Head units_ processors_ and amplifiers

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					Installing&OEM Integration

How to
Tweak and Tune
After an audio system is designed, and after the components are
installed, the components should be tweaked and tuned for maximum
performance. But before you start twisting knobs, make sure you know
what sound you want to end up with.

     By William Burton




                                                  Each component in a system has characteristics that need to be considered when tuning,


H
          ead units, processors, and amplifiers
          have controls that can have huge        like amplifier gains, speaker roll-off and distortion levels. But keep in mind that the
          effects on sound quality and SPL        ultimate “ear” for the perfect system will eventually be your customer’s.
performance. You can have an excellent
system design, excellent components, and              Many systems can be tuned for              Setting Levels
excellent installation, and awful performance,    maximum (undistorted) signal level, optimal        Whether you use an oscilloscope or
if the controls are not set correctly. Bad        filtering, and preferred equalization (tonal   your ears, levels (gains) should be set
tuning can make customers very unhappy.           balance). Sophisticated systems can also be    properly to minimize distortion and noise.
However, if you tune things just right,           tuned by controlling the arrival times of      Levels that are too low will avoid
customers will be very happy.                     sounds coming from different speakers.         distortion, but will cause noise. Levels that

80    MOBILE ELECTRONICS O c t o b e r 2 0 0 5
are too high will minimize noise, but can
cause distortion.
    It’s especially important to set levels        Tuned for What?
correctly for SQ competition. Noise and
distortion add up from each component to           Musical instruments can be tuned a number of different ways. Audio systems
the next, so even if each component has an         can also be tuned to achieve different goals, such as:
inaudible 0.5 percent THD, that can quickly        1. Accuracy: low distortion, tonal accuracy (spectral balance), accurate image
add up to an audible 2.0 percent, 2.5              placement, accurate image focus, accurate ambience. Headphone sound.
percent, or more.                                  Imagine the sounds recorded on the medium going directly into your brain.
    Level controls on head units are often         2. Realism: low distortion, tonal realism, realistic image placement, realistic
called “volume” controls (they are not part        image focus, realistic ambience. For realism, different people recommend
of this process); on other components, they        different frequency-response curves, but I think Tom Nousaine (speaker tester
are often called “gain” controls. Setting          for Road Gear magazine and associate of DLC Design) has the right idea: aim for
levels, which is done from the front of the        a curve that is loudest in the bass and slopes down at a rate of two or three dB
system to the back, is often called “setting       per octave. If you want light bass, aim for two dB; if you want louder bass, aim
the gain structure.”                               for three. If the system can do it and it’s appropriate, you could kick up the bass
    Todd Ramsey, consultant at the Ramsey          under 50 Hz or so without ruining the natural sound of male vocals, and adding
Consultant Group, explains the process like        some real loud low bass. Wehmeyer at Harman prefers “ruler flat from 150 to
this: “It’s best done using test tones—or a        20,000 Hz with a bump in the bass. The slope from high to low makes cars
CD—with a range from 40 Hz to five or six          sound dull, thick, and lifeless. It’s a matter of preference.”
kHz at zero dBFS, test-point RCA, load             3. Personal (or customer) satisfaction: tuning to taste (not accurate, not
resistors for the amplifier, and an                realistic).
oscilloscope. It’s all about locating the          4. Winning competitions such as those put on by dB Drag Racing, IASCA,
maximum undistorted output of each                 MECA, USACi, and others: Levels and filtering would probably be set the same
component and making sure it does not              for all four goals, but EQ would definitely be set differently for all four. Delays
overload the next component in the signal          would probably be set similarly for accuracy and realism, SQ competitions, and
chain. The scope helps you see that                perhaps for personal taste as well, but not for SPL.
distortion.”
                                                  like stuffing a basketball into a pigeon—           frequencies pass through at the same level
Setting Filtering                                 neither will survive. Any speaker can be            and reduce the level (attenuate) lower
     You know that there are three types of       killed by a combination of inappropriate            frequencies. These filters are low-cut filters
filters (low pass, high pass, and bandpass),      frequencies, excessively high levels, and too       because they cut lows.
but let’s review why audio components             much heat for too darn long. If you set                 When setting filters, it is important to
have filters in the first place.                  filters correctly, you will minimize chances        distinguish between cut-off frequencies and
     Most importantly, filters protect            of dead speakers because they will be               crossover frequencies. A cut-off frequency
                              speakers.           protected from frequencies they can’t               is the frequency at which output is down
                                Pumping lots of   handle, but they can still get high levels for      by 3 dB (you can see this on an RTA). A
                                 bass to a        too long in temperatures that are too hot.          crossover frequency is the frequency at
                                   tweeter is          Not only do filters protect speakers, but      which two outputs are equal in amplitude.
                                                  they keep them from sounding bad. Even if           Many people confuse the two; don’t be
                                                  a pigeon could swallow a basketball, it is          one of them.
                                                  not going to sing very sweetly. It’s dumb to            When first using filters to set cutoff
                                                  ask a big dog to sing high notes; give the          points, you can follow recommendations
                                                  low notes to woofers, and the really low            from the manufacturer. For precise setting,
                                                  notes to subwoofers.                                use a tool like the Helix X-just. You can also
                                                       OK, let’s look at the three types of filters   use your ears, or the ears of an experienced
                                                  that you’ll find in equalizers, crossovers,         tweaker. You should also be aware of the
                                                  and other processors, and in amplifiers:            frequency response of each speaker. You
You can                                                  1. Low-pass filters: these let lower         may be able to use acoustic roll-offs in
adjust filters by                                      frequencies pass through at the same level     addition to electronic roll-offs, but speakers
ear, or use an                                           and reduce the level (attenuate) higher      should be selected for their sound in their
electronic aid                                             frequencies. These filters are high-cut    passband, not for how they roll off.
which sends a tone                                           filters because they cut highs.
through an amplifier                                             2. Bandpass filters: these allow a   Setting Equalization
and displays the cutoff                                   band of frequencies to pass through at         Different people like to hear different
frequency as you make                             the same level, cutting both lows and highs.        frequency-response curves just as they like
adjustments to the amp.                                3. High-pass filters: these let higher         to see different curves on a human body.

                                                                                                               O c t o b e r 2 0 0 5 MOBILE ELECTRONICS   81
                                                                                                             Installing&OEM Integration
        MITO...your source for                                                                               The curve on an RTA screen shows you

      safety mirrors inside & out!                                                                           what the FR curve is. See the sidebar on
                                                                                                             page 81 for some FR-curve options. As
                                                                                                             Andy Wehmeyer, Harman’s product
                                                                                                             marketing manager, reminded me, “Use all
                                                                                                             the tools at your disposal.”
                                                                                                                 It’s easiest to tune to your own taste; it’s
                                                                                                             like cooking for yourself. Play with EQ until
                                                          Alerts Others of                                   you hear what you like (just like adding
                                                         Your Turn Intentions                                spices to a soup). If you are tuning for
                                                       MUTH Turn Signal® Mirror
                                                                                                             someone else’s preference, play with an
                                                                                                             equalizer until they hear what they like.
                                                                                                                 As for competition curves, these are
                                                                                                             tough. I suggest trying flat and sloped
                                                                                                             curves for SQ. See what scores best. For
                                                                                                             SPL, use your RTA and your SPL meter to
                                                                                                             see how you can focus the sonic energy of
                                                                                                             the right frequency in the right place.
                                                                                 Eliminates                      Three tools are necessary to set EQ
                                                                            Dangerous Glare                  correctly: One real-time analyzer and two
     Call 1.800.433.6486                                                          Gentex Automatic-Dimming
                                                                                           Rearview Mirror
                                                                                                             ears. This procedure works for most
                                                                                                             systems:
                                                                                                                1. Set up the RTA.
     54905 County Road 17 • Elkhart, Indiana 46516                        www .mitocorp .com                    2. Play pink noise (a mixture of
                                                                                                                     frequencies with equal energy per
                                                                                                                     octave).
                                            Rapid Response #122
                                                                                                                3. Swim the mike (move it around in the
                                                                                                                     area of the listener’s head or heads).
                                                                                                                4. Hit the averaging button (which will
                                                                                                                     take many measurements so they can
                                                                                                                     be averaged) as you swim the mike.
                                                                                                                5. Look at the curve.
                                                                                                                6. Set bass, treble, or both to get the
                                                                                                                     curve to look more like you want it to
                                                                                                                     look.
                                                                                                                7. Repeat steps 2 through 6.
                                                                                                                8. When you have done your best with
                                                                                                                     bass and treble, repeat the steps, but,
                                                                                                                     instead of using bass and treble
                                                                                                                     controls, use available filters to fix
                                                                                                                     any bumps or dips. This is where you
                                                                                                                     may have cut-off points and
                                                                                                                     crossover points that are different.
                                                                                                                9. Now that you have used tone
                                                                                                                     controls and filters to do their best,
                                                                                                                     go to EQ controls on your amplifiers.
                                                                                                                10. Finally, use the equalizer to equalize.
                                                                                                                     Focus on cutting more than boosting.
                                                                                                                     Excessive boosting will cause
                                                                                                                     distortion.
                                                                                                                11. After you have used all the controls
                                                                                                                     at your disposal to get the curve you
                                                                                                                     want on your RTA, then start to
                                                                                                                     listen. It’s easiest to tune for what
                                                                                                                     you would want. If you are tuning for
                                                                                                                     a customer, the customer should be
                                                                                                                     there.
                                            Rapid Response #112
82   MOBILE ELECTRONICS O c t o b e r 2 0 0 5
RTAs (Real-Time Analyzers) show you a curve which represents the frequency response
of a system at the point where the microphone is located.

Setting Delays                                  center, and right speakers so those signals
    Signals can be delayed to improve           arrive at the listener at the same time. This
sound quality and SPL.                          can be a really good thing. In fact, one of
    Sophisticated systems let you delay         the best vehicles I’ve ever heard, Chris
signals going to all the speakers in the        Lewis’ Chevy Impala, uses Sony
system. This has been called Time-              components to delay signals going to
Alignment, a term trademarked by E. M.          speakers closer to the driver’s head so those
Long Associates, but please understand          signals arrive at the same time as signals
that the alignment that happens is arrival-     from speakers on the right side of the car.
time alignment, delaying signals going to       Images are sharp, clear, and well placed.
one or more speakers so those signals               However, as Wehmeyer points out,
arrive at a listener’s head at the same time.   making arrival times better for a listener in
This is also called “time delay,” but you       one seat will make the sound worse for
cannot delay time; you can delay signals.       other listeners in other seats.
    Should systems be set up so the signals         For SPL competition, you want to delay
from all speakers arrive at the listener’s      signals so the maximum pressure variation
head at the same time? No. And it could         happens where the microphone is.
result in horrible sound, or in a system that
sounds like headphones. Signals coming          The Importance of Tweaking
from the ambience speakers in the rear of           The most important variable in both SQ
the vehicle should arrive at the listener       and SPL is speaker placement, but
much later than the signals from the other      tweaking and tuning can made a huge
speakers. How much later? It depends on         difference in the performance of any audio
how much ambience is desired, how big a         system. I bet that I can tweak any system
concert hall you want to simulate. The          and make it sound hugely different, to a
digital delay unit in my Toyota RAV4 can be     much greater degree than changing any
set to 800 milliseconds to simulate a big       component, even speakers.
space.                                              With the right tools—such as an
    OK, so delaying the signals going to        oscilloscope, an RTA, and a Helix X-just—
your ambience speakers increases                some people can tweak systems to sound
ambience; what else can you do with             good. However, it takes exceptional skills,
delay?                                          ears, and brainpower to tweak a system to
    You can delay signals going to left,        sound real, or really loud.
                                                                                                    Rapid Response #269
                                                                                                O c t o b e r 2 0 0 5 MOBILE ELECTRONICS   83
 OEM Integration
Tech Tips
  All-in-One Spot for 2006 Mustang
  Scott West from CDS Solutions in Fontana, Calif., posted this tech tip about installing security on
  the 2005 and 2006 Mustang. “We get all the wires in one place,” he wrote. Lower the fuse panel
  by removing one 10mm bolt, and turn the unit over. You’ll see six plugs, top to bottom:



Plug 1 (top-most, gray in color):                     Green/Yellow: Door trigger (-)
Plug 2:                                               Dk. Blue/Green: Door Unlock (-)
                                                      Note: Depending on trim level, this wire may unlock all doors on a single pulse, or unlock only the
                                                      driver door on one pulse, and all doors on the second pulse. Also, an extended pulse will roll
                                                      windows down if the vehicle performs this function from the key cylinder.
                                                      White/Purple: Door Lock (-) / OEM Alarm Arm (if equipped)
                                                      White/Yellow: Trunk pin (+)
Plug 5 (five-pin):                                    Red/Orange: Passenger unlock motor wire
                                                      Yellow: Driver unlock motor wire


Plug 6 (large plug on bottom):                        Lt. Blue: Lock motor wire
                                                      Flip the fuse box over. Locate the front harness that meets the
                                                      harness from the floor and goes up into the dash.
                                                      Dk. Blue: Horn (-)
                                                      Black/Green: Parking lights (-)
                                                      Lt. Green/Purple (16ga.): 12V (+) Constant
                                                      White/Yellow (16ga.): 12V (+) Ignition
Harness to the rear:                                  Orange / Pink: Trunk release (+)




                                                                                         What’s Shipping
      Avoiding Grand Prix Remote                                                         This Month
      Start Issues
        Michael Betts, a frequent contributor to installercentral.com                  Metra (800) 221-0932; metraonline.com
                                                                                       99-7869 – Installation kit for 2005 Honda Odyssey; ISO mount
        answered a concern about a 2005 Pontiac Grand Prix not
                                                                                       99-7870 – Installation kit for 2005 Honda Ridgeline; ISO mount
        starting with the key after a remote-start system was
                                                                                       99-8901 – Installation kit for 2005 Subaru Legacy / Outback
        installed. Surmising that the system was seeing both keys                      (excluding Outback Sport). Retains climate controls, hazard button;
        and therefore engaging its theft deterrent system, he                          ISO mount, Silver
        suggests using a relay to disable the bypass when a key is                     99-2006 / 99-2006G – Installation kit for 2003-2005 Cadillac CTS
                                                                                       and 2004-2005 Cadillac SRX; ISO mount. 99-2006G available in
        inserted. In the diagram, the key sense wire energizes the
                                                                                       Black or Gray
        relay, disconnecting the bypass from the “Ground When
        Started” wire from the remote starter.
                                                                                       Peripheral Electronics (727) 572-9255;
                                               Bypass                                  peripheralelectronics.com
                                                                                       PNVI Video Interface – provides two video sources for factory
                                     87
                                                                                       screens – harnesses for Acura, Audi, BMW, GM, Honda, Infiniti,
                                86               85                                    Land Rover, Nissan, Toyota and VW
                     12v+            87a                  Key Sense (-)
                                                                                       Scosche (800) 363-4490; scosche.com
                                          30                                           TA2052B – Installation kit for 2005-up Toyota Tacoma; single-DIN,
                                                                                       Silver
                                                                                       TA2052BLKB – same as above in Black
                               Ground When
                                  Started                                              TA2053B – same vehicle, ISO double-DIN, Silver




                                           Got Tech tips? Got Questions?
                            Post them on the Vehicle Information forum at installercentral.com!
                                                                                                                        O c t o b e r 2 0 0 5 MOBILE ELECTRONICS   85
OEM Integration
Product Awareness
CleanSweep: Simple Solution for Superior Sound
                                                        Jl Audio’s CleanSweep is designed to give installers the ability to work on vehicles
                                                           in which the head unit cannot be replaced. It provides a flat frequency response
                                                             to supply to aftermarket speakers and amps, resulting in optimal conditions for
                                                               musical reproduction. The installation process is straightforward: run four
                                                                 speaker-level inputs into the CleanSweep. Set the head unit volume to
                                                                   between 50 and 75 percent of its capability and play the supplied test
                                                                    CD. As it plays a test tone, press the Calibrate button on the
                                                                      CleanSweep. After about 20 seconds, the four LEDs on the unit
                                                                        should turn green, indicating that it has equalized each of the four
                                                                         channels. To add a subwoofer, you can run the outputs into an
                                                                         amp or crossover that creates a subwoofer output.


                                                                       Summing Outputs
                                                                    Since the CleanSweep processes four-in / four-out, any summing of
                                                                   outputs needs to be done before the signal reaches it. For instance, if
                                                                   you have an application where the factory amp has separate
                                                                   midrange and tweeter line-level outputs for the same channel, you’ll
 need to run these into a line output converter (LOC). Then, connect RCA cables to its output, cut off the ends, splice them together and
 run them into the CleanSweep.



 Better Sound, Fewer Features
 It’s very important to make sure your customer knows what to expect
 from the installation of the CleanSweep. Since it provides four
 channels of full-range signal, any equalization or filtering done at the
 factory amp or before (at the time of CleanSweep calibration) is
 eliminated. Also, any additional features using a center channel or 5.1-
 channel playback, such as DVD-Audio or Dolby ProLogic II, are
 converted to conventional front / rear stereo.
 One more consideration: because the Cleansweep equalizes the OEM
 signals at a set volume, using the factory volume control will result in a
 slight a variance from the flat signal. JL Audio recommends using the
 volume knob that comes with the Cleansweep, especially if the
 customer is utilizing the CleanSweep’s auxiliary input, since the knob
 also switches between sources. However, if your customer’s not keen to
 having a different volume control, and they’re not using the aux input, simply set the control at a decent volume level and bury it.




 TekHeadz Notes
 Here are some “heads-up” type posts that top installers have added to the Vehicle
 Information forum on installercentral.com:
 Found at the Foot: On the 2005 BMW 7-series sedan, you’ll find an ACC wire in a
 not-so-obvious place – the brake switch. – MarkJ19 – Installer Mailing List (IML)

 Control the Keyless: On the 2005 Kia Sportage, you can find the following wires in the driver kick panel: Factory Arm –
 Brown; Factory Disarm – Pink. Both wires require a negative pulse. – John, JDK Auto Sound & Security

 Take It All Out: On the 2005 Nissan Altima, the speakers are all two Ohms. Therefore, if you’re changing the head unit,
 you may also want to replace the speakers. – Michael Betts


86   MOBILE ELECTRONICS O c t o b e r 2 0 0 5
Tech Info
                                                                    2006 Chevy Cobalt
                                                                   About the Vehicle
                                                                   Data Bus Architecture: GM LAN

                                                                   Entertainment Equipment / Options:
                                                                   Stereo / CD / 4 speakers
                                                                   Stereo / CD / MP3 / 4 speakers
                                                                   Pioneer Premium system (Amplifier / Subwoofer / Tweeters)
                                                                   Steering Wheel Controls (LT 2LT and above)

                                                                   Security Equipment / Options:
                                                                   PASS-Key III Plus
                                                                   Keyless Entry (all except LS)
Integration Options
 Kits: Scosche – GM1593B; American Int’l – GM-K350;
 Best Kits – BKGMK350; Metra 99-3302                                 I n t e r i o r                         Hood/Trunk
 Harnesses: Scosche – GMLAN; American Int’l – GWH-
 404; Best Kits – BHA2103T; Metra – 70-2103
 Antenna Adapters: Scosche – MDA-1; American Int’l –
 GM-6; Metra – 40GM10

Security Wiring
 FUNCTION           COLOR /POLARITY         LOCATION
 12V+ Constant      Red / Black (+)         BCM (C3, pin D1)
 12V+ Ignition      Yellow (+)              BCM (C4, pin D3)1
 2nd Ignition       White, White/Black      See notes1
 Accessory          Brown (+)               BCM (C4, pin C8)1
 2nd Accessory      N/A
 Start Signal       Yellow (-)              PCM(Pin 48 or 46)
 Starter            White, White/Black      See notes1
 Key Sense          White, White/Black      See notes1
 Lights             Brown (+)               BCM (C3, pin A7)2
 Door Pins          Gray/Black, Tan/White   See notes
 Dome Light         Gray (-)                BCM (C3, pin A10)
 Hood Pin           N/A
 Trunk/Hatch        Orange/Black (-)        BCM (C1, pin 55)
 Trunk Release      Tan (-)                 BCM (C2, pin 10)3
 Lock               White (-)               See notes2
 Unlock             Same as Lock            See notes2
 Fact. Arm/Disarm   N/A                     Remote only
 Lock Motor         Gray (+/-)              BCM (C3, pin A4)2
 Unlock Motor       Tan (+/-)               BCM (C3, pin B1)2
 Horn               Tan (-)                 BCM (C2, pin 14)3
 Tach               See notes               At fuel injectors
 Speed Sense        N/A
 Brake              Lt. Blue (+)            BCM (C2, pin 54)3
 Parking Brake      Lt. Blue (-)            BCM (C1, pin 14)3      Tech Notes
 Reverse Lights     Lt. Green (+)           Driver kick panel       Dash Disassembly – Pop out trim panel above radio, then trim around
                                                                    radio. Note: Dash is hard plastic and clips are tight; use caution.
 PCM – driver-side fender.                                          Radio Removal – OnStar disabled if radio is removed. Use T-harness to
 BCM – part of fuse/relay box on pass. side of center console.      retain OnStar function.
 C1-Gray plug, 72-pin                                               Siren Mount – Next to driver-side headlight.
 C2-Gray plug, 72-pin                                               Pass-Thru – On firewall near driver-side shock tower.
 C3-Red plug, 41-pin                                                Tach – Use any wire EXCEPT Pink or Pink/Black.
 C4-Lt. Gray plug, 68-pin                                           Remote Start – Directed Electronics suggests to request its Document 1610
 1Also at ignition harness.                                         for specific remote-start information.
 2Also in driver kick panel.                                        Lock / Unlock – White wire at BCM (C1, pin 7). Negative to lock; negative
 3Also at switch.                                                   through 1500-ohm resistor to unlock.
                                                                    Door Pins – Driver: BCM (C1, pin 22); pass.: pin 19. Diode-isolate.


                                                                   Contributors
Verify circuits before testing. Mobile Electronics and its          Directed Electronics – (800) 753-0600
contributors assume no responsibility for damages resulting from    Victory Technologies – (877) 474-8835
the use of this information.


                                                                                                            O c t o b e r 2 0 0 5 MOBILE ELECTRONICS 87

				
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