Speaker Cabinet Design Considerations

[RickS]

As I read other parts of the forum, found there was not an obvious home for speaker cabinet design, so hope this helps organize a bit better. Personally am interested in whatever can be done to improve the sound quality of a speaker, but also how it affects the speaker cost. Whether it be panel material, bracing, damping materials, shape or fancy design tools, they all can affect sound quality and cost of the speaker.

I have seen some really interesting commercial cabinetry (notably my flood-damaged Vandersteen 2Cs, B&W 800 series, etc.) and built a number of subwoofer boxes that taught me the importance of bracing large panels (big subwoofer drivers really can vibrate a box as well as the room).

Recently I came across @Floyd Toole post of the impact of resonances on timbre on one part of the forum and some approaches taken by the BBC to tackle cabinet resonances in another. There is often more than one way to tackle an engineering problem, so please share what you have encountered!

 

[RickS]

Here is a link to Dr.Toole's post that I referenced:

https://www.audiosciencereview.com/...h-monitor-30-speaker-review.11108/post-317705

Note he does reference his book or an AES paper. It is the newer edition of his book (I have the older one).

Am probably just going to buy the new edition as it is now in electronic form and will be easier to search.

 

[pma]

BBC RD paper
http://downloads.bbc.co.uk/rd/pubs/reports/1977-03.pdf

Some hints on measurements
https://sound-au.com/project181.htm
http://www.tonestack.net/articles/speaker-building/cabinet-sound-insulation-measurement.html

 

[RickS]

Here is link to some great info on thread discussing how KEF (based on BBC) has evolved their speaker cabinet design:

https://www.audiosciencereview.com/...-about-speaker-measurements.11139/post-320348

 

[stevenswall]

Unsure how much of an audible difference it makes, but when I look at a speaker cabinet, I'm looking for a a few things ideally:

-No parallel surfaces
-No sharp edges along the entire front
-A waveguide or a front that is spherical
-Not shaped like a box
-Not made from panels of regular wood

Not too many that follow all of these. a Devialet Phantom and Genelec 8260 come to mind, along with an "egg" shaped speaker some grammy winning artist uses, and maybe MBL speakers minus the lower woofer portion since there is no cabinet?

I'm curious what the tradeoffs are doing internal bracing (JBL) vs using a stronger, thinner material to maximize internal volume (Genelec.) Seems like the latter would be easier to work with due to the lack of internal braces. Not sure how crowded it is inside of a Genelec compared to something of the same volume with traditional cabinet design.

 

[Frank Dernie]

https://shop.us.kef.com/pub/media/wysiwyg/documents/ls50/ls50_white_paper.pdf

Interesting paper on some modern methods.
I have a close friend who does this sort of analysis for OEM clients.
Doing it by making loads of prototypes is the old fashioned way of doing it but probably even more expensive and long winded and probably not as effective.
I wouldn't make a DIY speaker again since I am no longer confident the sort of cabinet I used to make is good enough.

 

[Frank Dernie]

Not too many that follow all of these. a Devialet Phantom and Genelec 8260 come to mind, along with an "egg" shaped speaker some grammy winning artist uses, and maybe MBL speakers minus the lower woofer portion since there is no cabinet?

Cabasse make some interesting speakers.
The ones a colleague of mine had sounded brilliant.
https://www.cabasse.com/en/

 

[maty]

https://www.diyaudio.com/forums/multi-way/347912-benefits-minimal-baffle.html

 

[stevenswall]

Cabasse make some interesting speakers.
The ones a colleague of mine had sounded brilliant.
https://www.cabasse.com/en/

Looks like they actually design their cabinets based on the picture posted above... 99% of companies just make boxes, even on the high end.

 

[Frank Dernie]

Looks like they actually design their cabinets based on the picture posted above... 99% of companies just make boxes, even on the high end.

They have a big range of speakers at all price points. "La Sphere" is their top model. There are links on this web page to their other products.

 

[direstraitsfan98]

£108,000 or $176,000

 

[Frank Dernie]

£108,000 or $176,000

The Devialet Phantom is definitely better value

 

[direstraitsfan98]

The Devialet Phantom is definitely better value

They design better amps then speakers. Phantoms are impressive feat of engineering but have host of issues that make them not much more than a gimmick. The SAM technology begs to be licensed out to the mass market instead of being relegated to a module on their highest end amplifiers.

 

[Doodski]

The Devialet Phantom is definitely better value

The low frequency drivers look heavy in the Devialet Phantom. Are they simply using brute force to move them or am I missing something?

 

[Frank Dernie]

They design better amps then speakers. Phantoms are impressive feat of engineering but have host of issues that make them not much more than a gimmick. The SAM technology begs to be licensed out to the mass market instead of being relegated to a module on their highest end amplifiers.

I am intrigued what you think are these "issues" (I presume by issue you mean problem) are?
I have owned some for years and apart from early ridiculous firmware bugs (mine are from the first production batch) they have been fine for years now. For me the only problem is they are oriented to file based music whereas I am not.
I have a lot of loudspeakers and the Phantoms are certainly the best value for money.

 

[RickS]

https://shop.us.kef.com/pub/media/wysiwyg/documents/ls50/ls50_white_paper.pdf

Interesting paper on some modern methods.
I have a close friend who does this sort of analysis for OEM clients.
Doing it by making loads of prototypes is the old fashioned way of doing it but probably even more expensive and long winded and probably not as effective.
I wouldn't make a DIY speaker again since I am no longer confident the sort of cabinet I used to make is good enough.

Thanks for sharing.

At least you have a friend that could help. While I started DIY when I was younger and had less money, I still do it as I have found no real alternative. Unless you are very wealthy or a speaker reviewer, there is no alternative to know whether you are about to buy someone else's great design or their hype (or maybe a bit of both). Maybe ASR will find a better way (one can hope)!

 

[Frank Dernie]

The low frequency drivers look heavy in the Devialet Phantom. Are they simply using brute force to move them or am I missing something?

No idea if they are heavy or not but of course the big thing is their use of DSP to compensate for the small cabinet volume, which works well.
Mine use 20 watts when idle, about 25 playing normal music at a reasonable listening volume but 75 when playing a film sound track with bass effects. The bass amp is capable of 3000 watts peak, apparently.

 

[direstraitsfan98]

I am intrigued what you think are these "issues" (I presume by issue you mean problem) are?
I have owned some for years and apart from early ridiculous firmware bugs (mine are from the first production batch) they have been fine for years now. For me the only problem is they are oriented to file based music whereas I am not.
I have a lot of loudspeakers and the Phantoms are certainly the best value for money.

Compression in the bass regions at higher SPL. Very disingenuous of Devialet to market it as being full range down to 14hz when you really wouldn't want to be playing it that low at loud volumes. It kind of irks me but I guess the marketing department behind the phantom range of speakers is completely separate entity from their engineering department.

Also my skepticism of Devialet speakers is more to do with my opinion they are not even close to as good as the value proposition of DIY. Which is of course what this thread was about. I scoff at the idea that two phantoms at a price of $6000 is a good value proposition when you will get much better measured performance out of a pair of cheap bookshelves and two actual subwoofers in a substantial volume enclosure to get their SPL numbers.

That's nice you own a lot of speakers. I would too if I had the space. At one point I had 3 pairs in my small-ish room but I really just didn't have the space. You also are also more than 3 times my age, so you win on experience. -shrugs-

 

[nm4711]

Here is some interesting stuff regarding baffle design from a site selling plans for DIY speaker. I think speakers from their site are in your (@Winkleswizard) list for DIY speakers, in your other thread already:
https://heissmann-acoustics.de/en/kantendiffraktion-sekundaerschallquellen-treiberanordnun/

 

[bigx5murf]

With a lot of vintage speakers, I've noticed a lot more attention to front baffles than more modern designs. Such as dampening materials on the exterior of the front baffle. Or grills acting as waveguide extensions.

What were those cabinets trying to achieve? Why has it fallen out of favor?