so i got a mtx 6500d amp. i looked up reviews and specs and its rating is:
250 watts max at 4 ohms
500 watts max at 2 ohms
750 watts max at 2 ohms @ 14.4 volts ( which from what i read is achieved by using a cap) is that true?
the problem is i don't know what size cap i would need for this. does anyone know?
i also read that its an amp that is way under rated and pushes into the 1000's.
i have 2 ma audio subs that are 250 rms and 500 max and they are dual voice coil and 4ohms.
i read that if you parallel wire two speakers you can achieve 2 ohms from two 4ohm subs. would that be possible with my subs? and i've been trying to find a free program that will allow me to find the exact measurements needed for my sub box. does anyone know of one that works well?

 

No. A cap is a bandaid for a poor charging system. Having a good battery and strong, possibly aftermarket alternator will work much better.
MTX makes powerhouse amps that easily exceed their power ratings. I doubt this one got into the 1000's, but I wouldnt be suprised. Probably more along the lines of the low to mid800's.

No. You can get a 2 ohm load from one sub but with both subs youre only options are 4 ohms mono or 1 ohm mono.

http://www.bcae1.com/spboxnew2.htm

 

so as long as i have a good battery i'll never need a cap for an amp to reach its peak performance?
i was talking to my friend who's dad owns a speaker shop and he said i need a mono amp thats rms is about 750 watts. Does anyone know of a good amp that runs that at 4 ohms? how would i wire the subs to get 4 ohms mono? series or parallel?

 

series will double your ohmage....so to achieve a proper 4ohm rating with your subs you will have to wire in parallel.......guessing you are planning on having this amp bridged? while it will produce more power from the decreased ohm load....it will shorten the life span of the amp...but with wattage running around a dollar a watt these days......can just as easily buy a replacement amp.....make sure your amp is stable under reduced ohm loads also


they typically state on the packaging "stable at 1ohm" or something along that line.

Most MTX are stable for reduced ohm loads anyways

 

to get a 4 ohm load with your subs, wire each sub in series, then parallel the two subs together when run to the amp.

 

Mac, this is rare since you definately know your crap with A/V, but I have to disagree with you about capacitors. True that if you have an oversized charging system their effect will be less, but caps definately DO help a car system as well as the electrical system of the car itself. Their greatest benefit is that they buffer the electrical system from the large spikes caused by the huge bass hits that in turn cause the amp to draw it's max power. This is most easily noticed by the reduction of the dimming headlight syndrome. Also, your amp RMS should not exceed about 75% of the alternator output, but if you are at this limit, the max will. In this case, the cap will definately improve the overall electrical situation.

This does not apply to SPL competition where you have to sustain a 30 second burp and a cap has no chance to recharge. A cap is for hit, not suspension.

 

You are 100% right. A cap does do all this.

However, if you have an adequate alternator and battery working, then the cap will not be needed and will only be an extra draw on the charging system.

A cap wont hurt anything, and can help act like a band aid on an overtaxed charging system - but youll get better results by upgrading the charging system and unless youre running 50,000 watt amps, youll never need a cap. In fact, the large majority of SPL competitors I know dont use caps. And while they do compete in the 30 second average runs they also do the split second single burps.

 

A properly functioning cap won't cause a draw. The positive and negative sides are seperated by insulation. The cap simply evens out the electrical draw. The average power draw should not increase from adding a cap. Also, aren't SPL comps done with the car off to minimize interference and sound that is not generated by the stereo?

 

I agree about using a cap...not everybody can afford a hi output alt. or heavy duty wiring upgrades and using a cap will store that energy for a hard bass spike (although I am talking non-competition, everyday regular driver cars here), iused a cap on my chevy truck...worked wonders for me even after I upgraded the alt.

best part about the truck...two 12's had the rear glass shking so much you would think it was gonna pop out. miss that box...built really solid

 

A capacitor is a load on the charging system. Albeit not a very big one. It holds a charge so it can discharge quickly when needed, but its the alternator that is feeding it its charge.

SPL has different classes. Some do judge with the engine off but these are the lower level classes. The big dawgs run with the engine running up to 1200 RPM's..