Scosche SLC-4, 1999 Mazda Miata

Good morning.

I have a 1999 Mazda Miata with the Bose system.

I have a high powered head unit.

My GOAL is to BYPASS the Bose amp and to use the AMP in my head unit.

I was sold a SCOSCHE SLC-4 to accomplish this.

I know how to hook it up (or so, I Know how the Crutchfield guy told me to) - here is my question... How does this thing work? To me, all logic indicates that it simply lowers the line level of my Head unit (amp) and then uses the BOSE amp. Well, this is exactly the opposite of what I want to be done. I am told this is not what is happening, but it seems to me that if I connect speaker wires from radio into the Scosche and then wires out to the BOSE... and then adjust the levels of the input wires from my radio... well... logic says I'm adjusting my stereo output.

Please explain to mo how this is bypassing the BOSE amp.

Also, do I select Common ground or Factory AMP (on the side)

Any clarification on this will be appreciated. I hate not knowing how something works - especially when it doesn't sound like it should be working the way I am told it should.

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Dwaine Stroud
Sing, Worship, Live the Life

I think the tech at Crutchfield thought you were replacing the factory amp with an aftermarket amp.

The problem you may run into is that many Bose systems use speakers that are less than 4 ohms. If this is the case, it's not as simple as just bypassing the factory amp.

You didn't say, so I'm assuming you still have the factory speakers installed. If you do, just pull one and test DC resistance with your multimeter. If it measures 2 ohms or less, you should install new speakers.

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My ex once told me I have a perfect face for radio.

My apologies.

I have my own after market speakers.

So...
Powered head unit- scosche - Bose Amp - speakers.

I’ve been told the scosche bypasses the Bose amp


I tried to find the photo requirements - I only remembered the 5M limit. If I made it too big, I apologize and will reupload.


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Dwaine Stroud
Sing, Worship, Live the Life

That's not a bypass, just a line output converter.

https://www.youtube.com/watch?v=9AVtthMQ53k

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My ex once told me I have a perfect face for radio.

Yes. I've watched that before, but I will watch it again.

So, it DOES do what I think it does, right? It lowers the level of power my head unit is putting out, and thus my BOSE amp is doing the amplification; not my head unit?

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Dwaine Stroud
Sing, Worship, Live the Life

Yes.

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My ex once told me I have a perfect face for radio.

Am I correct in believing that my new head unit AMP is better than the twenty-year-old BOSE amp?

Link to the radio
https://www.us.jvc.com/car/multimedia/kw_v820bt/

BTW - I truly appreciate you taking the time to respond and help me out. Thank you!

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Dwaine Stroud
Sing, Worship, Live the Life

Better is really an open ended question. The Bose amp may be more powerful, but I think it's worth bypassing because the sound produced will be more accurate. The Bose amp may have it's own equalizer curve built in to try and compensate for the factory speakers' limitations. This would likely mean unwanted distortion in your setup. Not only that, you'd also be eliminating another potential point of failure.

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My ex once told me I have a perfect face for radio.

I want to thank y'all for helping on this.

This is what I learned:

1. The Scosche does NOT bypass the factory amp.
2. The Scosche lowers the level of my head unit's amp (means I'm not using it)
3. I really need to physically bypass the amp
4. Physically bypassing the amp will be a fun challenge

I'll let you know how it turns out.

Dwaine

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Dwaine Stroud
Sing, Worship, Live the Life

https://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=171627
https://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=174521
wiring for the audio system with and without bose amp.
looks like bose amp is biamping front speakers, rear speakers are mono.