gregr@tekig1.UUCP (Greg Rogers) (03/22/84)
Steve Winograd has complained that I ridiculed his claim that a 4-inch cassette deck speaker caused his system to have a "very muddy low bass". Steve may very well have heard some change in the low bass, notice I never said he didn't, but it is simply not possible for the 4-inch speaker to be the reason. Several other writers have suggested alternative explainations but Steve hasn't commented yet on their probability. In Point 1, below, I will try to give a simple non-technical arguement as to why the speaker cannot be at fault. I went on to discuss the sad (I believe) problem of Audio myths. Steve took exception to my comments on audio myths and presented a rebuttal. He is certainly free to disagree, but I take exception with his method of rebuttal in which he quotes me and then follows up with an arguement against a proposition that isn't expressed in the quote, nor is it one which I discussed at all, (infact we are somewhat in agreement in several cases). This is a good debating style for political debates but isn't acceptable in scientific discussions. I will, as briefly as possible, respond to his complaints so that my position will be as clear as when I stated it originally. (I'm afraid that I am very sensitive to others misrepresenting my position to support their arguments). Unfortunately, in my opinion, Steve has made several additional claims about how to "improve the sound of any system" that are MORE AUDIO MYTHS and simply not true in general as he claims. Since my original purpose in disputing his 4-inch speaker claim was to hopefully prevent inexperienced, non-technical (as far as physics and electronics goes) readers of this newsgroup from being misled, I can hardly let another set of MYTH's go by unexplained. I hope Steve takes no offense from all of this, since there is nothing personal going on here, (I never mentioned his name in my original reply). I will discuss the AUDIO MYTHS at the end of my remarks relative to the previous paragraph (such is the price of education). Point 1. I stated the relative absorbtion capability of a 4-inch cassette deck speaker to low frequencies was insignificant compared to everything else in the room. You seemed to agree, saying you could also explain the relative absorbtion capabilities. You then stated, "I fail to see, though, how you can use the existence of other factors to conclude that the effect which I reported doesn't exist." I'm sure that you aware that the absorbtion coefficient of materials at low bass frequencies is very dependent on the weight and surface area of an object. In any event certainly you would agree that the low frequency energy absorbed by several people is orders of magnitude greater than a 4-inch speaker.If the presence of the 4-inch speaker so disturbed the low frequency energy balance in the room that it caused a "very muddy low bass" and its removal from the room restored this low frequency energy balance, then the effect of the absorbtion of the additional salesmen from the audio store which were with you at the time of your discovery must be many times larger. Since I assume that you don't invite people of the same weight and surface area of the audio salesmen into the room every time you listen to the system and haven't reported this as a requirement to prevent the "very muddy low bass" I must then conclude the system is insensitive to absorbtion orders of magnitudegreater than the 4-inch speaker and hence cannot be sensitive to absorbtion by the 4-inch speaker. Other additions or deletions to the room such as a coat or sofa pillow would have effects of at least the magnitude of the speaker. Do you maintain a controlled inventory of the room's contents? I hope this explains the relevence of these factors. Point 2. I suggested that technically unknowledgeable people should be skeptical about a "new discovery" that ONLY surfaces amongst the golden-ears or the underground audio press. You again objected stating that "anyone can tell if a new discovery is fact or myth by listening to the effect it has on the sound. If it sounds better to you, then the discovery is worthwhile." You then cited pro's and con's about the underground press, however I wasn't making any judgement's about them except to say valid "discoveries" will not be somehow kept secret and confined to those pubs only. In principle your assertion that if you can hear an improvement, then it is a worthwhile "discovery" is valid, but only if you can be sure that the effect you hear is a result of the "discovery" you are trying to prove, and that in fact what you BELIEVE you hear is really occurring. Unfortunately, neither of these constraints is easy to obtain for experienced researchers and is nearly impossible except in trival cases for the technically unknowledgeable. To cite just a few simple examples, it is well known that hi-fi salesman often sell inferior products by simply demonstrating them at slightly higher volumes than a better product. This is probably the oldest trick in the book, but very effective. The salesman might claim the better sound is the result of any one of hundreds of possible "discoveries" between two similar products, i.e. AC coupling vs. DC coupling, lower TIM distortion, straight arm vs S-shaped, yellow LED's vs. red LED's, etc. In general whether the salesman "cheats" or not the customer has no way to isolate the "discovery" included in one product from the other differences between two apparently similar products. Another related problem, which I believe you have fallen prey to as I will show later, is to believe that just because a "discovery" seems to work in one system, or one room, it is therefore valid in all cases. This kind of thinking is easy to avoid when the actual principle is understood because then the interactions with the rest of the system can be predicted. Finally the need for double-blind testing to ensure that one actually hears what he thinks he hears is a well established principle in all disciplines but has proven to be particular crucial in validating audio facts and myth's. Point 3. I also stated that significant new ideas or principles will almost certainly receive coverage in the popular press if they can withstand the examination of the technically knowlegeable. New ideas that can be QUICKLY refuted are not likely to be advanced in the popular press for obvious reasons. I also stated but you did NOT quote, "I'm not saying believe everything you read in the popular press (particularly with regard to specific products)...". You followed these quotes with a number of comments about how bad the equipment reviews are in the popular press (which I also agree with) but this has nothing to do with what I said. In fact you chose not to quote the last sentence above which specifically excludes reviews about specific products. I can only take that as a deliberate attempt to distort my position. I referred to coverage about new ideas or principles that would obviously appearas feature articles i.e. Audio's articles on plastic capacitors, slew induced distortion, etc. I also never stated and in fact specifically warned against believing every claim made in the popular press as well. My point was, and history has shown, that controversial ideas will be intensely examined once they appear in these pubs and it is possible that initial ideas will be disproved or that no definitive conclusion will be reached, i.e. TIM distortion. However, the same type of intense examination may likely never occur if a "discovery" is confined only to the underground press and the golden-ears. Please feel free to continue to disagree with me Steve but if you are going to debate me "item by item" at least debate the same topic as discussed in the itemand don't imply I believe something I haven't said. Finally, you said that you didn't want my sympathy, and claimed it was an arrogant statement when I expressed sorrow for people who lacked the background in physics and electronicsto understand the plausibility of some claims made for commercial purposes. Perhaps you don't know any people like I'm talking about, that don't know AC from DC, or why woofers are large and tweeters small, or why two wires run to the speakers instead of one, but I know a whole lot of them. When faced with a whole lot of audio myths with which they must deal when all they want is good sound, those people have my sympathy, Steve, you don't need it. This brings me to the second topic MORE AUDIO MYTHS. In my opinion, some of the items presented in Steve's rebuttal are incorrect for the general case. While I have no doubt that each was an improvement in his system some of them may either help or degrade the sound of another system. This has nothing to do with price or quality but depends on interactions with specific characteristics of the components involved. To quote Steve's rebuttal, >> Each step costs little or nothing and will improve the sound of ANY >> SYSTEM of whatever cost or quality. >> 1. Place the turntable, absolutely level, on a rigid, lightweight table >> so that sub-audible vibrations from footsteps, refrigerator motors, >> traffic, etc are reduced as much as possible. The key here is the word lightweight. In my opinion, the table should be as heavy and sturdy as possible. The object is to prevent the table from vibratingeither from airborne coupling or mechanical coupling through the air. If a solid concrete floor is available the table should be mounted directly to the floor if possible and the table and turntable held as rigidly to the floor as practical. If the floor is wooden it will vibrate from the sources Steve mentions but also and very importantly will transmit low frequency energy from the speakers to the turntable via the floor. This can most certainly contribute to "muddy bass". Hence if the floor is wooden, the table should actually be isolated as much as possible from the floor using foam rubber, or some other compliant material. Now the mass of the table is especially important to minimize airborne vibrations. Since the mass of the table and turntable and the compliance of the isolating material form a resonant circuit, it must be tuned to fall below the audio spectrum. Also the speakers containingthe woofers should also be isolated from the floor through some type of compliance since that will reduce the vibration to the floor in the first place. >> 2. Place the speakers at ear level on rigid stands in such a way that >> they are not free to rock back and forth. This is simply not true in general. Different speakers have very different directivity patterns. Some actually show high frequency radiation to be directed at a fairly well defined angle either upward or downward from the direction the tweeter faces. This is particularly true for speakers with several drivers. Some speakers are designed to be mounted with an upward tilt hence mounting them at ear level would direct the high frequency radiation toward the ceiling. Some speakers are actually too bright on axis and sound better if the listener is somewhat off axis vertically. This is a good subject about which to consult the manufacturer and to experiment. Note also that the tweeter isn't the only concern. If the speaker box also contains the low frequency woofer the bass response of the speaker will be reduced considerably the farther the woofer is removed from the floor. For some speakers this may be desirable, for others it may be intolerable. Also be very careful about creating cavities between the speaker and the floor with a closed box kind of stand. This can really mess up the shape of the low frequency response, the stand should have open sides and open front and back (four legs best). >> 3. Always open the drapes behind the speaker when listening to the system. This is simply not true in general and depends on the room and directivity of the speaker. Opening the drapes behind the speaker will reduce the absorption behind the speaker. If the speaker is omnidirectional, or a dipole radiator this will have a major effect on the sound of the speaker. It may improve the sound or degrade it depending on the brand of speaker and the reverberation time and frequency response of the room. There is simply no way to generalize about the best position of the drapes. Even very conventional directivity speakers will be affected although to a lessor degree. Respectfully, Greg Rogers