Hacía tiempo que no leía un hilo tan interesanteLástima porque está siendo un post de lo más interesante.Luismax escribió:
Así que con vuestro permiso no voy a discutir más sobre los efectos perniciosos de los rebotes de la radiación trasera del altavoz porque no creo que sean tal problema.
Luismax
Hombre , no seamos tan radical. Yo en lo único que quizás tenga una ventaja es en la zona media y media grave. Y a lo mejor se debería hacer alguna prueba ciega al respecto. Por lo demas el tuiter va cerrado y la zona muy baja falla. Por lo tanto se produce un empate.atcing escribió:
Un saludete
P.D.: No me gustan los dipolosy sigo sin verles ventaja alguna ..................
En el caso de las Orion evidentemente el tweeter no funciona como dipolo. Un dipolo toda banda ..... bufff......... todavía peorPor lo demas el tuiter va cerrado y la zona muy baja falla. Por lo tanto se produce un empate.
Quizás .......... pero yo sigo sin tenerlo claro. Por mucho que le doy vueltas no veo dónde está la ventaja del dipolo ni siquiera en esas frecuencias respecto a una TL ideal o una BR "pequeña" o como ha comentado Luismax una mayor con pequeños compartimentos internos que "rompan" la onda + material absorbente.Yo en lo único que quizás tenga una ventaja es en la zona media y media grave.
Finally, dipoles have a natural 6dB/octave bass response drop due to front/rear wave cancellation. This requires a low pass compensation filter to flatten the response. Which means very high power consumption and extremely large driver excursions. The net result is lower sensitivity and higher bass distortion.
For a long time two specific types of speakers have been sold to the unsuspecting public that have by design severe behavioural problems in this range. One type is the Full Range Dipole and the full range omnipolar speaker. Neither type is found in serious Studio or sound reinforcement applications for exactly this reason.
Dipoles and Omnipolar Speakers create way more problems than they solve, by radiating energy over a very WIDE frequency range and also a very wide area. Think simply of a naked lightbulb in a room. THis is your omnipolar speaker and to a lesser degree your dipole. this makes the frequency response in room within the reverbrant range maximally dependant on the room symetry, absorbtion etc. and thus will require major efforts on room treatment to correct for the problem. Of course, a notable minority of listeners actually likes the presentation of omni's and full range dipoles and they by all means are welcome to their preference.
Another major problem source are modern "conventional" HiFi Speakers. They missuse a semi omni directional HF unit (the dome tweeter was designed by Stu Hegeman for applications radiating upards and giving omni directional hemispherical response) in combination with a cone unit that at higher frequencies coming up to the crossover frequency is actually quite directional and as a result the directionality changes strongly with frequency.
http://books.google.es/books?id=FLV21al ... &ct=result"if you are mixing movies sounftracks, the surround speaker should be dipole design rather than direct-radiator types. The dipole speakers proyect sound forwards and backwards to creatyte un diffuse effecct"
http://www.aesnashville.org/PDFs/Techni ... elines.pdfOne of the main differences between 5.1-channel setups for music and those for home
theater playback is the type of speakers used for the surround positions. The goal of
surround reproduction in the cinema (accomplished using multiple speaker arrays) is
to provide surround playback to large audiences.
Surround effects are often very diffuse, ambient soundscapes. Dipole speakers are
sometimes used in the home environment (rarely used in movie theatres) at the
surround locations to help create the wide wash of sound created using an array of
speakers in the cinema.
However, in 5.1-channel music production, as well as in films, the surrounds are
sometimes used for distinct placement of featured performers. Accurate reproduction in
this case requires the use of direct-firing speakers that match the overall characteristics
of the front speakers. Use of matched direct radiator or monopole speakers in 5.1-
channel music production is recommended for achieving the greatest control of level,
timbre, and image location
Un saludeteDirect radiators
Direct-radiating loudspeakers, as their name implies, radiate sound in only one direction (directly at the listener). They tend to image very precisely and those that have exceptionally good imaging characteristics are said to have "pinpoint imaging." By that I mean objects such as voices, musical instruments, or sound effects occupy a very definite and precise location within the soundstage and are easily distinguishable from one another.
The argument for using direct-radiating surround speakers is that discrete digital surround formats such as Dolby Digital and DTS allow for stereo surround effects, and the precise imaging characteristics of these speakers are required to accurately position these effects in the rear of the room.
Things to consider with direct radiators
When direct-radiating surround speakers are placed to the sides of the seating position and pointed directly at the listener, I find them to be excessively conspicuous, with all the sound seeming to come directly from the speakers. To avoid this, these speakers should be positioned a foot or two above ear level. I also like to place direct radiators a bit behind the listeners and angled slightly away from them. If they are to be placed directly behind the seating position, I like to have them set back at least several feet and spaced relatively far apart, angled inwards towards the listeners.
Direct-radiating loudspeakers require adequate distance from the listener for their drivers to integrate and to sound their best. Because surround speakers are typically positioned closer to the listener than the front speakers due to space limitations, their sound can become too localized, which can be distracting. By experimenting with their height, position, and angle, they can be made less conspicuous yet still maintain good image specificity.
Dipoles
Paradigm uses what the company calls Adaptive Dipole technology in their ADP surround speakers.
Dipole speakers radiate sound in two, usually opposite directions with the sound traveling in one direction being out of phase with the other. Dipole speakers tend to have less-precise imaging characteristics than direct-radiating designs, but they seem to present a better sense of space by spreading out the sound and presenting a larger soundstage.
This results in a diffuse rear sound field that envelops the listener in an immersive surround ambiance that can be very involving. Although the sound is diffuse, dipoles do still localize sounds, just not with the same image specificity as direct radiators.
Things to consider when using dipoles
One major advantage I find with dipole surround speakers is that they do not seem to require as much distance from the listening position to sound good. They also seem to be bit less placement sensitive, which I suspect is due to their reliance on reflected sound to avoid a sharp image, which is the opposite of what we normally want from a speaker.
As with direct radiators, I prefer to place dipole surround speakers a couple of feet above ear level, but directly to the sides of the seating position so that the "null" is pointed at the listeners as intended. Placing them behind the seating position will also work as long as the drivers do not point directly at the listeners.
When positioned properly, dipole surrounds do provide an enveloping diffuse rear sound field, but still retain enough imaging to give directional cues for stereo surround effects. One trick that you can use if the sound of dipoles is too diffuse for your tastes is to angle one radiating face of each speaker slightly more towards the seating position so that the listener receives more direct sound.
Un saludeteThanks for all your valuable recommendations! After several days of agonizing which surround speakers to get, I decided to get B&W 685 bookshelf speakers. I'd like to share my insights based on my research which might be helpful to those who are deciding which one to get:
1. Dipole surround speakers pre-date Dolby Digital 5.1 and 7.1 processing technology. Dipoles were designed for the early dolby pro-logic processing with diffused mono surround.
2. Dolby Digital labs recommend the use of direct radiating (bookshelf) speakers. http://www.dolby.com/consumer/home_...roomlayout.html
[It's interesting to see pictures of speakers resembling B&W 802D and 805S.] DTS seems to advocate bookshelf speakers too as surround speakers.
3. THX, on the other hand, recommend the use of dipoles/bipoles as side surround and direct radiating speakers at the rear. http://www.thx.com/home/setup/speakers/71.html
4. Cost-wise, dipoles are more expensive than bookshelves. Bookshelves are more flexible because they can be used as mains, put on stands or hanged in walls. I personally doubt it is ideal to use DS3 as main speakers since its frequency response is not full range. So choose DS3 primarily for its dipole function; its monopole function is secondary.
5. Dipoles give you a closer cinematic experience since they mimic the several bookshelf speakers hanged in cinemas and are recommended for large room with more than one row of seats. On the other hand, monopoles are used by sound engineers in Dolby Digital and DTS when they mix surround sounds so using monopoles would give you surround sounds as the sound engineers intended in the first place.
6. Sound engineers and professional mixers use 5 identical bookshelves (not dipoles, nor floorstanders or center speakers in HT) in reproducing sound effects.
7. Dipoles produce diffused sounds that are difficult to localize while monopoles' sounds can be localized. In some movies, sound engineers intentionally mix surround effects that are meant to be localized (e.g. people talking at the right back of the screen, a car running from the right rear passing through the front, etc.) which cannot be properly reproduced in dipole speakers because of non-localization. However in some movies, the sound effects are best heard diffused (dipoles) and would sound annoying in monopoles.
8. Several blind tests show that listeners prefer dipole over monopole in HT setting. For multichannel music application, monopole is preferred.
9. There are only 322 THX certified DVDs as compared to thousands that are not THX certified. Source: http://www.thx.com/home/dvd/search.html
Summing it up, choosing dipole vs. monopole is a matter of preference and taste, and most importantly whether your HT room has a side wall or not. So with these things in mind, budgetary constraints as well as WAF, I choose 685. Should I go 7.1 someday, I might consider dipoles as side surround...or perhaps stick to monopoles. Let tomorrow worry about itself.
) :
...de hecho dicho sistema 2.1 ya las tiene muy similares incluso pelíiiiiiiin mejores ..................dependiendo del SPL al que estén medidas las del dipolo, claro 
No las mezclo, ya en el primer post las separo no ya en dos puntos distintos, sino en dos familias...Luismax escribió:
Puede pero ahora estás tu mezclando dos cosas distintas, la distorsión por vibración de la caja y la distorsión por el choque de la emisión trasera del cono. Están relacionadas pero no es lo mismo.
Imagina una caja teórica sin vibraciones completamente inerte. Esa distorsión/coloración no existiría, pero la radiación trasera del cono seguiría sieno un problema puede que incluso superior pues permanecería completa sin absorción alguna. Si el recinto es inerte quiere decir que no almacena nada de energía y por tanto es reflejada en un 100% al interior.
El problema es que entre reflexiones y vibraciones dentro del recinto hay un ruido considerable, que se parece algo a la musica que sale por delante, pero bastante distorsionado.Luismax escribió: Por cierto se supone que radiación frontal y posterior están en contra fase, luego la última sólo puede hacer vibrar al cono después de rebotar en la/las paredes. Obvio. Y estás absorven una parte, transmiten otra parte por su estructura vibrando hacia el exterior, etc... Así que sigo sin ver la radiación trasera como ese demonio distorsionador.
Luismax
ahora comprendo tu sobresalto...Luismax escribió: Es que lo del cono semitrasparente lo he leido en un reportaje sobre las B&W y sus conos de Rohacell o como se diga. Textualmente. Una membrana tipo sandwich que deja pasar el aire controladamente y tal...
Obviamente el texto sería de Danglá....
Luismax
ese es un tema que yo no tengo muy claroatcing escribió: ...y teniendo en cuenta que la zona grave es zona de presión (no de reflexiones)
Un saludete
En la revision 2 de las Orion ya no, ahora tambien lleva un tuiter disparando hacia atras...atcing escribió:
En el caso de las Orion evidentemente el tweeter no funciona como dipolo. Un dipolo toda banda ..... bufff......... todavía peor
Exacto, yo también lo entiendo así ......y yo lo veo como "un efecto positivo" vemntaja de la caja convencional que cuando tiene unas dimensiones internas "X" que no sobrepasan las críticas que pueden crear desfases en los graves ................ es una manera de ganar THD vs SPL sin problemas de agujeros en la respuesta.es por eso que poniendo el woofer directo emitiendo contra una pared del coche (la trasera en este caso, por ergonomia), la onda directa y la reflejada casi coinciden, y en fase, con lo que te quitas marrones de posibles agujeros en la respuesta percibida desde los asientos
. El mismo tipo de debate técnico mas o menos 