Printer Friendly Forum Posts - 5x7 boxes/ home amp

I have some 5x7 infinities that don't fit my car and i can't sell, so I was wondering how I can figure out how much volume i need for them if I build a couple boxes for them.
Also, since the speakers are rated at 4 ohms, what happens if I power them with an 8 ohm reciever meant for home use. Will it damage either the amp or the speakers? Do i just have to be careful and not turn it up too much because it will be easier to blow the speakers cause the amp is meant for higher resistance speakers? Thanks for any input.

you want to use 4 ohm car speakers on an 8 ohm house receiver? Is that what you are saying/

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1990 Honda Civic HB:
Clarion DXZ545MP H.U.
2- 6.5" Power Acoustik interiors
Diamond Audio 600.1 amp
Diamond Audio 15" M6MKII
Pyramid PB881X 4 CH. Amp

How many do you have? If you have four, then you can series-wire two together to make 8 ohms, and do the same for the other two. 5 X 7's are made to be infinitely baffled, such as their use in a car door or rear parcel shelf, so you won't find a formula to figure volume for those. Just don't make the box too small. Try maybe a cabinet for each pair about 20" X 8" X 12" (I'm just looking at a pair of old speakers I have here, that is their size). Do not connect them to your receiver at 4 ohms! Volume is not the issue with ohm load on an amplifier.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

so what is the issue? What would happen if I connected the 4 ohm speakers to the 8 ohm receiver? Which would be damaged? Does it go the other way, hooking 8 ohm speakers to a 4 ohm amp? I'm just trying to get som clarification. Thanks

An amplifier will try to send current depending on the ohm load presented to it. Most home receivers are built to take an 8 ohm load. Presenting the amp with a 4 ohm load means the amp will respond by sending much more current through its circuitry to provide the power asked of it. The problem, then, with too low an ohm load is with the amplifier, not the speaker. It is the amp that will be abused.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

OK, i get that, but what happens if 8 ohm speakers are hooked up to a 4 ohm amp, is it the speakers that take the abuse in that case?

No abuse to anyone. A lighter load for the amp, and less power to the speakers.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

hmm, ok. I guess I'll have to get another pair of speakers or something, so I can wire my 5x7's. Except i won't wanna buy anymore. Hmmm. I;'ll figure somethin out. Thanks. I want to use them as speakers for my computer.

Another question, aren't the voice coils in speakers designed to have the flow of electricity go one direction? I just don't understand how wiring them in series works. I get the actual wiring and how to do it, but not what's really going on. Thanks

Sell em on ebay .. I think you'll be disappointed with a car audio coax speaker for home use. I don't think it is worth buying another set of speakers.

Signal flows to the speaker coil on the pos. and back to the amp on the neg. Series, the first speaker flows into the second speaker, then back to the amp. You should read a good tutorial.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

What kind of car do you have? I would think that some company would sell a 5 X 7 speaker adapter plate to fit those speaker where you need them. That is a Ford size speaker.

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Harv

I have a '94 civic. The speakers are out of my old 84 plymouth reliant.... boy was that a beauty. Anyway, i've ordered speakers for my civic already.

Stevdart could I use a 4 ohm resistor in place of a second speaker, wiring it in series.Such as this: https://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=017-4

Do you think this would work?

thanks

No, that is for a circuit board. You can get 5 X 7 speakers on flea-bay for $20 shipped a pair any day of the week. Or pull two of the speakers out of your car that you will be replacing and use those.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Why wouldn't it work? If I mount it inside the box, it offers 4 ohms resistance and I wouldn't be pushing more than 20 watts. Regardless of whether it's for a circuit board, it still has the same function, and should be able to be mounted and used for the purpose it was intended for. I don't want to pair my infinities with some cheap brand off ebay.

Sorry to break this news, but a 5 X 7 Infinity is no better than a 5 X 7 Pioneer, and several other mid brands. Just FYI, no offense intended. I am saying there are closeouts available on a lot of coaxials, and you will find Polk, Infinity, Pioneer, and others. Match sensitivity as close as possible.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

ok, i understand that about the speakers. but can you offer me an expanation about the resistor? From my experiences it seems that would work, Can you tell me reasons for not attempting this?
thanks

You can read this explanatory resistor tutorial to see why it would not do what you want it to do. Or, you can experiment. Whatever you do I suggest you take an ohm reading with a multimeter before connecting to your home receiver. You want close to 8 ohms per channel load.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

current flows both ways through the coil, one way pushes it out, the other way pulls it in.

You wire them - + - + so the two series coils stay in phase with eachother....otherwise it would sound like garbage. Especially if its a DVC sub you're wiring in series....

I used a Pioneer IMPP 12" sub in a small sealed box with my Audio Source self powered subwoofer (home theater) The AS sub was blown, so I ran speaker wire to the Pioneer sub from the amp board. The amp happened to be 4 ohms, for the dual 8 ohm coil, the pioneer was a single 4 ohm......Now let me tell ya...

That was a good sounding home system!!