Beolab 5 - Four Questionable Technologies

Shadorne,

I just have a question for you regarding your audition of the BeoLab 5.

You said that the speakers were in a square-shaped room with glass on both sides and no acoustic treatment. How much space was there between the speakers and the side walls?

The reason why I ask is because of the design of the Beolab permits almost 180 degree dispersion throughout the treble and midrange, and the high reflectivity of the glass surfaces would undoubtedly play havoc with the speaker's ability to produce accurate imaging and soundstaging.

I've never heard the BeoLab 5 yet, but I am quite interested in hearing it for myself. So far my most favourable impression of an omni-directional speaker was a Morrison, but that's going back many years. My current speaker is the Merlin VSM-MM, so it would be interesting to hear firsthand how the BeoLab 5 sounds in comparison.

Aside from this, I just have to call you out on two claims you made.

1. "Other conventional box speakers can have wide dispersion and hence a large sweetspot AND image like there is no tomorrow."

It has to be clarified that any conventional front-firing box speaker will be highly directional the higher you go up in frequency. If you observe the lateral frequency response graphs published by Stereophile, typically for box speakers the treble frequencies from 10Khz on up will fall off rapidly the more that you move off axis. "Wide dispersion" in this case just cannot be compared to the dispersion characteristics of a true omnidirectional loudspeaker design, which means that special consideration is required for room positioning, in order to minimize early reflections that can cloud the sound and make it seem congested.

2. "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 "

I would agree that your lateral seating position isn't overly critical for a box speaker with wide dispersion if you were only listening for tonality. However, I completely disagree with you that seating position does not matter if you are listening for imaging and soundstaging.

While it is true that the human ear perceives spatial relationships through detection of amplitude and timing differences in the sound that reaches our left and right ears, I think that your example is rather exaggerated, and isn't very helpful to Hdomke's attempt to understand how to optimize his ability to hear proper imaging and soundstaging.

A 10 DB difference in amplitude would make speaker "A" sound twice as loud as speaker "B". Thus if both speakers and the listener were positioned like points on an equilateral triangle, the centre image would be perceived to be shifted toward the side that speaker "A" is on. In practical terms, if you were listening to a vocal track where the singer is supposed to be situated dead centre, now the singer will sound like s/he is standing to one side.

In order to equalize the effect of the amplitude difference, you would have to significantly increase the spatial distance between speaker "A" and the listener, until the increase in arrival time and the attenuation in perceived volume of the sound coming from speaker "A" no longer predominates over speaker "B".

Should anyone auditioning speakers have to go through this? I don't think so. If you want to listen for imaging and soundstaging, then sitting in the sweet spot (equidistant between both loudspeakers) is essential in my opinion.

Hdomke, one of the issues that comes up in high end audio is system synergy. A great system functions better than the sum of its components. Speakers like the Beolab greatly simplify the issue. If you were to purchase a speaker like the B&W or Wilson you would have to match them to an appropriate amplifier, preamp, digital converter, interconnects and speaker cable. At the sonic level you're dealing with each component interaction can be critical to the overall system's performance. The Beolab narrows your choices down to a single digital source component.. For most audiophiles this would completely eliminate the Beolab from consideration since part of the fun of being an audiophile is working out the system synergy issues! I would also advise you to look at Audiogon members virtual systems and see if you like the visual effect of having a large amount of audio equipment in your living space. Audiophiles like big hulking speakers and 100lb. amplifiers dominating a room. Is that what you want?

Two people have taken the time to listen to the Beolab and report their findings. In reading their comments you should take into account that both writers favor monitor type speakers which excel at pinpoint imaging. If you go to a concert hall you won't hear pinpoint imaging, but a more diffuse type of sound. Instruments emerge from clearly defined areas, but they are not point sources. I also suggest that you re-read the available reviews of the Beolab in light of the posters' comments. A reviewer typically has a product for weeks if not months in order to evaluate its performance. That gives someone ample time to work out issues that can't be resolved in an hour or two audition.

One other thing to consider is that you could get a "better" speaker than the Beolab and paradoxically end up enjoying it less. There are countless posts about people who comment that their highly resolving systems make their music collections sound "bad". This is partly due to the synergy issue I mentioned earlier, but it also involves listener preference in both sound and music. You may not want the most accurate speaker.

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

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.

Shadorne,

Right *after* I had submitted my question to you regarding the positioning of the BeoLab 5 during your audition, audiogon posted this from you.

"In my audition they were about three feet from the corners - so to me the congestion was from the speaker not the placement."

Based on this, I must say that the it's no surprise that the speaker sounded so disappointing. To place an omni speaker three feet from a corner where the side-wall is made of a highly reflective material like glass is nothing short of a disaster. Honestly, the people in the B&O store should have known better. That's about as silly as putting a set of QUAD ESLs 3 feet from a front wall that's made of glass. It's so ridiculous that it boggles the mind.

One must consider that unlike a conventional box speaker, an omnidirectional speaker is radiating almost full-range in all directions. The amount of reflected energy coming off those glass walls would have definitely caused smearing of musical detail and this would almost certainly be a prime contributor of the diffuse sound you heard.

In comparison, a conventional box speaker may be close to flat across its frequency range when measured on-axis and up to about 30-degress off-axis, but as you go further off axis the amplitude of the radiated energy starts to fall off non-linearly across its bandwidth. Therefore you may get away with putting a front radiating box speaker 3 feet from a side wall (although even here, some acoustic damping from furniture or curtains would be helpful), but the same configuration for an omni speaker is just silly.

To quote from Don Morrison: "Yes, the speakers should be brought out from the side and back walls. And yes, there should be room treatment on the side walls to tame the first reflection".