth forum Alan Shaw's comment about how the SuperGrille (their name, not mine) is specifically designed to treat the diffraction problem, which is why he recommends listening to the HL5s with the grills on. He sees the SuperGrille as an integral part of the speakers, and not as a protective cover... as any Super HL5 owner would know, the grills truly are a bitch to take off. I know a lot of Harbeth owners like to listen with the grills off, probably for more immediacy, etc., but why mess with the intentional design of the designer? After reading that, I've never taken the grills off my Harbeths; I'm sure Alan Shaw's not just BS-ing...

I bet you that you can get a more detailed answer if you post your question at the Harbeth forum, Buddha. Alan Shaw usually is very involved with the site, and answers a lot - if not most - of the questions thrown at him.

dcstep
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Re: Speaker cabinet diffraction...

Audio Note actually claims to build the cabinet that way on purpose. I think it's a slippery slope and very dependent on a room that will accomodate the suggested placement, but, when done right, it can sound pretty darn good. For maximum satisfaction buyers should consider how the speaker will work in their room and can they really put the speakers where they'll work best.

Dave

Jan Vigne
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Re: Speaker cabinet diffraction...

Control the dispersion pattern of the tweeter and you control the diffraction at the cabinet edges.

linden518
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Re: Speaker cabinet diffraction...


Quote:
Control the dispersion pattern of the tweeter and you control the diffraction at the cabinet edges.


Yup. At first I didn't understand why the cloth of the grill on the Super HL5s touches the tweeters. Weird. Apparently, Alan Shaw designed them to be so.

Jan Vigne
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Re: Speaker cabinet diffraction...

Harbeth was one of the manufacturers licensed to build the BBC's LS3/5a. Look at the felt "ring" around the KEF tweeter on that speaker. It's an early version of diffraction control meant to minimize the effect of what was then (1975) the traditional way to build a cabinet.

http://www.ls35a.com/

Audio Note seems to prefer using a wide baffle as a way to minimize baffle step notches in frequency response. The wider the front baffle the less energy is present at the edge of the cabinet while probably providing a moderate boost in level to the tweeter's output.

"The AN

dcstep
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Re: Speaker cabinet diffraction...

You gotta give A-Note a lot of credit, they spout their sh*t no matter how inappropriate in many circumstances. They can sound very good, but often don't because that wide baffle design doesn't work in a lot of real world situations.

I'll consider the A-Note seriously for my next purchase, but it won't be due to the BS they spout.

Dave

Jan Vigne
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Re: Speaker cabinet diffraction...


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They can sound very good, but often don't because that wide baffle design doesn't work in a lot of real world situations.

I'm not sure why you consider the design to be "BS" other than it deviates from what is being sold by most manufacturers wishing to appeal to a market where the cabinets will occupy space in a family room and must have high Spouse Approval Factors. The wide baffle makes sense for the tweeter and has been employed in other designs from well regarded manufacturers. It essentially sets up a "virtual" infinite baffle which increases the output of the driver (which, in effect, provides higher power handling), lowers its usable frequency cut off (making crossover design more flexible) and minimizes diffraction all of which together have the potential to provide smoother response and better driver integration. That doesn't sound like BS to me. If the AN speakers don't "sound good" in your experience, I would suggest you not place the blame on the size of the front baffle.

dcstep
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Re: Speaker cabinet diffraction...


Quote:

I'm not sure why you consider the design to be "BS" other than it deviates from what is being sold by most manufacturers wishing to appeal to a market where the cabinets will occupy space in a family room and must have high Spouse Approval Factors.

There you go, spouting their BS to support their BS. That's such a crock of sh*t, implying that no other design has no merit and is merely a WAF ploy. It's crap like this, that eveyone knows is untrue, that hurts their sales potential and makes them so distrusted by many of us.

I listened to the Snells years ago and was pretty impressed, despite room issues, so I'm going to try again with the A-Notes, but their high and mighty, holier than thou marketing is embarrassing to a potential customer. There pricing is really strange also, running from expensive buy understandable to outrageously expensive, all with the same design with various drivers and crossovers. Oh well, I'll deal with that after a listen to one of the lower range models (over $10,000).

Dave

Buddha
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Re: Speaker cabinet diffraction...

So, would you expect a speaker of this type to have narrower driver dispersion and, therefore, maybe a narrower sweet spot?

That wouldn't be so drastic a trade off. Kind of like some planar speakers!

That would sure make it important for multpile drivers to somehow keep their combined act together coming from different places on the same big flat baffle!

Which probably explains why it was such an accomplishment by Mr. Snell!

I'm getting a DIY jones and I've seen some cool "OB" ideas that seem like they would be fun to implement with full range drivers.

I find full rangers very seductive. Maybe each of us has certain anomolies we just don't cotton to. For me, I think it may be crossovers.

This thread is going to merge in my mind with the one about the PHY full range drivers. Hopefully, it will lead to some mischief!

linden518
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Re: Speaker cabinet diffraction...


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This thread is going to merge in my mind with the one about the PHY full range drivers. Hopefully, it will lead to some mischief!


Take pictures!

dcstep
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Re: Speaker cabinet diffraction...


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So, would you expect a speaker of this type to have narrower driver dispersion and, therefore, maybe a narrower sweet spot?

Not really, when placed as designed (near a back wall and corner). In the right room, placed right, the image is big and the bass is deep. If you get frustrated trying to balance out all the reflections and just pull them way out into the room, then they'll suck big time, with a small image, fast bass roll-off and other issue, BUT they're not designed for that and should be purchased by anyone without the right room.

It's actually an elegant design, that works very well when applied correctly. Unfortunately lots of people don't really understand how to use them; therefore, user experience is all over the board.

I haven't looked, but I bet that the archives of Stereophile have a lot of discussion of the Snells. Everything said there would still apply to A-Note. Art's more recent reviews don't really dwell on the placement issue much. (He found the hemp drivers very stimulating).

Dave

Jan Vigne
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Re: Speaker cabinet diffraction...


Quote:
There you go, spouting their BS to support their BS. That's such a crock of sh*t, implying that no other design has no merit and is merely a WAF ploy. It's crap like this, that eveyone knows is untrue, that hurts their sales potential and makes them so distrusted by many of us.

If it weren't for the decent spelling and punctuation I would have thought that had been posted by dup. I give you a rationalization for why something is done and you accuse me of spouting BS. I did not imply any other approach could not or would not work just as well. You seem to have a blind spot for reasoning. Please, imagine I posted something here that Stephen would send to the Dead Zone. Then explain how "everyone knows" something to be untrue in this hobby. That is a pile of BS stacked high. If you have not yet learned that everything in audio is a tradeoff, you have plenty left to discover. With that much unknown you really shouldn't be labelling anything BS.

The AN speakers work. They work in various rooms and various positions. That's not any different than a thousand other speakers out there. I assume you either never heard of or have forgotten Allison speakers. They were also a crock of BS according to your thinking. If you are wedded to an ideology and have no interest in any other thoughts slipping into your skull, you are going to be disappointed in hifi. One thing that is abundantly clear in audio is there can be more than one way to butter your biscuit.

smejias
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Re: Speaker cabinet diffraction...


Quote:
One thing that is abundantly clear in audio is there can be more than one way to butter your biscuit.

I think we can all agree on that.

dcstep
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Re: Speaker cabinet diffraction...

I see why DUP likes you so much.

Jan Vigne
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Re: Speaker cabinet diffraction...

Yeah, I don't like being called a liar and a shill by someone who doesn't know their stinkin' elbow from the rear parts of a rat's anatomy.

Why don't you try explaining the "everybody knows" remark now that you've stuck your foot in your ... mouth.

dcstep
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Re: Speaker cabinet diffraction...

Liar?? I didn't say that, but if the shoe fits...

My feet are firmly on the ground. No explaination required.

Dave

Jan Vigne
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Re: Speaker cabinet diffraction...

You deny "liar" but you're happy with "shill"? And I'm supposed to be OK with that? This is why dup doesn't like me. I can always prove he has nothing to say worth reading. Guess who just joined that club.

Look, I'm really not interested in getting into this with you. And I'm really, really not interested in your little boy with big mouth parlor games. But either you called me a liar or you believe what Audio Note claims (and what I posted) which makes it not BS. Which is it?

I assume you won't provide an explanation because you have none to provide. Do you have any idea what "baffle step" refers to? It's obvious you don't have a clue what Snell's concepts predicted or that other manufacturers have used this design idea in numerous models of loudspeakers. So why open your yap?

RGibran
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Re: Speaker cabinet diffraction...


Quote:
I'd say at least 50% of this forum is someone brow beating someone else. If it weren't, there would be a lot of good people who still particpiated in this forum.

RG

Buddha
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Re: Speaker cabinet diffraction...

Ya, know, I looked at the Audio Note, and was kind of surprised to see they use what looks like a Scan Speak dome tweeter.

Since I already started with a kind of dumb question, another...

What is it they'd do to that dome tweeter to alter its dispersion to match the front baffle? Or, is it really just a matter of putting it in the right spot on the baffle?

At first, for these large baffle speakers, I was kind of picturing a tweeter that had a dispersion pattern kind of like a quasar, to minimize the baffle's efefct.

So, are other speakers really "fashion victims," or are they also correct?

Jan Vigne
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Re: Speaker cabinet diffraction...

Are you asking me? Or would you prefer to have RG, the guy who has never contributed a positive thought to this forum, answer your question? Or do you want the guy who thinks it's all BS to provide his view of how dispersion is controlled?

linden518
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Re: Speaker cabinet diffraction...

Wow, guys. Let's cool off a bit. The discussion started so well w/ this thread... btw: what would be a good book to read on speakers & speaker designs?

Jan Vigne
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Re: Speaker cabinet diffraction...

It depends on what you want to learn. You can start with "The Loudspeaker Design Cookbook". There's plenty on the web that will give you a good start on speaker design.

http://sound.westhost.com/index2.html

http://www.speakerbuilding.com/

http://www.quarter-wave.com/

Just enter what you want to find in a search engine and you'll get plenty to read.

linden518
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Re: Speaker cabinet diffraction...

Thanks, Jan. VERY helpful.

dcstep
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Re: Speaker cabinet diffraction...

Shill?? I never called you a shill, but if the shoe fits...

Makes me wonder why these things pop into your mind. I never called you a liar or a shill, but then you claim I did. You may need some meds, seriously, you're imagining things and overreacting. I suspect that you've got worse problems than DUP.

Dave

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Re: Speaker cabinet diffraction...


Quote:
Wow, guys. Let's cool off a bit.

It's the girls who won't play fair!

RG

Jan Vigne
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Re: Speaker cabinet diffraction...

You're talking like a punk.

Take your meds and then read what you posted.


Quote:
There you go, spouting their BS to support their BS. That's such a crock of sh*t, implying that no other design has no merit and is merely a WAF ploy. It's crap like this, that eveyone knows is untrue, that hurts their sales potential and makes them so distrusted by many of us.

I am not the one who has over reacted. And I am not the one trying to back out of what I posted.

You are purposefully ignoring an explanation and ignoring whether you believe the AN reasoning is BS. You haven't even Googled "baffle step" or Snell yet but you keep on spouting off. Address that whole "crock of sh*t" and the matter will very likely be cleared up.

Jan Vigne
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Re: Speaker cabinet diffraction...

If you're serious about learning more, you can go to Parts Express and Madisound, both raw materials retailers, and find several books on various aspects of speaker design. Here are a couple useful links from the Elliot pages;

[url=http://lenardaudio.com/sitemap.html]

http://lenardaudio.com/sitemap.html[/url]

http://www.linkwitzlab.com/

http://www.audioxpress.com/

dcstep
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Re: Speaker cabinet diffraction...


Quote:
You're talking like a punk.

Take your meds and then read what you posted.


Quote:
There you go, spouting their BS to support their BS. That's such a crock of sh*t, implying that no other design has no merit and is merely a WAF ploy. It's crap like this, that eveyone knows is untrue, that hurts their sales potential and makes them so distrusted by many of us.

I am not the one who has over reacted. And I am not the one trying to back out of what I posted.

You are purposefully ignoring an explanation and ignoring whether you believe the AN reasoning is BS. You haven't even Googled "baffle step" or Snell yet but you keep on spouting off. Address that whole "crock of sh*t" and the matter will very likely be cleared up.

Where did I call you a liar or shill???

You must feel guilty. Since you like so much attention and want me to call you a name I'll call you a name you deserve, Stereophile's drama queen. If no one insults you then you make something up so you can moan, groan and cry about how abused you are.

I'm through talking to you. Don't send me any emails or I'll post them here for all the boys to see.

Dave

Jan Vigne
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Re: Speaker cabinet diffraction...


Hmmph! All you had to do was explain what "everybody knows".

Shill:

Quote:
There you go, spouting their BS to support their BS.

Liar:

Quote:
That's such a crock of sh*t ...

And I never said this;

Quote:
... implying that no other design has no merit and is merely a WAF ploy.

OK, so you don't know what you're talking about, you can't remember what you posted and you're nuts.

HELLO, dup!

You have no explanation.

You can't back up what you post.

You have a blind spot for reasoning.

And somehow that's my fault.

Well, rest assured I won't send you any more emails than I ever have before. Which is none so you can stop that game too.

Jan Vigne
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Re: Speaker cabinet diffraction...

http://sound.westhost.com/bafflestep.htm


Quote:
Some speakers are designed for "boundary reinforcement" - in other words, they are meant to be used right against the wall. These include the Naim Audio range and some of Linn's speakers, and don't take the baffle step into account. http://www.soton.ac.uk/~apm3/diyaudio/Diffraction.html

You can alter the dispersion chartaceristics of a driver by changing the size, shape or type of driver. You can place the driver in the throat of a waveguide or horn. Coaxial drivers such as the KEF Uni-Q suffer from problems which stem from the waveguide formed by the larger driver moving back and forth relative to the tweeter as the high frequency driver operates. (KEF has just introduced a revision to the Uni-Q series to address this problem. I believe JA discussed this when he reviewed the latest KEF monitor speaker.)

Changing how the driver terminates at its surround will alter its dispersion. Some crossover types tend to lobe and this affects vertical dispersion as does the position of the driver in relation to other drivers in the speaker system such as found in a MTM arrangment.

Obviously, the width of the baffle affects dispersion where once the width of the baffle is three times the longest wavelength the driver must reproduce the driver effectively sees a hemisphere and operates into half space which gives it a mild boost in output and an extra bit of extension at its low frequency limit similar to placing a woofer against a flat wall.

You can affect the dispersion of the driver by limiting its highest frequency response since any driver will beam once the wavelength of the reproduced signal is smaller than the diameter of the driver.

You can absorb the dispersed wavelength with soft material placed around the driver such as the felt ring on the LS3/5a or the thick felt mat Spica used on their front baffles.

You can also alter the dispersion characteristics of the system and the in room output levels by changing from a monopole, to a dipole, a bipole or an omnidirectional dispersion pattern.

Elk
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Re: Speaker cabinet diffraction...


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I'm through talking to you. Don't send me any emails or I'll post them here for all the boys to see.


I don't even bother opening them.

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