Beolab 5 - Four Questionable Technologies

the BeoLab5 radiates full power throughout the mid-to-treble range towards the side (unlike a conventional box speaker whose output sharply attenuates to the sides)

Not all conventional box speakers have narrow dispersion ( no side radiation ) - good speakers will have wide dispersion at least as wide as far as it matters (to be affected by side wall reflection to listener).

Just be aware that omnidirectionals work best pulled way out into the room (6 to 8 feet from wall/window). The Wilsons will give you more placement options, IMHO.

If you place the BEO 5's too close to those glass windows then the soundstage may collapse and it will sound "claustrophobic". These type speakers are not as forgiving with regards to placement as conventional forward radiating designs.

20+ years is a long time - so choose wisely. If you want a statement/conversation piece then the Beolab looks like it came from Forbidden Planet - no guest will miss it - it is a stunning art item as well as a speaker. Since you listen to music as a background thing then it may well be the correct choice. However it is towards the "unconventional" fringes of designs. The Wilson's may not elicit automatic comments from guests but they are a more conventional tried and proven box speaker design with plenty of models in service for many years and with many parts available.

From this plot it sure looks as if the direct sound from the driver and the reflected sound from the frizbee above it are mixing. I was expecting or looking for this but it took me a while to find a plot so let me explain...

This is an effect called flanging and it can be quite pleasant as it creates an extremely spacious sound effect such that you cannot locate the source. This trick is well known and can be used to create the impression of stereo from a mono track. One signal is delayed by a fixed amount relative to the other and when summed you get the characteristic "comb filter". In this case the flanger is a fixed delay rather than a swept delay (like you get from pumping a guitar pedal).

You can tell this is likely going on from the characteristic sharp notches on the frequency response of the horizontally mounted drivers with frisbees: the dome midrange and dome tweeter)

I am surprised Tom Nousaine did not remark on this possible issue. He is an engineer and should have at least explained why it might not be a problem of this design.

Clearly the dome drivers are visible from the side and therefore the listener must be hearing two tweeters and two midranges: one directly and one delayed by the distance between driver and the frizbee that it reflects from. The fact that some reviewers have reported being baffled that even a lone BeoLab 5 speaker makes it hard to detect the source of the sound is a dead give away that this might be happening: the spacey rock guitar sound. Since the tweeter is aimed upwards at the frizbee then this signal will be much stronger than the one radiated sideways directly from the driver to the listener, which means the notches will not be that deep (as seen on the plot).

I am sorry to say but this design fails the basic acoustic physics back of the envelope test. I remain flabbergasted by the outstanding reviews - perhaps I am completely missing something? Ironic that a spacey looking speaker might also make a "spacey sound".

YMMV, this is conjecture as I don't have these speakers available to me in a lab to test out what appears to be happening. Perhaps B&O have a perfectly reasonable explanation of how they deal with this design issue, in which case I would apologize for my erroneous ramblings/conjecture.

Why in god's name would you suppose to know of a deficiency that you have not heard? What motivates you to caution against something you are guessing about?

Macrojack - I am curious and cautious because

1) this is a novel design
2) rave reviews
3) barely any audiophiles seem to own this design (yet it has been around for 4 years)

There are tens of thousands of ordinary box speakers with forward facing drivers that have been built over the years, with good reason => this type design works well. A novel design that looks like a Dalek has my "hype alert" sensors showing yellow warnings!

I agree that an audition is the best way forward but perhaps it helps to be aware that pleasant sound effects may not necessarily be accuracy and that there is very little of a track record behind this novel & very expensive design.

specifically the use of acoustic lenses to achieve omni-directional dispersion, has actually been around for a while and is a proven concept (see Hegeman / Morrison, Walcott, Duevel).

Oxia,

Thanks for the info, I would add MBL to that list. I am not against omnidirectional and from my understanding most omnidirectional designs would not create the flanging effect (one signal delayed with respect to another).

you ought to listen first and then let your ears decide.

I agree fully but it does not hurt to be an informed buyer about the possibility of audible colorations. Sorry if I offended anyone.

Hdomke,

There is a store locally - I will see if If they have them. Please understand that flanging can be pleasant sounding and it is done on many recordings. George Martin of the Beatles fame found that you could achieve this by messing around with tape recorders and adding a slight delay to one tape recorder to produce "thicker sounding vocals". So this effect is inevitably on many pop recordings. Also microphone height from a reflective wooden floor will have some influence too. So it is more than likely a pleasant coloration that gives more openness or spaciousness to the sound. That this issue will occur seems inevitable to me given that you can physically see the dome drivers sticking up out of the bottom frizbee in the photographs taken at what would approximate a listening position with respect to the speaker...it seems inevitable that some sound will go directly from the driver to the listener whilst the majority of the sound is intended to reflect off the lens above.

I listened to the Beolab 5 today. It was in the local B&O store. They were setup in a special listening room (also set up for 7.1). A bit square in shape and with glass on two sides and with no acoustic treatment - so not an ideal set up - although ceilings were high (good) and as with all B&O decor and industrial design everything was modern but impeccable and tasteful.

The B&O rep was very knowledgeable and clearly understood the physics of the speaker although he said the drivers were made by B&O (however I am not sure of this as IMHO is looks very much like the Vifa 3" Dome Midrange D75MX-41-08 or at least it is indistinguishable from this 3" vifa dome).

I listened to mostly "Brothers in Arms", Dire Straits and a few demo disks as well as some DVD's.

Observations:
Excellent articulate bass (it definitely does not need a sub) and they can play fairly loud cleanly. As I had feared, there is some "flanging" in the upper mid range and treble giving an airy or atmospheric quality to the sound with the imaging not nearly as precise as it is on my home system. Vocalists were still centered but not perfectly tangible so that you could say the singer was there in the room standing between the speakers. As has been reported by others, the sound field is very even in a horizontal plane around the room - you could move around and it sounded much the same, however, there is a significant difference between the seated and the standing presentation (I was sitting 10 feet back with the speakers 8 feet apart near the corners of the small room). You need to be seated at the correct height to enjoy these speakers. I also perceived something missing in the lower mid range. It seems the lower mid is covered by a forward facing 6" driver and somehow (to my ears) there was a dip somewhere between 400 and 1 Khz ; perhaps this 6" driver was not as dispersive as the dome mid or I detected a crossover issue. Overall the sound was similar to Ribbons except that you had serious high quality bass, placement was much easier ( no problem 2 feet from a wall) and that the sweetspot was way larger than you find for ribbons.

Nevertheless for some $23,000, this is an expensive speaker and as far as I am concerned the ATC SCM 100ASL is a much better speaker. Personally I would also prefer similar priced Wilsons over this speaker but I am not keen on "atmospheric"or "airy" sound - I much prefer precision. So that is just my taste.

""The term applied to the use of comb filters to obtain special sound effects."

Is that what you mean by flanging?

Henry

What I mean by flanging is exactly that. In the case of two tape recorders playing the same signal slightly out of time then you will get a "comb filter" frequency response - some frequencies double where the signals reinforce and other frequencies completely cancel. There is a harmonic relationship between the signals that cancel and the signals that reinforce. The sound can be either "full" or "thin" depending on the instrument. True "flanging" as done on the guitar will give a "swirling effect", perhaps this is what Marty expected to hear and did not, --- with true flanging the time delay is varied (not fixed) with a foot pedal and this creates dramatic movements of the sound.

In the case of the Beolab 5, the sound is bouncing off the frizbee on top, it is also posssibly bouncing off the bottom frizbee on the bottom and thirdly it is hitting your ears directly from the dome drivers themselves ( no bounce ). So in essence it is like having three tape recorders all playing exactly the same music with a FIXED time delay between each recorder and the volume levels different (the loudest sound probably comes from the reflected sound bouncing off the underside of the frisbee above the dome driver, the next loudest may be either the direct energy from the driver itself or the sound reflected again off the bottom frizbee after it has already hit the top frizbee) These three signals are identical except they are offset (time delay) with respect to eachother and of course the principal one is much louder than the others. Critically these all radiate into the room with their fixed delay. So your ears will hear all three signals mixed or muddled together (they are much too close in time to separate into "echos"). The time delays are very similar to natural reflections and what I am describing are all well known facts about how audio delay can affect the perception of audio. Notice how Figure 5 - Comb Filter With Signal Level Adjustment bears a slight resemblance to this frequency plot.

In the case of the Beolab 5 the delays (if they exsit) would be of the order of 1/2 to 1.5 millisecs (governed by the distance between the frizbees of around 8 inches and the speed of sound in air). This may affect cymbals, horns, vocals and lead instruments. IMHO, it will likely make the treble sound less harsh or piercing.

With me was an experienced audiophile friend. He has a pair of Wilson Sophia speakers at home. He was not impressed. He described the sound as "analytical" "dry" and "lacking certain timbral nuances."

I would agree with your friend. I found the sound to be slightly congested/cluttered in upper midrange. Treble sounds were not crystal clear and precise. It made for a softer more agreeable and less revealing sound then I would normally associate with Wilsons or another forward "precise" type speaker. I agree about the timbral nuances and this is perhaps my perceived issue with the lower mid range sounding too "thin" (and this could indeed be room related). However, as Marty pointed out the speaker was, on the whole, very neutral sounding.

Bear in mind that my criticisms are aimed at a $23,000 speaker...on the whole the sound was what most anyone would call wonderful, amazing or awesome (as it darn well should be at this price!!). The bass response, as I have previously stated was particularly impressive.

However, given my taste for transparent sound; take my comments with a good pinch of salt! I want to hear the sound as close as possible to what is on the source...additional colorations, no matter how pleasing, are something I try to avoid. Since you are looking for something that you can live with for twenty years then your judgement is what counts!

I gather you are referring to the lack of the illusion of the musicians laid out properly in space in front of you.

Yes Exactly.

I wonder if that flaw is the price one pays for the benefits of the Acoustic Lens technology? This technology allows for a much wider “Sweet Spot” but perhaps the sweet spot we get isn’t as sweet as it would be in a more conventional speaker.

No. Other conventional box speakers can have wide dispersion and hence a large sweetspot AND image like there is no tomorrow. Like Marty - I fully expect a vocalist to appear as a solid single image in a mix - clearly positioned - not dispersed vaguely in front of me. When a duet is singing I can clearly hear that they are positioned two feet apart in the soundstage when they are mixed that way. I felt that the Beolabs hinted or gave glimpses of precise imaging in certain sounds or vocals but did not do so solidly all the time - much of the time there was a certain diffuseness to everything)

To help accomplish this{Soundstage}, do Audiophiles always try to sit at precisely the right spot when they are doing active listening?

No it is not necessary to sit at precisely the right spot on widely dispersive high quality speakers such as you can find at this price. Location of sound is NOT all about volume level in fact this is a misconception propagated by the industry to try and sell more center channels. You can have one speaker 10 DB louder than the other and yet the sound can come from directly between them....it is timing that tells us the location much more than volume level (most people are unaware of this). Of course the image will move slightly as you sit in front of one speaker or the other but the soundstage should not collapse. Also if timing is messed up or poor then volume level will weigh more heavily in how you determine the position of instruments in the soundstage.

You both also complained about “congestion/compression” and “congested/cluttered in upper midrange”. Please help me understand. I’m guessing that you mean that in parts of the music the differences between instruments might blur, which makes it hard to differentiate or even identify the instruments?

Yes is was "blurred" or not razor sharp clear in the upper mid range. It sounded "softer" or less piercing and less harsh then I would expect from natural sound. It made for a less exciting or involving sound as there was no "edge" to leading instruments or vocals. If this is indeed the 3' Vifa Dome Midrange driver that is being used then it only has a linear Xmax of +/- 0.5 millimeters - which is not much better than most tweeters (i.e. terrible) - this dome midrange will compress all to easily if driven too low in frequency which means that either you lose lower midrange energy from compression at high levels or you need to crossover very high into the midrange with the 6 inch woofer - either way this concerns me but it is conjecture as I have no proof that is definitely is the 3" Dome Midrange from Vifa that Beolab 5's are using. (The midrange dome on my speakers has an Xmax of 3.0 mm or six times more linear excursion than the Vifa mid - so I get more than enough crystal clear midrange energy before non-linearities/compression sets in)

I spent a couple hours in the afternoon listening to the B&W 800Ds in a very fine listening room. The words that kept coming to my mind were “natural” and “real”. Perhaps those are the speakers I will buy…

Yes do buy these over the Beolab - far better, IMHO. This is a fine speaker. A bit hard to drive but with the right SS amplification they will sing. The large midrange tends to "beam" slightly in the top of the midrange (less wide dispersion or even sound field from 2 to 4 Khz) and they come on a bit strong around 4 Khz (when the widely dispersive tweeter kicks in) - however this is nitpicking - this is an absolutely outstanding speaker. World class.

It would seem to me that the ideal next step would be to get the Beolab 5s and the B&W800Ds into my listening room at home, preferably at the same time for some extended A:B comparisons.

I am not sure I agree but it is your taste that counts not mine. (As you know by now I think the 800D is a far better speaker, however, I also think you owe it to yourself, at this price, to audition a few other speakers. It would be worth the price of a weekend trip to CES just check out other designs, at your price point.)

Also, the congestion I heard at demo may be due to distortion generated by the speaker as loudish, complex musical passages tax the drivers and force them to misbehave. Or, as I noted, it could have been the set-up or some defect. I was not listening at crushing levels and I found the problem instantly identifiable.

Marty, I agree with you. It was immediately identifiable. In my audition they were about three feet from the corners - so to me the congestion was from the speaker not the placement. I too felt that taxing passages at higher volumes stressed the midrange, as the lower/middle mid range seemed to get buried by the bass and treble. However, like you say, it is impossible to be "conclusive" about this in a short listening test with a Sales Rep over your shoulder. All I can say is that it was pretty obvious to me, although I am used to a rather forward midrange presentation so my impression could be influenced by my reference. In any case, there is no way I would be reaching for the checkbook for this sound. So it seems we heartily agree. I would add that there is no way I would bother to get these in the home (given my tastes for precision - they just don't suit me at all except for their impressive tight bass response).

Finally, if you like the Beolab concept you should also consider the Meridian line of active speakers.

I agree wiith this suggestion. I am partial to active speakers - so it is goes against my preference to recommend a passive speaker over teh active Beolab 5's.

Onhwy61 is correct that I prefer mointors that image like no tomrrow and sound as accurate as possible and that this is not what the majority of people seek. These speakers will sound harsh just like real instruments ....when a trumpet is played loud then your hair will part - not everyone's cup of tea!! So as I said above in a previous post- take into account my preferences when you read my impressions of the Beolab 5 (it is after all a fine and awesome speaker)...a grain of salt if youu like.

How much space was there between the speakers and the side walls?

About 3 feet - so enough not to ruin the image.

If you want to listen for imaging and soundstaging, then sitting in the sweet spot (equidistant between both loudspeakers) is essential in my opinion.

Correct. You should indeed listen in the center to maximise the imaging experience and especially when making evaluations. On reflection I agree that you have a good point. My point about 10 db is actually referenced in the link I gave....

The Haas Effect is, simply stated, a factor in human hearing where delay has a much bigger effect on human perception of direction than level does. Helmut Haas in Germany showed that although identical audio sources sent to two speakers at equal level resulted in a center image, a 5 - 20 ms delay to one of the signals shifted the image to the non-delayed side, and the delayed side had to be made 10 dB louder to get the image to shift back to the center. This is also called Precedence Effect.

Oxia,

I agree. I do not like omnidirectional or dipoles or forward and rear radiating panels or ribbon speakers for the very reasons you give about the reverberation they create. It creates ambience at the expense of imaging and soudstage and clarity. BTW: I have soffit mounted my mains - so I have eliminated the nasty rear radiation in the omnidirectional mid bass (with its inherent quarter wavelength cancelations that the listener hears as a "comb filter", altering certain notes as it affects harmonic balance in the lower midrange) The improvement from soffit mount versus non soffit mount is significant - image and tangibility of sounds improve further and make for a very solid soundstage but most people would never bother to go to this much trouble.