mostly OT: bass diminishes under acceleration

None of which has anything to do with my point compared to that of the person I responded to. I would act like a dick too and ask if YOU got that, but it's quite apparent that you did not...

You don't think your ignition system takes more power to run at higher RPM, under a load than it does to idle?

You need two people to do this properly and safely. The last thing you want is to be watching a DMM while accelerating to the point where the bass fades. If you use an analog meter make sure the needle movement is perpindicular to the motion of the car.

-John O

What the HELL is wrong with the one in the cluster?

Am I on an alternate planet here? Accuracy doesnt matter, only relative position!!!

Sheesh!

"WindsorFox" wrote>>> Bass is fine with engine off, running with key in accessory position!

What I was replying to is the fact that the bass won't diminish with the car in ACC since there is no draw anywhere else unless the battery starts dying. Obviously while the engine is idling the amp is getting its power from the alt. But I was commenting about when the engine is OFF and the only power supply is the BATTERY!

"WindsorFox" wrote

Where did I state the engine was drawing more power than the alt puts out!?!?!?! What I said was that the AMP was being starved because the engine needed the power provided by the alt more than the amp did. If he had an amp that drew less amperage, then the problem, would be les noticeable. THAT'S WHY PEOPLE USE CAPACITORS in their stereo systems, to overcome those times when the car needs the power more than the amp does.

"My Names Nobody" wrote

Which is exactly my point. He needs either a bigger alt to supply the power needed when the total drain is higher, or add a cap to the power (+) line before the amp.

No, it kinda does. It's just backwards from the way your going at it. WF is saying that the load goes up as the engine draws more power and RPM's rise. Thus causing the alt to max its output for any given RPM.

MNN is saying that if you add a bunch of accessories to this same system and turn them on. The engine is still gonna want what it wants for any given RPM, the accessories are gonna want what they want and the alt has to divide up the power, causing a power drop across the entire system. As the RPM's go up the alt output will go up also until it reaches it's max output, then you're stuck with the whole system then losing efficiency. You're both right, now stop acting like 9 year olds or I'll send you to your rooms.

The OP's problem is that his alt can't keep up with what the engine wants AND what the amplifier wants, so both suffer. Obviously the amp is the most noticeable since it's a noise in his ear. 2 simple solutions either of which should work. higher output alt OR a mobile audio capacitor in the (+) line before the amp. The bigger alt will obviously make enough power for BOTH systems to get what they need if big enough, and the cap will store energy for those short times while he's accelerating and the total power drops. The amp can draw from the cap to make up for the shortage from the alternator. Or he could do BOTH which many people do. This is not rocket science.!!

The multiple battery thing is a pain in the ass and I wouldn't mess with it.

Well, I've always kinna thought that myself... lol

I know all about caps, but how much current can these things provide and over what time? My experience tells me a capacitor is a way to overcome short-duration supply dips caused by music peaks, duration in the hundreds if milliseconds or less. If I read the OP's symtoms right, he's got full seconds (or more) to deal with. Can a couple 1F caps do that?

-John O

"JohnO" wrote

So what you're asking is, "does size matter?" LMAO!!

Just kidding. In this case it does. If I were the OP I'd go over to rec.audio.car and ask some questions there. My experience is that the big caps can last for several secs, but not any extended amount of time. IF I were the OP I'd just get one of these...

200 amps. That oughta just cover it, ya think? Course It's not my money I'm spending.

Sounds good.

IF I

This is the part I love about this...I wonder what that big alternator does for horsepower. You don't get 200 A of potential current for nuthin, after all.

-John O

"JohnO" wrote

Nope. It'll just mean that the engine will get all it needs. IF it were OVER charging you'd have some real problems. Like batteries exploding and sparkplugs melting. :)

Sorry, I meant power in the the other direction. A bigger alternator can become a bigger drag on the engine. So with that 200 A beastie, the OP gets the juice for his sub but loses some measurable (but maybe not noticable) amount of acceleration.

-John O

"JohnO" wrote> Sorry, I meant power in the the other direction. A bigger alternator

Huh? It's a factory 6g alternator with the internals reworked to output 200 amps. That wouldn't have ANY effect on acceleration. Same size, shape and weight. How does THAT decrease his acceleration abilities????

Physics...you cannot create more power from the same motion. OK, so the new alt may be more efficient, but not 70% more, unless the old ones are total crap. Even so, when you put a load on the generator it creates magnetic drag. Have you ever pedaled one of those bikes hooked up to a generator that powers light bulbs? It's exactly the same deal. (Or look at home AC generators...5k amp models have 15-hp engines, and little 500 amp models have 3-hp engines...)

I'll give you that this may be a negligible amount of drag for a big engine, but it is measurable.

I might be a bit out of whack on that part, but a few sends of digging finds claims that each 25 A of generated juice requires about one hp of input energy. That stat is in relation to AC generators, but with some translation is just as relevant to auto alternators.

-John O

It turned out to be a loose connection. One RCA plug from the head unit to the sub amp (there are two of these, I don't know why) wasn't pushed in all the way, and acceleration (even slight) would bring the connector out of contact. Off the gas, it would make contact again. Anyway, I pushed the connector all the way in and problem is gone. I have nice bass under all positions of the pedal. :-)

I had checked the connections before but only the ones that were readily visible/accessible. I was just about ready to buy a 140A alternator. :-)

Thanks for all the suggestions.

John

93 GT

p.s. My wife has been driving the car and commenting on its lack of power. She said it needs a serious power boost. Problem is, it's a TIRED old engine (298k miles) that was rebuilt at 250k and I don't think it could handle a power adder. I think my only option would be an engine of some kind, either a crate engine or a swap from a wrecked car. I'd love to get something beefy in there.

Backyard Mechanic wrote:

Well, that was good and easy! I was waiting to suggest one of these:

One farad?Ha! How about 58 farads? :-) Good luck with the engine.

-John O