Amazing stone speakers in the making

What inspired him to do this, good looking speakers. We might have to rename this forum the 20,000lbs forum.


Fred Flintstone would be proud

I hope he is doing something about the baffle diffraction nightmare that is that tweeter placement...

Matt

WOW.

Those things are going to be amazing. I cannot weight until you can actually test them and see how they sound.

Apparently it's not a problem. The original designer, Ingvar Öhman, sells all he can make. He's out of Sweden and sells a range of speakers doing business as Ino Audio. Apparently, in order to buy, you have to make an appointment with him for a demo and interview. There is then a cooling off period before he will accept an order from you. You then return to his site to take possession of the ordered speakers on completion, as he will not ship. The speakers are not intended to be sold outside of Sweden, but it's possible to buy them if you're willing to make the necessary trips. It's said that there are kit's in some form available, but I have never found the information. I understand it can easily take more than a year after placing an order before delivery. He also is said to have some very unique cross over designs; maybe the answer to your tweeter observation.

Ingvar Öhman does have a commercial business model for the rest of the world known as GURU PRO AUDIO. http://guruproaudio.com/ The designs seem to be somewhat limited from GURU, but, they get very good reviews.

There was a thread or two here at AVS that discussed his work awhile back.

You're right. Both in thats not a problem and that he is selling all he can

It's not a problem for anyone knowing a little bit of the mechanisms benind difraction. I saw a couple months ago a remark on his design from a commercially well recognised speaker designer here at AVSF bashing the "difraction ledges" that are almost a "tellsign" of his speakers.

Anyone with *some* knowledge of the matter know that the shorter wavelenghts from the tweeter bounce of the "ledge" never to reach the listener directly -just as intended by the desiger, and for the lower wavelenghts from the boomer, the "offset, lede and angles" dosn't really matter because they're so close to the driver compared to the wavelengths not to produce any conterproductive diffraction.

As a matter of fact, I have still to see a speaker that is as accurately waveform-reproducing as the Ino designs. The sinc2 reproduced by these speakers are no less than perfect. Perfect.

And the distortion is silly low. And they are easy to drive. The hat is officially of for Ingvar Öhman. He is quite a character but he really knows his s**t. Period!

H

Hell, I'm at least 6 hrs ahead of you guys (which equals at least 10+ bears and just to show you the engineering effort gone in to these speakers I'll post a pic of the impulse response from one of his speakers. I challenge anyone to find a speaker that has more accurate impulse response than the Pi60s. Now, does anyone see any signs of the severe diffraction these puppies MUST suffer from? Nah... :-)

I have noticed that this craftsman seem to be near finishing this project.

You rule Komorok!

Didn't Celestion experiment with stone enclosures back in the day?

Green Mountain Audio does marble and granite enclosures.

Haha, I know the design. Those speakers are not even full range. They are made to be cut off @ 80 Hz and combined with multiple subs. I would really like to own such a system if I had room for it.

Wow. And I thought my humble granite baffle project was involved...

Speaker cabinets made of stone is nothing new. What I think is unique with this projekt is that this cabinet is laminated. I have seen some stone cabinets with bitumen on the inside, but that will not do much good because the mass is too small compared to the stone.

I am not shure of how big the problem is with resonaces in the cabinet, but this cabinet is quite dead . And the designer of this speaker has made clear to me that he wants the cabinet to be dead. Other designs demands other cabinets I guess.

I hope you will excuse my lack of vocabulary. I am from sweden and seldom use my english anymore. I hope it will suffice to describe what I am doing in my workshop this summer.

/ Mikael

I wonder what the "impulse response" would look like if the test mic use moved 10 or 20 degrees to the side and up and down.

In seemingly related news, some of the heads are missing off Easter Island...


Looks very cool!

That is an interesting question. Ask him on the Swedish fora faktiskt . I am not allowed to post url's yet, but I am sure you can find it. I am as curious as you are.

But if I have to guess I would guess that it looks the same in those angles. But I am not sure. I know too little about how waveforms integrate.

Fantastic craftsmanship Komorok!

Would that be:

http://www.faktiskt.se/modules.php?n...opic&p=1111722

That is the right fora, but find "wänner af Ino" and start a new thread there.

http://www.faktiskt.se/modules.php?n...viewforum&f=20

Oh, I was allowed to post a link now. Happy happy, joy joy!

I hope you guys are better at formulating the right questions than I am.

Chamfer one and two are finished. Finally.




The progress is slow, but on monday the work will continue with the two remaining chamfers. Flip over time



I have one more week before my vacation and on my vacation I will try to finish this project and bring them home.

That is impressive. Don't drop them.

No worries, I am always careful.

----

I am halfway finished with chamfer three and four.

They are quite big (I am 1.75m tall). Estimated weight will be 200-275 kg each.



For more pics, please visit my photobucket site:

http://s169.photobucket.com/albums/u205/komorok/stereo/

10, 20 and 30 horizontal it still looks exceptionally good with perfectly maintained time coherence (that's why the tweeter is ofset in the first place!). On the vertical axis -as any non-coaxial design it will deteriorate when going exessively off-axis.

Ingvar Öhmans floorstanding 2(.5)-way speakers have been critisized (and routinely rediculed and dissmissed by self proclaimed "knowitalls" at many hifi-forums) for years and years for the offset tweeter and the severe diffraction effects this *must* cause, as well as for the huge directivity missmatch between the 1" tweeter and the 8" mid/bass drivers that simply *must* exist due to gemoetrical reasons, the small voicecoil etc. etc. etc. The list goes on.

Now, in Sweden, (where his "floorstanders" have been available for the last 15-20 years or so) they have been scrutinized, measured and put to the test in absurdum and they measure and perform pretty much imaculately.

All in all, sure there is diffraction happening (as with any edge) just no where nearly as much that one would first expect

Now, first thing to understand about this particular case is that due to the acoustically close proximity of the point source to the edge, the wavefront from the tweeter is is not straight -it is significantly curved, and at the distance of the edge, it is curved with a radious that is acoustically "small" compared to the wavelengths the tweeter emmit. This in turn will cause the continuum of diffraction reflections along the horizotal edge to "fire out of phase" with eachoter which will significantly reduce the diffraction effect within the listening window.

The other thing to realize is that with "normal" edge diffraction for a baffle with sharp edges, the soundwave travel from the speaker along the baffle (the edge of the wavefront is fully supported by the baffle) to the edge where the support abruptly disapear. The more abruptly the baffle transfer into full space (the sharper the edge), the more diffraction effect. A way to significantly lessen baffle edge diffraction is to angle or round the edges of the baffle.

Now, if you look at the tweeter again, the part of the wavefront is hitting the edge at an angle -it is not travelling along the horizontal part of the baffle to the edge, it is arriving at the edge at an angle, and hence the impedance change is much less abrupt than it might seem at first, reducing the diffraction even more. The specular reflections caused by the horisontal baffle parts are a much greater problem (potentially), if not properly taken care of.

Are you saying that the design features result in a directivity match at XO that has been verified by measurement?

If so, can you point to them?

It would need to be the off-axis responses of the individual drivers.

On a "lighter" note while heft in no way assures quality audio in any one of a # of Audio components beyond speakers, it would indeed suck to be a high end reviewer stuck in a flat with no elevator!

The directivity match and resulting on- and off-axis response is *very* smooth and controlled. Both the tweeter and the mid/woofer are designed from the ground up by Ingvar specifically for his "reference speaker" geometry.

Not to go all technical here, but what Ingvar has done is to design an 8" driver with a very light weight semi-rigid cone and a carefullly designed surround. The cone material properties and geometry has been carefully engineered to make the cone smoothly transition from piston movement at low frequencies to a bend wave transducer at higher frequencies. Due to the material properties in the cone, the bend waves in the cone travel with the speed of sound from the voicecoil to the surround (where its energy is dissipated). At the highest frequencies the sound is generated by the dustcap (desgned as a midrange dome), all in all creating near perfect concentric waves (and thus wide dispersion) way beyond frequencies that rigid piston cone drivers are capable of. There are some other drivers out there that utilize this design "trick" (the budget Seas P17RCY, comes to mind) but he has taken it to a completely different level in terms of dispersion, distortion and max SPL.

Apart from the drivers having controlled dispersion, since he design the drivers from scratch himself, he can also optimize the driver responses to integrate perfectlt with the usuallly pretty advanced, passive XO he uses (and vice versa).

Ingvar basically design all his mid/bass drivers this way and whilst he does not provide any official measurements himself, the extraordinary dispersion and frequency response of his mid/bass driver designs are a well known fact since he has made all(?) his drivers available to the Swedish DIY-community.

Oddly enough, I can't seem to find any off-axis measurements on the net of his Pi60s 60 litre vented floorstanders (reincarnated as the commercially available Guru Pro Audio QM60). I, however, have done a series of measurements on my i32s (the "smaller sibling" to the monstrous i64s speakers depicted in this thread) to verify that I had actually built them correctly and that they performed according to spec. However limited the measurements was by my cluttered listening room, the measurements clearly indicate text book off-axis "controlled rolloff" (IIRC I measured to about 70 degreees or so and it still wasn't any sign of off-axis integration problems...just some minor proximity artifacts caused by me beeing forced to measuring at ~1.2m, which is about 1m to close for the driver array of the i32s to allign properly- they're designed for aprox 3 meter listening distance...).

That's why I am deliberately delaying my visit to him until I have undisputable evidence of them "rockpiles" actually beeing in his listening room .

On a side note, I am amazed at the craftmanchip displayed here. Doing a cabinet this elaborate entierly in stone and largely by hand, takes some serious skill, time and guts. If you mess up it *will* cost you. What Komorok is so casually leaning over in the pic is easilly around $40k-50k worth of speakers (my estimation), when finished.

Thanks for the explanation, hevi; I'm much less unconvinced but would sure like to see some polar plots.