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Modérateurs: Modération Forum Haute-Fidélité, Le Bureau de l’Association HCFR • Utilisateurs parcourant ce forum: bandicootfr, douda, erictours, Faz13, fernous, hiik, jupal, parager, streetbob, tovarich007 et 216 invités
» 07 Fév 2004 0:17
youl a écrit:BPhil a écrit
A titre indicatif le 38CM du HGS15 a une Frequence de Resonnance en dessous des 15HZ et a -3db qu'on ce le dise
Regardes la deuxième page, avec tous les essais.
http://www.hometheaterhifi.com/volume_1 ... art-1.html
» 07 Fév 2004 0:19
» 07 Fév 2004 0:23
youl a écrit:Archi je l'avais donné:wink:
Commentaires de curt c (velodyne)
DD-10 DD-12 1800 cubic feet (environ 49m3 3mx6mx2.70)
DD-12 DD-15 3000 cubic feet (environ 80m3 4.5mx6.6mx2.70)
DD-15 DD-18 >3000 cubic feet
» 07 Fév 2004 0:38
youl a écrit:Archi je l'avais donné:wink:
Commentaires de curt c (velodyne)
DD-10 DD-12 1800 cubic feet (environ 49m3 3mx6mx2.70)
DD-12 DD-15 3000 cubic feet (environ 80m3 4.5mx6.6mx2.70)
DD-15 DD-18 >3000 cubic feet
a 15 Hz après corrections
With the servo setting at 8, THD dropped to 3%. So, the servo does its job.
a 20 Hz après corrections
Servo setting 8 reduced THD to less than 2% at 20Hz
a 31.5 Hz après corrections
At 31.5 Hz, maximum SPL was 117 dB. This is really room shaking volume, and distortion was at 1.24% at 100 dB, and servo setting 8. At this, and other higher frequencies, I did not find significant differences in the amount of THD with respect to the particular servo setting
» 07 Fév 2004 0:40
Archi a écrit:youl a écrit:Donc pour moi ce serait un DD15 ou 18 selon leur brochure
» 07 Fév 2004 0:42
» 07 Fév 2004 0:45
» 07 Fév 2004 1:06
Archi a écrit:En finition noire, les 4 modèles se tiennent dans une fourchette de 1300 € je crois.
On débute à 2700 € pour arriver à 4000€ pour le DD18.
» 07 Fév 2004 1:38
» 07 Fév 2004 3:00
» 07 Fév 2004 9:38
Youl ta pièce fait combien de M3 ?
» 07 Fév 2004 11:07
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» 07 Fév 2004 11:16
le DD18 ne permet pas un parametrage tenant compte de deux caissons. quel facteur d'asservissement utilisez vous ?
Shown below is the graph with the two subs operating, and with EQ applied from the DD18. As expected, I was able to get the response much flatter, and it points out that just adding the DD18 to a multi-subwoofer system can work in flattening the room response, even though the other subwoofer(s) do not have digital EQ.
One other point about digital EQ is that it eliminates phase shift that is caused by analog crossover components (inductors and capacitors). This is very important in getting time alignment of the bass with the midrange and high frequencies in the other speakers.
Aussi on peut se demander si le DD18 n'est pas moins rapide que le DD15 par exemple ....
Cajun,
This is a hotly debated topic but of course, I do have an opinion. In short, I agree with Uncle Eric, but let me explain in my own (numerous) words.
As I see it, the implication that folks make when they say that a 15" or 18" driver is "slower" than a smaller 10" or 12" driver is either that the mass of the driver is such that the motor cannot move its weight with the same precision as that of the smaller driver and/or the cone is flexing enough so that the woofer sounds boomy or muddy. The latter effect will have more impact on the perceived boominess and muddiness of the driver (in that it will produce more distortion) so let’s address that first. This of course relates to cone stiffness, and a larger cone made of the same material will bend more and, in the worst case, buckle under the load of long throw bass combined with cabinet pressure. This is overcome with stiffer materials and/or cone reinforcement, and while it is true that a larger cone is subject to less linearity along the cone surface, this effect is minimized with a stiff enough cone. Too often, large drivers are made out of the same materials as smaller drivers and so aren’t stiff enough – this is where this perception likely started.
Regarding the driver being heavy to be moved correctly, there are three main forces opposing the motion of the cone structure: the weight of the cone, the pressure inside the box, and the resistance of the suspension (i.e. the surround and spider). It's true that the bigger the cone the more mass there is, but you'd be surprised how much the air pressure in the box and the suspension stiffness affect cone movement too.
All of these factors can be overcome by motor force, otherwise known in speaker land as BL. BL is the combination of magnet force combined with the length of voice coil wire in the gap. The higher the BL, the more motor force is applied to the cone. As a speaker designer, one has to ensure that there is enough BL to overcome the cone mass, suspension stiffness, and box design you are planning on. Not enough BL and your cone doesn't move correctly, and too much and you spent too much on the driver. Of course, one also needs sufficient amp power to drive the motor. We also use a high gain servo to make sure the cone movement is true to the input signal.
An often overlooked spec in comparing speakers is magnet weight. We use 310 ounce (19.3 pound) magnets for the DD-10 and DD-12 and 380 ounce (24 pound) magnets for the DD-15 ad DD-18. Why so big? Because we never want to run short of motor force and we need more BL for the 15 and 18.
Now let's talk efficiency. SPL= sound pressure level = amount of air moved by the speaker cone. Given similar travel distances (all DDs go up to 1.75" peak to peak), the formula is 2 pi r (i.e. cone area) * travel. Some simple math shows that a 15" cone moves a heck of a lot more air than a 10 or a 12. And an 18 more yet. Yet, the additional motor force to move the larger cones is disproportional to how much more air they move - so the larger the cone the more air is moved for less energy.
Lastly, let me comment on the phrases "slow" versus "fast". To us, these terms almost entirely describe the amount of perceived distortion the speaker is producing. That idea is somewhat radical, but we've based our designs on it for almost 20 years with a fair bit of success. We've strived for very low distortion in all our subs, and the DD-15s and DD-18s have no more than the DD-10s and DD-12s. So, we consider them as "fast" as anything going.
Re the 1812 - what we did there is let the 18 handle the lowest bass, since it's efficiency lets the long excursions needed for 40 Hz and below be reproduced with optimal use of BL and amp power. The 12's job is to handle the upper bass frequencies and not spend its headroom trying to recreate 20 Hz. The result is a sub that will play louder than either alone, or even in tandem, because we've optimized the efficiencies of both. This does not mean that a stand-alone 18 cannot play 100 Hz or that a stand alone 12 cannot play 20 Hz - but combined (and crossed over internally with special software) we can squeeze out more clean bass since the efficiency of each driver is optimized
» 07 Fév 2004 11:55
ano a écrit:question a mmikeul 01 : apparement deux caissons sont intégrés dans votre install à savoir un revel B15 et un DD18 . comment avez vous fait pour parametrer le DD18 , car pour parametrer ce dernier un signal sonore couvrant la bande 15 -200 htz est genéré par l'amplificateur "intégré " et envoyé d'une part sur les satellites et d'autre part sur le caisson . le DD18 ne permet pas un parametrage tenant compte de deux caissons. quel facteur d'asservissement utilisez vous ? ( zone de parametrage theater / music allant de 1 à 8 dans le menu de system settings ) et pourquoi n'avoir pas pris un second revel B15 plutot qu'un DD18 ? ( est ce que le système n'aurait pas été plus équilibré ......? )
8mois que je suis dans le hom cinema...)en faite mon b15 me satisfaisait deja bien , mais etant un gourmant en grave et infra grave, je me suis dit avec mon revendeur k il faudrai completer par le 2e caissons, au bien sur on a penser a remettre un 2e B15 mais le dd18 m interressait aussi car il y a un 46 cm et ki ai tres rapide, j ai deja vu un dd12 je peut dire ke le dd18 est aussi rapide, en faite au sein de l install il fallait pour les films que lors d impact ca soit tres violent , tres dynamique..tres realisme...donc c est ce qui est maintenant.en hifi c est encore mieux......
» 07 Fév 2004 14:20
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