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How to Install Modern Audio Into Vintage Corvettes

High-Tech Tunes

John Pfanstiehl Jul 6, 2018
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Amazing advances in automotive audio systems have been witnessed over the past several decades. Before we explore integrating these modern technologies into vintage Corvettes, let’s look back at how the Corvette generations evolved almost in lockstep with the evolution of car audio.

The first generation of Corvettes was born in a time limited to AM radio. The only aftermarket audio enhancements available were a reverb box and a bulky automotive record player that only worked well when the car was parked. C2s made a big step forward in the audio arena by offering an AM/FM radio. However, buyers were apprehensive of this new technology. In 1963, more Corvettes were ordered with AM radios than the AM/FM option. On the aftermarket scene, the big audio breakthrough in the mid-’60s was the eight-track player. Millions of drivers could now choose their own music at will while driving, although this tape format had a number of problems. When the C3 hit the showroom in 1968, an optional AM/FM stereo radio was offered for the first time.

In hindsight, it seems strange that most Corvette buyers in the early-’70s did not choose the stereo option. Perhaps the sound of the engine was far more enticing back then. It wasn’t until 1974 that the stereo radio out-sold the standard radio. In 1977, Corvette finally offered a radio option with an eight-track player. But by then many car owners were realizing the benefits of the next aftermarket audio advance: the cassette player. Cassettes were about one third the size of eight-track tapes and had a number of advantages, including much better durability. In 1979, Corvette buyers could choose from radios with either eight-track or cassette players. The previous year, CB radios were also added to the options list, providing quite a number of audio choices for several years.

The introduction of the C4 in 1984 offered the first Delco-Bose stereo system. Although much more expensive, this was an instant hit with car buyers and showed a growing desire for premium audio systems. In the aftermarket audio world, CDs were replacing cassettes. The 1997 model year saw the first C5s and the first options of factory CD players and 12-disc CD changers, although the radio with cassette player was still available until the C6 debut in 2005. By then, compressed digital music was growing exponentially thanks to Napster and the iPod.

The C6 introduced radios with MP3 and XM satellite capability. During the C6 production run, the convenience of transferring digital music wirelessly via Bluetooth gained in popularity and became part of Corvette’s audio offerings. The desire for high-quality audio and commercial-free personal music is now firmly entrenched in the car buying public. The current C7 generation started off with a nine-speaker audio system as standard that incorporated Sirius/XM, MP3 and Bluetooth.

Fortunately, owners of older Corvettes now have a number of choices on how to upgrade to new audio technologies and expansive music choices without altering the original console or dash. Today, inexpensive USB flash drives allow you to carry over 10,000 of your favorite songs on a keychain. Music services such as Pandora and Spotify can give you free access to millions of songs via your smartphone. These radio upgrades are relatively inexpensive and definitely make enjoying music in your car easier and more pleasurable. Follow along as we install a Bluetooth/USB radio from Zip Products into a C3. This radio fits into the factory gauge housing, looks good with its retro style and has far more features and performance than the original radio. Along the way, we’ll show interior disassembly and radio installation tips applicable to all generations.

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1. Remove the passenger-side sill plate to begin gaining access to the radio and speakers. Tip: tighten each interior screw before removal and note which ones won’t tighten. It’s common for one or more of these screw holes to be stripped and it is better to remember to fix the problem when the interior parts are removed.

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2. Remove the two side screws from the lower right of the dashpad. A short Phillips screwdriver is needed to remove the lower screw. Also remove the one screw from each small access panel at the front side of the shifter console and then slide the access panels forward and down then out.

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3. Remove the screw holding the front side of the kick panel. Don’t be surprised if it isn’t there. People often leave it off because it’s difficult to install and frankly it’s not essential. (This is the one fastener I don’t install on my C3s.)

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4. Pull back the lower right side of the dashpad and then ease the lower side of the kick panel down and to the left as you pull the panel’s upper right corner down and back from the dashpad. Tip: Be gentle, these plastic parts get brittle after many decades.

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5. Remove the three black screws from the top of the lower right dashpad. They can be hard to see if their ferrule (eyelet) was lost and screwed too far into the pad. Remove the two chrome screws holding the pad’s left side to the center gauge housing.

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6. Pull the upper edge of the right dashpad out and then ease its lower left corner up and off from the shifter console. After disconnecting the wiring harness from the clips on the backside, remove the dashpad and place it safely out of the way.

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7. The side of the radio is now exposed and its support strap can be removed. Removal of this aftermarket radio, although smaller than the original radio in some dimensions, also required removing the center gauge housing.

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8. First, remove the windshield wiper switch plate from the gauge housing. Note that the switch connector has a protrusion on its right side. This was intended to make sure the connector was installed properly, but many people have managed to put it back on incorrectly.

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9. Tip: Inspect each screw as it is removed and note or mark where it goes. This makes reassembly much easier because there are a number of different sizes and types. Upper row left to right are screws for sill plate and right dashpad on its right, center and left. The three different screws on the lower row are all from the windshield wiper switch plate.

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10. The only fasteners that are awkward to reach are the two nuts on the studs at the lower edge of the gauge cluster, but in my experience many people have left them off. They can be reached with a 3/8-inch flex-socket on a 1/4-inch drive extension. Being a contortionist helps.

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11. We’re also replacing speakers in the upper dashpad. First, remove both sunvisors and the six other screws attaching the windshield header trim molding. Gently ease this long, narrow trim piece down; it can be fragile at this age.

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12. Next, the interior windshield post moldings are attached with a screw at the top and one or two Velcro-like clips along the post. If your moldings are damaged, replacements in original colors are available from Zip Products, as are the other moldings and dashpads.

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13. Remove the three screws from the upper edge of the lower left dashpad and don’t forget the one screw attaching the upper dashpad to its support bracket. The bracket is located to the right of the defroster duct.

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14. It is necessary to bend the upper dashpad to get its front corner to clear the windshield post. Gently push up on the center of the pad while pulling down on its right end. After it gets clear, disconnect the speaker wires and pull the pad back up and out. Tip: Be careful not to touch the pad in the perforated speaker area; this can be very fragile.

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15. The speakers we’re installing are Kenwood two-way speakers from Zip Products. These 4-ohm speakers are rated at 60 watts peak power with a frequency response from 50-25,000 Hz; a huge improvement over the original speakers.

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16. The center portion of the speaker support was removed by a previous installer to make room for the tweeter, which extends about 1/16-inch higher than the speaker’s mounting surface. Alternately, shims can simply be added for clearance if necessary.

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17. Dense rubber foam was trimmed to make an acoustic barrier around the perimeter of the speaker. Although this step is not essential, it can help the speaker reproduce sounds in the lower frequencies (and sound less “thin”).

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18. Reassemble the speaker supports into the upper dashpad. Larger diameter screws may be needed if the plastic in the pad was stripped, but make certain the replacement screws are short to prevent dimpling or perforating the pad’s upper surface. Tip: A dab of glue around these screws can prevent them from loosening from vibration.

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19. It’s critical that the dash speakers are not too deep because there is very limited room underneath the speaker on the driver side. Zip’s Kenwood speakers measured 1 5/8-inch from their mounting flange and cleared the instrument cluster. Tip: This is an opportune time to check all those hard-to-reach instrument lights.

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20. CD player input jacks are on the rear of the radio along with audio outputs for an amplifier. An installation wiring diagram is located on the bottom. This is a welcome feature, too, because manuals often get misplaced.

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21. Tip: Installation is simplified by preparing and grouping the wires. The ground and power wires are grouped to the left. The speaker wires are grouped and routed to the right. Also shown is a right-angle antenna extension. This helps radio installations where the antenna wire is too short or space is limited.

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22. The yellow wire is switched power. The orange wire for the clock and interior light circuit is nearby to provide power for the digital radio’s memory. Black is ground. The gray wire is for instrument/radio lights and is not needed for most modern radios.

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23. After connecting the speaker wires, reassemble the interior parts in the reverse order of removal. Zip Product’s extensive interior screw set is well worth the $27 to replace rusted, damaged or missing fasteners.

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24. Speakers can also be installed behind the kick panels in the cavity above the body mounting bolt. Speakers in this location are more effective in the low range, so it is a good idea to fabricate a panel to acoustically isolate the front of the speaker cone from the rear. Zip Products also offers self-contained speaker assemblies for the rear compartment of coupes and convertibles.

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25. The three screws attaching the top edge of both lower dashpads require special attention. Each of these screws has a ferrule that prevents it from going too far into the dashpad. Sometimes the ferrules come out when the screw is removed but look closely because sometimes they stay in the pad, as shown here.

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26. The sill plate screw holes often need special attention. Tip: If the holes are enlarged to the point that the screws no longer can be tightened, bend a small paper clip and insert one side into the hole. Secure the other end with tape to hold it in place.

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27. This new Bluetooth/USB radio from Zip fits into the original gauge housing with no modifications. The retro-looking radio face is available in black as shown here or in chrome. Two sets of knobs come with this radio: chrome knobs or wider, lower-profile black knobs.

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28. Connecting to Pandora or Spotify is easy. Press the radio’s mode button to select “blue,” start the free music service on your smartphone and turn on Bluetooth. Now you have access to over 20,000,000 songs. And the improvement in sound quality is amazing. (I wish I made the upgrade sooner.)

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29. CDs are too wide to fit through the stock radio opening on early C3 Corvettes, but Zip Products offers modern, powerful CD radios that come with a custom metal center instrument housing so owners can save their original housing. This 200-watt Pioneer stereo CD also has MP3 and USB inputs plus many more audio and lighting features.

Master Bluetooth

Music lovers get tired of hearing the same songs over and over on broadcast (FM) or satellite (Sirius/XM) radio. In fact, you can run out of new music during a two-week road trip even when equipped with an iPod, dozens of CDs and satellite radio. Expand your music horizon dramatically through streaming music from an app on your smartphone connected via Bluetooth to your car radio. If you want to utilize the Bluetooth feature on your car radio to access literally millions of songs—but are too embarrassed to ask a 9-year-old for help—follow along to see how to do it.

The only step that requires a little research or decision-making is choosing your music streaming app. Pandora is one of the most popular streaming apps and has a major advantage in setting up song lists that you like. Simply enter a favorite artist or song to name a “station” (its term for a list or music genre). Pandora will then randomly play songs similar to that when you select that station. You can then tap the thumbs up or thumbs down icons while any song plays to make Pandora refine the selection criteria according to your tastes based on 200 song parameters. It is remarkable how well this works to create a stream of songs you like. You can also create different personal song lists, like “I Can’t Drive 55” for faster paced road trip music. If Pandora’s library of over 800,000 songs isn’t enough, try Spotify, which claims 20,000,000 recordings. However, you’ll find that Spotify’s music selection algorithm isn’t as refined. Both offer free services or subscription services that have no commercials. On Pandora’s free service, I found commercials to be few and far between.

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1. Preparation: Install a music streaming app on your smartphone. For example, on an Android phone, press the ‘Play Store’ icon and then enter Pandora. A number of sources offered Pandora apps; I’d recommend choosing the one directly from Pandora.

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2. Apps require you to accept a number of conditions. Fortunately, Pandora’s conditions are relatively modest and benign. By comparison, the Uber app requires access to your contact list and many other things on your phone. Enter some personal data to help it better select music you’ll like.

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3. Turn your radio on and select the Bluetooth mode. Then, on your smartphone find Bluetooth (under Tools on Android phones) and turn it on. Select the device that is displayed on the phone. There will be only one displayed if there are no other Bluetooth devices nearby.

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4. Press the Pandora icon on the smartphone and select any personal station you want to listen to. You may need to press the play icon and wait several seconds for the music to come through your car radio. Now you have access to a mind-blowing library of music.

Radio and Speaker Options

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1. The Classic Style radio for 1968-’76 Corvettes has a metal face with large metal pushbuttons similar to the factory radio and you can use factory-style knobs. It features updated electronics, aux and USB inputs, and is rated at 180 watts.

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2. This Bluetooth Reproduction radio is one of coolest radios around. Updated electronics lie behind a completely factory front. In addition to Bluetooth, it can play iPods, MP3s or Satellite radio. Models available are 1956-’62 Wonderbar, 1963-’67 and 1968-’76.

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3. All C3 Corvettes now also have the option of placing additional speakers in their rear compartments. Zip Products offers the fully assembled cabinets with or without their 6x9 speakers. They locate in the upper corners to preserve storage for T-tops and other items.

Photography by John Pfanstiehl

Sources

Zip Products
Mechanicsville, VA 23111
800-962-9632
www.zip-corvette.com

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