Vivid Audio Giya G3, puis Kii3+BXT, puis Magico S3 mkII dans une pièce dédiée

[pda0]

(05-09-2016, 12:05 PM)ThierryNK a écrit : Si, si, il a parlé de filtre. Une interview a été mentionnée sur le fil Vivid de Hcfr que tu suis aussi.  J'en reproduit ici une partie http://www.ultraaudio.com/index.php?opti...&Itemid=46

Citation :"When I first joined forces with Philip [Guttentag], I was firmly dedicated to active-only solutions. I thought that the only way of getting a decent, matched, prescribed filter function was to use an active filter. But one of the essential parts of why our partnership works is that Philip has a realistic perspective on things. He was quite frank: "To start with an active solution, we might as well just chuck the money into the sea and go fishing. We would absolutely be shooting ourselves in the foot to start with active loudspeakers. We are making a product that is difficult enough as it is. From a design perspective it is an expensive loudspeaker from an unknown brand. All those things. We do not need to add ‘active’ to the list of reasons why people won’t buy it."

So OK. I was forced to get back into the world of passive crossovers. But things had moved on since I first took a go at passive crossovers. There now exist some excellent computer-aided design tools. Network modeling and optimization have radically changed things. I was so forced into it -- but once I got there, I was amazed at the possibilities in passive networks. The important thing is to do your driver-design homework in the first place -- drivers which behave in a linear fashion, which have constant properties so that, irrespective of where the voice-coil is, the driver impedance remains the same. With such linear, constant drivers, you don’t modulate the performance of the passive crossover. Also, frankly, taking care with acoustics so that actual driver performance within the cabinet is a fairly smooth shape. It doesn’t matter too much what the shape is, as long as it is free of nasty wiggles. The crossover-design software works incredibly well, and we achieve matches between measured performance and the target function within 0.5dB. It is amazing! I would never have thought. Ultimately, I think it’s probably true that the active solution has to have the slight edge, but only a marginal one compared to what I used to think.

So I have been converted somewhat, assuming we’re talking about minimum-phase crossover function. But if you move the debate into the digital active realm, then a whole new world opens up. We could do linear-phase filtering with a digital active crossover. This means we could actually end up with a system capable of reproducing squarewaves properly, with flat group delay. How sensitive our ears are to that phase distortion is a matter of debate, but certainly we can tell the difference. If you switch between a system with a flat group delay and one with a phased response, you can hear a difference. But actually, it is rather hard to tell which is the correct reproduction. Nevertheless, we know the linear-phase alternative is correct by definition. At some point, I’m sure we’re going to go down that avenue. Whether we supply an active filter module or work with an electronics manufacturer to supply a complete package with amplifiers, there exists that possibility."

Ce qui se résume en français par en gros:
- cela lui cassait les pieds de retourner vers du filtre passif
- les logiciels de conception sur ordinateur ont permis de faire d'immenses progrès
- le filtrage actif est toujours meilleur mais pas avec autant d'avance que ce qu'il avait imaginé 
- il y aura à terme de l'actif chez Vivid, que le scénario soit la fourniture d'un filtre actif ou l'association avec un concepteur d'électroniques pour fournir une solution complète d'enceintes amplifiées. 

Ce sont des raisons commerciales qui ont conduit Vivid a d'abord proposer des enceintes passives pour ne pas se retrouver devant un marché vide en étant nouveau venu. 

Commentaires de la quadriamplification/filtre actif/Trinnov Altitude/Vivid G2 de la part de Vivid:
- le filtrage actif n'amène pas grand chose
- par contre la correction de phase de Trinnov!...

Amitiés 

Oui j'avais lu cet article intéressant sur l'autre forum, mais ce n'est pas à ça que je faisais référence, mais à l'abondante documentation (et bien faite) qu'on trouve sur le site de Vivid, où ils expliquent comment ont été conçues les Giya et les HPs qui vont avec. Je trouve que c'est instructif même pour ceux qui ne s'intéressent pas à Vivid.
J'ai trouvé frappant que chacun des problèmes qui y sont discutés soient ceux dont parle l'article dont tu as donné le lien.
Cela dit, ce sont surement des problèmes vieux comme le monde de la conception des enceintes, mais les solutions de Dickie sont intéressantes à beaucoup de titres me semble-t-il.