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100w speakers, 70w amp - safe?

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Old 01-27-2008, 06:55 PM
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Default 100w speakers, 70w amp - and Wiring

I just bought a set of Alpine Type R speakers, for front and rear and I want to power them with the Kenwood amp I already had. It's a Kenwood KAC X40, 70w RMS x 4 at 4 ohms, where as the speakers I bought say 100w

If my language hasn't given it away, I wouldn't even consider myself familiar with the basics when it comes to speakers and wiring

No clue what an ohm is, but at 2 ohms my amp can do 100w x4. Anyways, I don't know what I'm talking about anymore so, basically I'm asking is my setup safe? Or do I need to only hook my front speakers to my amp and run the rear speakers off my headunit (Pioneer Avic-D3)

Thanks, and sorry for being a noob


Modified by Cody2289 at 6:38 PM 2/10/2008
Old 01-27-2008, 07:14 PM
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Default Re: 100w speakers, 70w amp - safe? (Cody2289)

Your basic aftermarket coaxial speaker is a 4 ohm speaker, so if you are running 4 speaker to a 4 channel amp stereo (using all four channels) then the amp will make 70w X 4. If the speakers you have are really 100w rms then 70 is enough for riding around. It should be loud as hell if you are putting a true 70 watts on them. You dont have to worry about 2 ohm stereo. That would only come into play if you were running 8 speakers. So the answer to your question is YES you will be fine, aslong as you dont distort the speakers. Keep the crossover around 100 Hz
Old 01-27-2008, 08:01 PM
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Default Re: 100w speakers, 70w amp - safe? (Cody2289)

If i were you I would look at the alpine pdx 100.4 and run your type r speakers. They will be much more happier and will sound better. And you won't clip your amp trying to get volume out of them that will destroy your speakers. Because you are underpowering them by 30 watts. I rather be over then under.
Old 01-28-2008, 05:00 PM
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Default Re: 100w speakers, 70w amp - safe? (Cody2289)

70W RMS would be fine to run the Type Rs as long as you do not overdrive the amp into constant clipping, as mentioned it will damage the speakers, burn the speakers VCs, [voice coil] also as mentioned a 100-125 watt amp would be better.

Some clarification...

Do you have 2 sets of Type R speakers, and what model numbers?

MM&Y of car?

I assume they are the 6.5", [100W] so the question is how are they installed?
The Alpine SPR-17C is an over-sized 6.5" speaker, your Honda/Acura uses standard 6.5" speakers. 94


Modified by fcm at 1:31 PM 1/30/2008
Old 01-30-2008, 10:04 AM
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Default Re: 100w speakers, 70w amp - safe? (fcm)

I have the SPR17S and SPR17C. I'm putting them in a 98 Integra, 2 door. For the front doors, I'm using a wooden spacer to make them fit and for the rear I think they'll fit without any modification but I haven't looked at it much yet. I've still got the interior stripped because I'm laying dynamat. (It will probably be 2 weeks before I get everything put back together.)
Old 01-30-2008, 07:08 PM
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Default Re: 100w speakers, 70w amp - safe? (Cody2289)

Return your rears. Buy a 2ch amp that is 100-150 rms and hook that up to the components up front and then buy a sub with an amp to match and hook that up.
Old 01-31-2008, 05:20 AM
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Default Re: 100w speakers, 70w amp - safe? (Cody2289)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cody2289 &raquo;</TD></TR><TR><TD CLASS="quote">I have the SPR17S and SPR17C. I'm putting them in a 98 Integra, 2 door. For the front doors, I'm using a wooden spacer to make them fit and for the rear I think they'll fit without any modification but I haven't looked at it much yet. I've still got the interior stripped because I'm laying dynamat. (It will probably be 2 weeks before I get everything put back together.)
</TD></TR></TABLE> The Alpine SPR-17S are 110W continuous the SPS-17C are 100W continuous.
Assuming your Teg is a hatch, it takes standard 6.5" speakers in the doors and the rear sides, modifications will be needed for both the front and the rears, the rears can be tricky to install over-sized 6.5" because of the shape of the stock speaker housings.

The SPR-17S need all of the 110W to sound good when pushed hard, I would suggest you replace the amp, look for something with at least 2x125W RMS, keep the stock speakers in the rear and run them off HU power, all they are needed for is "rear fill" and add a sub and sub amp.

If your like me and you do not want a sub, but still want good bass response, go the extra step and replace the stock, plastic door speaker housings with custom MDF speaker housings, it will add more mass and your speakers will sound better, and Dynamat the doors, [replace plastic vapor barrier with a Dynamot one] , [better bass extension], and if you want to keep it simple, replace the Alpine SPR-17Cs with a set of standard 6.5" mid-range/mid-bass drivers, or a coax and disable the tweeter, you do not need or want high frequencies coming from behind you,
The Eclipse SP6500 is a good "coax" to use as the tweeters are removable and it is a standard 6.5"

Then find a 4x110W - 4x150W RMS amp, bridge the amps rear channels and wire the rear speakers in series for an 8 ohm load so you have a mono rear fill, it will make setting the staging and imaging up properly a lot easier. 94
Old 01-31-2008, 07:00 PM
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Default Re: 100w speakers, 70w amp - safe? (fcm)

My currect amp is 200W RMS x 2 bridged output at 4 ohms. Is it fine for me to run the SPR-17S off the amp and run the SPR-17C off my headunit?

I realize now that the SPR-17Cs were overkill and unnecessary but I replaced my stock speakers because one didnt work anymore. I'd prefer to go ahead and use them since they're sitting in my room. Assuming I can make them fit, which I'm pretty confident that I can, would it be fine to run them off the headunit? If it makes any difference, I don't listen to loud music at all really. My main reason for upgrading was because one of my speakers didnt work and I figured I'd go ahead and get the best I could afford.

I do plan to add a sub and another amp sometime this summer but I'd prefer to use my Kenwood KAC-X40 for the front speakers if I can.

Thanks for the help and putting up with my ignorance
Old 01-31-2008, 08:23 PM
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Default Re: 100w speakers, 70w amp - safe? (Cody2289)

I also prefer to over power them rather than underpower them but I'm running my Polk DB's that are rated for 100 watts off a 70w X 4 Alpine amp and they seem to do fine although I've only had them a month or so. I'm overpowering the rears though so thats why I chose this amp. It was inbetween it overpowers the rears and slightly underpowers the front speakers.
Old 02-01-2008, 04:45 AM
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Default Re: 100w speakers, 70w amp - safe? (Cody2289)

I would bridge the amp into a 2 channel and use it to drive the fronts only.

Yes, you could use HU power to drive the SPR-17Cs in the rear but as I said, installing them in the rear will not be easy, I pulled out and checker my stock rear speaker mounts and speakers yesterday, [stored at work] and if they have not changed, [no reason for them the change] from my 94 Teg to your 98 Teg the Alpine SPR-17C, or any other over-sized 6.5" will not fit the stock housing. 94
Old 02-01-2008, 02:23 PM
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Default Re: 100w speakers, 70w amp - safe? (fcm)

yeah i checked them out last night also and it isn't a direct fit.
I'd rather custom make a mount for it then have to sell these speakers and buy new ones though. I've had my car stripped since late December, I'm ready to get everything back together.

Thanks for the advice everyone
and FCM always seem to have the answer
Old 02-10-2008, 03:37 PM
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Default Re: 100w speakers, 70w amp - safe? (Cody2289)

So I managed to fit the rear speakers into their housings without too much of a problem but I can't figure out how to wire the rear speakers to the headunit without using the amp. Can anyone help explain? Right now, the wires go from the speaker to the radios harness which connects to the orange-wrapped wires that lead to the amp and then the RCA wires go directly from the amp to the headunit. I'm clueless, embarrassed and feel like a noob.

The (orange wrapped) wires that normally connect to the amp:


Where those wires connect to the head units harness:


The mess that is my car:


So if anyone can help explain, my stress level would lower drastically.

Being an electrical noob FTL
Old 02-10-2008, 06:52 PM
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Default Re: 100w speakers, 70w amp - safe? (Cody2289)

I am not sure exactly what it is you are doing, however, it does look like you are using a harness adapter to plug into the stock radio harness plug, in which case you should just connect all the leads from the HU to the harness adapter, color for color, [unless of coarse the HU does not have a "standard" color coded power/speaker harness, as it looks like] you do not have to connect the front speaker outputs from the HU, [ standard colors are grays and whites, with black tracers on the neg.(-) leads] although it can't hurt as you should be running speaker leads directly to the door speakers from the amp, so the stock ones would not be used, they would stay disconnected in the doors.

With that done, the stock rear speaker leads would be connected to the new aftermarket rear speakers, done. 94
Old 02-11-2008, 08:58 AM
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Default Re: 100w speakers, 70w amp - safe? (fcm)

well looking at things more today, i realized the previous owner used the stock speaker wiring for the front speakers also, which makes high power speakers pointless right? so right now I'm leaning towards prolonging the project and completely rewiring all four speakers. atleast it would be a learning experience and i'd know how and where everything is for future reference or modifications.

i'm going to do some reading and see how feasible this is. thanks for all the help
Old 02-11-2008, 09:28 AM
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Default Re: 100w speakers, 70w amp - safe? (Cody2289)

Although running new speaker leads to the front speakers is really a must, it is not necessary although it can't hurt. 94
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