trdsparks

I give up.

tCizzler

I understand what he's saying but just got the wording a little mixed up. If you bridge those in parallel, POP goes the subs!! But if you do it in series, POP goes the subs also.

Parallel = 8 ohms and 8 ohms = 4 ohms
Series = 8ohms and 8 ohms = 16 ohms

http://rockfordfosgate.com/rftech/wo...2&woofer_imp=2


You DO wanna put them in parallel, just don't bridge them, put them on 1 single output. That is probably the safest bet, and will sound the best. Make sure the polarity is correct on the subs. Some amps require the subs to be out of phase to work properly. I think it has something to do with the internal crossover, but i'm not totally sure on that one. If they don't hit at all (and you'll know what i mean) just pick a sub and then change it's polarity.

UV7

Yes, gain control is always a factor in any setup. That is not in question. But I think you have the order backwards in Ohm's law. By definition, Ohm's law states that output varies inversely to resistance. This means that as resistance DECREASES, output will increase accordingly. This also means that as resistance increases, output will DECREASE accordingly.
Simply put, a basic single-channel amplifier that pushes 100 watts at 4 Ohm, will push 200 watts at 2 Ohm, 400 watts at 1 Ohm, and so on, theoretically. The amp will eventually cook when it exceeds its capability.
The inverse is also true. The same amp that pushes 100 watts at 4 Ohm, will only push 50 watts at 8 Ohm, 25 watts at 16 Ohm, etc.. The amp does not have to work as hard since it is not producing the same amount of power, so there is not a risk of "frying" transistors due to more resistance. Eventually, resistance will increase enough for output to be too little for the speaker to play. Hence, no output. This does not mean that the amp will suffer any damage, only that it will no longer be producing enough power to run the woofer.
Wiring the woofers to one channel is not a bright idea. If the amp cooks, it will only do so on one channel. Good luck getting it serviced under warranty. Manufacturers are picky enough about warranty service that they may consider that as "misuse."
You'd be surprised how much crap Orion gave me on warranty service back in the day, and I was on their competition team.

tCizzler

Not starting a fight with you, i'm trying to keep this civil and help this guy out.
But If you hook these up bridged at 4 ohms like you say, according to the specs, that would be 1000W RMS. The speakers only handle 400W RMS when combined, so how would he "have no problem" running more than double the wattage to the speakers than they can handle?

I will say it again, as someone who has tons of experience ruining systems by hooking them up wrong the first time. I have learned a lot along the way. I don't want random to ruin his equipment. Audio equipment is not cheap

tCizzler

Well put OK, I will admit that is a great explaination. I personally blew out 2 amps, which i believed the reason to be incorrect impedance matching. But i am willing to leave that alone.

This is a serious, no sarcasm intended question... Why is it so bad to put both subs in parallel on one channel? Isn't that like only hooking up one sub to a two channel amp. Shouldn't damage anything, right. I have been running mine with this setup for years with no problems, Different amps and speakers too. Why would the amp cook? And if only one channel would "cook", i would switch to the other channel. And if that one cooked too, I would just play the "i don't know what happened" role. How would they know how i set it up? And secondly both channels would be cooked at that time so it wouldn't be suspicious.

Is there a real reason to why it's not a good idea, or is it just the fact of trying to explain why only 1 channel is cooked. Which if properly matched with the power output of the amp to the sub, and the impedances, it shouldn't cook

J1slim

that is why amps have a GAIN. of course if everything is at full blast somethings gonna go wrong.....I hope randomsuper got something out of all of this besides a headache..!?!?!? good luck to you

randomsuper

i think i actually know less than when i started. i'm seriously sitting in my office right now scratching my head and laughing reading all this jargon. i do appreciate the help though so keep it coming.

if someone could show me a diagram of how i should wire these suckers up, i'd appreciate it. and thanks again.

UV7

You are correct. In an ideal world, under ideal conditions, the amp would never fry. But, as the infamous saying goes, $#!t happens.
With regard to most amplifier manufacturers, running only one channel of a multi-channel amp should not cause the device any harm. After blowing up a set of small co-ax 4x6s, I ran only two channels of an Orion 4-channel amplifier for a few months before getting around to replacing the rear fill without any problems. I am actually using the same 4-channel amplifier today in my xB.
After going through all the nonsense (some of it justified, by the way! You should try plugging an 8" Orion XTR woofer into a wall outlet. It's hillarious! ) from a few manufacturers while trying to get service under warranty, I just like to play things as safe as possible.

tc-guy

if i were u i would bridge the amp and run the speakers in parallel. although ur amp says its 1000 watts bridged ur speakers should be o.k. just turn down the gain on the amp all the way. the reason i say this is that i had a fosgate 200 watt h.e. 12 in. sub powered by a 1000 watt kenwood amp and it was still working fine when i traded the car in 5 years after i put it in.

yesti

Here, draw a picture if it helps:

+ = positive terminal on speaker/amp
- = negative terminal on speaker/amp

parallel:

amp + -> first AND second speaker +
amp - -> first AND second speaker -

to calculate ohm seen at amp:

ohm of first speaker: x
ohm of second speaker: y
ohm the amp will see: z

(1/x) + (1/y) = (1/z)

if you have two 8 ohm speakers:

1/8 + 1/8 = 2/8 = 1/4 (so 4 ohms at amp)

series:

amp + -> first speaker +, first speaker - -> second speaker +, second speaker - -> amp -

add the ohms of the two speakers to get ohm seen at amp:

8 + 8 = 16 ohms

-----------------------------------------------
the amp is rated at 4 ohms and if you go HIGHER (using the formulas above) then you should be safe. If you go LOWER then the amp has to provide more current (hence more wattage: Watt = Voltage * Current in amperes) which it may not be able to do before frying itself.

The more current it has to provide, the more it will suck from your charging system, through the wiring (so it has to be able to handle the load as well by being thicker), and the more heat it will generate. An amp rated at xxx watts at 4 ohms is said to be '2 ohm stable' if it can operate at 2 ohms without self destructing, provided the wiring isn't the weakest link. looking at the specs you posted it is stable to 2 ohms but not to 1 ohm. that is what that means.

NOTE: you can create 'custom' ohms seen at the amp by combining series and parallel wiring but lets not get into that.

i think tcizzler was confusing terms when he said the speaker has to be '4 ohm stable'. to my knowledge that term was used with the amplifier.

the specs on the amp say 1000 watts 4 ohm bridged. maybe that is what you want. does the manual say how to wire it up in bridged mode? since you have two 8 ohm speakers, wire them in parallel and connect them to the amp so it operates in bridged mode and you will get the most watts for your buck. HOWEVER, your speakers are only rated to 200W each so start with low gain on the amp.

second choice as has been said is wire them in parallel and just hook them up to one channel of the amp. bass is mostly mono anyway so you won't be missing any music this way.

chadfo

Hook each sub up to each channel of the amp and forget about it. You don't need to have a perfect impedance match to the capability of the amp unless you are trying to win SPL competitions. The sensitivity of the speaker, in most part, will determine the loudness of the speaker. Remember that you only get 3dB more every time you double your power so you aren't losing a tremendous amount by using 8 ohm subs on a 4 ohm rated amp. The rating is there to give you a basis to plan your system and in some cases let you know the limitations of the amp.

Let's look at the specs:

250 watts RMS x 2 chan. @ 4-Ohm Stereo < Provided because most car stereo speaker have 4 ohm impedance.
500 watts RMS x 2 chan. @ 2-Ohm Stereo < Provided because this is probably the least amount of impedance the amp can handle and it's popular to have dual voice coil subs at 4 ohms each coil, which wired in parallel is 2 ohms.
1000 watts MAX x 1 chan. @ 4-Ohm Bridged < Provided so you know that the amp is bridgeable and what to expect out of it. Also notice that the stats changed from RMS for 2 channel operation to MAX for 1 channel operation. Either their documentation isn't accurate or the circuitry in the amp isn't very efficient in a bridged configuration. I'd be willing to bet you can't tell a difference between wiring each sub separately to a channel and wiring them in parallel with the amp bridged other than the sound quality will probably go down in bridged configuration.

If you are looking for sound quality, what you have will probably do just fine. If you are looking for SPL neither the amp or the subs are the best choice.

UV7

Here are a few simple diagrams that show different types of wiring and the ultimate yield at the amplifier. Keep in mind, these are not specific to any woofers even though the Rockford logo is shown on the woofs. These are simply to be used to help others understand how to keep their setups within the capabilities of the amplifier while optimizing output capability.

This diagram shows two Single Voice Coil woofers wired together in parallel. As you can see, each woofer has only one set of Positive(+) and Negative(-) terminals. Each Positive(+) terminal is connected to another Positive(+) all the way to the amp's Positive input. The final impedance can be calculated by taking the impedance of one coil and then divide that by the number of coils in the scheme. In this case:
4 Ohm/2 coils = 2 Ohm load at the amp.

In this diagram, we have the same two Single Voice Coil woofers wired in series. Notice that the first woofer's Positive terminal is connected to the amp's Positive, but the woofer's Negative is connected to the other woofer's Positive rather than to the amp's Negative as it was in the Parallel wiring scheme. The second woofer's Negative is then connected to the amp's Negative terminal. The final impedance can be calculated by taking the impedance from one of the coils and multiplying it by the number of coils. In this case, 4 Ohms x 2 Coils = 8 Ohm load at the amp.

Here, we have a diagram of a set of two woofers, only this time, the woofers are Dual Voice Coil rather than Single. The wiring is Parallel-Parallel, with each Positive connected to the next, all the way to the amp's Positive input, and each Negative connected to the next, all the way to the amp's Negative input. The formula to calculate the final impedance is the same for Parallel-Parallel as it is for just Parallel. 4 Ohm coil/4 coils = 1 Ohm load at the amp.

This last one is called Series-Parallel wiring. Each woofer is a Dual Voice Coil with the voice coil of each woofer wired together in series, but the chain itself is wired parallel to the amp. Notice each woofer's second coil is wired Negative to Positive.
To calculate the final impedance, you would need to calculate each woofer in series first. Each woofer has two 4-Ohm coils wired in series, giving each woofer an 8 Ohm load. Remember, 4 Ohm coils x 2 coils = 8 Ohms. Now, we take the two 8 Ohm speakers and wire them together parallel. 8 Ohm/2 speakers = 4 Ohms at the amp.
Keep in mind, a dual voice coil speaker is no better or worse than the same woofer as a single. The DVC just has more wiring options. These same techniques can be used to wire up multiple woofers and acheive the same mathematical results.
Something to keep in mind: NEVER wire up a DVC woofer using only one coil! You will damage the woofer and void your warranty.
I hope this info helps to clarify wiring schemes for those of you who have not had the chance to get this deep into audio yet. Good luck, play it LOUD, but don't blow your woofs!

randomsuper

in true randomsuper fashion, i bought 2 new subs that are a perfect match for the amp at 4 ohms. no fuss, no muss. i appreciate all the help from everyone here though. i learned some new things i might apply later on.

chadfo

I thought you were on a budget.

randomsuper

i was. but, i figure i'm better off spending the money now and being happy now, then sitting around for 2 weeks till i get paid. besides, i'm selling my old stuff so it really isn't that bad. ebay is crack.

in 2 months, i bought a new headunit, new components, new amps, new subs, and now i have to make a new box as well as rewire the car since i wasn't 100% happy how i did it the first time. i got a little lazy and cheap and now have super cheap speaker wire all over the place. no one will ever see it but it bugs me when i think about it. did i also mention i'm picking up some sound deadener too? i know i love my car but this is getting absurd.

UV7

Dude, it never ends. I haven't competed in car audio in a decade, but EVERY car I have to drive ends up with yards of cabling, acres of sound deadening, subs, components, amps out the yin-yang, and countless hours of tuning, fiddling, and just plain messing around. Trust me, it is an obsession that never quits.