ftp.pasteur.org/FAQ/

home *** CD-ROM | disk | FTP | other *** search

/ ftp.pasteur.org/FAQ/ / ftp-pasteur-org-FAQ.zip / FAQ / AudioFAQ / part2 < prev next >

Wrap

Internet Message Format | 2004-04-18 | 25.9 KB

Path: senator-bedfellow.mit.edu!dreaderd!not-for-mail Message-ID: <AudioFAQ/part2_1082200966@rtfm.mit.edu> Supersedes: <AudioFAQ/part2_1079601013@rtfm.mit.edu> Expires: 31 May 2004 11:22:46 GMT References: <AudioFAQ/part1_1082200966@rtfm.mit.edu> X-Last-Updated: 2002/09/04 Newsgroups: rec.audio.tech,rec.audio.opinion,rec.audio.misc,rec.audio.marketplace,rec.answers,news.answers Subject: FAQ: rec.audio.* Systems 2/99 (part 2 of 13) Followup-To: poster Reply-To: neidorff@ti.com Approved: news-answers-request@mit.edu From: neidorff@ti.com Organization: Texas Instruments Corp. Summary: Answers to common questions about audio equipment, selecting, buying, set-up, tuning, use, repair, developments, and philosophy. Originator: faqserv@penguin-lust.MIT.EDU Date: 17 Apr 2004 11:27:31 GMT Lines: 592 NNTP-Posting-Host: penguin-lust.mit.edu X-Trace: 1082201251 senator-bedfellow.mit.edu 576 18.181.0.29 Xref: senator-bedfellow.mit.edu rec.audio.tech:181975 rec.audio.opinion:656776 rec.audio.misc:88787 rec.audio.marketplace:487239 rec.answers:86575 news.answers:269868 Archive-name: AudioFAQ/part2 Last-modified: 2020/09/04 Version: 2.16 9.0 High Fidelity Systems People frequently use the term "Stereo" to refer to a sound reproduction system. To be more accurate, we will use the term High Fidelity System to refer to a pile of equipment including at least one source, at least one amplifier, and at least one speaker. Common sources are turntables, CD players, tape players, tuners, and receivers. 9.1 What is a receiver? A receiver is a tuner, power amplifier, and preamp combined. A common receiver has inputs for a turntable, a CD player, a tape deck, and perhaps one or two other sources. It probably also has selector switch(s), tone controls, and a volume control. A receiver may have outputs for two speakers, or for more. Some receivers do | not have phono preamps, a trend that may become more common as vinyl loses popularity. Many receivers contain surround sound processors. 9.2 What is a tuner? A tuner is a radio reception device which can not drive speakers. Sometimes, the radio in a tuner is higher quality than the radio in a receiver. A tuner may or may not receive the AM broadcast band, but 99.999% will receive the FM broadcast band. Some also receive short wave bands, frequencies used for long-distance rather than for local commercial broadcasts. 9.3 How should I go about selecting a system? If you're looking to buy something, the first step is to figure out what you can spend. If you're looking for a whole system, this gets tricky, because you have to allocate amounts for the different components. The most popular current rule-of-thumb for a single source system (speakers, amp, 1 something-player) is to divide the money about equally among the three parts. If you want several players, you'll have to decide whether they are all equally important, and so deserve the same amount of money; or whether some are less important, in which case you can spend less on them and put the savings elsewhere. This rule isn't hard-and-fast. It's just meant as a starting point so you don't have to listen to every possible combination of equipment. If you are building around a CD player, you might spend a bit less on the player and a bit more on the speakers. If you are buying turntable (or something else which plays by physical contact) on the other hand, it might be good idea to put a bit extra into the player. The reason for this is that if you skimp on the turntable, then when you come to buy a better one you may find that your records have been worn out by the cheap player. If you skimp on the speakers, on the other hand, then when you can afford better speakers the music will still be there on your records. Another perspective says that you should spend the most you can on your source, as the sound can never be better than what you get off of the record/CD. See also 12.1, 12.2, and 10.1 for information on what to listen to and what to listen for when evaluating speakers, turntables, CD players, tape recorders, and systems in general. 9.4 How can I improve the sound of my stereo? The cheapest improvement you can make, and perhaps the most effective, is to position your speakers carefully and correctly. See 13.1, below. This will improve the frequency response flatness, making it easier to hear every instrument and voice. Setting speaker position correctly can also improve the three-dimensional recreation of a stereo image. 9.5 Do I want a combo system or separate components? Combo systems used to be cheap jokes; that's not always true now. Some sound very nice; there are even some made by "audiophile" companies, and they sound even nicer. They've got lots of advantages. They take up less space. The controls tend to be well-integrated, especially if they are remote-controlled. Therefore, they are easy to operate; this can be a major plus if some of the people who'll use it are afraid of, or not very good at, technology. Also easy to set up, and don't leave millions of wires dangling all over everywhere. If you do go for a combo, get a brand name; either an audiophile company, or a good "consumer electronics" company. Brand-X combos are generally overpriced and unpleasant. If possible, buy it where you can listen to it first, such as a "real" hi-fi shop. Mid-range hi-fi shops sell combos, as a way of introducing beginners to quality sound. In most good combos, the speakers are the weak link. If you do go for a combo, you can almost always improve the sound drastically by buying a set of better speakers. Better speakers start in the $100-$200 price range. Some of the best combos come without speakers, forcing you to do this. A good combo with replacement speakers will give you very pleasant music. Sounds good, you say, so why do people bother with components? Well, you can get better sound with a component system -- but usually at the expense of convenience and size. A good component system will normally require a mixture of boxes from different makers to get the best results, so you've got to spend more time listening to things. However, if you listen to your music seriously, then the performance of a component system is the reward for that extra work. Components are harder to set up and operate. However, as noted, you can get better sound. You also get more flexibility. If, for example, you decide you want a better CD player, you just replace the CD player. With a combo system, you've got to replace the whole system. If your component tape deck breaks, you can remove it from the system and take it in for repair or replacement. With a combo, the whole system has to go in for repair or be replaced. When you want to add some new recording medium to your system (laserdisc, VCR, DAT, DCC, MD, ...), if you've got components you just go buy the appropriate box. Many combo systems do not have places (or many places) to attach extra bits, so again you could be looking at replacing the whole thing. With a component system, you can add a turntable; most modern combos can't cope with turntables any more. Do you have a record collection? If you're really not sure, components are the safer bet; if you're going to make a mistake, that's probably the better way to be wrong. But, if you're sure that a combo would be best for your needs, it can be a totally reasonable choice. Now, some people may be tempted by one-maker 'component sets', particularly the modern, miniature ones. They tend to be equivalent to combos. Most use non-standard connections, rather than the normal twin phono plug, so that it's likely you can't swap or add components anyway. Even where they use standard interconnects, they may rely on non-standard interconnections for control purposes. In a few cases, they also rely on sharing power, with a power supply in only one of the boxes and the rest taking low-voltage connections from that. And, no one maker makes the best everything. By default, assume that they will have the same disadvantages (and most of the same advantages) as combos. If it's important for it to work with "standard" components from other makers, be sure to ask before you buy. One-maker 'component sets' are also often of lower quality than true individual components. Component sets are designed for convenience and appearance, rather than sound quality. And, if you're in doubt, go for separate components. 9.6 How can I get better FM radio reception? A. Use a (better) antenna. (See 9.7 and 9.8 below) B. Use a (more) directional antenna. (See 9.7 and 9.8 below) C. Aim your directional antenna. Rhombics are ungainly to move, but Yagis and dipoles are small enough to point right at the station. With the dipole, to tune in a station to the East, run the antenna North-South. With a Yagi, point the individual elements North-South with the smallest element on the East end. 9.7 How good are these compact FM antennas? For receiving, small is ugly. The bigger the antenna (all else equal) the better. Of course, all else is never equal, but these fancy, expensive mini antennas tend to be awful. Some compensate for their small receiving structure with a small antenna signal amplifier. However, the quality of that amplifier is often no better than the quality of the amplifier in your tuner or receiver, so the antenna just gives you a stronger signal, complete with stronger noise. All of that said, some compact FM antennas can work better than a simple dipole in some situations. Some have an internal amplifier, which helps with weak signals if the input stage in your receiver is poor. Some are directional. Some aren't. If possible, be sure that whatever you buy can be returned for a refund if it doesn't work out well for you. 9.8 What makes the best FM radio antenna? Although there is no "best" antenna for everyone, one of the most directional is the "rhombic". Being very directional, this antenna can select one weak station out of many strong ones, or one group of stations originating from a general direction. In addition, very directional antennas are good at reducing multipath interference, a problem which is more severe in cities with tall buildings. This antenna is very long, and made up of four pieces of wire with feedline at one end for antenna connections and a resistor at the other for termination. Rhombics for FM broadcast band use are at least 15 feet (4.5 meters) long, but can be made fairly narrow, less than 3 feet (1 meter) wide. A more narrow antenna will be more directional. A longer antenna will give a stronger signal. Another very directional antenna is the "yagi", which looks just like a common TV antenna. You can even use a common TV antenna as a very good FM antenna. The FM and TV bands are very close together. It has the advantages of being cheap, directional, and easy to rotate. One of the simplest and easiest to make antennas is the folded dipole, made from 300 ohm twin lead. It is approx. 58" long. This antenna is surprisingly good for receiving signals in a moderately strong signal area. Folded dipoles come with many tuners and receivers as a standard accessory. They are also available for approximately $2 at audio and department stores. Whatever antenna you have, you can often get it to work better for specific stations by moving it. In the case of the folded dipole, sometimes it works better vertically, and other times it works best horizontally. Sometimes, you can get that one elusive station to come in perfectly if you bend the two ends of it at funny angles. Don't be afraid to experiment. One warning. As atmospheric conditions change, the best antenna placement may also change. An excellent reference book on antennas is printed by the American Radio Relay League (ARRL). It is called The ARRL Antenna Book. Currently in its 17th edition, it is a 736 page large, illustrated paperback which includes a disk of MS-DOS software. It costs $30 plus s/h. It has fairly complete antenna theory, practical information such as charts, drawings, comparisons, and tips on construction and adjustment. ISBN 0-87259-473-4. The ARRL is founded and chartered as a non-profit organization to better amateur radio, and antennas are a vital part of amateur radio. American Radio Relay League 225 Main Street Newington CT 06111 USA 203-666-1541 Also useful: Practical Antenna Handbook by Joseph J. Carr Tab Books #3270/McGraw Hill - ISBN 0-8306-3270-3 9.9 What about power line conditioners? Each home and each outlet has slightly different power line impedance and power line noise. Each amplifier is affected by power line impedance and power line noise differently. Power line conditioners try to reduce this line noise. Some also change the power line impedance in a way which is supposed to be better. We will leave it to your ears to decide if these devices help the sound of your system enough to justify their expense. 9.10 How can I reduce vibration sensitivity? Some complain that heavy foot falls will cause skipping or more subtle sonic problems with CD players or turntables. If you have these problems, there are a few different things which you can try to reduce the problem. One is to add weight to the rack which holds the equipment. Heavier things move slower. If you can get the motion slow enough, it won't cause sonic or tracking problems. Another solution is to add rubber or elastomer (Sorbothane) cushions under the CD player or turntable. This might make it better, but might also make it worse. Experiment. A third solution is to increase the coupling between the rack and the floor using spikes, which concentrate the weight on a very small area. Another way to increase the coupling between the rack and the floor is to use a plastic adhesive like HoldIt, sold under the UHU trade name in office supply stores. 9.11 What equipment can I buy that is 100% made in the USA? There are many lines of equipment that are carefully hand crafted in the USA. Unfortunately, these systems are usually the high-end ones. Some US companies also make gear in the far east. When in doubt, ask. Some US audio manufacturers are: Adcom (some made in Japan) http://www.adcom.com Audio by Van Alstine Audio Research http://www.audioresearch.com B & K http://www.bkcomp.com California Audio Labs (CAL) http://www.calaudio.com/ Carver (some made in Japan) Jeff Rowland http://www.jeffrowland.com Krell http://www.pcnet.com/~krell Mark Levinson http://www.madrigal.com/MLHP5.htm McCormack McIntosh http://www.mcintoshlabs.com Proceed http://http://www.madrigal.com/PROHP2.htm PS Audio http://www.psaudio.com Spectral http://www.spectralinc.com Sumo (Power amps, preamps, CD transports, D/As) Wadia http://www.wadia.com/index.html 9.11.1 Any information on equipment made in other countries? Thanks to Stephane Tsacas, we know: Australia: Krix Loudspeakers http://www.krix.com.au Metaxas http://www.metaxas.com Canada: | Bryston http://www.bryston.ca Coincident http://www.coincidentspeaker.com Energy Speakers http://www.energy-speakers.com Newform http://www.barint.on.ca/newform Paradigm http://www.paradigm.ca Psb Speakers http://www.psbspeakers.com Sonic Frontiers http://www.sonicfrontiers.com Waveform http://www.waveform.ca Czech Republic: KR Enterprise http://www.kr-enterprise.com Denmark: Bang & Olufsen http://www.bang-olufsen.com Bow Technologies http://www.bowtechnologies.com Bruel & Kjaer http://www.bkhome.com SEK Acoustics http://www.adpointer.net/sekacoustics France: Audax http://www.audax.com Audio Aero http://www.audioaero.com Audioreference http://www.audioreference.com Cabasse http://www.cabasse.com Confluence http://www.a-t.fr/confluence J-M Reynaud http://www.charente-fr.com/jm-reynaud Kora http://www.kora.net/index.html JM Lab http://www.focal.tm.fr Triangle http://www.triangle-fr.com Verdier YBA http://www.phlox-electronique.fr Germany: Lehmann audio http://www.lehmannaudio.de Steinmusic http://www.steinmusic.de Italy: Audio Analog http://www.hi-fi-forum.com/audio_analogue.htm Pathos http://www.hi-fi-forum.com/pathos.htm Korea: Pulsus http://www.pulsustech.com Netherlands: Final http://www.hi-fi-forum.com/final.htm Philips http://www.philips.com New Zealand: Perreaux http://www.perreaux.com Plinius http://www.pliniusaudio.com Norvegia/Norway: Electrocompaniet http://www.electrocompaniet.no Tandberg http://home.sol.no/~johandor Switzerland: Nagra http://www.nagra.com Goldmund http://www.goldmund.com Revox http://www.revox.ch Lenco AMT UK: Audio Note http://www.audionote.co.uk Cambridge Audio http://www.cambridgeaudio.com Newtonia http://www.newtonia1.freeserve.co.uk Quad http://www.quad-hifi.co.uk 9.12 Should I buy "xxx"? Which is better: "yyy" or "zzz"? We can provide facts and opinions (and you get to decide which is which :-), but we can't recommend if, or which way, you should jump, because we don't know what your priorities are. (That won't stop us from trying, though!) For example, if you are considering a used item at a low price vs. a new one at a higher price, one of us might say "go for the new one because of the warranty", when another would say that you can fix it yourself if it breaks. They're both right. This also applies to speakers. One may have very good, flat bass, but only go so low, where the other may go lower, but have less flat frequency response. Which is better? Depends on the buyer. Good speakers are carefully designed to achieve a balance of performance that matches the priorities of the designer. Some designers put much of their budget into appearance. Some designers put their budget into very high efficiency. Others strive for the smallest box which can deliver an acceptable low frequency performance. Do you really want people on the network making that decision for you? 9.13 What is Surround Sound? Pro Logic? In an effort to make movie soundtracks more dramatic and engaging, Dolby Labs created a signal encoding which encodes more than just two channels of audio onto the stereo signal. Many popular receivers and home-theater systems include the required circuitry to decode these signals. These components are referred to as Pro Logic, Dolby Pro Logic, or Surround Sound components. Very few audio recordings contain this encoding, but it is very common with movie soundtracks and some network TV programs. Best Surround Sound reproduction requires five separate speaker systems, but some improvement is claimed from a surround sound receiver and three speakers over two speakers. In its best implementation, surround sound will give a fuller sense of being in the middle of the action. The quality of the image is a function of the recording, the broadcast quality, and the choice of reproduction components. 9.14 What do they mean when they say "It sounds warm?" There are many subjective terms used to describe slight differences in frequency response, distortion, noise, etc. Thanks to Bruce Bartlett and Pro Audio Review, we present this Sound Quality Glossary. This glossary puts a meaning behind many different, common terms. There is no guaranty that people mean the same thing when they use these terms. However, these definitions give insight into why a system sounds the way it does and may also help bridge the communications gap. Airy: Spacious. Open. Instruments sound like they are surrounded by a large reflective space full of air. Good reproduction of high-frequency reflections. High-frequency response extends to 15 or 20 kHz. Bassy: Emphasized low frequencies below about 200 Hz. Blanketed: Weak highs, as if a blanket were put over the speakers. Bloated: Excessive mid-bass around 250 Hz. Poorly damped low frequencies, low-frequency resonances. See tubby. Blurred: Poor transient response. Vague stereo imaging, not focused. Boomy: Excessive bass around 125 Hz. Poorly damped low frequencies or low-frequency resonances. Boxy: Having resonances as if the music were enclosed in a box. Sometimes an emphasis around 250 to 500 Hz. Breathy: Audible breath sounds in woodwinds and reeds such as flute or sax. Good response in the upper-mids or highs. Bright: High-frequency emphasis. Harmonics are strong relative to fundamentals. Chesty: The vocalist sounds like their chest is too big. A bump in the low-frequency response around 125 to 250 Hz. Clear: See Transparent. Colored: Having timbres that are not true to life. Non-flat response, peaks or dips. Crisp: Extended high-frequency response, especially with cymbals. Dark: Opposite of bright. Weak high frequencies. Delicate: High frequencies extending to 15 or 20 kHz without peaks. Depth: A sense of distance (near to far) of different instruments. Detailed: Easy to hear tiny details in the music; articulate. Adequate high-frequency response, sharp transient response. Dull: See dark. Edgy: Too much high frequencies. Trebly. Harmonics are too strong relative to the fundamentals. Distorted, having unwanted harmonics that add an edge or raspiness. Fat: See Full and Warm. Or, spatially diffuse - a sound is panned to one channel, delayed, and then the delayed sound is panned to the other channel. Or, slightly distorted with analog tape distortion or tube distortion. Full: Strong fundamentals relative to harmonics. Good low-frequency response, not necessarily extended, but with adequate level around 100 to 300 Hz. Male voices are full around 125 Hz; female voices and violins are full around 250 Hz; sax is full around 250 to 400 Hz. Opposite of thin. Gentle: Opposite of edgy. The harmonics - highs and upper mids - are not exaggerated, or may even be weak. Grainy: The music sounds like it is segmented into little grains, rather than flowing in one continuous piece. Not liquid or fluid. Suffering from harmonic or I.M. distortion. Some early A/D converters sounded grainy, as do current ones of inferior design. Powdery is finer than grainy. Grungy: Lots of harmonic or I.M. distortion. Hard: Too much upper midrange, usually around 3 kHz. Or, good transient response, as if the sound is hitting you hard. Harsh: Too much upper midrange. Peaks in the frequency response between 2 and 6 kHz. Or, excessive phase shift in a digital recorder's lowpass filter. Honky: Like cupping your hands around your mouth. A bump in the response around 500 to 700 Hz. Mellow: Reduced high frequencies, not edgy. Muddy: Not clear. Weak harmonics, smeared time response, I.M. distortion. Muffled: Sounds like it is covered with a blanket. Weak highs or weak upper mids. Nasal: Honky, a bump in the response around 600 Hz. Piercing: Strident, hard on the ears, screechy. Having sharp, narrow peaks in the response around 3 to 10 kHz. Presence: A sense that the instrument in present in the listening room. Synonyms are edge, punch, detail, closeness and clarity. Adequate or emphasized response around 5 kHz for most instruments, or around 2 to 5 kHz for kick drum and bass. Puffy: A bump in the response around 500 Hz. Punchy: Good reproduction of dynamics. Good transient response, with strong impact. Sometimes a bump around 5 kHz or 200 Hz. Rich: See Full. Also, having euphonic distortion made of even-order harmonics. Round: High-frequency rolloff or dip. Not edgy. Sibilant. "Essy" Exaggerated "s" and "sh" sounds in singing, caused by a rise in the response around 6 to 10 kHz. Sizzly: See Sibilant. Also, too much highs on cymbals. Smeared: Lacking detail. Poor transient response, too much leakage between microphones. Poorly focused images. Smooth: Easy on the ears, not harsh. Flat frequency response, especially in the midrange. Lack of peaks and dips in the response. Spacious: Conveying a sense of space, ambiance, or room around the instruments. Stereo reverb. Early reflections. Steely: Emphasized upper mids around 3 to 6 kHz. Peaky, nonflat high-frequency response. See Harsh, Edgy. Strident: See Harsh, Edgy. Sweet: Not strident or piercing. Delicate. Flat high-frequency response, low distortion. Lack of peaks in the response. Highs are extended to 15 or 20 kHz, but they are not bumped up. Often used when referring to cymbals, percussion, strings, and sibilant sounds. Thin: Fundamentals are weak relative to harmonics. Tight: Good low-frequency transient response and detail. Tinny, Telephone-like: Narrowband, weak lows, peaky mids. The music sounds like it is coming through a telephone or tin can. Transparent: Easy to hear into the music, detailed, clear, not muddy. Wide flat frequency response, sharp time response, very low distortion and noise. Tubby: Having low-frequency resonances as if you're singing in a bathtub. See bloated. Veiled: Like a silk veil is over the speakers. Slight noise or distortion or slightly weak high frequencies. Not transparent. Warm: Good bass, adequate low frequencies, adequate fundamentals relative to harmonics. Not thin. Also excessive bass or midbass. Also, pleasantly spacious, with adequate reverberation at low frequencies. Also see Rich, Round. Warm highs means sweet highs. Weighty: Good low-frequency response below about 50 Hz. Suggesting an object of great weight or power, like a diesel locomotive. COPYRIGHT NOTICE The information contained here is collectively copyrighted by the authors. The right to reproduce this is hereby given, provided it is copied intact, with the text of sections 1 through 8, inclusive. However, the authors explicitly prohibit selling this document, any of its parts, or any document which contains parts of this document. -- Bob Neidorff; Texas Instruments | Internet: neidorff@ti.com 50 Phillippe Cote St | Voice : (US) 603-222-8541 Manchester, NH 03101 USA Note: Texas Instruments has openings for Analog and Mixed Signal Design Engineers in Manchester, New Hampshire. If interested, please send resume in confidence to address above.