Premium 8 Speaker System, Details/questions on the stock system Options

[mportobello]

What I have found so far from my 1997 GTS hatchback....

Overview
The system has 1 head unit, 2 amplifiers and 8 speakers. The head unit is a double DIN CD/cassette unit without a built-in amplifier. The primary amp is underneath the A/C controls, the secondary amp is under the driver's seat. On the front door, there is a 1" tweeter, a 4" mid and an 8" mid. The rear sub is mounted beside the rear passenger. Are these the correct names for these speakers? "Mid", "Sub", "Tweeter"? Is the rear really a sub? Can you suggest better names?

Amps
The primary amp provides battery power, ACC and ground to the head unit and, I believe, also to the secondary amp. The amp accepts line-level audio from the head unit and passes it on to the secondary amp.

The primary amp drives the front tweeters, front 4" mids, and rear subs. The secondary amp only drives the front 8" mids. The front tweeters and 4" mids are wired in parallel to the primary amp. All other speakers are wired directly to the amps.

The primary amp is easy to find, but difficult to remove. It is mounted by 4 bolts, 2 along each side. You need to remove the trim piece that surrounds the amp and holds the A/C controls and shifter trim. However to remove this piece you need to remove the shifter knob, shifter trim, center console, lower driver's side dash and the glove box and teh A/C controls. To access the secondary amp remove the driver's side seat. You can disconnect the wiring if you move the seat all the way back.

The amps are manufactured by Fujitsu Ten Limited. According to my dealer the amps were manufactured from Sep 1993 - Aug 1999. They should be the same part for all 6th generation Celicas with the premium 8 speaker system. For the primary amp, they produced 2 versions with different part numbers. Both versions are compatible.

Speakers
The speakers cones are made from a paper-like material. Mine are starting the warp. All the speakers appear to use custom mounting. It is unlikely you can just bolt on an aftermarket speaker.

The front tweeter and front 4" mid are wired in parallel to the primary amp. All other speakers are wired directly back to the amp.

To access front tweeter, remove the plastic cover by pulling directly away from the window. To the access the other front speakers remove the door panel (see the How To on installing 6.5" speakers for instructions and pictures). I haven't tried to access the rear speakers. I believe it involves removing the reat seats.

Wiring
Speaker and power wiring comes in one bundle from under steering wheel to the left side of the amp. This bundle terminates with 3 connectors: 2 blue, 1 white. The blue connectors are the standard Toyota wiring harness. The 1 white connector contains 4 wires which run to the front 8" mids. These 3 connectors are actually mounted underneather the amp by plastic clips.

From these 3 connectors, the wires are routed to the 2 amps. From the primary amp is a bundle of wires that runs to the head unit. Metra sells a wiring harness that plugs into this bundle. It is called an amplifier integration harness (Metra part 70-8112). It provides 4 RCA connectors for line-level audio as well as the other standard wires: battery, acc, ground, power antenna and amp turn on.

Installing a new head unit
When installing a new headunit you have a few wiring choices:

1) Use the existing amps. Purchase the amp integration harness, manufactured by Metra. Part number is 70-8112. This lets you use all 8 speakers without buying a new amp and it is easy to install. Just replace the headunit. The amps expect line-level audio, so you may need to get a converter (do they make speaker-to-linelevel converters?). Search the board for Metra for more info on using this harness. You will likely have to purchase it from a specialty car audio retailer and ask for it by part number otherwise you may get the generic Toyota harness used in option #2 below.

As a test, I have successfully used this Metra connector and gotten a Discman hooked up to the existing 8 speakers. Sounded great. To perform this test, I used a headphone-to-RCA wire to connect to the harness. To turn on the amp I wired the yellow battery lead (from the harness) to a diode to a 1K ohm resistor to the Blue/White Amp TurnOn (from the harness). Be very careful with exposed wires! I accidentally let the yellow battery wire touch ground and ZAP, no sound and a funny smell. I now have 1 dead amp!

2) Bypass the existing amp but use the existing wiring. Purchase the generic 94-99 Toyota wiring harness from WalMart. Connect it to the 2 blue connectors under the primary amp. This connector goes to the existing speakers, except the front 8" mids. Search the board for Install Doctor, they have PDF tutorial with pictures. You will need a 4 channel amp. Will a 4 ohm stable amp suffice? Since the tweeter and 4" mid are wired in parallel, do you need a 2 ohm stable amp? With a multimeter, the tweeter shows infinite resistance so the 2 speakers appear as a 3.6 ohm load. I imagine you can splice into the 1 white connector to get at the front 8" speakers.

3) Bypass the existing amp and wiring. Run you own wire to the speakers. The difficulty is finding an amp to drive all 8 speakers and running new wire. See the How To section on this site for tips on running wire. What specs should you look in an aftermarket amp to drive all 8 stock speakers? Power rating, # channels at what ohm rating?


Speaker Size
Front Tweeters ....... 1"
Front 4" Mids .......... 3.5" - 4.25"
Front 8" Mids .......... 7.5" - 8.25"
Rear Subs ............... 6"
How do you measure speaker size? Size of the cone or size of cone + mounting hardware?

Impedance and Power
These specs were taken by markings on or near the speaker where available.
Front Tweeters ....... 4 ohm
Front 4" Mids .......... 4 ohm, 15 W
Front 8" Mids .......... ?
Rear Subs ............... ?

Measured Resistance with Multimeter
Front Tweeters ....... infinte
Front 4" Mids .......... 3.6 ohm
Front 8" Mids .......... 1.8 ohm
Rear Subs ............... 5.3 ohm
How do you measure impedance? Can you measure DC resistance to get a ballpark number? Why do I get infinte resistance when I measure the tweeter? Is it because of the capacitor attached to the speaker?

Speaker Wire Colors
Front Tweeters ....... Left: Pink/Grey, Purple/Grey; Right:?
Front 4" Mids .......... Left: Pink/Grey, Purple/Grey; Right:?
Front 8" Mids .......... Left: Blue/Red (+), Blue/Black (-); Right:?
Rear Subs ............... ?

Part Numbers
Front Tweeters ....... 86160-2B180
Front 4" Mids .......... 86160-2B200
Front 8" Mids .......... ?
Rear Subs ............... ?
Primary Amp ........... 8628020371, 8628020371 (older revision)
Secondary Amp ...... ?

References
Metra Amp Integration Plug: 70-8112
How to remove the door panel
Installing 6.5" Components In the Front
Installing 8" Subwoofers in the Front Doors


Do you have any information to add? Any corrections? Please post!

Brian

This post has been edited by mportobello: Apr 18, 2004 - 11:48 PM