Help! I'm overwhelmed! (And I'm a newb!)

[audioholic 5,000+ posts]

Um, wow... I don't even know where to begin again. This is kinda' how I wound up here in the first place. While I very much appreciate the explanation given by BnGRacing and the depth of context, keep in mind that I stated from the outset that much of this tech speak eludes me. While I understand what everybody has broken down for me, I'm not so concerned with how many watts are carried over which channels depending on how many ohms are resisitng them. If I want to stand on a ladder, I don't need to know the definition of what a pound of pressure is or what the tensile strength of steel is. I need somebody to tell me that the ladder is strong enough to hold me. When I assist a client with the purchase of a new PC or a server, they rarely care how many Ghz their processor is working at or whether it's a single or dual core -- they want their machine to be "fast" and to perform well. I now have multiple opinions conflicting with each other and I'm really no better off than I was before. I'll keep it simple.
I have (Qty 2) Kicker 07CVR124 (CVR12/4Ohm) Subwoofers. No box yet (That's a question for another discussion). Check out the specs here: http://www.kicker.com/sites/default/files/2007CompVR.pdf

I also have a Rockford Fosgate P700-BD1 amplifier. It can be seen here:

Rockford Fosgate® - P700-1bd

and the product manual can be viewed here:

http://www.kicker.com/sites/default/files/2007CompVR.pdf

Now then, without explaining how the clock works when I ask what time it is -- can somebody just tell me if this is a decent match? I'm off to a rocky start and once I get past this I can consult with those who know for other componant parts to make this a fun car stereo system to have. That's all. Thanks.

- Dodds

Your subs are rated for 400 watts each. With the subs and amp you have, assuming wired correctly (to 1ohm mono), each sub would receive approximately 250 watts. In other words, your subs could handle a larger amp, and I personally would go with a bigger one, but that is up to you.

I dont know the size of your stock alt, or your listening habits (how loud and how often you will listen to the stereo), but with an amp that size most stock alts would be sufficient. There are no guarantees though, as there are too many variables to account for to give a specific answer.

Yes, I would recommend doing the 'big 3' (use forum search function). It will simply make your vehicle more efficient at transferring this newly added electrical current.

Your subs are dual 4ohms. Realistically you have two options for wiring them together. Parallel the coils from each sub together for a 2ohm load, then parallel the subs together for a 1ohm final load. In this instance you will probably want to find a class D amplifier. The other wiring option is, parallel the coils of each sub together for a 2ohm load like before, but then series the subs together for a 4ohm final load. In this case, you would be looking for a class A/B amplifier to power the subs.

 

[Buck 5,000+ posts]

Need a box design? lol

If you have any questions about enclosures, feel free to email me and ask, I can give you some //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif's

 

[superdodds]

Audioholic -

Thanks so much for a little clarity. I bought my subs on Sunday night, found the amp on Monday and bought it on Monday night. This is a huge impulse buy but I'm committed now so I gotta do it!

1.) Have you ever seen the inside of the cab of a Chevrolet Silverado 1500 (Extended Cab)? There's not a lot of space in there! I don't mind so much if my subs are a little underpowered. For the price I got the amp for, I just couldn't pass it up. I'm thinking that this amp will power these subs enough to make me happy. Furthermore, I'm not going be blasting and bassing all the time everywhere I go, so hopefully the draw from the amp won't hurt my alternator. I was just wanting to be sure that I'm not going to blow something up or burn something up in the process of my doing this.

2.) I don't know about my stock alt either but I'm willing to take my chances given the advice and opinions I've been given here.

3.) I am aware of the Big 3 and will implement this prior to my installation of this stereo equipment.

4.) This is a class b/d amplifier so it should support wiring the subs either way. From other postings, I am of the assumption that wiring them for a 4 Ohm load will be easier on my amp than wiring them for a 1 Ohm load? I understand that I won't be sending as much power to each sub, but it might help preserve my amp for a longer life? Or not. The amp is rated to support subs at 1,2, or 4 Ohms.

Again, thanks so much. I appreciate your time.

- Dodds

 

---------- Post added at 03:33 PM ---------- Previous post was at 03:33 PM ----------

 

Audioholic -

Thanks so much for a little clarity. I bought my subs on Sunday night, found the amp on Monday and bought it on Monday night. This is a huge impulse buy but I'm committed now so I gotta do it!

1.) Have you ever seen the inside of the cab of a Chevrolet Silverado 1500 (Extended Cab)? There's not a lot of space in there! I don't mind so much if my subs are a little underpowered. For the price I got the amp for, I just couldn't pass it up. I'm thinking that this amp will power these subs enough to make me happy. Furthermore, I'm not going be blasting and bassing all the time everywhere I go, so hopefully the draw from the amp won't hurt my alternator. I was just wanting to be sure that I'm not going to blow something up or burn something up in the process of my doing this.

2.) I don't know about my stock alt either but I'm willing to take my chances given the advice and opinions I've been given here.

3.) I am aware of the Big 3 and will implement this prior to my installation of this stereo equipment.

4.) This is a class b/d amplifier so it should support wiring the subs either way. From other postings, I am of the assumption that wiring them for a 4 Ohm load will be easier on my amp than wiring them for a 1 Ohm load? I understand that I won't be sending as much power to each sub, but it might help preserve my amp for a longer life? Or not. The amp is rated to support subs at 1,2, or 4 Ohms.

Again, thanks so much. I appreciate your time.

- Dodds

 

[audioholic 5,000+ posts]

Your amp will only put out 200 watts at 4ohms, so each speaker will only receive 100 watts. Run it at 1ohm, it will be fine.

 

[Kangaroux 5,000+ posts]

Your subs are rated for 400 watts each. With the subs and amp you have, assuming wired correctly (to 1ohm mono), each sub would receive approximately 250 watts. In other words, your subs could handle a larger amp, and I personally would go with a bigger one, but that is up to you.
I dont know the size of your stock alt, or your listening habits (how loud and how often you will listen to the stereo), but with an amp that size most stock alts would be sufficient. There are no guarantees though, as there are too many variables to account for to give a specific answer.

Yes, I would recommend doing the 'big 3' (use forum search function). It will simply make your vehicle more efficient at transferring this newly added electrical current.

Your subs are dual 4ohms. Realistically you have two options for wiring them together. Parallel the coils from each sub together for a 2ohm load, then parallel the subs together for a 1ohm final load. In this instance you will probably want to find a class D amplifier. The other wiring option is, parallel the coils of each sub together for a 2ohm load like before, but then series the subs together for a 4ohm final load. In this case, you would be looking for a class A/B amplifier to power the subs.

How do you propose they will get 250? the amp puts out 700, split that and you have 350.

 

[BnGRacing 10+ year member]

You are incorrect. If you hook 2 subs to a 1000 watt amplifier, each sub will receive 500 watts (be it wired in parallel, series, or in stereo). If what you suggest were true, we could hook 16 subs to a 1000 watt amplifier and all the sudden we have a 16,000 watt setup. That is obviously not the case.
Furthermore, power is divided among the speakers based on impedance. If you wire one 8 ohm sub and one 4 ohm sub together, the 8ohm sub will receive half the power that the 4 ohm sub does.

It doesn't matter what kind of woofer or how many. What matters is the load the amplifier sees and the voltage at the speaker leads. That voltage does not disappear when you add 1 subwoofer or 10. The load the amp sees and the voltage at the speaker outputs are the only things that are important.

Remember, speakers do not "make watts". 10 subwoofers running off a 100w amp does not make it a 1000 watt system. It's a 100w system with 10 subwoofers, nothing more. Likewise, a DVC 500w subwoofer does not mean you need a 1000w amp to feed both VCs or a pair of 250w amps to run each coil individually. It means you should not exceed 500w for one woofer or a pair. The load the amp sees means more than the sticker on the back of the woofer's magnet.

Think of the wiring in your home. When you use a power strip and plug in your PC, computer speakers, monitor, lamp, etc; does the voltage change in the wall socket? No, just the load demands. Same thing goes with speakers. 10 woofers wired at 4ohm will have the same draw as 1 woofer at 4ohm; that's how much you're asking the amp to work.

You can get to the point where current demands can exceed an amplifier's output capacity, but that's another discussion. For this thought experiment were having, that's neither here nor there.

 

[nauc 10+ year member]

"It means you should not exceed 500w for one woofer or a pair"

bs. you can run 500 watts to EACH sub. so if you have a pair of subs, you can run 1,000 watts (500 per sub)

and even if you have a 500 watt sub, it doesnt mean you cant hook it up to a 1,000 watt amp or a 2,000 watt amp. you just better know how to set the amps gain properly

 

[BnGRacing 10+ year member]

Your amp will only put out 200 watts at 4ohms, so each speaker will only receive 100 watts. Run it at 1ohm, it will be fine.

Never run anything at 1ohm. Ever hear a system someone bought OTC, installed in an afternoon, and it sounded good at 1ohm? No, you haven't. The woofers will lack any kind of definition and sound sloppy & boomy. By running the coils in parallel, it also raises the Qtc of the woofer...making it sound even sloppier and more boomy. Likewise, this will put extra strain on the amp and unless it's a high $$$ amp (which it is not) it'll switch to thermal protection quicker. There really is no benefit to putting a load like that on an amp for a daily driver.

If an amp puts out 200w @ 4ohm, each sub will see 4 ohm. Ohm's law only applies to the output of the amp. Power does not "split" when you wire up several subs. As long as the impedance stays the same, so will the voltage. Use ohm's law and you can figure out that nothing changed. If you have very small hands or know a very tiny friend; test the VC for voltage. Even better, set up a rig with a bunch of resistors and test it with a MM. You'll see.

May I ask, how many speakers & amplifiers have you blown up in your lifetime?

 

[audioholic 5,000+ posts]

How do you propose they will get 250? the amp puts out 700, split that and you have 350.

The specs I found here say it does 500 watts @ 1ohm:

Rockford Fosgate P700-1BD 700W RMS Punch Series Monoblock Amplifier

That's the figure I was going off of.

 

[BnGRacing 10+ year member]

"It means you should not exceed 500w for one woofer or a pair"
bs. you can run 500 watts to EACH sub. so if you have a pair of subs, you can run 1,000 watts (500 per sub)

Just because "you can" doesn't mean you should. Yes, you can run 500w to each sub...but you only need a 500w amp to do so. When you hook up 2 subwoofers together and wire it to a 500w amp, guess what? They're both getting 500w.

When you hook up a 1000w amp to a pair of speakers, take a guess what happens. I'll give you 3 tries...

and even if you have a 500 watt sub, it doesnt mean you cant hook it up to a 1,000 watt amp or a 2,000 watt amp. you just better know how to set the amps gain properly

Gains have absolutely nothing to do with what speaker is hooked up to the amp or how loud you want to be. Absolutely nothing. You adjust gains to match the voltage of the input signal (RCA). I highly doubt you or most people here have the knowledge and equipment to "properly" set gain levels. Why? Oscilloscopes are not exactly cheap and that's the piece of equipment to accurately set gains.

Turning your radio up 3/4 of the way and listening for the speaker to break up isn't the proper way to gas an amp. Unfortunately, it's the way most were taught.

 

[audioholic 5,000+ posts]

It doesn't matter what kind of woofer or how many. What matters is the load the amplifier sees and the voltage at the speaker leads. That voltage does not disappear when you add 1 subwoofer or 10. The load the amp sees and the voltage at the speaker outputs are the only things that are important.
Remember, speakers do not "make watts". 10 subwoofers running off a 100w amp does not make it a 1000 watt system. It's a 100w system with 10 subwoofers, nothing more. Likewise, a DVC 500w subwoofer does not mean you need a 1000w amp to feed both VCs or a pair of 250w amps to run each coil individually. It means you should not exceed 500w for one woofer or a pair. The load the amp sees means more than the sticker on the back of the woofer's magnet.

Think of the wiring in your home. When you use a power strip and plug in your PC, computer speakers, monitor, lamp, etc; does the voltage change in the wall socket? No, just the load demands. Same thing goes with speakers. 10 woofers wired at 4ohm will have the same draw as 1 woofer at 4ohm; that's how much you're asking the amp to work.

You can get to the point where current demands can exceed an amplifier's output capacity, but that's another discussion. For this thought experiment were having, that's neither here nor there.

Now you are referring to the final impedance at the amp, when my point was on individual speaker impedance. Almost everything you've said here is not only elementary info I already knew, its completely irrelevant to the issue. Lets go back and look at what you said originally that I took issue with and posted about...

... the A/C current flowing out of the 800w amp does not magically 1/2 itself when you hook up 2 drivers to it....If you have 800w pumping thru the wires each sub will have 800w pumping through it (including each voice coil)...

You are saying that if you have an 800 watt sub, each of the two subs will receive 800 watts. This is simply 100% incorrect. Each speaker will receive 400 watts. Your most recent reply deals with total ohm load at the amp, which dictates the wattage created. But our point of contention id how that power is distributed.

 

[BnGRacing 10+ year member]

You are saying that if you have an 800 watt sub, each of the two subs will receive 800 watts. This is simply 100% incorrect. Each speaker will receive 400 watts. Your most recent reply deals with total ohm load at the amp, which dictates the wattage created. But our point of contention id how that power is distributed.

What I'm saying is that the load the output channels on an amplifier sees and the output voltage means everything. Ohm's law only applies to the amp; not the individual speakers. You're doing your math in the wrong direction.

Hook up some big resistors, run some sine waves through your amp, and test voltage. You'll see for yourself. An even easier test would be to run separate speaker runs to the amp output for each subwoofer. Measure voltage...they'll be the same. Now, when you do your math for ohm's law; do you use the impedance going towards the subwoofer or the impedance the amplifer sees? I say use the impedance the amplifier sees while marketing departments think you should use the speaker impedance. Hell, crack the amp open and test there. There's your real impedance and since you know the voltage, you can figure out the power. Math can be misleading...

 

[audioholic 5,000+ posts]

Never run anything at 1ohm. Ever hear a system someone bought OTC, installed in an afternoon, and it sounded good at 1ohm? No, you haven't. The woofers will lack any kind of definition and sound sloppy & boomy. By running the coils in parallel, it also raises the Qtc of the woofer...making it sound even sloppier and more boomy. Likewise, this will put extra strain on the amp and unless it's a high $$$ amp (which it is not) it'll switch to thermal protection quicker. There really is no benefit to putting a load like that on an amp for a daily driver.
If an amp puts out 200w @ 4ohm, each sub will see 4 ohm. Ohm's law only applies to the output of the amp. Power does not "split" when you wire up several subs. As long as the impedance stays the same, so will the voltage. Use ohm's law and you can figure out that nothing changed. If you have very small hands or know a very tiny friend; test the VC for voltage. Even better, set up a rig with a bunch of resistors and test it with a MM. You'll see.

May I ask, how many speakers & amplifiers have you blown up in your lifetime?

Never running an amp at 1ohm is an old wives tale. Different amplifier topologies are specifically designed to make optimum power at different impedances (A/B's usually being at 4ohms, D's being 2 or 1 ohm). So to make a blanket statement that running an amp at 1 ohm will mean the amp will not competently control cone motion is simply over generalizing a more complex topic.

If an amp puts out 200w @ 4ohm, each sub will see 4 ohm. Ohm's law only applies to the output of the amp. Power does not "split" when you wire up several subs.

Yes, yes it does 'split'. If the amp is seeing a final load of 4 ohms, each speaker is half of the load that creates that 4ohms. They do not each receive the power created by the amp at 4 ohms.

 

[audioholic 5,000+ posts]

What I'm saying is that the load the output channels on an amplifier sees and the output voltage means everything. Ohm's law only applies to the amp; not the individual speakers. You're doing your math in the wrong direction.
Hook up some big resistors, run some sine waves through your amp, and test voltage. You'll see for yourself. But if you would like to continue to purchase larger amps than you need you go right ahead.

Im not doing my math in the wrong direction. You are claiming that if 2 speakers wired together create a load that means the amplifier outputs 800 watts, 800 watts is 'flowing thru the wires' so each speaker sees 800 watts. Again, for like the 4th time, this is completely incorrect. The two speakers wired together created the final impedance the amp sees, and thus share the power created between them in a ratio parallel to each one's individual impedance. Since each speaker will be half of the final impedance to the amp, each speaker will receive half the power created (400 watts, not 800). If each one received 800 watts, 1,600 watts of power would need to be produced.

 

[whitedragon551 5,000+ posts]

Never run anything at 1ohm. Ever hear a system someone bought OTC, installed in an afternoon, and it sounded good at 1ohm? No, you haven't. The woofers will lack any kind of definition and sound sloppy & boomy. By running the coils in parallel, it also raises the Qtc of the woofer...making it sound even sloppier and more boomy. Likewise, this will put extra strain on the amp and unless it's a high $$$ amp (which it is not) it'll switch to thermal protection quicker. There really is no benefit to putting a load like that on an amp for a daily driver.

Also simply not true. Plenty of Class D amps out there sound just as good as their class A/B counter parts. Thats without pulling full range class D amp into the mix. Its all subjective.

Perhaps your referring to a time when you first joined. Now days its not an accurate statement. Technology has come a long way.