Speaker Wood

[SaSi]

In the design process for a speaker (and I will focus for simplicity on sealed, acoustic suspension types) the enclosure is simply the container for enough volume of air to form a spring to load the back of the woofer cone.

The shape of the box generates two sets of issues: internal resonances and external, parasitic radiation caused either by pointy edges and/or resonating panel material.

The sound we listen to comes (or should come) solely from the speaker driver (the woofer). The tweeter doesn't even have to be mounted on a sealed box if it is a sealed dome type of driver.

For decades, designers have been focused in finding ways to reduce box resonances either by following the brute force approach (heavy thick panels) or trying to be clever (thinner walls with heavy bracing and internal sound deadening material glued on the panels). Some tried to be inovative, like Wharfedale, by using dual wall cabinents with sand filling the gap between the inner and outer enclosure.

Everyone seems to be trying to reduce or eliminate box resonances. Could they all be wrong?

 

[marc mc]

Everyone seems to be trying to reduce or eliminate box resonances. Could they all be wrong?

Harbeth and AudioNote seem to think so. And many regard them as the best around.

Thinned walled high efficency speakers with set amps is something to behold.

marc mc

 

[spkrdtr]

Worth a read:

http://www.hqspeakers.com/krell-lat-1000/

http://www.avguide.com/review/krell-lat-1000-loudspeaker

http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1193710250&openusid&zzMicrostrip&4&5

I'll be bold enough to say that in 10 years time the minority will own cabinets made from anything other than Aluminium.

The Audiogon reviewer David's assessment of the KRELL LAT cabinet is spot on: "insanely inert". I think the operative word here is insanely ($55,000 price). I firmly believe if those cabinets were made of thick, well-braced multi-ply wood or MDF in the exact same geometry, David would not be able to hear any difference between his 3 inch thick aluminum ones and the wood ones.

I still haven't seen anyone quantify what % of the total distortion in a reasonably designed, built & braced loudspeaker is attributable to cabinet resonances. IOW, if one is playing music in the typical 75-90 dB range, I'd say maybe a few dB of that could be resonances? Music is such a dynamic medium. How can one stay focused on any one portion of it long enough to identify exactly what is resonant artifact and music?

There does, however, appear to be a small group of speaker buffs who seem to obsess about cabinet resonances. Perhaps Krell's LAT's and other, over-the-top cabinet designs are/were intended to appeal to that faction. I don't know. They're out there and that's fine with me. It just gives the speakers companies something else to focus on to help sell their products. The B&W Matrix series was one of the first to focus on addressing the cabinet resonance issue. Check their website now. It's hardly mentioned anywhere.
As the sayiing goes.....YMMV

 

[RayW]

There's a major conceptual difference between a speaker cabinet's function in preventing backwave cancellation, changing the speaker's free-air resonance, providing proper porting if the design calls for it, etc. on the one hand, and radiating sound as a result of cabinet panel vibrations on the other. It is the last of these that has been the main focus of this thread.

Good on ya, Rich. I was going to point that out but I need to either stay up later or wake up earlier to beat you.

 

[BradV]

The Audiogon reviewer David's assessment of the KRELL LAT cabinet is spot on: "insanely inert". I think the operative word here is insanely ($55,000 price). I firmly believe if those cabinets were made of thick, well-braced multi-ply wood or MDF in the exact same geometry, David would not be able to hear any difference between his 3 inch thick aluminum ones and the wood ones.

I still haven't seen anyone quantify what % of the total distortion in a reasonably designed, built & braced loudspeaker is attributable to cabinet resonances. IOW, if one is playing music in the typical 75-90 dB range, I'd say maybe a few dB of that could be resonances? Music is such a dynamic medium. How can one stay focused on any one portion of it long enough to identify exactly what is resonant artifact and music?

There does, however, appear to be a small group of speaker buffs who seem to obsess about cabinet resonances. Perhaps Krell's LAT's and other, over-the-top cabinet designs are/were intended to appeal to that faction. I don't know. They're out there and that's fine with me. It just gives the speakers companies something else to focus on to help sell their products. The B&W Matrix series was one of the first to focus on addressing the cabinet resonance issue. Check their website now. It's hardly mentioned anywhere.
As the sayiing goes.....YMMV

Marketing is a tricky area could be why B&W abondoned any reference to a term that has some negative conotations, I'd do the same thing.

It would be an interesting experiment to have the LAT speaker made from conventional material and compare the sonic differences. IMO the clean look, longevity of the product and using a material that is more eco friendly and mega abundant like Al (AlO2 is one of the most abundant minerals on the Earth) would still be plusses. Tooling costs are an issue.

I suspect you would still notice a sonic difference because of the material used and my preference from what I've been experiencing lately would be Aluminium.

 

[Plitron]

With so much new information, I'm wondering about all of this resonance stuff and which way to go?:scratch2:

 

[spkrdtr]

With so much new information, I'm wondering about all of this resonance stuff and which way to go?:scratch2:

You face the same dilemma many newbies face when seeking advice from this and many other sites. Many are willing to offer advice and in many instances, you get too much.

You've asked only one question here regarding cabinet wood. There are 50 or so more similar questions that could come along as you proceed with your project. I would advise against building your 'right' speaker on an 'ask-as-you-go' basis.

However, in the end, it is you who must decide which route to take.

You've given yourself a nearly impossible task - to build the 'right' speaker. There is no right speaker; which is exactly why there are so many different ones out there.

Go and try your best and enjoy the journey!

 

[Plitron]

You face the same dilemma many newbies face when seeking advice from this and many other sites. Many are willing to offer advice and in many instances, you get too much.

You've asked only one question here regarding cabinet wood. There are 50 or so more similar questions that could come along as you proceed with your project. I would advise against building your 'right' speaker on an 'ask-as-you-go' basis.

However, in the end, it is you who must decide which route to take.

You've given yourself a nearly impossible task - to build the 'right' speaker. There is no right speaker; which is exactly why there are so many different ones out there.

Go and try your best and enjoy the journey!

Thanks, but there has to be a right way.:sigh::sigh::sigh:

 

[DavidGoncalv]

Pliotron, it is generally bad form for somebody asking advice to so quickly dismiss it, especially from people more experienced than you.

I'd try to listen to as many different speakers as possible, as research for future designs. I think you will find that more than one type will be 'right' for you.

 

[Plitron]

Pliotron, it is generally bad form for somebody asking advice to so quickly dismiss it, especially from people more experienced than you.

I'd try to listen to as many different speakers as possible, as research for future designs. I think you will find that more than one type will be 'right' for you.

Hmmm?:scratch2:

Okay, thanks I will, and apologies.:yes:

 

[RayW]

Thanks, but there has to be a right way.:sigh::sigh::sigh:

I think what Carl is saying is that there isn't a speaker (or speaker design) out there that is "right" for every person/situation/room/whatever. There are various ways to design a speaker and after design there are various ways to construct one. It's not about doing research into design and/or contruction methodologies to find what's "right", it's about finding out what works and is right for you.

Ray

 

[marc mc]

I thought I would throw a log on this. I stumbled onto an article I had with Alan Shaw. He owns Harbeth speakers which he bought from the original owner Dudley Harwood, who made the origianal BBC speakers including the very popular LS3/5a.

Talking about the original designs being made for remote locations monitoring and thus size and weight both being a factor. Shaw said, It was determined by the BBC engineers that by attaching accelerometers to the sides of various speakers, they could identify particular resonances occuring somewhere within the box. The discovery was that, as long as the resonances were supressed by, say 30 dB, they were inaudible. But if they rose above that threshold they became audible resonances. They conclusion was that it was only neccassary that the cabinet be good enough to suppress those resonances sufficiently, and no more.

When asked about the advantages of suppressing resonances completely. Shaw answered that "It's bad engineering, because it adds cost and complexity without improving the product"


I only mean this as food for thought, not to start a flame and if it were not for the fact that Harbeth speakers are about the best I have ever heard! I would probably dismiss it myself. But I can see me as an old man sitting with a pair of Harbeth HL5's which a few people believe to be the best on the planet.

marc mc

 

[Plitron]

I thought I would throw a log on this. I stumbled onto an article I had with Alan Shaw. He owns Harbeth speakers which he bought from the original owner Dudley Harwood, who made the origianal BBC speakers including the very popular LS3/5a.

Talking about the origianal designs being made for remote locations monitoring and thus size and weight both being a factor. Shaw said, It was determined by the BBC engineers that by attaching accelerometers to the sides of various speakers, they could identify particular resonances occuring somewhere within the box. The discovery was that, as long as the resonances were supressed by, say 30 dB, they were inaudible. But if they rose above that threshold they became audible resonances. They conclusion was that it was only neccassary that the cabinet be good enough to suppress those resonances sufficiently, and no more.

When asked about the advantages of suppressing resonances completely. Shaw answered that "It's bad engineering, because it adds cost and complexity without improving the product"


I only mean this as food for thought, not to start a flame and if it were not for the fact that Harbeth speakers are about the best I have ever heard! I would probably dismiss it myself. But I can see me as an old man sitting with a pair of Harbeth HL5's which a few people believe to be the best on the planet.

marc mc

Hmmm?:scratch2:

Definitely food for thought, thank you:thmbsp:

 

[Zilch]

Of COURSE there's a "right way."

[I haven't found it yet, is all.... :tongue: ]

 

[Plitron]

Of COURSE there's a "right way."

[I haven't found it yet, is all.... :tongue: ]

:lmao::lmao::lmao:

 

[RayW]

Of COURSE there's a "right way."

[I haven't found it yet, is all.... :tongue: ]

That's because you keep looking at those silly horns for your salvation.

 

[spkrdtr]

There you go again Ray using that 'horn' four letter word:lmao:!


Marc MC you're the first to share some quantitative information regarding cabinet resonances. 30 dB is more than I suspected was the threshold of resonance problems. If that's really the case, obsessing over cabinet resonances belongs WAY down the cabinet design priority list.

Live and learn I guess!

 

[Plitron]

"There you go again Ray using that 'horn' four letter word"!

 

[Zilch]

"Oh, YEAH, MESS with me, FOOL...!"

 

[Plitron]

"Oh, YEAH, MESS with me, FOOL...!"

:lmao::lmao::lmao: