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how much drain on alt.

Discussion in 'Audio' started by anatomiczero, Oct 8, 2001.

  1. anatomiczero

    anatomiczero 1/2 ton status

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    How many amps is a stock alternator, can it supply enough juice for an amp consuming 40 amps at 4 ohm. what is 4 0hm, 2 ohm?

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    soon to have a blazer/jimmy
     
  2. flblazer

    flblazer 1/2 ton status

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    i am runnin a 900 watt amp with a stock alt with 2 oms an 4 fogs still runs my k5

    can some 1 find me a ford i need to take a pee still peein on that ford just have to keep goin dam i can not stop pissin:) k5s kings
     
  3. anatomiczero

    anatomiczero 1/2 ton status

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    Cool, I should have no problem then.

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    soon to have a blazer/jimmy
     
  4. solowookie

    solowookie 1/2 ton status

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    you also gotta realize that unless you got it cranked you're not drawing the entire 40 amps... also, these are rated at 12 volts, and your truck is running at 14.4v.

    I ran a 750 W amp, and a 500 W amp in my GTP with a 105 amp alt, and never had a problem.

    <font color=blue> Jeff - may the force be with you</font color=blue>
    <a target="_blank" href=http://coloradok5.com/gallery/Jeffs-Stuff>link to k5's</a>
     
  5. '73 K5

    '73 K5 1/2 ton status

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    Stock alternator ratings are different through the years. For my 1973 K5, the ones that came without A/C came with a really weak alternator somewhere in the 40's amp range. The ones with A/C got a 63 amp version.
    There is a very small number of amps that consume 40 amps of power and even when they do it, its only for a very short period of time. What I'm trying to say is, as long as you don't have the volume maxed out 24/7, your alternator should be fine.
    4 ohm and 2 ohm are ratings that refer to the resistance that an amplifier sees. The smaller the number, the less resistance of course which means more power...but not all amps can handle a lower ohm load. You change the resistance for the amp by wiring your subs differently...series or parallel or a combination of the two.

    '73 K5
    Chevy good...Ford bad
     
  6. '73 K5

    '73 K5 1/2 ton status

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    I think 14.4 volts is a little optimistic. All of my trucks have been in the 13 volt range when they were running. Amp makers use all kinds of different voltages to test their amps...not just 12 volts. Even though the power supplies are regulated, it still helps to get as many volts through as possible. Thats why you'll see alot of those companies listing the power output of their amps xxx@14.4 volts or higher because it will pump out more power. Its kind of like cheating, but as long as you keep that in mind when you shop for an amp usually you'll be fine. I like it best when they test the amps at 13.8 volts...its the most "real world" in my opinion. Or even better, sometimes they will have a couple rows of results from tests at different voltages...something like 12, 13.8 and 14.4.

    '73 K5
    Chevy good...Ford bad
     
  7. anatomiczero

    anatomiczero 1/2 ton status

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    Thanks for the help. Do two 12" subs sound a lot better than two 10"?

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    soon to have a blazer/jimmy
     
  8. solowookie

    solowookie 1/2 ton status

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    oh you are gonna start a debate with that question! LOL

    my personal opinion is that 10" subs are more 'accurate' then a 12" sub... I like the sound better, and so that is what I typically run.

    subs are puchased for 2 reasons; for kids to make noise, and for sound quality. I guess it depends on why you would want yours? however, I also know several people who use 12" &amp; 15" for sound quality.

    did I confuse you enough???

    <font color=blue> Jeff - may the force be with you</font color=blue>
    <a target="_blank" href=http://coloradok5.com/gallery/Jeffs-Stuff>link to k5's</a>
     
  9. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Atomic,

    Yeah that's real 'firestarter' all right..... [​IMG]

    I've got a couple of ported 10"s in my K5 along with four 6" midbasses and two tweeters....it is LOUD and CLEAR and DEEP!!!! ....even with the top off.

    There are a couple of things to keep in mind:

    1. Bigger speakers can move more air, but are harder for the amp to control....that's why people generally say that the larger subs sound "sloppy". It is very hard to create instantaneous motion from a heavy cone, and equally hard to stop it on a dime. There is a term called "hangover", and unless you have a VERY powerful amp you are likely to experience it on the larger speakers.

    2. In my opinion, much of what people enjoy and call "BASS" is actually handled by the midrange or midbass drivers. The "snappiness" or "punch" of a system does not come from the frequencies in the 80Hz and below region....they are at frequencies above that, maybe up to around 200Hz. When you build a system that integrates the subwoofers and the midrange drivers well.....the "BASS" feels very deep and tight. My opinion is that this is what most people want, but are under the assumption that the subwoofers alone will provide this.

    I don't know where you live, but if you are in the San Jose area, I'd be happy to demo my new system for you. I even set it up in such a way that I can shut off the various speakers and listen to the specific frequencies of just the subs, or just the mids, or tweets....it's a good way to learn which speakers are doing which "sounds" in the music.

    Just my .02

    -Greg72
     
  10. solowookie

    solowookie 1/2 ton status

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    actually I don't think that is that optomistic...

    I've had several vehicles which run that, and walk into a stereo shop with that same question.

    now I haven't measured my 2 k5's, but in the US I think that is a pretty common voltage to assume.

    <font color=blue> Jeff - may the force be with you</font color=blue>
    <a target="_blank" href=http://coloradok5.com/gallery/Jeffs-Stuff>link to k5's</a>
     
  11. anatomiczero

    anatomiczero 1/2 ton status

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    Thanks for the help everyone.

    Greg...What about 2 ported 10's in the back, 2 6" midbass between the front and rear seats with tweeters on the side by them and 4"x6" in the doors? So would I hook the 6's up with the teweeters to the reciever for the rear, then an amp for the 10's? Thanks for the offer but I live in WA.


    &lt;edit&gt; I looked at some prices for tweeters and mids and they're too expensive seperatly for me, how bout a 3 way 61/2"?
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    soon to have a blazer/jimmy<P ID="edit"><FONT class="small">Edited by anatomiczero on 10/09/01 07:12 PM.</FONT></P>
     
  12. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Atomic,

    Are you planning on buying a 1st Gen K5? What years are you focusing on?

    I know that the 1st Gen K5's have a TON of space in the doors for speakers up front. I am not sure why you mention the somewhat oddball size of 4x6" speakers, unless maybe you have them already?

    Here's what I would do:

    If you already have the 4x6s...use them for the rear seat passengers, and run them off the built-in amp of the deck. Use either an electronic crossover or "bassblockers" to keep the low frequencies out of them. They'll sound better and play louder.

    Buy an amp that can run the 10" subs, AND the front door speakers. I can personally tell you that ported 10's can be made to sound AWESOME and will play plenty loud even with the top off. I am using a roughly 1 cubic foot ported enclosure for each one, with a JL Audio 10W3 sub. Eack sub gets a 200W channel off the amp, and that seems to be plenty of power to really make them 'dance'!!!!! [​IMG]

    For the front door speakers, you could get really wild and go with two 6" drivers in each door, and a tweeter up high (near the vent window). After completing my own K5 system recently, I now believe that having more mid-bass drivers in a system is the KEY to having a really "punchy" bass effect in a vehicle. A single 6" in each side would probably work fine too....it's really a question of how insane you want to go.....

    The reason that I suggest putting the larger (and higher quality) speakers up front is to give you a better overall sound. The majority of the sound should appear to be coming from the front of the vehicle, so you need to concentrate on that, and give those door speakers some GOOD power from a dedicated amp too. The subs are in the back, but if you set the crossover point correctly (less than 80Hz) it will seem like they're up front too!!!

    Anyway, that's my idea for you. Others may have different opinions. Try to find someone with a system you can listen to, and find out what's in it equipment-wise. It will help to determine what you like, and where to spend your $$$$$. Obviously, try to find big trucks to listen to.....and convertibles! You can't fully appreciate how much sound is lost in an open top vehicle and how much power it's probably going to take to hear it clearly when the top's off.... something else to consider. [​IMG]


    -Greg72
     
  13. anatomiczero

    anatomiczero 1/2 ton status

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    Thanks for the ideas again, i'll know what to do now!

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  14. txguy

    txguy 1/2 ton status

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    FYI, for those of you wondering about the ole does two of "X" sound better then two of "Y", and if so how much...

    There used to be a company that made a set of 4 eights, that ran with the big boys "15"s... Basically they have subs that also have a separate monitoring loop (accelerometer if you will). What they do is take the input signal, and compare it to the output signal (from the accelerometer) and when there is a difference in the two signals, they amp/computer makes adjustments to match them up as closely as possible on the fly. From what I understand, this made it almost impossible to distort the sound. It was the best of both worlds. Accurate, and massively hard hitting.

    Also go to http://www.aurasound.com/, then under bass shakers...
     
  15. DesertDueler

    DesertDueler 1/2 ton status

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    I use to have two 12s (Pioneer) in a bandpass box with a 600 watt amp (Keenwood), two eights in truck boxes with tweeters (Rockford subs with motarola tweeters) with a 250 watt amp (Rockford), two 6x9s and four 1" tweeters (Keenwood) powered by a 400 watt amp (Keenwood). You could here the music clear from one end of a parking lot to the next. My parents could here the music from the Jimmy at the stop sign by the house. Thats 1/8 mile away!! Build it with quality stuff and it will sound great. BTW I used my stock 65 amp alt. I needed a strike cap though because the last time I ran all that for a 1.75 hour trip I smoked the wire that is suppose to recharge the battery because it was pulling so much through it for so lone it fried the wire. Best bet is to run at least a 8 gauge wire to the battery from the alt. The reason I dont have it anymore is that all of it got destroyed in the rollover.

    86Jimmy 4"&35"MTRs,87 burb 4"&35"MT,69Firebird w/525 hp,and 70GTO live in PHX,AZ<a target="_blank" href=http://www.geocities.com/modifierperformance>My vehicles</a>
     

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