[mikebert]

Hey guys, I need some help getting some tunes back in my 'stang since some assclown decided to break in and take my stereo and amp.

The stereo is under control, I have sound coming out of all the cabin speakers just fine. My problem is the amp - I had an 100w x 2 channel amp. I think it was a Jensen affair, anodized light blue, aluminum case? Does that sound right to anyone familiar with Jensen's old products? The amp, along with the subs, came with the car. I don't know anything about the subs except they were made in China; there are no other markings. The entire system came with the car and worked fine for years, so I doubt the problem is with wiring, etc.

Anyways, I plugged everything up and no sound comes out. I finally get the idea to check the 25A fuse in the amp, and it's toast. One late night trip to Wally's World, I have 5 more fuses. One fuse after that, I grab the multimeter and see that the amp is getting 34A.

Is any of this normal? The line coming from the battery has an intact fuse, but I have no experience working with amps. Is ~34A normal? Is this just a pissy little amp that can't handle normal power? Should I buy a line that steps down the power coming from the battery? I honestly just don't want to spend the bones on a good amp since I have no idea what the specs are for the subs and if I'm going to lay out a few hundred on an amp, I'm damn sure going to match it to the subs. Plus, I have a lot more important car parts laying around my room (heads, intake) that I'd rather spend my time and money installing first.

Any help guys?

[TheUNZippee!]

I would suggest taking it to an audio store that deals in car audio, and have them bench test it. Jensen is typically not a high end product however, and I wouldn't be surprised if it's fragged. One nice thing about car audio, is you can build it slowly in stages, just like doing up the performance of the car, so if you buy a good amp, and it turns out you have crappy subs, you can just take it easy on them until you have some cash for decent subs. Nowadays, you can get really decent equipment for affordable prices.

[fogged306]

Whats 34A? Do this... hook up just power ground and remote, nothing else, no speaker wires and no RCA's and see if a fuse blows and make sure you have a solid ground. If the fuse is blowing on the amp with just the power connections hooked up, it is toasted. If its the fuse in the power line then that might be another story.

If you buy another amp, definitely make sure you get the right amp. What speakers are you running, how many coils per sub, how many ohms are the coils, and whats the RMS rating on each?

[mikebert]

Ok, let me rephrase my bit of writing since I was under stress when I wrote it and left something out.

First of all, let me repeat that I know NOTHING about the subs. They came with the car, they have no markings or stickers. I have no idea what max or RMS power is. How can I test ohms with a multimeter?

The Jensen amp got stolen. I have some cheapo thing from Best Buy that I got in the hope of at least being able to listen to music again. 302 - cats + Flowmasters /= audible unless I have some help with the bass.

My problem is that I keep blowing out the 25 amp fuse in the amplifier. I have checked the cable from the battery and it looks good, without being pinched or rubbed somewhere. I am getting 34 amps from the battery to the ground wire in the trunk.

So is 34 amps from the battery normal? Do I need to find an amplifier with a 35 amp fuse? Can I make this amplifier work by somehow reducing the amperage coming into the amplifier?

[320hpPony?]

THe fuse on the amplifier itself is usually for the pre-amp stage of the amplifier. If it keeps blowing, your sub might be blown. THats what that fuse is there for, if your sub blows, the fuse pops and saves your amps pre-amps from damage. AS for the 34 amps from the battery, the reading depends on the size of the battery, guage of power wire and its impedance per foot rating. My amp is getting 100 amps ( as i have a 100 amp fuse righjt off the battery).
How big is the fuse on the power wire ( the one that should be within 18" of the battery)? It most likely be a 60 or 80 amp blade fuse (Just like the ones in the fuse box of the car but a lil bigger). If your amps fuse keeps blowing, do what fogged said, hook up the amp without any speakers hooked up. If it still pops fuses, retrack your wires and make sure they go to what they are suppost to go to. Big red wire to battery, black wire to a "good" ground, and little red or blue wire to the power antenna or remote turn on wire on the back of the stereo. If they are all in the right places and the fuse doesnt pop without any speakers hooked up, i will almost promise that your sub is smoked. If the fuse opos without the speaker hooked up, return that amp and get another as the pre-amp is fried. YOu might have caused it or it might be a factory defect.
THere is no reason to try and regulate the power coming from the battery, the more power the better as the rating of the amplifiers (from the factory ) are measured with 14.4 volts as opposed tp the common12.9 volts in our cars. THe subs also may be wired with to low of an impedance for the newer amp ( which i doubt because if a Jensen will run it then about any amp should be able to handle that load). To check the impedance with a multi meter, set it too the symbol that looks like the "omega" sign. THat is the sign for "ohms"
IF ya need anymore help, feel free to email or IM me.

[mikebert]

Thanks for the feedback, I had already taken the amp back before reading your reply.

The fuse in the amp would blow as soon as I connected the amp to the ground and power. So I guess it was toasted like you said.

I do not know the rating on the fuse from the battery. It looks like a sealed unit and I cannot tell how to get the fuse out. By the way, the fuse is about 8 feet from the battery, so I guess I need to relocate that 18 inches from the battery. Previous owners, ya know?

So does blowing the amp fuse not have anything to do with the amperage on the line from the battery?

[fogged306]

Originally Posted by mikebert Ok, let me rephrase my bit of writing since I was under stress when I wrote it and left something out. First of all, let me repeat that I know NOTHING about the subs. They came with the car, they have no markings or stickers. I have no idea what max or RMS power is. How can I test ohms with a multimeter? The Jensen amp got stolen. I have some cheapo thing from Best Buy that I got in the hope of at least being able to listen to music again. 302 - cats + Flowmasters /= audible unless I have some help with the bass. My problem is that I keep blowing out the 25 amp fuse in the amplifier. I have checked the cable from the battery and it looks good, without being pinched or rubbed somewhere. I am getting 34 amps from the battery to the ground wire in the trunk. So is 34 amps from the battery normal? Do I need to find an amplifier with a 35 amp fuse? Can I make this amplifier work by somehow reducing the amperage coming into the amplifier?

The amperage has nothing to do with it. It is the voltage that you should be concerned with. if you are between 13.8v and 14.4v when the car is running then you are fine (anything above like 11.5v and up when off should be fine also). Test this right at the power connections at the amp and put the black lead on the ground connection and the red lead on the power. You should get a reading similar to the ones mentioned above.

Another question that would shed some light.. does the fuse blow instantly or does it blow when you turn the key on?

Electrical circuits will draw only as much amperage as needed. I dont know where you are getting the number of 34 amps to be completely honest, must good multimeters will only have the abilitly to test up to 15A circuit and when testing that you have to break the circuit open to get a reading. Not to doubt on your knowledge, but if you are getting a reading like that you are doing something wrong, especially when there is a blown fuse in the mix because that constitutes an open circuit, meaning that you will get a reading of 0 amps.

Yes like said above a multimeter will tell you how many ohms a sub is. If it is a 4 ohm coil you will get a reading of about 3.7 ohms or so and a 2 ohm coil will actually meter at around 1.8 or 1.9 ohms. If you can, post some pics of the subs and maybe myself or someone else can tell you what they are.