22 replies to this topic

[eyeballumbrella]

I am thinking of putting a JL Audio 12w7 in my 98 volvo s70. I know the car has a stock 100 AMP alternator but the question is, is this enough? (the 12w7 runs between 750-1000 rms) Also if it isnt anyone know a bigger alternator I can put in? or another solution?

Thanks!

[Che'_Moderator]

The short answer is no.

You can add a second battery and be ok as long as you do not play it loud all of the time or with some retarded amount of bass boost. If you plan to play hard though go to a 150amp rewind

[eyeballumbrella]

Ive done some reading online (because we all know everything on the internet is true ahaha) but anyways they said that 1000 watts rms will draw 80 amps of power. Is this true?

[Ghost Shadow]

just add up the numbers for the fuses on the amp and it can give you a general idea of the draw

[Che'_Moderator]

eyeballumbrella, on 03 July 2009 - 01:13 AM, said:

Ive done some reading online (because we all know everything on the internet is true ahaha) but anyways they said that 1000 watts rms will draw 80 amps of power. Is this true?

Watts_RMS/13=AMPS
So
1000/13=76.9amps

Thats RMS so peek draw will be a little higher but ANL are slow blow fuses so an 80 amp fuse SHOULD do it but usually you would run a 100a.

[Young Burnsy]

Watt's law is Volts + Amps = Watts.

In a perfect world the electrical system in your car will run at 14.4v.

Do the math.

[Che'_Moderator]

Young Burnsy, on 03 July 2009 - 02:11 AM, said:

Watt's law is Volts + Amps = Watts.

In a perfect world the electrical system in your car will run at 14.4v.

Do the math.

13Volts + 80 amps = 93 watts?

Ok

In a perfect world we would force moderation approval on all your posts........ Maybe I can do my part

[BEJinFBK]

OK...There's a lot of math getting thrown around here, but I have a much simpler approach.

That 80 amps everyone keeps talking about would only get drawn if you ran flat out all the time.
And only with HEAVY bass. Go ahead and install everything. A decent B+ lead to the amp will get
you by for moderate use. Go big. Maybe 4 gauge. Add a cap to carry the bass hits a little better.

If you listen so loud that you do start having charging system problem, upgrade from there.
An Optima yellow top in the back at the amp will do wonders. And a bigger alternator if needed.

But honestly, with one woofer and an easy hand on the volume and bass knobs, you probably won't need it.
Enjoy!

[Young Burnsy]

Thanks Chuck I'm tired I'm glad you know you're here for me from now on I'll send everything to you for approval first.

[Che'_Moderator]

BEJinFBK, on 03 July 2009 - 11:02 PM, said:

OK...There's a lot of math getting thrown around here, but I have a much simpler approach.

That 80 amps everyone keeps talking about would only get drawn if you ran flat out all the time.
And only with HEAVY bass. Go ahead and install everything. A decent B+ lead to the amp will get
you by for moderate use. Go big. Maybe 4 gauge. Add a cap to carry the bass hits a little better.

If you listen so loud that you do start having charging system problem, upgrade from there.
An Optima yellow top in the back at the amp will do wonders. And a bigger alternator if needed.

But honestly, with one woofer and an easy hand on the volume and bass knobs, you probably won't need it.
Enjoy!

And that kiddies is how you clip an amp.

[B Mac]

Chuck do you actually have every toy in the world? What the hell are you using scopes for in your house

[Che'_Moderator]

B Mac, on 04 July 2009 - 01:21 AM, said:

Chuck do you actually have every toy in the world? What the hell are you using scopes for in your house

Trouble shooting. Most recently was tracking out a problem with the PDUs transfer capacitor for my house generator.

[BEJinFBK]

Che makes a good point. Pushing gear too hard burns stuff up! And once the smoke gets out, it's a PITA to get back in.
Sure, if you turn anything up too far, and you'll go into clipping. All I'm trying to say is: you CAN install it, go easy on the volume
and bass levels, and keep current draw of the amp below what the stock charging system and your wiring can handle. As long as
you don't over do it, no problem.If you're really worried about it, set up a voltmeter at the amp power feed that you can keep
an eye on. Good Voltage? Party On! If it sounds distorted and crappy, turn it down. It's just that simple.

In a perfect world, it'd be great to beef everything up, but not everyone can afford it. Life ain't cheap. 'Specially these days.
All I'm suggesting is moving forward with your install in steps. There's no reason you can't get started at a minimum.
Sure, you can hook it up, but you won't get full tilt boogie out of it. At least you'll get some bottom end into your rig.

The trick with ANY system is not driving your tunes into clipping.
If you haven't got a stack of Tekscopes and the know-how to use'em,
It's really all up to you, your ears and your level controls.

Best of Luck!

[eyeballumbrella]

Thanks Everyone!

[Che'_Moderator]

BEJinFBK, on 04 July 2009 - 07:27 AM, said:

Che makes a good point. Pushing gear too hard burns stuff up! And once the smoke gets out, it's a PITA to get back in.
Sure, if you turn anything up too far, and you'll go into clipping. All I'm trying to say is: you CAN install it, go easy on the volume
and bass levels, and keep current draw of the amp below what the stock charging system and your wiring can handle. As long as
you don't over do it, no problem.If you're really worried about it, set up a voltmeter at the amp power feed that you can keep
an eye on. Good Voltage? Party On! If it sounds distorted and crappy, turn it down. It's just that simple.

In a perfect world, it'd be great to beef everything up, but not everyone can afford it. Life ain't cheap. 'Specially these days.
All I'm suggesting is moving forward with your install in steps. There's no reason you can't get started at a minimum.
Sure, you can hook it up, but you won't get full tilt boogie out of it. At least you'll get some bottom end into your rig.

The trick with ANY system is not driving your tunes into clipping.
If you haven't got a stack of Tekscopes and the know-how to use'em,
It's really all up to you, your ears and your level controls.

Best of Luck!

My point was if you look at wave form 2 you can hear that kind of slipping for sure, but waveform 3 sounds totally clean. Real music is not a single wave form, but many over lapped wave forms. All it takes is one to clip. Not saying you need to scope the system to verify it, just saying he may, probably, will have better results pushing a single 12" hard at 700 watts than taking it easy on 2 at 1000 watts.

[eyeballumbrella]

Che, on 04 July 2009 - 02:49 PM, said:

My point was if you look at wave form 2 you can hear that kind of slipping for sure, but waveform 3 sounds totally clean. Real music is not a single wave form, but many over lapped wave forms. All it takes is one to clip. Not saying you need to scope the system to verify it, just saying he may, probably, will have better results pushing a single 12" hard at 700 watts than taking it easy on 2 at 1000 watts.

The only thing is its my buddy's sub so I was going to buy it off him

[kirbo]

Hi VS crew,
just throwing some experience in here, hopefully helping those who are curious. A case study?

My 850R stock alternator is feeding 2 x 75Ah dry cell battery’s which at full volume powers well over 2KWRMS worth of amplification. Being that the STOCK alternator cannot replace the energy as quick as it is being used at full volume, I monitor voltage to ensure: A. The amps are getting enough juice to power the speakers cleanly B. Prevent equipment failure and C. Ensure there's enough juice left to crank the next day. Yes just like the next person I like to crank it to club levels from time to time... But on average the systems @ half volume or less, in this case I don't bother looking at voltage as the alternator charges adequately which is expected.

To this day, after 2 years of constant calculated abuse, I have never had a flat battery or equipment failure including fuses.

If that made no sense or you don't give 2 hoots about my story because it doesnt contain dragons, I'll throw in my advice...
1. Ensure you have 4Ga power cable running to the amp(s) if their total RMS value is >1KW RMS
2. Ensure your fuses can also handle the current draw (I choose ANL fuses). Be sure to keep the number of connections down & the terminal quality up.
3. Ensure your battery is holding over 14 volts @ idle & has over 12.2V shelf life. Anything lower than these values can be caused by either a bad battery, bad connections to earth/alternator or a bad alternator.
4. Loud bass can drain out distortion, so make sure you know your systems max volume before cranking the sub. Don't pass that threshold & be sure to trial assorted music.
5. This is an everlasting subject.

Cheers,
Kirbo.

[Che'_Moderator]

kirbo, on 07 July 2009 - 01:53 PM, said:

5. This is an everlasting subject.

Cheers,
Kirbo.

Its really not. Take your car to a shop and have them hook it up to a scope. You will know in a few seconds if your set up is working correctly or not and if it has enough headroom.

[BEJinFBK]

Che, on 07 July 2009 - 03:39 PM, said:

Its really not. Take your car to a shop and have them hook it up to a scope. You will know in a few seconds if your set up is working correctly or not and if it has enough headroom.

IF you can find a shop that even knows what an oscilliscope IS, let alone how to use one...
90% of the shops I've ever seen are woefully clueless about actual electronics theory.
Unfortunately, "Install, Bill, Repeat" seems to be the norm.

Sad but true, many shops are just in it for the money. The Best Buys and such are usually jokes.
Check around with the indys in your area. If you look around, hopefully you can find a good one!
Look for things like MECP certificates and IASCA qualifications on the wall.

[Che'_Moderator]

Best buy is not an audio shop. Around here I cannot think of a shop without a scope.