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Discussion Starter · #1 ·
...run my ~600w RMS system with my car(engine) off for 60-90 minutes?

I have a Cadence ZRS7000 amp for my sub (900w RMS @ 2 ohms @ 13.8v) and Zapco Ref750.2 for two speakers run out of my trunk (175w RMS x2 @ 4 ohms @ ?? volts)

the ~600w RMS is an estimate as of course I won't be pushing my equipment to the limit, but I do blast it pretty hard while tailgating :cool:

Right now, I can't play music at a moderate volume for more than 10 minutes before my battery drains to the point of needing a jump start to start the engine.

Is this possible without spending a ridiculous amount of money on a ridiculous amount of batteries? Should I just keep my engine running while tailgating/chillin? What do other audio enthusiasts do in this case?
 

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It would be cheaper to leave your car running.

Have you load tested your current battery?

It sounds like it is going bad IMO
 

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look at the deka intimidators. great batteries and they are pretty cheap. I dont know about lasting an hour though. just put in as many as will fit lol.

another option would be to bring a battery charger and find a place to plug it in. something like a 20amp charger and a G31 battery should keep you going.
 

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Best thing to do is run a more efficient setup, then it is a matter of how many batteries you need. By efficient I mean class D amps and ported subs, preferably all drivers of lower wattage as you can go with will be more efficient, and use larger drivers. Beyond that you can get into pro setups with horns and all that, they don't need huge power to get loud. These small box subs everyone runs are anti-efficient they take the most power. I had a system long ago with tens in large ported and 6x9 in a flip up box all in a hatch, it worked great on two 2x75 or 2x60 amps for hours on the standard battery in the car. Did the same thing with quad 10s IB in another car and made great party music.

I found that super loud made the chicks leave and impressed only the guys, I didn't really want that to happen anyway lol so just loud and reasonable SQ was perfect. Later I installed a lot of 6x9 and 7x10 into boats for the same reasons, and IB subs. It really sucks to not have your 500hp BBCs want to start up after partying for a while so we figured out the best systems to run for that. Sound for open spaces is a different game than in a car.
 

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Discussion Starter · #8 ·
shoestring, you beat me to it.

I have a thread over on CA.com where I brought up the topic of system efficiency. (I don't know why I even try to start intelligent conversation there....)

What I have realized is that with only one more tailgate left in the season for me (maybe two if I go to Jets-Patriots), is it far more economical to just leave the engine running. Exhaust fumes are negligible at worst, as I can always point the car away from the wind, as New England weather is always significantly windy.

But when I get a new car, and start my future build(s) this is now something to keep in mind. Most likely I will have two "separate" systems -- one for driving use with a sealed sub, and another with ported subs and boxed, free-standing speakers flanking the ported sub(s).

After reading other helpful threads online, and onerously going over the math, I've figured it is feasible to build a system that is more than loud enough and that can last 60+ minutes using <$400 worth of reliable batteries.

A basic sketch of such a system would be:
  • Two 12" subs (15" if they will fit) in a ported encolusre of APPROPRIATE SIZE
  • Subs mentioned above chosen with efficiency in mind. That is, if one were to trust manufacturer ratings and/or subjective reviews by users.
  • Efficient class-D amp for the subwoofers. Preference given to amplifiers with published and credible efficiency ratings.
  • 6x9" speakers with efficiency in mind. Unfortunately, speaker sensitivity ratings are not standardized. (Many speakers are rated at 2.83 volts instead of 1 watt. This makes it harder to cross-reference speakers with different impedances. Also, some don't even specify what standard is used to rate their speakers). The speakers that I have considered that are rated at 1W/1m all fall within the 89-91db range, which arguably isn't much of a difference
  • consideration of a class-D full range amp (how much will I gain/lose by doing this?)
  • possibly using 4 speakers instead of 2. Not only will this increase efficiency a little, but it will decrease stress on the speakers. This will give me more options as I would be less restrained to speakers with the highest of power handling.

Thoughts?
 

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In general with 6x9 and such, usually the best are a name brand of lower power rating. Back then they had Kenwood 7x10 that worked really well, I don't know if Kenwood has gone up or down market today, but back then they were not that cheap either so likely better K-wood stuff. In cars I used coax not the triax high power/etc. Used alpine, sansui, infinity, etc. (more brands than I can recall) In a boat the multiple tweeters were better, they were brighter and you needed it unlike a car. So pioneer for example were brighter as well as most Kenwood. Typically overpowered the drivers a little, but was careful not to clip them much, you get the most out of the higher efficiency the lower power drivers tend to have....if you could use lower power drivers. I did blow tweeters once in a while. In the boats we pushed them harder usually ran 300w 12v rated amps at 2 ohms, on the other hand most of the time the boat was not running. More 6x9 were better in the boat quads were ideal and three pair better yet. One pair and 6.5s was marginal better have good ones, but pair of 7x10 and 6.5 was not bad. Using x9s and x10s you could get away with out subs, some did because subs are heavy and slow you down and most of us raced people a lot. Some of us built motors and swapped cams/etc all the time doing it low buck on our own. Far as subs sure ported would be ideal. The only issue is if you can't run IB for x9s and large boxes for ported...the higher efficiency drivers will tune poorly when it comes to bass. Those x9s had serious midbass especially quads or more. Or you could always just hit a pawn shop and buy some old huge home speakers with 12s or 15s, then run subs with them, lol, it should work well and even though they are 8 ohms they still should play nearly as loud. Class D will help save power playing midbass, but not nearly what you will see on subs. When I test amps the Kenwoods tend to go pretty loud on 10A with their class AB, all the class D tend to do well but some AB are power hogs. That does not tell you what they do at max power though. One was the kac7202 (720*) and the 910*D sub amps. Anyway, how much room do you have to haul stuff? Pro drivers would work even better, but same deal they need a large cabinet and back to the same thing they don't play bass. I would try quad 6x9 and ported subs, sonotubes would be cool if you can fit them, and much lighter.
 

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Discussion Starter · #10 ·
A little aside here, now that the topic of coaxial speakers arose...

You say you use "coax" as opposed to "triax" or "n-ax" speakers.

I have read into the fact that 4- or 5- way speakers (I own a pair myself) are rather gimmicky, that people buy them sometimes just based on the fact that they are "separated" into as many different components as possible.

I have seen the response curves of many tweeters and woofers, and realize that a good tweeter/woofer combo can sound great and give linear response from the nadir to the zenith of the human range of frequency perception. It's not hard to convince somebody that, at moderate volume, and a well-controlled acoustical environment, a speaker system broken into no more than two components is all you need for a damn near perfect musical reproduction.

But then I thought of this defense of n-axial speakers... maybe, if trying to design a low-cost loudspeaker, breaking it down into 3 (or even four) components may be the best mix of cost-to-performance... ...?

Or, is it still just a gimmick?
 
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