Aino gradient - a collaborative speaker project
 

Ok folks, inspired by the discussions of room acoustics, sound perception and boundary reflections here at diyaudio.com, I hereby start a new thread for a collaboratory speaker project named

Aino gradient

The inspiration to this project is the legendary and revolutionary home stereo speaker by designer Jorma Salmi, the Gradient 1.0 and it's siblings.
History

We will discuss it's design principles and we try to reconstruct and perhaps even go beyond it's performance and sound quality in contemporary domestic room environment.

This is not a commercial project and if we break some patented or otherwise protected things/issues, it is not intential.

The name of the project combines the very popular finnish first name for women (also wife of composer Jean Sibelius) and the concept of sound pressure gradient Sound speed gradient - Wikipedia, the free encyclopedia

The guidelines for development are as follows:
- to create a pair of stereo speakers that makes use of laws of physics, specially room acoustics to:
- minimize the early reflections from boundaries and to
- utilize the floor boundary gain by
- combining controlled directivity and controlled reflections

The means to achieve this are guidelined by the innovative pioneering work of Jorma Salmi, and they are mainly these:
- the bass utilizes a down-firing driver
- the mid is a large dipole tilted upwards
- the tweeter has controlled and quite narrow directivity (cascaded line array), perhaps dipole/bipole radiation

Ladies and gentlemen, start your engines!
Juhazi

For boundary gain and minimizing of early reflections it doesn't make much difference whether you have the bass down-firing or just close to the floor. Side-firing would allow different principles like cardioid and dipole - even with the choice to rotate the directivity axis.
To my mind down-firing is only useful if you are looking for a sort of bandpass behaviour.

Rudolf

Ok, and now some concretia..

Using a minidsp give us more possibitities of usable drivers and we can also use passive components too.

The bass bin could be a closed box of some 30L and the driver Dayton RSS315HF-8 Dayton Audio RSS315HFA-8 12" Reference HF Subwoofer 8 Ohm - Subwoofers - Loudspeaker Drivers By Type - Loudspeaker Components. The lowest end should be pushed up in the xo (minidsp) The original was a br box but I like the closed better for impulse and phase behaviour. The boost might be minimal due to floor gain

The dipole mid should be a 15" which has clean midrange, minimal breakups and a light cone. Cone flexing at high frequencies is an advantage here! Perhaps some JBL pro or Beyma 15LW30 http://profesional.beyma.com/ingles/pdf/15LW30.pdf

The tweeter line of the grandmother has four 2" -2,5" paper cones, but perhaps it is wiser to make a 4-way using a supertweeter? four 2,5" cones with a cascaded LP and OW1? Peerless has many options Full Range | Tymphany

The xo frequencies and filter types give the grain of salt here. Matching the real acoustic properties and transition zones between the segments is the key to good sound. There is some theoretical and practical info but experiments and listening tests are of crucial importance here.

Like Rudolf - I think that the:

"- utilize the floor boundary gain by
- combining controlled directivity and controlled reflections"


-is a not a helpful design choice with respect to minimizing the effects of the room.

I think in the case of the gradient design that it was an easier method under a passive crossover system in a small form-factor to get the sort of freq. response they wanted.


IMO, when considering the use of a minidsp, you should "ditch" many of the ideas behind the Gradient 1.0 and look to super-cardioids.

Here is an idea of the effect:

Duran-Audio shows off super directional cardioid speakers - YouTube

I say - take a big Pro coaxial, put it bare on the floor, tilt it towards listener, if You like it more this way, then equalize, and BABAM! - this is it :D

or at least very likely it may be :)

read this: Experience 2

:cool:

The Vifa TC7FD00-04 should make a superb line with respect to "front + rear" arrays with the rear array adjusted to increase directivity of the frontal array via the minidsp.

Zaph|Audio

Aino, great name ! Something deeply Finnish :D

http://www.vaasapages.com/pics/histo...o_Triptych.jpg





I take a small objection here, why not make three speakers ? Eventually you could try linear stereo matrix ;) or HT if you're into it.




If you want to keep Beyma, try MI series, they have good looking 15" mid drivers.

Even lighter cone Mms only 62g and high Qts for dipole could try cheaper alternative Celestion TF1520
LF Pressed Chassis / Ferrite - TF1520 - Celestion - Guitar, Bass & Pro Audio Speakers


Or even line of ribbons. Nowadays there are many alternatives, not like 30 years ago.


Have fun !

- Elias

Found this interesting as well,

Whispering at Long Distance and directional audio.mp4 - YouTube

How about a SEOS high end with line array mids?, Ive made a sketchup image,
Search sketchup for "SEOS"

What about a design marriage with some of Stig Carlssons work? Scrap the dipole mid idea and make better use of the front wall.

Nice comments, thank you!

I must say that I fancy the looks of G1.3 a lot! The looks is also an important factor to me. That's why downfiring oval shaped bass box, open 15" and a tweeter line. I might not get the best possible sound an definitely not the easiest way, but...

Things to concider:
- a coaxial 15"
- ribbon tweeters with waveguide and open back (RAAL are too expensive, what else)

These will sit in my living room and a pair is the only possible setup. There is a 42" plasma tv on a cabinet that holds AV amp etc. Other speakers for 5.1 are small 2-ways and a diy-sub.