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Path: bloom-beacon.mit.edu!hookup!europa.eng.gtefsd.com!howland.reston.ans.net!vixen.cso.uiuc.edu!uxa.cso.uiuc.edu!jsc52962 From: stealth@uiuc.edu (Jeffrey S. Curtis) Newsgroups: rec.audio.car,rec.answers,news.answers Subject: rec.audio.car FAQ (part 3/3) Supersedes: <rac-faq-p3-052805Apr61994@uxa.cso.uiuc.edu> Followup-To: rec.audio.car Date: 6 Apr 1994 05:47:18 GMT Organization: University of Illinois at Urbana Lines: 413 Approved: news-answers-request@mit.edu Distribution: world Expires: 6 May 1994 05:00:00 UT Message-ID: <rac-faq-p3-054711Apr61994@uxa.cso.uiuc.edu> Reply-To: stealth@uiuc.edu (Jeffrey S. Curtis) NNTP-Posting-Host: uxa.cso.uiuc.edu Summary: This article describes the answers to the frequently asked questions on the rec.audio.car newsgroup. This article is posted once per month. Originator: jsc52962@uxa.cso.uiuc.edu Xref: bloom-beacon.mit.edu rec.audio.car:14905 rec.answers:4774 news.answers:17722 Archive-name: car-audio/part3 Rec-audio-car-archive-name: FAQ/part3 Version: 2.1 Last-modified: 5 Apr 94 5 Installation This section describes how to do what you want once you know what it is you want to do. 5.1 Where should I buy the components I want? [JSC] Most of the time, you will either buy from a local dealer, or from a mail-order house. Buying from a local dealer can be good because you get to deal directly with a person: you can show them your car, ask specific questions, haggle prices, get quick service when there are problems, get deals on installation, etc. But there can also be advantages to buying mail-order: generally cheaper prices, sometimes better service, etc. In either case, you should always check prices before you buy, inquire about warranty service, and ask about trial periods. 5.2 What mail-order companies are out there? [JSC,JM,MM] Crutchfield 800/955-3000 1 Crutchfield Park Charlottesville, VA 22906 USA Advantages: great customer service; generally knowledgeable sales and tech support personnel; custom mounting kits, wiring harnesses, etc. free of charge. Disadvantages: limited product line; generally higher prices than local shops. J.C. Whitney 312/???-???? ? Chicago, IL 6060? USA Advantages: 10kW amps for $19.99 Disadvantages: 10kW amps that really only put out 1mW and break after first 10 minutes of use. Parts Express 800/338-0531 340 E. First St. Dayton, OH 45402 USA Advantages: large selection of electronics supplies at respectable prices. Showroom prices said to be better than catalog prices. Disadvantages: also carries some of the same quality-level components as J.C. Whitney. Classic Research/Z-Box 602/571-0171 5070 E. 22nd St. Tucson, AZ 85711 Advantages: creates custom door panels with car audio in mind. Disadvantages: only services expensive sports and luxury cars. MCM Electronics 800/543-4330 650 Congress Park Drive Centerville, OH 45459-4072 Advantages: sells lots of decently priced trinkets (fuses, fuse holders, wire, etc.) and has excellent service and available technical support. Disadvantages: ? 5.3 What tools should I have in order to do a good installation? [JSC] Electrical tape - lots of it. Make sure you get some that can withstand extreme temperature ranges. Wire cutters/strippers and crimpers. Get a big pair with stripper holes precut for individual wire sizes. Angled screwdrivers. Makes taking dash and rear deck speakers out a lot easier. Multiple size screwdrivers, both flathead and Phillips. Magnetic screwdrivers can be a big help when trying to get screws into (or out of) tight spaces. Various wrenches, pliers, and socket sets, depending on your vehicle. Metal drill and saw. You'll need these if you need to modify your vehicle for new speaker cutouts or to accommodate a new head unit. Hot glue gun. Good for putting carpeting or door panel trim back in place after modifications. Razor knife. Helps for detailed modifications of door panels or carpeting, especially when installing new speakers. Wire. Shrink wrap or flex tubing. Good for protecting wire, especially in the engine compartment. Multimeter. Helps to diagnose installations. Extra hardware (screws, nuts, bolts, connectors, etc.). Fuse puller and extra fuses. Wire ties. Helps to tuck wire away in otherwise exposed areas. Small light source. A flashlight will do - you just want something that you can poke around the innards of your car with. Tape measure. 5.4 Where should I mount my speakers? 5.5 What is "rear fill", and how do I effectively use it? [HK,JSC] Rear fill refers to the presence of depth and ambience in music. A properly designed system using two channels will reproduce original rear fill on the source without rear high frequency drivers. Since recordings are made in two channels, that is all you will need to reproduce it. What is captured at the recording session (coincident pair mics, Blumlein mic patterns, etc.) by a two channel mic array will capture the so called "rear fill" or ambience. Many of the winning IASCA vehicles have no rear high frequency drivers. Also a lot of this has to do with system tuning. If rear high frequency drivers are added, however, the power level of the rear fill speakers should be lower than that of the front speakers, or else you will lose your front-primary staging, which is not what you want (when was the last time you went to a concert and stood backwards?). The proper amount of amplification for rear fill speakers is the point where you can just barely detect their presence while sitting in the front seat. Separates are not a requirement for rear fill; in fact, you may be better of with a pair of coaxial speakers, as separates may throw off your staging. 5.6 How do I set the gains on my amp? [JSC] The best way to do this is with a test tone and an oscilloscope. Since most people have neither item, the following will work approximately as well. 1) Disconnect all signal inputs to the amp 2) Turn all sensitivity adjustments as low as possible 3) Turn head unit on to around 90% volume (not 100% or else you'll have head unit distortion in there - unless you've got a good head unit) with some music with which you're familiar, and with EQ controls set to normal listening positions 4) Plug in one channel's input to the amp 5) Slowly turn that channel's gain up until you just start to notice distortion on the output 6) Turn it down just a wee little bit 7) Disconnect current input 8) Repeat steps 4-7 with each input on your amp 9) Turn off head unit 10) Plug in all amp inputs, and you're done If by some chance you do have an oscilloscope (and preferably a test disc), you do essentially the same thing as above, except that you stop turning the gains up when you see clipping on the outputs of the amplifier. Note that if you are paralleling multiple speakers on a single amp output, you need to set the gains with all of the speakers in place, since they will be affecting the power and distortion characteristics of the channel as a whole. 5.7 How do I select proper crossover points and slopes? 5.8 How do I flatten my system's frequency response curve? 6 Competition This section describes the competition branch of the car audio world - what it is, and how to get involved. 6.1 What is IASCA, and how do I get involved? [JSC,HK] IASCA is the International Auto Sound Challenge Association, a sanctioning body for car audio competitions held throughout the world. Competitors earn points at each competition, and those that perform the best each year can advance to the finals. Prizes (trophies, ribbons, and sometimes cash) are usually given out to the top competitors in each class at every competition. There are registration forms for IASCA in every issue of Auto Sound and Security (see 7.1). 6.2 What is USAC, and how do I get involved? [HK] USAC is another sanctioning body, similar to IASCA. However, USAC places greater emphasis on SPL measurements than IASCA. 6.3 What are the competitions like? [HK,CD] [HK writes:] They are much like loud car shows: a lot of cars parked with their hoods/doors/trunks open showing their audio systems. There are two types of judging styles: 1) drive through - where competitors drive their own vehicles to judging stations to be judged, and 2) walk-arounds - where the teams of judges will walk around the event site and judge vehicles that fit within their judging assignments. Typically SPL is done first with the mic stand in the driver's seat and the competitor in the passenger side adjusting only the volume. Hearing protection must be worn. After SPL measurements are completed, RTA measurements are performed by playing pink noise. When the volume level is within the specified "window" around 90db-110db, the RTA judge will signal you out, and at that point you must exit the vehicle for the actual scoring measurements. The next area for judging should be sound quality where two judges will sit in your car and judge the sound quality based on IASCA's reference CD/tape. The next area is installation judging where the competitor has 5 minutes to explain and show the installation of his/her vehicle. It is very useful to have a picture book/album of photos of the installation that may not be visible to prove that items not visible do exist. When that is completed, the competitor can park the vehicle and show spectators the vehicle. These procedures may differ from show to show, and at the regional/final levels they are very strict in what can and can't be done, e.g. a judge will make sure no adjustments are made after SPL until after sound quality judging is over, ear protection, etc. [CD writes:] Most involve a lot of waiting around. Thus, they are perfect for meeting other people interested in car audio, and seeing some installations which may give you some ideas. They're also perfect for listening to some cars that sound a lot better and a lot worse than your own. In IASCA competition, the cars are judged on: Sound Pressure Level (30pts) Frequency Response (40pts) Staging (40pts) Stereo Image (40pts) Frequency Separation/Clarity (40pts) Sound Linearity (20pts) Absence of Noise (40pts) Ergonomics (20pts) Wiring/Electrical System Cosmetics and Integrity (35pts) Cosmetic Integration Consistency (40pts) Component Installation Integrity (55pts) General Creativity (20pts) Attention to Detail (15pts) 6.4 Should I compete? [CD] You should compete if: a) You have an ok sounding stereo b) You have an ok installation (i.e. no amps/changers sliding around in the trunk) c) You'd like some pros to comment on your system d) Your feelings won't get hurt if you don't get first e) You've been to a contest and talked to competitors about it f) You've read the IASCA rulebook g) You've listened to the IASCA Test Disc in your car, and understand what the sound quality judges are listening for You can compete even if you don't do all of the above, but the recommendations will help you understand and gain the most from competing. 6.5 What class am I in? [HK,JSC] [HK,JSC write:] There are three classes: novice, amateur, and pro. The novice class is intended to be an unintimidating level where beginners can start out; however, a competitor may only be in the novice class for one year, at which time he is automatically moved to the amateur class. Most competitors stay in the amateur class indefinitely, unless they become affiliated with a car audio shop or manufacturer, at which point they are moved into the pro class. [CD writes:] Are you or were you employed by a car audio manufacturer or dealer? Yes: You compete in pro No: Is this your first year of competing? Yes: You compete in novice for the first year No: You compete in amateur Note that modifying your amplifiers, buying your equipment below retail, or being sponsored by a manufacturer or dealer will get you kicked into pro. Also note that any home built active gear in the signal path (e.g. custom built equalizers, crossovers, or noise gates) will get you kicked out of novice. Once you know what group you are, you next need to know what power category you are in. Add up the 4-ohm non-bridged rating of all your amplifiers, including your head unit if your head unit is powering speakers (rather than exclusively feeding amplifiers). Then, find the category you fit into: Novice: 1-50 51-100 101-250 251-500 501+ Amateur: 1-50 51-100 101-250 251-500 501-1000 1000+ Pro: 1-100 101-250 251-500 501-1000 1001+ Thus, if you had a Rockford Punch 40 (20Wx2) and a Punch 60 (30Wx2), with a head unit that put out 6Wx2 (powering, perhaps, a center channel) you're in the 101-250 class. It does not matter if your amps are bridged down to .002 ohms; it's only the 4ohm rating that counts. If you no longer used your head unit to power speakers, you would be in the 51-100 class (or the 1-100 class if you were a pro). Competition is usually most viscious in the 101-250 and 250-500 categories at typical contests. 7 Literature This section describes various literature which you can read to brush up on your car audio skills, or to keep current, or to see other people's installations, or whatever else you'd like. 7.1 What magazines are good for car audio enthusiasts? [JSC,MI,NML] Car Audio and Electronics $21.95/year P.O. Box 50267 (12 issues) Boulder, CO 80321-0267 800/759-9557 Car Stereo Review $17.94/year P.O. Box 57316 (6 issues) Boulder, CO 80323-7316 303/447-9330 Auto Sound and Security $28.95/year P.O. Box 70015 (12 issues) Anaheim, CA 92825-0015 714/572-2255 Car Hi-Fi #23.60/year Freepost (8 issues) TK660 081 943 5943 Leicester KE87 4AW 7.2 Are there any newsletters I can read? [MO,HK] Autosound 2000 Tech Briefs $35.00/year 2563 Eric Lane, Ste D (6 issues) Burlington, NC 27215 800/795-1830 7.3 What books can I read? [JSC,JW,TT] Loudspeaker Design Cookbook by Vance Dickason Published by Audio Amateur ISBN 0-9624191-7-6 $25-$30 Designing Speaker Enclosures by David Weems Published by ? ISBN ? $??.?? Killer Car Stereo on a Budget by Daniel L. Ferguson Published by Audio Amateur Press ISBN 0-9624191-0-9 $19.95 8 Credits [JSC] Jeffrey S. Curtis (stealth@uiuc.edu) [JLD] Jason Lee Davis (jdavis@wizard.etsu.edu) [MI] Matt Ion (matt@ship.net) [JW] Jerry Williamson (jerry.williamson@amd.com) [CD] Cal Demaine (demaine@ee.ualberta.ca) [MO] Mark Obsniuk (Mark_Obsniuk@sfu.ca) [HK] Harry Kimura (harry@alsys.com) [RDP] Dick Pierce (DPierce@world.std.com) [BG] Brian Gentry (brian@eel.ufl.edu) [JM] Jeff Meyers (meyers@tellabs.com) [MH] Marvin Herbold (11mherbold@gallua.gallaudet.edu) [TT] Trevor Tompkins (tt17+@andrew.cmu.edu) [MM] Matthew E. Meiser (meiserme@nextwork.rose-hulman.edu) [NML] N. M. Lines (csznml@scs.leeds.ac.uk) -- Jeffrey S. Curtis - stealth@uiuc.edu <> "You say these days are made of rust: Network Coordinator - UI Housing Div <> ``Counted out! Counted out in loss!'' Proton < Dodge > Pioneer <> I've got plans to prove them wrong.." Phase Linear < Stealth > StreetWires <> -- INXS _Full Moon Dirty Hearts_ 1993