TorchedC5

Ok, well I know it isnt a weak battery, my next target was gonna be the alternator. I'm just worried cause I'm upgrading my system soon to roughly 800 watts rms and if I do this at half that, who knows what's gonna happen. I was thinking alot simpler.

robvuk

I just got a call from a good friend who read my post about the bass tone or sine wave being able to deliver full rms power. I guess there are many car audio amplifiers with digital power supplies that are capable of delivering full PEAK power but not true RMS. I was not aware of this detail since I'm not a car audio nut. Although his point was that the true rms amps like his McIntosh's are capable of this but not the "cheaper" peak power amps. He is correct about this and will definitely make a difference on the test bench but I don't know that it would make much difference with musical program material.

2fast4sanity

Now that I've read all this, I think my head might explode...

RanGer498

where did you buy the 200 amp H.O. alternator?

knewblewkorvette

I had to take two naps before I read it all.
I'm not a cap fan even though my Corvette and Expedition have them.
Running about 1700 watts rms in Vette with 0-gauge upgrades everywhere, yellow top. I have a G.A.P. 15 farad cap but I still get dimming lights at night.
In the Expedition, I'm running 1900 watts rms with 0-gauge upgrades everywhere. I have a Tsunami 40 farad cap and still get major dimming lights at night, I need an larger alternator big time.
I had a 92 Talon TsiAWD with o-gauge everywhere, two Opitima reds, and GAP 15 farad cap. The light dimming was so bad I could pull cars over because they thought I was a cop behind them. If I went louder I the car would die going down the road.
So, where are some good shops to get a RELIABLE hi-output alternators that doesn't cost an arm and leg?

markcz

I'm pretty sure those two choices are either/or

I love the hi cap alt I got from DC Power, but it wasn't cheap.

Gadget01

Something to consider in your battery vs capacitor discussion is response latency. This is important in a system with subwoofers since the amplifier draws such a large amount of power with each bass note. Batteries supply voltage by means of a chemical process and a capacitor discharges from magnetic field collapse (faster) and can therefore better respond to transient demand peaks (just my theory) when installed as close as possible to the amplifier. I like to think of a capacitor as a filter that smooths out the the demand on the entire electrical supply system, hence why in many systems... capacitors have "cured" dimming headlights with bass drops, assuming the charging system can keep up with the total demand.

I have heard the difference a capacitor makes when installed- bass hit with more forceful impact.

johnnyko12

That line I highlighed in red is the important one ppl :-) I think most people who go out and get a cap forget about the whole "if it wasn't good enough in the first place, it's still going to not be good enough with a cap" part of it.

knewblewkorvette

The wasn't cheap part was understated, cha ching. Still, I really need one for my Expedition I might get the cheapest one which is still rated at 185 amps. I'm guessing my JBL sub amps draw up to 180 amps (they are fused at 120 amps each) since I'm just running them at 3 ohms.

I did watch some of the videos on that site, the 3 18"s ripping sheet metal was awesome

Its been a long time since I've been to a sound off. Are they still using caps in SQ and/or SPL vehicles?

0RAAMaudio

I have not had the need for caps in many years but the last time I was running them I was convinced, by a demo, by one of the all time best installers(dozens of mag articles, many world championship builds in SQ, been on numerous TV shows, etc....) to use Batcap products.

A 2 lb Batcap, moderately high output system, old beater truck, horns, big mids, listening with the lights on, engine off, weak battery....The battery died in 5 minutes but before that the system sounded incredible, lights did not dim with bass hits, etc....

I started to get out to grab some jumper cables, he said wait a bit, a couple of minutes later he was able to start the truck, due to what was left of the battery(they recover slightly sometimes) and the Batcap. I was shocked to say the least.

The system came back up, sounded incredible again, no dimming lights, I was convinced and ordered some but parted ways with my high powered system and have ran simpler once since so never had a need to use them.

Rick

Mr.T.

One thing that did not seem to be addressed totally in the discussion, was not just how much power was available, but how quickly it is available.
I say "totally" as the dynamic range discussion did touch on it.

The alternator and battery combo may be rated for prodigious amounts of continuous current, but if the amplifier needs a quick peak to hit an instantaneous low note, the alternator and battery combo may not be able to "react" quickly enough, and you experience a momentary voltage sag. For examples in some power supplies I have seen that use NI-CAD batteries for portable applications, a capacitor is used to supply the peak current, that the NI-CAD is unable to do.

That being said, one could compute the time constant and thus the cap required to address this. I am not talking about being able to sustain the audio system for 5 minutes on a cap!

Open up a car amp sometime: there are actually caps in the power supply section to supply those instantaneous peaks of current requirements.

Additionally, for such peaks you want the cap AS CLOSE TO THE AMP as possible. Wire has resistance, (no matter what the gauge of wire).
If you are drawing say 10 A of current through a wire, and say that length of wire has 0.1 ohms of resistance (for the sake of discussion), V=IR = 1 volt. So the amp would see a voltage drop of one volt from what the power supply (in this case the AMP +Battery ) was providing. Might be another supporting factor for a cap, BUT CLOSE TO THE AMP.

i'll stop rambling now.

0RAAMaudio

Every high end amp I have seen the insides of in person or good pictures of, have a substantial capacitor bank. I have seen many serious power supply internals as well, worked on a bunch, some for high output radars, comms gear, etc....in my 20 years as a tech in the USN.

They were never outside the power supply, all nice and close by, same as when I ran caps in my systems, right by the amps, wire gauges calculated to carry the load, etc...

Rick