Hi all I'm new to the forum and a newb to car audio installing.

I decided to give my tired old stock setup in my corolla an upgrade after a friend gave me an unused Sony 2 channel amp and a fusion slimline 8" sub with built in amp.

One trip to the the car audio shop later I returned armed with

alpine 121e head
infinity kappa 50.9cs mids and tweeters
Sony 2 channel amp 50w rms per channel
Fusion 8" sub with in built 100w amp

The sales person assured me that these would round out a nice little system.

Having rushed in and ripped out the old head and wiring harness it dawned on me I could have problems with the setup.
The alpine head has two RCA preamp outs that can hook into my powered sub
no problem but .. That leaves no outputs to amp my mids and tweeters

The rms from the alpine is like 18w if I can't amp my mids and tweeters are they going to give me problems because they are under powered?
Can I run my Sony amp between the speaker outputs and the crossovers for my mids and tweeters or is this no go?
Please pardon my ignorance as I said I am a newb
Any advice here would be appreciated

The head puts out about 18 watts rms and the kappas Are rated
as 2-85 watts rms.

 

IMO you should trade the deck for one with two sets of preouts. If the store knew you had two amps I would give them greif over selling you a deck with one set in the first place..

If you keep that deck, either use a set of RCA Y-cables to split the signal to the two amps or run one of them high level input off of the Alpine speaker outputs.

 

Thanks Dukk
I will give the shop grief because they have led me up the garden path selling me this head
Trouble is I have have already unpacked and partially installed the head so I expect a big fuss from them if I try to trade the thing now.

If splitting the pre amp output is viable then I may be able to get the shop to spring for the cables, however it does appear the output is just designed for one channel sub woofer .

If running an amp 'high level input from the speaker outs' is just a matter of connecting My amp to the speaker outputs from the alpine I may just try that instead

 

If the Sony amp has high-level inputs, I would go that route; it should give you the ability to fade between the front/sub where splitting the signal would not.
My $.02

 

Yes! The amp has high level inputs . I will install the amp and put the speaker outputs from the head unit through these. Thanks

One other thing I have noticed is that the speaker crossovers for the kappas have a switch that can set the unit to 0db or -6db, any idea what this means and what I need to set them to?

 

Giddy-up; sounds like you'll be in business in no time brother.
The 0dB and -6dB are tweeter level attenuation modes which you can choose from. 0dB would be 'flat'; start with that and if you find the tweets too bright (loud, overpowering the mids), switch it to -6dB, Personal preference on that one.
Let us know how it works out!!

 

I hooked up the speaker outs from the head to the high level inputs on the amp wired up the crossovers and speakers Xmas tree style on the backseat
and it Didn't sound too bad
The amp is An xm502z it's only tuning device is a level adjustment screw, I couldn't get huge amounts of volume without distortion but more than enough setting the adjuster well under half way. Once the speakers are mounted in the front it should have decent sound and plenty of volume for me
I do wonder if the RCA outputs would give me better sound so I may try that too.
Need to door mount the speakers next the mids are a doodle but finding a place for the kappa turret style tweeter mount could be a challenge ,the turret looks like it takes a lot of space , could end up velcroing the tweets

 

Sure- try the RCA inputs on the Sony and see if there's a diff. Splitting the RCAs will still result in a lower signal input on the RCAs though; it's not apples to apples just by trying the RCA inputs as opposed to the high-level in.
Maybe you could attach the tweets to the door panel using a single screw through the door panel, into the mounting body/base of the tweet?

 

Although this is a common misconception, it usually is not the case. Splitting does not lower the voltage, it only increases the current draw, so as long as the output devices in the deck can drive both amps there should be no drop in voltage. You do lose control between the fronts and sub though.

In a simple setup like this there really isn't any big drawback to using high level inputs. The speaker outputs on the deck might distort before the RCA ouputs do but you can use the gains on the amps to maximize output at, say 25, instead of maybe 30. Net result is the same volume from the speakers either way.

 

I'm going to leave the high level inputs through the amp they actually sound really good to my ears .
Head and wiring is installed and finished , the sleeve supplied with the alpine head was useless for fixing it in place. I had to take the brackets off the stock head and retrofit to the new one, it's solid as now.
The speakers were a mission I ended up glueing the crossovers inside the doors with a hot glue gun. I attached the tweeters with Velcro to where the door sails normally would be this is temporary until I can customize the door sails to better house them.
Just need to run power to hook up the slimline sub under the seat tomorrow then work out how to balance that with rest of the sound and I should be in business!