What's 2.5 way?
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Bronze Member Username: JsoosaiBangalore, Karnataka India Post Number: 20 Registered: Mar-05 | Hi, There are speakers like Kef Q5 that are specified as 2.5 way. What is this 2.5 way? How is it different from 2 way and 3 way? Another question - For good(deep) bass output what kind of floor stander is prefered? A 3way floor stander with the 3rd driver of size 8" or above? Any good examples? Clarifications appreciated. Jude |
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Gold Member Username: Edster922Abubala, Ababala The Occupation Post Number: 2278 Registered: Mar-05 | I think that 2.5 way means 3 drivers but only 2 crossovers...I welcome anyone's correction. |
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Bronze Member Username: RsxmanPost Number: 65 Registered: Jul-05 | i dunno...i worked at best buy...i dont know anything1 lol |
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Silver Member Username: ShahrukhdMumbai, Maharashtra India Post Number: 128 Registered: Nov-04 | A 2.5 way speaker, as far as I know is a 2 way speaker with a separate driver to handle lower frequencies. Then again, correct me if I'm wrong! |
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Silver Member Username: DiabloFylde Coast, England Post Number: 249 Registered: Dec-04 | A 2.5 way is a normal 2-way with the addition of a second woofer/midrange to handle the baffle-step compensation. In other words, one woofer/midrange is used to run all the way up to crossover frequency where the tweeter takes over, and the other woofer/midrange only goes up to around 500Hz (or whatever is required due to response and baffle width). Baffle-step compensation is required since lower frequency wavelengths "wrap around" the baffle. In other words, the woofers energy is spent radiating into 360 degrees rather than 180. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 5880 Registered: May-04 | Unless the baffle is fairly large, compensation in the lowest frequencies is not required. http://sound.westhost.com/bafflestep.htm While diablo's description is essentially true, a clarification on my part would say a 2.5 way speaker is somewhat different than diablo's description. A simple two way speaker is easy enough to understand. It is a speaker with the frequency range divided in two. A three way speaker does the divison into three ranges. A 2.5 way speaker is often more similar to a three way speaker than a two way. Typically the .5 is a low frequency driver which works in a similar, but not identical, frequency range to another low frequency driver. So two low frequency drivers which have a division in the frequencies they reproduce. The lowest frequencies will be handled by both drivers to give additional "oomph" to the lowest octaves. One of the drivers, the .5 driver, will be rolled off after the lowest octaves and the second driver will continue to operate up to the XO to the high frequency driver. If the roll off of the lowest frequency driver is done electronically, the speaker has the elements that would typically be found in a three way speaker. Since both low frequency drivers cover the same lowest octaves, it is not technically a three way speaker but, instead, is termed a 2.5 way. |
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Gold Member Username: DmwileyPost Number: 1204 Registered: Feb-05 | Pay no attention to Jan. He's an idiot. The MOFO has spoken. |
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Gold Member Username: T_bomb25Dayton, Ohio United States Post Number: 1046 Registered: Jun-05 | Well Dale since Jan is such a idiot,then tell us about the 2.5 way since your so smart.A smart guy like you and your only able conjure up 8 words on a technical subject like this,aside from that horse crap you write at the bottom of your posts all the time.I guess it must feel good to have photgraphic memory huhh? Jan very very well put. |
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Bronze Member Username: ZorroPost Number: 36 Registered: Jul-05 | Everyone, pay attention to Wiley he is indeed the smartest parasite on earth. Just for you MOFO ahhhh.. and he is so bad too....uhhhh scary ! LMAO |
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Silver Member Username: GavincummPost Number: 238 Registered: Feb-05 | a 2.5 way will have usually 2 bass drivers. Where it differs from a 3 way, is as follows: ONE of those woofers will cover the full bass / midrange octaves to blend with the tweeter. The other one will cover the bass range up to 3 or 500 hz (approximating this) and then roll off with help the crossover. A full 3 way would have a woofer playing just the bass frequencies, a midrange playing the frequencies between bass and treble, and the tweeter filling the highs. Is this a good explanation? A properly done 2.5 way speaker will sound FANTASTIC IMHO! |
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Bronze Member Username: JsoosaiBangalore, Karnataka India Post Number: 21 Registered: Mar-05 | Hi, From the responses I understood that the 3rd driver reinforces the 2nd driver in the lower part of the freq range(bass to mid ). Hope this is correct! In the 2.5 way design does the 3rd drive normally of the same size or it could be different? If I need bass extension (deep bass), which design is prefered 3 way or 2.5 way or does it depend on how big is the 3rd driver? Any speaker suggestion (3 or 2.5 way) with good bass extension (for music). Thanks. Jude |
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Silver Member Username: DiabloFylde Coast, England Post Number: 250 Registered: Dec-04 | There are several good reasons for using identical bass/mid drivers in a 2.5 way speaker design. I cannot think of any speakers of this type which do not use the same type of driver for both bass/mids, but that is not to say that 2.5s with a huge bass driver are non-existant. The 2.5 way is not designed to give extra bass extension. The purpose is to re-enforce the existing bass response to compensate for the wrap-around effect where the lower frequencies have a tendency to be sent rearwards and therefore away from the listener instead of being directly beamed at him. The level of bass compensation can be varied by the designer, by tweaking the crossover. It is usually estimated that half of the bass which is lost by the main bass/mid will be reflected from the rear walls of the listening room and this can be compensated easily. If , however, the designer opts for a full 6db increase from the second driver, then considerable bass boost will be achieved in an average room, especially if the speakers are placed near to the wall and/or in corners. The speaker will still measure as having a flat response in an anechoic chamber though. The room gain of a 2.5 will re-enforce whatever bass response there is, but will not enable it to produce lower frequencies. It appears that you want bass extension rather than 'extra' bass response. There are three way designs which will go a bit lower in frequency response but I cannot personally recommend any. Most people nowadays seem to opt for powered sub-woofers in order to get the really low notes and I cannot advise on these either! diablo |
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Silver Member Username: ShahrukhdMumbai, Maharashtra India Post Number: 129 Registered: Nov-04 | B & W 603 S3 is a good 2.5 way design. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 5899 Registered: May-04 | Daiblo - I still am in disagreement with what you have posted. Baffle step compensation is typically done either with a rising frequency response in the design of the woofer or is accomplished with active or passive circuitry. The frequencies where the step occurs is well above the range where the real benefits of the second driver occur and the baffle step loss has smoothed out by the time the most significant benefit of the additional driver comes into play. http://www.soton.ac.uk/~apm3/diyaudio/Diffraction.html http://www.trueaudio.com/st_diff1.htm Here's a reveiw of a Spendor which qualifies as a 2.5 way design. While I cannot hold Stereophile up as the bastion of technical reporting, they generally do a good job of informing their reader about the technical design of a product. There is no mention of the additional driver being used to compensate for baffle step in this review. Diablo, if you can find a reference for your claim, I would appreciate the information as I have never come across this idea. My understanding of the .5 way design is to use mulitple drivers which are smaller, lighter, faster, stiffer, more easily controlled with less distortion product. The surface area of two 6" drivers is roughly the equivalent to one 14" driver. Therefore the two smaller drivers can move more air and thus give better response at the low frequency extreme. Each driver's excursion is lessened so the distortion product goes down significantly while the bass extension is not affected. The speed of the drivers is much faster, in general, than one large driver with comparable design. To use this second driver for baffle step, as I see it, would require one of the drivers to have a specific frequency response which peaks within a certain bandwidth and then flattens out as the frequency descends. Since both drivers cover the same frequencies from about 700Hz downward, I find this an odd way to compensate for baffle step when a small network in the XO would be just as efficient at much lower cost. Again, I would appreciate any information to the contrary. Jude - You can see in the Spendor review a 2.5 way speaker where the two bass drivers are similar but not identical. |
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Anonymous | "The surface area of two 6" drivers is roughly the equivalent to one 14" driver.Therefore the two smaller drivers can move more air and thus give better response at the low frequency extreme" Jan, using this analogy, are you telling me that a speaker that uses 2 4inch "woofers" will have better bass response than a speaker that uses a single 8 inch woofer because of the superior surface area of the dual drivers? LMAO! and I used to think you were intelligent. Using THAT philosophy, I will go buy myself some Bose 901's, with their many small drivers, I am sure will have better bass response than a properly set up pair of wilson audio WATT-puppies. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 5907 Registered: May-04 | All things being equal, yes, I am telling you multiple small drivers have advantages over a single larger driver. "Apparent" surface area being just one of those advantages. Any single driver is limited by its excursion capabilites and can move only so much air depending on how the motor system is designed and constructed. Obviously anyone who is familiar with the quality of materials utilized by Wilson and by Bose can see the folly of your argument. The two systems are not equal in any way other than they both take up space. You can, however, believe me when I tell you using two drivers of similar excursion capability will couple the drivers and create a "virtual" driver which is larger than the sum of the two parts. Is it not true you will gain an additional 3dB for each speaker you add to a system? We're talking the same basic idea; acoustic coupling. It is a portion of what made the Double Advent system work so well. To think the Bose analogy is the best example of mocking my information is to not consider the many other variables which influence speaker performance and bass extension. The 901 does utilize the same acoustic coupling technique, though that is not the principle reason for Bose using the same driver in multiples. But, since a 4" driver, even in multiples, can only produce so much bass extension when confined to such a small cabinet as the 901's, equalization is required to make the Bose system have deeper bass extension than would normally occur. In the case of the 901, it is the enclosure volume which becomes the limiting factor more than the multiple 4" drivers. Two similar drivers will require a larger enclosure than one such driver. Make that nine drivers in one enclosure and the 901 is not even close to the proper internal volume for reasonable bass response. The physical limitations of how much excursion a 4" driver can accomplish limit the ability in the real world, but if you had a driver that could move enough air by way of its excursion, you could produce reasonably deep bass with a small driver in a large enclosure. A portion of this concept is incorporated in the 4" full range driver T8 uses in his Ling. http://www.adireaudio.com/Files/XBL2TechPaper.pdf#search='adire%20xbl' The idea a small driver can produce deep bass should not be that hard to understand. Nor should the idea that drivers will couple and become more than the sum of their parts. If I need to explain the advantages of small, light, stiff, fast drivers, I will do so. If I need to explain the idea of bass response being dependent on several factors, I'll do my best. That two quality drivers working in tandem are better than one driver trying to do the same amount of work should be evident to almost anyone. If you have evidence what I have stated is not correct, I would be more than happy to look at what you can produce. Otherwise hold off on buying the Bose. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 5911 Registered: May-04 | While not exactly the idea I am discussing, many of the same principles apply. Try these instead of your Bose: http://www.stereotimes.com/nearfield_acoustics_pipedream.htm |
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Silver Member Username: DiabloFylde Coast, England Post Number: 251 Registered: Dec-04 | Jan, I was a little confused by your initial post, because whilst you disagreed with me, you then stated the same idea in different words - "Typically the .5 is a low frequency driver which works in a similar, but not identical, frequency range to another low frequency driver. So two low frequency drivers which have a division in the frequencies they reproduce. The lowest frequencies will be handled by both drivers to give additional "oomph" to the lowest octaves. One of the drivers, the .5 driver, will be rolled off after the lowest octaves and the second driver will continue to operate up to the XO to the high frequency driver" That's exactly what I was trying to say and at the point of typing it I thought I had succeeded. The concept of having two bass/midrange drivers, with one of them restricted to the bass frequencies is not new, I recall reading about it over 20 years ago, though I don't think they had invented the term '2.5' at that time. There are other ways of dealing with the baffle step, but the questioner was asking only about 2.5 speakers. It may be that there are some speakers which operate two bass/midranges over the whole range up to the point where the tweeter takes over and which are designated by the manufacturer as 2.5 designs - I think Quad do this with their 22L speakers. But having googled '"2.5 way" speaker', nearly all of the search results seem to be speakers which operate with one of the bass/midrange units rolled off. e.g. - There are numerous 2.5 designs in the DIY speaker forums. Here is an example which shows the crossover design -- http://www.io.com/~patman/s1.html I'm not entirely convinced that it is a good idea to arrange the speakers in this way. I'm happy with my Castles which use two 6" drivers which both cover the same range. As you say, this gives many advantages compared to a single large driver. I don't call them 2.5s though and neither do Castle.  Regards, diablo |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 5914 Registered: May-04 | I will admit the idea of the two 6" drivers amounting to one 14" driver is a very broad statement with exceptions just like any other approach to audio. And, I am not implying that all 6" drivers in all enclosures will give the same results. However, by the time you add in the mutual coupling of well designed drivers in a well designed enclosure, the sum of the parts are more than the two parts by themself. I have heard many speakers systems where doubling the drivers made the situation worse. These were generally poorly designed speakers to begin with. And, the Double Advent System had a bit more magic to it than just more drivers. I would suggest to anyone who has a pair of speakers they like but you would like a bit "more"; try doubling up the speakers and listen to the results. Most well designed speakers do achieve more than a sum of the parts increase in quality. |
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