Printer Friendly Forum Posts - Need more juice?

i just installed a memphis mojo amp, and when i have my stereo up loud, the bass will hit like 3 or 4 times, then shut off for like 5 seconds, then hit 3 or 4 times, then shut off again. is this because my amp is starved for power? the amp produces 2400watts rms. would a 3 farad capacitor help at all? upgrading my alternator is the last thing i wanna do. so would a 3 farad help?

If you have a stock alternator and your amp is really pushing 2400 rms, I'm surprised that you even get that much out of it. Yes you need an alt BAD. You run a risk of torching your amp at a really low voltage like that (low to the point of shutting everything down) if you keep doing so.

very good way to melt a nice amp. Just imagin trying to breath through a little straw, then running as fast as you can. im shure you would pass out from lack of air right?.. maybe die..right?.........Common, give your amp some juice! A cap will do nothing for you in your case. Save the money and get a new alt for $300.

well i have a 1976 chevy, with a big v-8 so its not like my alternator is a wimp. but i do understand that i am probably gonna need a new alternator. where is the best place to buy one?

I doubt it is a power issue. Go through and double check your power and ground connections. I had this happen with a bd1000 and it turned out the tinsel leads on the subs were a little to long and would touch each other causing a dead short and sending the amp into protection for a couple of seconds.

-------------
Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.

I've been sick lately, sorry I won't be on much.

hey boss, you might actually be dead wrong. Most older cars have about 60 amp alternators (i know from experience). The lucky thing for you, is that alternators for your car are a bit cheaper than they would be for say.. a honda? I used to own a 1975 dodge dart, it had a 55 amp alternator. I upgraded to a 110 amp alternator. i didnt get to use it lol, i didnt know you had to charge the battery before installing an alt. Anyways, the point is, it only cost 125 bucks. there was a 145 amp alternator for about 180. I'd say, save up some cash, and get the alternator. It'll be cheaper than getting a 3 farad cap. Good luck.

-------------
1990 Honda Civic HB:
Clarion DXZ545MP H.U.
2- 6.5" Power Acoustik interiors
Diamond Audio 600.1 amp
Diamond Audio 15" M6MKII
Pyramid PB881X 4 CH. Amp

what do u mean by tinsel strands? i am unfamiliar with than term...enlighten me.

the small wires that run from the connections on the sub to the voice coil. i do believe correct me if you ment something else.

-------------
Quad L Handyman services

i doubt that its the tinsel strands cause these are brand new subwoofers.

When the amp shuts off, does it go into protection? It could be a low voltage issue, or it could also be a low impedence load. What kind and how many subs is your MOJO pushing?

I have 2 Memphis Mojo 15" subs. They are dual 2 ohm.

i dont know what it is called but they are wired like this.

lets see if i can explain it. + - + - this is on the side of the amp, there is one wire hooked up to the far left positive terminal, and one hooked up to the far right negative terminal. then each wire a splits into two positive and two negative wires. then one positive and one negative goes to each sub.

i have seen some alts for cheap in summit racing's catalog, i think they will fit your truck too.

-------------
2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

okay i went to summitracing.com and they have 140 amp alternators, now is that gonna be enough juice to power everything well?

anyone else have any other suggestions......bump bump bump

if i read it properly, he's got them wired to .5 ohms ohm. That might be the problem. I think... i forgot what amp he said he had. Let me get this right... what you are saying is that, from the positive end of the amp the wire goes to the positives on the subs, and the negatives goes to the negatives? right? alright, how do you have the subs them selves wired? positive to negative, or positive to positve? (series, or parallel)

-------------
1990 Honda Civic HB:
Clarion DXZ545MP H.U.
2- 6.5" Power Acoustik interiors
Diamond Audio 600.1 amp
Diamond Audio 15" M6MKII
Pyramid PB881X 4 CH. Amp

the mojo amp is only stable at 2ohms

-------------
Memphis MC-1300
2 12" JLw6v2
Diamond audio M3 6x9
Diamond audio M3 5.25 components
Audio control Matrix
Carputer

The Pimp from Chitown is right. You apparently have your subs wired in parallel-parallel and that will result in a 0.5-ohm load. The MOJO amp cannot handle that low a load and that is why your amp is cutting out. Assuming the amp you have is the 16-MC2000D, it is a mono amp stable to 2-ohms. Your subs need to be wired like this:

posted_image

If interested in a high amp alternator, just let me know the year, make, model, and engine size and whether or not it has a/c or not and I can let you know what we can do...Most of those old cars have at most a 61 amp alternator which isn't much of anything...For those old style alternators, we can usually build either a 160 or 200 amp alternator in a 1 wire set up...So just let me the specifics and we can go from there...

-------------

Upgrading your alternator is a good idea... I have a honda accord, with a 1500w amp.... It would shut off from time to time one day... I traced it to the ground connection, check and make sure that the connection is to bare metal, connected to the frame or as close to it as possible of your car.. make sure you scrape off anything that could worsen the connection, paint, dirt, grease etc... Hope this helps... Peace

I have a 1976 Chevrolet Silverado 1/2 ton Pickup with a 350 small block. and yes i have A/C but it is currently not working at the moment,

ok now about the wiring situation...first i had an audiobahn a2200hct amp hooked up to the Mojo 15"s. i had it professionally installed so anything behind the woofer, i havent seen how it is wired. all i did was unhook the wires from the audiobahn amp, and hooked up the mojo amp. could this be my problem? does the audiobahn amp have a lower impedence stability? on the audiobahn, the 2 channels were bridged to one.

4 Ohm Stereo: 200 X 2 Watts

2 Ohm Stereo: 400 X 2 Watts

1 Ohm Stereo: 600 X 2 Watts

4 Ohm Mono: 400 X 1 Watts

2 Ohm Mono: 800 X 1 Watts

1 Ohm Mono: 1600 X 1 Watts

I just looked up the vehicle and it takes a standard 10SI case...We can do a 10SI case in a 160 amp 1-wire alternator in both standard case and in chrome...Just send me an email at nickm@iwmaudio.com if interested in one of those 2 options...We can also discuss the price of those as well...

-------------

The Memphis amp you are using requires no less than a 2-ohm load. Using 2 of the DVC 2-ohm speakers, they can either be wired at 0.5 ohms (won't work, might have worked on your Audiobahn amp) at 2-ohms (what I suggested earlier) or at 8-ohms (would work fine and not drive the amp very hard, but you would not be happy with the loss of SPL.)

You will have to check your subs to see how they are wired. Taking straight resistance readings with a meter will not always tell you how they are wired.

It may still be that you are simply overloading your alternator, and I highly recomend you upgrade it as well. But if your speakers are overdriving the amp, no alternator will help you,.

Well i have a strong feeling that it has to do with my alternator, seeing is that my amp only shuts off when my volts drop to below 10 volts or so.

Well why didn't you say that before? Yes, if you voltage is dropping to 10 volts the amp will shut off on low voltage. UPGRADE YOUR ALTERNATOR.

If you are not going to fix the air conditioning soon, take off (or cut off) the belt to the A/C. You'll take a load off the alt.