Newbie Car Stereo Installation Questions

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Hello. First, I'm not an electronics wizard whatsoever, but enjoy the learning process and doing the work myself. I am upgrading the stereo system in my car with the following:

Head Unit: Alpine CDE-136BT (mounted)
Amplifier: Front - Kenwood KAC 7200 ('86 vintage - brand new / never used)
Amplifier: Rear - Kenwood KAC 8020 ('86 vintage - brand new / never used)
Amplifier: Subwoofer - TBD
Front Speakers: two way Kenwood KFC 1682 ('86 vintage - brand new / never used with new foam surround gaskets installed last week)
Rear Speakers: three way - TDB
Subwoofer: TBD

BTW: I value quality / function over cost and will spend the time and effort to evaluate products in order to ascertain what value and functions are gained when purchasing a product that is more expensive. Once I can understand the quality and functional differences between products, only then does the price becomes important.

Question #1 - I want to add a relay between the HU and the (ultimately) 3 amplifiers) for the "remote turn-on wire" (500 mA). Recommendations of type needed and particular brands would be appreciated.

This is what I've come up with for stereo system wiring calculations after searching the internet and using the following data:

1. Maximum Power Cable Length of roughly 30 feet (bus is 14 feet long)

(from primary battery across engine firewall then undercarriage to front of car and up into cab to a (single or multiple)(?) relay or switch or (?) and then from relay/switch/(?) to amps #1, #2 and #3).

2. Maximum Ground Cable Length is currently unknown – do not know how grounding system should be designed yet.

3. Total RMS Power (watts) is guesstimated to currently be 185 W with possibly another 150-200 W added sometime in the future for a subwoofer amp (max) for a total RMS of roughly 335-385 (W).

4. The specs I’ve been able to locate for the two amplifiers are:
Amp #1 (front): 45 W into 4 ohms, 1 Khz @ 10% THD
Amp #2 (rear): Maximum output 140W+140W with Power Output of 95W+95W, 1 kHz 10% THD

Note: For RMS, I used the highest (W) value listed (which is most likely incorrect, but if anything the rating I gave it should be too high?)


Using the Recommended Power and Ground Cable Sizes & Speaker Wire Size and Length charts on this page of the 12volt.com website,

Recommended Power and Ground Cable Sizes & Speaker Wire Size and Length

I came up with the following:

a) Power and Ground Cable by Load and Distance: 4 gauge

b) Speaker Wire Size by Load and Distance

b.1) Front Speakers: 18 AWG (technically could get by with 20 AWG)

b.2) Rear Speakers: 16 AWG (if mounted near back seat) or 14AWG (if mounted at very rear of bus)

Question #2 - Do these power wire sizes look anywhere correct? Undersized? Overkill?

Question #3 - Do these speaker wire sizes look correct?

Question #4 - I'm not sure how to terminate the power wiring at front of car and then provide power to both the HU and the three amps using these three wires coming from the HU wire loom (ignition / battery / remote turn-on).

Any & all help / opinions / recommendations will be appreciated.

TIA

wb
 
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Question #4 - I'm not sure how to terminate the power wiring at front of bus and then provide power to both the HU and the three amps using these three wires coming from the HU wire loom (ignition / battery / remote turn-on).

Update. Well, I've learned a bit more regarding this subject after reading online a few more hours @ bcae1.com. Looks like a Distribution Block and a Relay will help get me there.

Here is my understanding so far:

4a) From the battery, install an in-line fuse adjacent to battery and route either 4 or 6 ga wire to front of bus and terminate in a distribution block. Run (perhaps) lighter gauge cables to each amp from the distribution block. This will provide the power source to each of the amps.

4b) Install a relay between the HU and each of the amps using the remote power wire. If I understand this correctly, the amps are smart enough to receive the remote signal and (close?) a device (switch) internal to the amplifier which allows the power from the battery (through the distribution block) to enter the amp. Question: Am I understanding this correctly?

Regarding the remote power signal, evidently I could just daisy chain between the amps, but I don't think I want to do this.

Question: if the relay is designed for three (3) outputs (sorry don't know the correct terminology yet) and the last amp hasn't been installed yet, do I need to do something at the third connection (outlet) of the relay or will it be alright to leave it empty?

Finally, install a fuse on the remote power wire between the HU and the relay.

As always, if anyone who reads this thread has comments, suggestions, recommendations, opinions, etc. I will truly appreciate your input.

TIA
 
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