# New subwoofers



## StaticInMyHead (Sep 27, 2004)

I'm upgrading the low-end of my stereo in my GMC std. cab pickup. Right now, I have a Rockford Fosgate 12" P1 in a home-built box and an MTX RT202 amp. It sounds excellent, but the problem I have is that my amp overheats (I'm assuming) and the sub cuts out completely if I have the bass up too high for too long. Once it cools down, the amp is fine. So, this inspired me to redo it and put new hardware in. I have a neat box idea that I think will work really well, but it's going to require two 10" subwoofers. I've picked out the Rockford Fosgate 10" P3, but I'm not sure what amplifier to use. With my current setup, the amplifier wattage perfectly matches the RMS wattage of the woofer, and I'd like to do the same with the new setup. What is recommended for two woofers rated at 400 watts RMS each?


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## StaticInMyHead (Sep 27, 2004)

Update: I've decided to go with Kicker SoloBaric L7s instead of the Punch P3s. I'll be sticking with the 10" model, though. The L7 needs 600 watts RMS as opposed to the 400 for the P3s. I figure I'll also need a capacitor to keep the headlights from dimming and prevent pulling too much power from the electrical system in my vehicle. Would a 5 farad capacitor do the trick?


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## crazijoe (Oct 19, 2004)

The upside to SoloBarics, less space needed because it doesn't require a large enclosure.
The downside to SoloBarics, VERY inefficient, Requires a lot more power to drive them.


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## StaticInMyHead (Sep 27, 2004)

Their efficiency is rated at 85.6db; I'd say that's about average. I wouldn't mind putting a little more money into an amp if it helped the output, anyway. The only thing that makes me curious is the wiring, concerning the impedance. I'd be afraid to wire it wrong and burn something up.


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## daamon_vexion (Aug 6, 2006)

i know the feeling, i am afraid of the same thing in my own car


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## crazijoe (Oct 19, 2004)

The main thing is make sure you buy the amp and the sub at the same time. If you get an amp that is stable down to 2 ohms on a single channel, then you could get by with a dual coil sub that is rated at 4 ohms on each coil and tie them in parrallel.


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## StaticInMyHead (Sep 27, 2004)

I was actually considering buying a mono amp stable at 1 ohm and wiring two dual voice coil subs in parallel. That should keep the resistance balanced between the subs and amp. The thing is, though, I could buy a 1200 RMS watt amp with two Solobaric L7s _or_ three Fosgate P3s for the same amount of money. The P3s go lower in terms of hz, but the L7s have been known to handle a lot more power. I'm really unsure of what to do. If it helps, here's my budget: ~$500, and another $120 after a friend of mine buys my old setup. I'm willing to flex a bit if I have to, though. I'll have a sealed enclosure with about 4 cubic feet of inside volume. What should I do?


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## crazijoe (Oct 19, 2004)

$620 isn't that much to spend. Especially on a pair of solobarics and a good amp to drive them.


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## StaticInMyHead (Sep 27, 2004)

I know, but I've been getting quotes from eBay stores. For the same item, I'll pay 50% less money.


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## crazijoe (Oct 19, 2004)

It's just hard for me to get sold on solobarics. I gotta friend that destroyed an MTX amp with single solobaric.


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## StaticInMyHead (Sep 27, 2004)

Did it just pull too much power and overheat until it died? Seems like thats what it would be... I think I'm leaning towards the three P3s, anyway. They go a few hertz lower and have about the same efficiency. In addition to that, I know the Punch series works well with sealed enclosures because mine is great right now. So.. P3 it is. Back to my original question: what kind of amp should I use to drive all three of those subwoofers pulling 400 watts RMS each? Any links or even brand suggestions would be nice.


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## crazijoe (Oct 19, 2004)

He had it up high enough that the amp started clipping. The amp use to put out 300watts. 
Have you checked in to Audiobahn subs? The have efficiency ratings from 91 to 97.


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## yustr (Sep 27, 2004)

My son has a single solobaric (10" I think) in an ported box - driven by a 600W Kenwood mono amp. He's had it for three years now and the combo's been flawless. And it does kick - there are bits and pieces of his poor Neon falling off left and right...:grin:  :4-thatsba


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## StaticInMyHead (Sep 27, 2004)

I looked briefly at the Flame Q series, but they need a lot of power and space. The other problem is their physical size; the magnet extends too far back without narrowing to fit into a box in my truck. I'm trying to take the scientific approach to this and build a system that works well because its designed well, not because it has a lot of power. I know 1200 watts is considered to be a little high, so hopefully I'll find the perfect balance between quantity and quality.


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## yustr (Sep 27, 2004)

crazijoe said:


> He had it up high enough that the amp started clipping. The amp use to put out 300watts.
> Have you checked in to Audiobahn subs? The have efficiency ratings from 91 to 97.


There is no real audible difference between an efficiency rating of 85 dB and 91dB. 

And Static: rating of wattage for a speaker is meaningless. If you ran anywhere near 400 Watts into a speaker for more than a fraction of a second - it would be toast in a heart beat. 

I'm a firm believer in Kenwood. They're well designed, well made, widely available, and inexpensive. Here's the one my son has: LINK

($150 on eBay)


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## StaticInMyHead (Sep 27, 2004)

yustr said:


> And Static: rating of wattage for a speaker is meaningless. If you ran anywhere near 400 Watts into a speaker for more than a fraction of a second - it would be toast in a heart beat.


I find that hard to believe, yustr, considering people at competitions run several kilowatts into their subwoofers with no 'toasting' of any kind to be seen.


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## yustr (Sep 27, 2004)

Speaker efficiency is rated as the number of decibels produced when the speaker is driven by one (1) watt measured 1 meter away (usually - maybe sub mfgr's don't follow this rule). The frequency does matter - low freq's being more difficult to produce. 

The other rule to remember is the 3dB rule - a rise of 3 dB requires doubling of the wattage. So to go from sound pressure level (SPL) 91 dB to 94dB (on a speaker rated as 91 dB efficient) requires 2 watts. Then up to 97dB = 4 watts, and so on. To get into the kilowatt range would produce a SPL of >120 dB. This is ambulance siren level. Damage to your ears begins after about 1 minute at 112 dB. Even less at 120 dB. 

Then you have to look at the music. Is the note really continuous? Or is it a (fake) drum beat? If so then the SPL is only sustained for a fraction of a second. 

Competition rigs probably use exotic cooling devices to keep the speakers voice coil from melting or some other device generally not included in an "Average Joe's" installation. 

So I'll stick to my opinion that wattage is not a valid measure for speakers. 

In fact, the only thing that really matters is "How do they sound?"


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## daamon_vexion (Aug 6, 2006)

true and not true in the fraction of a second, in most cases when in a Sub competition, the subs in use are "competition" subs, which are very deap and have dual voice coils and heavy duty surrounds, the sounds used in these competitions are taylor made bass clips, that start off at a "high" bass note and go progressively lower, then they raise the volume, and do it again, these notes are not bass punches, but rather a consistant tone.
also most dont have exotic cooling systems, rather, a Kicker 15" L7 solobaric is good for 1200 watts RMS, a buddy of mine has two of those in is Probe, in a 5 cubic foot sealed enclosure, he ran a bass test tape through the subs, (which are connected to one 1k watt each) and proceeded to blow out every window in his car.. after about 2 minutes. Speakers nowadays are specially made for high wattage applications. Myself, i am looking at dual Kicker L7 Solobaric 12" with a 750 watt amp connected to them, this set up is good enough to blow out my back window (they will be pointing up to it in my '92 Stealth) at full volume if i am not careful.


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## crazijoe (Oct 19, 2004)

daamon_vexion said:


> he ran a bass test tape through the subs, (which are connected to one 1k watt each) and proceeded to blow out every window in his car.. after about 2 minutes.





daamon_vexion said:


> this set up is good enough to blow out my back window (they will be pointing up to it in my '92 Stealth) at full volume if i am not careful.


I take it you didn't see this episode of Myth Busters. 

BUSTED


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## StaticInMyHead (Sep 27, 2004)

Has anyone had any experiece with Lanzar, Bazooka, or Legacy amplifiers? These seem to be the budget amps, but if I can pick up a decent one, I'll go with that.


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## StaticInMyHead (Sep 27, 2004)

Ok, I hate to keep bumping this thread without making any progress, but I still have more questions. :normal: I have a power wire running from my battery to the amp, as is normal with all aftermarket stereos. My concern is, will the wire be big enough to support 1200 watts? I was helping a friend with his car today and noticed that the power cable for his 1200 watt amp was absolutely massive. It was over 1/4 of an inch in diameter, which is easily more than two or three times the size of mine. Am I going to need to replace mine, and if so, what is the recommended gauge?


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## crazijoe (Oct 19, 2004)

My 600W/RMS Sherwood amp required 4 gage power cables. I had a power distribution block in the back with a spare battery tied to it for the amps, a 10 gauge cable going from the isolator in the front to the rear battery, 4 gage to the Sherwood amp and 8 gauge to the other 4 amps. I had 2 power stiffening caps on the Sherwood amp and 2 for the others.


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## StaticInMyHead (Sep 27, 2004)

Well, I'll just take the easy way out and buy a new cable for it. :smile: I suppose I could go with something like 2, or even 1 gauge, just to be safe. What size was the fuse that ran your larger amplifier? The one I'm using on my 150 watt amplifier right now if a 30-watt blade type fuse. I looked at the fuse that my friend had on his 1200 watt amplifier, and I couldn't exactly determine what size it was, but the model number has "70A" at the end. I'm assuming it was a 70 amp fuse. Please let me know what size would suffice for my 1200 watts.


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## crazijoe (Oct 19, 2004)

The Sherwood amp had 2x 20 amp fuses on the amp itself and I had a 50 amp wafer fuse at the PDB for the Sherwood and another 50 amp for the other 4 amps..


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## Spacemonkey6401 (Jul 27, 2006)

crazijoe said:


> I take it you didn't see this episode of Myth Busters.
> 
> BUSTED


Sorry for posting something off the thread base, but I watched this episode of Mythbusters, and I don't know how anything didnt' break. But I have seen in person two twelves blow out a back window in a car.


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## StaticInMyHead (Sep 27, 2004)

Ok, here's a wrap on what I've gathered so far. I bought 3/4" MDF to build the box, and some caulking to seal it. I also bought the 5-way terminals for the box, as per the suggestion of the guy at Radio Shack. He gave me a few tips on how to make the power transfer more efficient; supposedly the 5-way terminals do the best job. I bought 4-guage wire for the power lead from the battery (my old wire was either 8 or 10 gauge) and an inline 60A fuse. I bought the three Rockford Fosgate 10 inch P3s like I mentioned before. As for the amp, I went with an MA Audio 1200 watt mono stable at 2 ohms, which is exactly what my wiring setup on the speakers calls for. Between the amplifier and speakers will be 10-guage wire. I haven't yet picked out a capacitor, but that shouldn't be too difficult.


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## yustr (Sep 27, 2004)

I'm confused (so what else is new?)

You have three speakers to connect. Each is a 4 ohm nominal load. You're amp is mono = only one output channel. As I see it there's two ways to connect them:

Series: woofer A + woofer B + woofer C = 12 ohms

Parallel: woofer A/woofer B/ woofer C = 1 ohm. 

You'll probably use series as your amp is not stable driving a 1 ohm load (not many are). So your 1200 W amp will actually be putting out something like 150 - 200 W into the speakers.

You might actually get more sound and better sound if you used two woofers and powered them with a separate mono amp for each.

Also, who designed the box you’re going to build? Was he an acoustic engineer? Did you get it from a reputable reference? If not, you might be compromising even the best equipment. 

Just some thoughts. 

Remember too that when you get free advice you get exactly what you pay for. :smile:


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## crazijoe (Oct 19, 2004)

Most of MA Audio amps are 1 ohm stable. 

@ StaticInMyHead, What model amp were you looking at?


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## StaticInMyHead (Sep 27, 2004)

I designed the box I'm going to build. The last one I designed was so efficient, I thought I'd try it again. I bought the cheapest equipment possible and it sounded just as good and just as loud as my friend's 1200 watt subwoofer setup. For the subwoofers, I'll be wiring the voice coils of each individual speaker in series and running them to a single terminal. From there, I'll wire each terminal in parallel. This creates a load of 2.67-ohms, which requires a 2-ohm stable amplifier. When you have dual voice coils, the wiring options expand a lot. :smile: 
Crazijoe, the model was HK1998


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## StaticInMyHead (Sep 27, 2004)

Ok, I received all of my parts. I finished building the box a few hours ago; now, I'm just waiting for the caulking to dry so I can paint it and put it in my vehicle. All power cables to the amplifier are new-everything is 4-guage. One more concern that I thought I might mention: the amperage of my battery. When my uncle owned the vehicle, he was definitely on a budget. Right now, it has a Walmart brand battery rated at 450Cca, 540Ca. It has run fine for the time that I've had it, but I'm afraid the new strain on the electrical system might overload the battery. I'm no automotive expert, but those amperage numbers seem a bit low. With my single 12" woofer and a 150 watt amp, the lights just barely dim when I play a super-low note on the stereo. I'll have a capacitor for the new setup in a few days, but in the case that I run the capacitor dry for a moment, it's really going to load down that battery. Does anyone have any suggestions as to how many amps I'd need to keep the system stable (preferrably no dimming lights) with the 1200 watts?


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## crazijoe (Oct 19, 2004)

Using the power calculation P = I x E 
1200 divided by 12 would be 100. 
So 100 amps


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## StaticInMyHead (Sep 27, 2004)

100 amps in addition to what my battery currently produces? I don't even know if my alternator could keep up with an extra 100 amp load on the electrical system; it only puts out 105 amps, as it is the stock alternator.


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## crazijoe (Oct 19, 2004)

Usually the amp will never run at a constant 1200 watts. You would have to keep a steady signal at the same level. I wouldn't worry about it.


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