What kind of amp?

[JTH1972]

I've installed my own auto stereos in the past, but I've never dealt with an amp before. I plan on installing it in my 88. I just picked up a new stereo that's nothng fancy that has 4x40w max. I found some dash speakers at the wreckers (Alpine) and I plan on mounting some 6x9's behind the seat. I don't plan on installing a sub (no room behind seat!). So if I wanted to hook up an amp for these speakers, what kind would I need? I'm assuming a 4 channel. What about ohms? I've seen some amps described as a low pass or high pass but i don't know what that means.

Thanks

 

[4x4fun]

first look at what your speakers can handel rms then get the amp to fit if you wanna amp all 4 of your speakers make sure they can all take it. hi pass and low pass is just that it lets one or the other passs thru. depending on what your doing. ohms is all about the specs lets say you have a 400W 2 channel amp. in the specs it will say 400wx1 @ 2 ohms or 200w x1 at 4ohms, then 200wx2 @ 2 ohms or 100wx2@ 4 ohms.

look at the ohms needed for the speakers, that part is automatic. what ever it takes o run the sub/speaker thats whats gona happen you dont set that your self. just make sure 4/2 ohms you have enuff balls to run it. but it wont be too hard with speakers. so if your speakers need 85w4 ohms make sue ur amp can put that out.

 

[JTH1972]

The more I look into this, the more I realise that I don't know nearly as much as I thought I did.

Just as an exmaple, the stereo is rated for max 4X40W at 4 ohms, and 4X25W RMS. The 4" speakers for the dash are rated 130W peak and 30W RMS. Now my understanding was that the speakers don't sound as good if they are being provided power from a unit with a lower RMS than what the speakers are rated for, or am I incorrect?

Or is there a website soneone can recommend for understanding the basic install?

 

[4x4fun]

The more I look into this, the more I realise that I don't know nearly as much as I thought I did.

Just as an exmaple, the stereo is rated for max 4X40W at 4 ohms, and 4X25W RMS. The 4" speakers for the dash are rated 130W peak and 30W RMS. Now my understanding was that the speakers don't sound as good if they are being provided power from a unit with a lower RMS than what the speakers are rated for, or am I incorrect?

Or is there a website soneone can recommend for understanding the basic install?

first i was in your shoes about 8 years ago, you think its just plug and play and there a shit load that really goes into it. it takes a while to really get a grasp on everything. and it gets hard to explain some times.

but you are correct to a point with your speakers but its only 5s off you have to be close not dead on but a lil more is better the a lil less. i know i posted a big thing on rms and watts. if you find it give it a read. idk of any website but feel free to ask questions i dont mind.

 

[4x4fun]

info you didnt ask for but i give it any way

now for the nerdy definition, distortion in a speaker, is the loss of control of the voice coil. the voice coil is connect to the speaker cone and with electric current it moves back and forth rapidly. the different rates that it moves back and forth are your frecs IE why some bass songs sound really good on a sub and bass songs sound like poop, the frecs were matched perfectly for the power and size of the sub.

now were RMS comes in, RMS on the speaker is the amount of power needed to control the voice coil at all ranges of frecs the the speaker is designed for.
when you have less the required RMS you forgo control of the voice coil at peak performance. and the less RMS you have vs RMS needed controls how high you can turn it up befor it distorts

the more distortion the faster you blow the sub speaker ect.

%80 of the time after market head units and any good pair of aftermarked speakers are good/close enuff that it will get to loud befor it distorts. but if you have subs they can cover the disortion and you blow your speakers so its best to test them by highs and lows.

i have noticed that its the lower frecs were you start to lose control first.
IE trying to push to much bass at to high of a level thru a 6X9

 

[dru]

why spend the money on an amp to run your junkyard alpines. the head is more than adequate to power them. better off getting a cheap sub/amp combo or powered sub. it will make a more considerable difference in sound quality then just powering the speakers with an external amp. (they'll be loud as hell with no low end output)

edit: a 6.5" bazooka or even a generic brand would fit behind the seat. or a pair of 6x9 semi subs with a 2 channel amp

 

[JTH1972]

or a pair of 6x9 semi subs with a 2 channel amp

What do you mean by semi subs? Do you mean 2 way or 3 ways?
Since we're on the topic too of behind the seat, what have guys run back there in a regular cab on a '86? There's some el-cheapo speaker box back there now (and I mean CHEAP! http://www.shopxscargo.com/product_catalogue/cat_product_details.asp?category_id=6&product_code=57221&sub_category_1_id=11&category=Car Audio#productDetailMore ) that came withthe truck, but it's a pretty tight fit.

 

[dru]

What do you mean by semi subs? Do you mean 2 way or 3 ways?
Since we're on the topic too of behind the seat, what have guys run back there in a regular cab on a '86? There's some el-cheapo speaker box back there now (and I mean CHEAP! http://www.shopxscargo.com/product_catalogue/cat_product_details.asp?category_id=6&product_code=57221&sub_category_1_id=11&category=Car Audio#productDetailMore ) that came withthe truck, but it's a pretty tight fit.

i call them semi subs, i think the term is mid sub (not sure) they arent true subs there frequency range/low end output isnt as good as a true sub.

no, they are not 2 or 3 ways they are made to produce low frequencies only. they arent great but are better than nothing. google: 6x9 sub.

i still recommend a 6.5 bazooka or comparable.

something like this http://www.crutchfield.com/p_204BTA6100/Bazooka-BTA6100.html?tp=114 im not saying you have to go with crutchfield or even bazooka, just an example. this is a powered sub. you can get a non powered version and run your own amp. dont be fooled by the low power out put of the amp . Bazookas are extremely efficent and will sound great with minimal power.

 

[4x4fun]

if you can fit the tube behind the seat by all means rock the tube iv never heard bad things about them. the only draw back i can come up with is the face there all in one so if the sub goes you may not be ab;e to replace it. and if you want to up grade you dont have an amp.

if you can find one at a local store ask to test fit it or keep the recept. and just see what its like to have it back there and seat position, and its ok to have it touching everything or even "crush" it in there cause its all enclosed. it might get hot tho

 

[Pistons23]

just run those speakers off the deck. your not going to notice much of a difference between 25rms from the deck and say 30rms from an amp. wait till you invest in some speakers worth amping.

 

[JTH1972]

Hooked everything up today as-is and is sounds pretty good. Funny how everything sounds better when all the speakers work! I might go find a small 2 channel amp later to drive the rear box. Thanks to everyone for their input.