Thin walled speakers...are they the answer?

DaveyF · Jan 20, 2014

Yesterday, I was pleasantly surprised by a pair of Spendor SP100R2's that I heard. Spendor's are, for those who aren't that familiar with them, an old UK speaker manufacturer. They believe in NOT using heavy and substantial ( thick? ) walls in their designs. In many ways, the opposite to Magico's AW dictum. In their advertising, the company states: "The SP100R² is a testament to Spendor's unique understanding of cabinet design. Critical positioning of the drive units and internal enclosures control and reduce unwanted resonances to an absolute minimum."

Since the current trend seems to be heavier and more substantial cabinets, I wonder why there are not more companies that are researching the opposite design?...Spendor and Harbeth ( another UK manufacturer who believes in "thin wall" ) are two great sounding speakers, IMO.

I would like to see a large speaker ( along the size of the Wilson XLF) with superb drivers and a thin wall design....might be a world beater?

JackD201 · Jan 20, 2014

I think these are great for people that like that particular sound and are locked into it.

I've always found Harbeths and Spendors very pleasing. They are speakers I would love to have in say a vacation house in the mountains or a beach house. They just have too much of their own sound for my tastes to be used in my primary rig which I like to use to make all sorts of things happen just for kicks.

DaveyF · Jan 20, 2014

Jack, that is what i also thought. However, the SP100R2's that I heard and the Harbeth's (some not all) that i have heard in the past seemed to have little of their own sound. Instead, the SP100R2's were pretty transparent and they were VERY dynamic. These speaker's wouldn't work in a small room like I use, BUT IMO they should be on everyone's audition list IF you do have the room. I would say the same for the Harbeth's that i have heard, particularly the Harbeth 40.1's. The thin wall construction seems to allow them to release energy quickly and that may lead to their dynamic ability.

JackD201 · Jan 20, 2014

Spendor just got a new distributor here so maybe I'll get a chance o hear them(100R2s) sooner rather than later. I've only heard 40.1s once and in a very unfamiliar surrounding. I've heard many of the lower models from both marks, both vintage and current, though as many friends have them.

garylkoh · Jan 21, 2014

I did the same thing with my latest design. Instead of brute force and using massive and extremely stiff materials, I went the other direction to manage the resonances and vibrations using light-weight materials and constrained layer damping. With lower mass, energy storage was minimized, but resonances came in at lower frequencies. It was a fun exercise managing different materials to get to where I wanted - ending up with a 11-layer construction - 2 different thickness and densities of mdf, 5 layers with three different types of wood and of all things..... bamboo!

andromedaaudio · Jan 21, 2014

Producing a thin walled speaker and claiming its somehow better then a ultra stiff /massive construction can also be a part of advertising , as the latter inevitably will increase costs .
I suspect harbeth and spendor have a certain pricepoint in mind at how much they want to place a design in the market
In my view its a fact that a vibrating LS unit ( signal freq) will set the housing in motion if it has thin walls .
As this freq at which it does that constantly changes , the old (vibration ) freq will interfere with the next causing distortion , the unit is set into motion by not only the signal but also by the cabinet
This is all theoretically spoken off course , whether or not someone likes one or the other is another story

PS in a short while l I ll be able to tell my expiriences as I am now producing a absolute massive stiff braced monocoque LS construction

garylkoh · Jan 21, 2014

Producing an ultra stiff/massive construction can also be a part of advertising as the cabinet cannot be infinitely stiff and infinitely massive. Any vibrating transducer will inevitably set the housing in motion to some extent. Especially when the transducer has a moving mass. Nevertheless, chaotic movement of the mass in the transducer transfers vibration to the cabinet totally differently from constant, uniform motion. The vibrational and resonant behavior is easy to model with uniform excitation, but a lot more difficult with chaotic excitation.

The Genesis 2 Jr was produced as a massive panel - HMWA (high molecular weight acrylic). It worked with the ribbon elements (very low transducer moving mass). However, when dynamic drivers were used (moving mass an order of magnitude higher than ribbons), even doubling the mass of the panel could not keep the vibration in the cabinet down far enough not to be heard. A totally different strategy had to be used with the Genesis 4.

Incidentally, constructing my own composite lightweight material (it's not just plywood) cost as much as HMWA and takes longer as it has to be laid-up layer by layer and the adhesive cured.

zztop7 · Jan 21, 2014

If cars [even hi-performance] were built like thick wall speakers, their weight would at least quadruple!
Bracing [tension & compression] is just as important as the walls.
Bracing can be the use of extra materials as braces, and/or the way materials are joined together / the shape & contour of materials: curved vs. flat, etc. / etc.

zz.

rockitman · Jan 21, 2014

Back wave reflections inside the enclosure should be absorbed/dissipated as much as possible by the cabinet material. I don't see how thin walled speakers achieve that.

Peter Breuninger · Jan 21, 2014

garylkoh said:
I did the same thing with my latest design. Instead of brute force and using massive and extremely stiff materials, I went the other direction to manage the resonances and vibrations using light-weight materials and constrained layer damping. With lower mass, energy storage was minimized, but resonances came in at lower frequencies. It was a fun exercise managing different materials to get to where I wanted - ending up with a 11-layer construction - 2 different thickness and densities of mdf, 5 layers with three different types of wood and of all things..... bamboo!

Gary's new speaker sounds very very good. As is being said on other threads here... there are many roads to Rome. Funny about using bamboo, I have the MBLs on multi layered bamboo platforms.

andromedaaudio · Jan 21, 2014

Some manufacturers use diffusor like internal walls of the cabinet to reduce back wave influence , with sometimes added absorbing coating, kharma does that for example

DaveyF · Jan 21, 2014

There's also the shape of the cabinet that needs to be taken into consideration. OTOH, Spendor and Harbeth only seem to produce the typical rectangular box style; perhaps thin wall construction requires that shape

garylkoh · Jan 21, 2014

Peter Breuninger said:
Gary's new speaker sounds very very good. As is being said on other threads here... there are many roads to Rome. Funny about using bamboo, I have the MBLs on multi layered bamboo platforms.

Thanks, Peter. I've been getting great comments about the new speaker, and I'm glad that you like it too. More importantly, did Terry like it?

Bamboo is really interesting as a material. It's not a wood, it is a grass. It has very, very long contiguous fibers (compared to wood), and the modulus of elasticity is very different in three dimensions.

andromedaaudio · Jan 21, 2014

Audio note UK seems to design in that direction as well

DaveyF said:
There's also the shape of the cabinet that needs to be taken into consideration. OTOH, Spendor and Harbeth only seem to produce the typical rectangular box style; perhaps thin wall construction requires that shape

kach22i · Jan 21, 2014

Several of the Sonus Faber models seemed to have mastered thin-walled cabinets combined with sympathetic forms/shapes to make "music instrument-like" enclosures.

It can be done, but I bet the results are not as predicable as engineering a brick-like enclosure.

It's the path less taken for a reason.

LL21 · Jan 21, 2014

DaveyF said:
Yesterday, I was pleasantly surprised by a pair of Spendor SP100R2's that I heard. Spendor's are, for those who aren't that familiar with them, an old UK speaker manufacturer. They believe in NOT using heavy and substantial ( thick? ) walls in their designs. In many ways, the opposite to Magico's AW dictum. In their advertising, the company states: "The SP100R² is a testament to Spendor's unique understanding of cabinet design. Critical positioning of the drive units and internal enclosures control and reduce unwanted resonances to an absolute minimum."

Since the current trend seems to be heavier and more substantial cabinets, I wonder why there are not more companies that are researching the opposite design?...Spendor and Harbeth ( another UK manufacturer who believes in "thin wall" ) are two great sounding speakers, IMO.

I would like to see a large speaker ( along the size of the Wilson XLF) with superb drivers and a thin wall design....might be a world beater?

Interesting...didn't Celestion make the SL600si out of some kind of Aerolam which was a superlite material that helped avoid the classical 'boxiness' sound of this speaker design?

In any event, i think in addition to the speakers mentioned here (like Gary's), the Vivid Giya is a super-liteweight structure as well on a similar principal, no? It is 5 feet tall and 2 people could easily pick it up. it is listed as having a cabinet made of "Glass reinforced balsa cored sandwich composite" and at 1.7m tall, it is 'only' 176lb (80kg)...which pales in comparison to the Magico Q7 which at a comparable height (5 inches shorter actually), weighs 750lbs (340kg).

zztop7 · Jan 21, 2014

LL21 said:
Interesting...didn't Celestion make the SL600si out of some kind of Aerolam which was a superlite material that helped avoid the classical 'boxiness' sound of this speaker design?

Aerolam was an aluminum honeycomb bonded between 2 sheets of aluminum. I made great work stands from Boeing surplus. Great strength with minimal weight.
zz.

DaveyF · Jan 21, 2014

LL21 said:
Interesting...didn't Celestion make the SL600si out of some kind of Aerolam which was a superlite material that helped avoid the classical 'boxiness' sound of this speaker design?

In any event, i think in addition to the speakers mentioned here (like Gary's), the Vivid Giya is a super-liteweight structure as well on a similar principal, no? It is 5 feet tall and 2 people could easily pick it up. it is listed as having a cabinet made of "Glass reinforced balsa cored sandwich composite" and at 1.7m tall, it is 'only' 176lb (80kg)...which pales in comparison to the Magico Q7 which at a comparable height (5 inches shorter actually), weighs 750lbs (340kg).

Lloyd, I am not sure that the Giya 1's ( I presume you are talking of these) are that "super-liteweight". However,IMO they are superb sounding speakers. The one's that I heard recently were able to plumb the depths with ease. What impressed me also was their ability to "articulate" the bass sounds. Something that I find very few speakers can accomplish.

kach22i · Jan 22, 2014

You know what, the box is only there as an acoustic amplifier because of the limitations of conventional dynamic loudspeakers to produce bass efficiently.

I like the openness of baffleless loudspeakers and flat panel speakers for this reason, just less coloration - no box.

andromedaaudio · Feb 16, 2014

here is a nice example

http://www.youtube.com/watch?v=I1KpWkhGFlM

Thin walled speakers...are they the answer?

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