Poll

Please indicate what kind of loudspeakers do you use in your main listening environment (RRP ZAR)

Small Bookshelf-below R20K
13 (9.8%)
Standmount Between R20-R50K
10 (7.5%)
Standmount between R50k-R100k
2 (1.5%)
Floorstander below R20k
31 (23.3%)
Floorstander between R20k-R50k
39 (29.3%)
Floorstander between R50K and R100K
12 (9%)
Floorstander over R100k
13 (9.8%)
Planars or electrostatics (can incl  conventional bass drivers)
10 (7.5%)
Horns (primarily based on typology)
3 (2.3%)

Total Members Voted: 133

Author Topic: Air Loudpeakers  (Read 41633 times)

Offline adie

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Re: Air Loudpeakers
« Reply #255 on: January 26, 2018, 10:25:59 PM »
That's not too long a post Stefan. Very interesting. Thanks for the lesson.

Offline Nirvana

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Re: Air Loudpeakers
« Reply #256 on: January 27, 2018, 12:09:43 PM »
^ +100

Fascinating and informative journey!  :2thumbs:
Never b flat,never b sharp,always b natural

Offline Air

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Air Loudpeakers
« Reply #257 on: January 28, 2018, 11:30:23 AM »
Hi guys, sitting on airport in DAR and waiting for my 8th flight in 2weeks. On my way to Nairobi and then on to Entebbe. So passing time...
Here are a few pics on a “mock up” of the carcass and wood to get a sense of perspective of what the Vivacé will look like


(Also 1st attempt to post pics from Taptalk)


Sent from my iPhone using Tapatalk

Offline Atjan

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Re: Air Loudpeakers
« Reply #258 on: January 29, 2018, 03:55:27 AM »
Thanks for the explanation about the port location. I learn much just by reading this sort of thing.

The speaker is going to be a real stunner!
It's only hifi people....

Offline Stanp

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Re: Air Loudpeakers
« Reply #259 on: January 29, 2018, 09:16:52 PM »
+1
I am looking forward to see the completed project  :)

Offline Air

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Re: Air Loudpeakers
« Reply #260 on: March 19, 2018, 06:41:56 PM »
Disappointing but still in holding pattern with the last major challenge, namely to get the wood press 100% correct. As said earlier it is small steps that we need to do this and although it doesn't take ages to machine the mould on the CNC, it is the workflow in the factory that needs to be accommodated. So we re-machine, then wait for a slot on the press and then make a sample, scan it and then back into the cycle with new data to make a call how much we must adjust the mould. We don't want to do it in big steps because if we make a mistake and overdo it the mould will be useless and we will have to start over again.. really frustrating and calls for extreme patience.

Here are 2 pics of the scan at 88.2 and 89.5 degrees.. aiming at 90 degrees of course. Nearly, nearly there but it is nerve wrecking
88.2

89.5



Offline Air

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Re: Air Loudpeakers
« Reply #261 on: March 19, 2018, 08:41:33 PM »
I previously posted comments and picture of the mid capsule but for those interested here a few better pics of the design. Difficult to really understand how intricate the part is with few if any parallel sides until one actually handles it. We made 3 samples, one of a light glass fibre and a new core that absorb most of the resin(yellow), a heavy glass fibre weave(brown) and a unidirectional carbon fibre(black). No doubt about the stiffness of the carbon version and the benefit in low mass, the heavy glass weave is interesting in the sense that is almost as stiff as the carbon but at a cost of higher mass and the yellow light glass with the absorbent core is in simple terms a total waste. Interesting as it does pave the way forward for the critical mid capsule.








Offline Nicholas

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Re: Air Loudpeakers
« Reply #262 on: May 17, 2018, 07:22:36 AM »
Good morning Stefan,

Have you managed to get the wood pressing tool to your liking?

Eager to hear an update on this exciting project of yours

Offline Air

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Re: Air Loudpeakers
« Reply #263 on: May 17, 2018, 04:22:13 PM »
Hi Nicholas,

Unfortunately, we had some more delays from the supplier of the wood panels. The production manager that was involved in the work resigned to start his own unrelated business, so the production schedule is even more stressed at the moment.

I was very concerned when I heard the news last week but fortunately, all CNC programming was done before he left at end of April and furthermore he is also house-friends with the owner of the business. There is, therefore, no serious risk that the ball could be dropped.

Things will, however, be even a bit slower. I told them the other parts are now gathering dust ;) and we have an agreement that it now is a priority. It might delay the development of the next model we had in mind though, the Voce.

The upside is that we have worked on a variation of the Vivace design, the high sensitivity model, Evocateur. We had many concepts previously on how best we can use the Vivace tooling to get to the 35% less volume that we require for the Evocateur in an economical way that passes our own aesthetic standards, and I think after many options, Alex nailed it a week or 2 ago. It is quite novel I believe. I will share as soon as I receive high res renders from Alex.

We have also been busy with another concept, this time making use of a design/mould that is used in the factory for producing a chair :D
This would be even a more affordable concept, still adhering to our design philosophy and quality standards both in terms of aesthetics and sonics. I really like this idea, sort of a retro or vintage concept. Once again as soon as I have high res renders I will give those interested a sneak preview.

What we have learned is that we should work from the outside in the design process. We should make the wood, use that as template or master for the carbon parts etc. With the Vivace, we approach it the other way around. Wood will always be a living material with its own unique character and it might be far better to use that character, it the way it settles as it comes out of the press and design with that as the baseline. Even the factory which we work with from now on, do their own designs this way. This way we could have avoided all the iterations that delayed us.

So yes.. we are still very much focused on getting the products out there..

Offline Nirvana

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Re: Air Loudpeakers
« Reply #264 on: May 18, 2018, 03:34:28 PM »
Damn...

Holding all thumbs and toes that it comes to fruition and make new owners very happy!!  :pray:  :cleansound:
Never b flat,never b sharp,always b natural

Offline Air

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Re: Air Loudpeakers
« Reply #265 on: August 10, 2018, 05:33:52 PM »
I was asked by a few on the forum for an update and if we are making progress with the project.

Basically here is where are at:

We still are waiting for final wood parts, but the rest of the parts(aluminium and sandwich panels are done(tooling and jigs are done)

We started with provisional assembly, testing how the wood will be bolted to carbon structure last week and below are a pic or 2  pics that might be of interest. One can see the layers of the Carbon fibre+Glass, Nomex and Glass+Carbon and the layers of the Grado birch ply. We will have a damping layer of felt but are also exploring cork. We drilled holes in the carcass and tested wood inserts to see how it might work. (It is the 1st carcass that we made- so not final part and the rods that pull the top and base together can also be seen. The rods will also be threaded aluminium and not the steel units we used in original testing. )

Negotiating on prices for short vs "longer runs" and

Testing cork as a core material in carbon composite structures instead of foam or Nomex honeycomb. The cork might provide us with more damping and is more cost effective. Nomex's weight to strength is still unsurpassed but the small gain in weight in speaker is negligible and the damping might be a huge benefit. 

If we can just get the last iteration of wood mould done we are up and running.

I might assemble a pair without wood panels to do some listening tests and voicing with(some final tuning of port and bass crossover)when I am back in SA in mid-September.

So lots going on in the background.. we also started with a formal project management approach(software based) to keep things in check.






Offline Stanp

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Re: Air Loudpeakers
« Reply #266 on: August 10, 2018, 05:50:13 PM »
Stefan, good to hear that you are almost finished.  :clap: Looking forward to see the completed speaker. Will cork not be too reflective to be used as a damping material; it is quite bouncy is it not?

Offline Air

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Re: Air Loudpeakers
« Reply #267 on: August 10, 2018, 06:10:48 PM »
Thanks, Stan,

Maybe to clarify, the cork is considered as a replacement for the honeycomb as core between the carbon kins to form the composite structure. Then also as a damping layer between the wood and carbon structure.

I guess you think of the damping material inside the bass and mid cavities? This will be treated lambswool or a combination of angel hair and lambswool.

Cork is a natural and ecological friendly material and is the material we are tested are crushed and compacted cork. Cork has an interesting structure in the sense that has many small veins of air that form a similar structure to a honeycomb material. It is slightly less effective as felt as a damping layer between  2 rigid skins(carbon) or between the carbon and wood. The problem with felt, our original idea as a layer between the wood and carbon is that as soon as you compress felt it loses it's damping qualities. In an uncompressed state, the micro fibres in felt capture air between them and also makes a "honeycomb" like material. When the felt is compressed like we will do when we pull the wood on the carcass, we will push the air out and the felt would be less effective as damping layer. Cork, on the other hand, will compress around the outer perimeter and keep the internal structure and maintain most of it's the damping qualities.

Vivid replace the foam core with balsa wood in their Giya range. Balsa and Cork in many ways have similar qualities.

We are however on new ground and will only make final decisions when we are satisfied that our reasoning is sound, and supported with some empirical test, even how crude initially. If we are not comfortable we will stay with Nomex and felt. 

« Last Edit: August 10, 2018, 06:15:06 PM by Air »

Offline Shonver

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Re: Air Loudpeakers
« Reply #268 on: August 10, 2018, 07:45:28 PM »
There is a difference in the effect produced by cork and foam vs that which is had from balsa or honeycomb. On the one scale is constrained layer damping, and on the other end is stiffening. See this video (I like this channel; it is like a video version of Popular Mechanics): https://www.youtube.com/watch?v=tiS8ArzEA58
« Last Edit: August 10, 2018, 07:56:23 PM by Shonver »
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Offline Air

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Re: Air Loudpeakers
« Reply #269 on: August 10, 2018, 09:48:11 PM »
Thanks,  Shonver, the video is interesting indeed

I am not sure about the foam and balsa on the one hand and balsa and honeycomb on the other hand view, nor the stiffing and damping continuum. All core material has unique properties in terms of stiffness, damping and weight and will sound different. The thickness of the core material, the amount of resin various core materials absorb and the bonding qualities can have an effect on the sound.  Drapeability is another factor we consider, especially if we want to achieve the accuracy of the designs.

One can almost view it as a painters pallet to create the structure that would be fit for purpose.

Honeycomb structures are also available in various materials like the Nomex the meta-aramid material developed in the early 1960s by DuPont, newer foam honeycomb materials and aluminium. There are so many developments on an ongoing basis it is hard to keep up.

We have made samples with Nomex and foam and want to experiment with cork as well. I also want to test the core material in terms of the different requirements for the carcass and mid capsule. We also used a combination of glass and carbon fibre. Glass adds more weight but has an inherent damping quality, carbon is lighter and stiffer but has less internal damping.

We are really in newish territory and we looking closely at what the benchmarks in this field do, whilst also on a small scale doing some experimentation ourselves.

It is really a fascinating exercise for me.