gregr@tekig1.UUCP (Greg Rogers) (01/12/84)
I had read some of the articles on listening to speakers in a demo room where other speakers also reside, but I hadn't realized the origin of this debate. While reading through an Audio magazine yesterday I came upon an ad by Linn Products which asserts; "The only valid and fair method of evaluating audio components involves assessing their performance in circumstances which approach a domestic environment. This implies that only one pair of loudspeakers can be in the room at any time. The presence of any other transducer, no matter how small, will significantly degrade the performance of any audio system." Now that I realize the famous company behind this hypothesis I feel compelled to make a comment. As far as listening tests go I would agree with the first sentence. (Listening tests are not the only good way of evaluating components, however. They are simply an absolutely essential step in their evaluation. Many problems which will be heard later can easily be missed in listening only tests. But that's another topic for another article.) However, I must disagree with the resulting conclusion in the second sentence, and the unsupported claim in the third sentence. The problem here, as in most things in audio, is the word significant. It seems in audio, like no other area that I know, a little bit of fact can be streched beyond all reasonableness. Does anyone really believe that the presence of a 1 inch dome tweeter in a room will "significantly" alter the sound of another loudspeaker? Their claim is apparently based on idea that the cones of other speakers will vibrate within the soundfield and hence absorb acoustic energy and alter the apparent frequency response of the system under test. Of course this is true and the effect could even be measured given sensitive enough equipment. This doesn't mean that it could be heard however. Many effects of small magnitude can be measured but never heard. (Many things can be measured but not seen.) Every object within the room, as well as the composition and surfaces of the walls will alter the sound by absorbing acoustic energy in a varying frequency selective manner. By the sheer size of the surface area's of furniture, carpets, walls, etc. the measurable and audible effects of these other variables will swamp out the effects of a few speaker cones. Oh yes, fill an entire wall with speaker cones and some effect will no doubt be audible but not from a single pair of speakers, "no matter how small", as claimed in the ad. Linn goes on in the ad to say something quite reasonable next (a good advertising technique no doubt); "The best retailers realize .... equipment demands higher standards .... than the familiar wall of speakers on wobbly stands." There is no doubt about this statement but the reason is more one of proper placement of the speaker with regard to height and freespace about the speaker to avoid reflections than due to absorbtion problems. Of course they finish by restating their original hypothesis; "The best retailers employ only single-speaker demo-rooms." They should also add -- This prevents the customer from making direct comparisons between speakers. This seems a more likely reason for encouraging this practice. My purpose here is not to pick on Linn for any reason other than their ad seems to encourage a dubious practice and provides a documented excuse for retailers to discourage direct comparisons between components. The really significant idea in this ad, I believe, is in that first sentence. If you want to know how a speaker will sound at home, then you had better find a dealer that will let you take his demo speakers home for a real audition. This is the only way I have ever been satisfied in making a purchase. The real differences between the retailers demo room and your room are nearly insurmountable. After all how many demo rooms have windows and how many home listening rooms don't? How tall is your ceiling compared to the demo room? How large are the rooms? How many demo rooms have a fireplace, overstuffed couch, deep pyle carpet, ad infinitum? And you're worried about another speaker in the demo room? Only if it's also playing at the same time! Still trying for REAL performance, Greg Rogers Tektronix