I know mtx is known for its toughness

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  • PoweredByDodge
    PoweredByDodge Posts: 4,185
    edited October 2005
    ehh... i'm not a big fan of just hooking it to switched 12 v... i mean, why leave your amplifier on when you're just toolin down the road with the radio off?

    rather, i suggest this... get a small 3 or 5 amp relay (you'll only need about 1 amp, but i dont think they make relay's that small)... hook the normally open terminal #30 to the amplifier's REM trigger and also use it to power the pre-amp device. hook #87 and #85 to the cigarette lighter 12 V switched power... then hook #86 to a small toggle switch under the dash - the other end of the toggle switch should be hooked to ground... this will allow you to turn the amp and the pre amp on and off with the toggle, but still will shut them off if you turn the car off.
    The Artist formerly known as PoweredByDodge
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  • hellohello
    hellohello Posts: 428
    edited October 2005
    there are very few times im in the car with the radio off... :)
    Picking ones nose signifies a strong sense of self discovery :)

    System in the works: ;)
    PP 6V6 with 12ax7 pre ~ 20 watts
    15" Jensen MOD 8ohm ~ 97db SPL
    DiMarzio HS3 and/or Tone Zone S
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  • hellohello
    hellohello Posts: 428
    edited November 2005
    well, i managed to find a steal on the mtx, now i need to figure out what kind of fuse i need for the battery, ill be using 2 amps most likely in the near future, so how would i calculate that?
    Picking ones nose signifies a strong sense of self discovery :)

    System in the works: ;)
    PP 6V6 with 12ax7 pre ~ 20 watts
    15" Jensen MOD 8ohm ~ 97db SPL
    DiMarzio HS3 and/or Tone Zone S
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  • neomagus00
    neomagus00 Posts: 3,899
    edited November 2005
    add up all the fuse values of the amps, and then find the closest fuse; round up rather than down
    It's not good, very fundamentally simply not good. - geolemon

    "Its not good enough until we have real-time fearmongering. I want my fear mongered as it happens." - Shizelbs
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  • PoweredByDodge
    PoweredByDodge Posts: 4,185
    edited November 2005
    figure out how much power you're using... this is probably the "best" way to do it.

    say 75 x 4 at 4 ohms to high = 300 w
    and 600 x 1 at 2 ohms on a mono sub amp = 600 w

    divide by 0.78 for class AB amps... and 0.85 for D's...

    300 / 0.78 = 384.6 / 14.4 v = 26.7 amps
    600 / 0.85 = 705.9 / 14.4 v = 49.0 amps

    49+27 = 76 amps... use an 80 amp fuse.


    Or... go with the simpler, more commonlyused type of way...

    add up fuse ratings for all your amps...

    4 channel has say two 25 amp fuses.
    mono sub amp has say three 25 amp fuses.

    that's 125 amps... knock 20% off... and use that as a fuse.. 125 - 20% = 100 amp fuse.
    The Artist formerly known as PoweredByDodge
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  • MacLeod
    MacLeod Posts: 14,358
    edited November 2005
    I doubt youd need anything bigger than an 80 amp fuse anyway unless youre running a LOT of power. Im running nearly 1000 watts and only use an 80 amp.

    The fuses in the amps arent necessarily the amount the amplifier will draw. In fact its doubtful the amplifier will ever draw anywhere near its fuse rating.
    polkaudio sound quality competitor since 2005
    MECA SQ Rookie of the Year 06 ~ MECA State Champ 06,07,08,11 ~ MECA World Finals 2nd place 06,07,08,09
    08 Car Audio Nationals 1st ~ 07 N Georgia Nationals 1st ~ 06 Carl Casper Nationals 1st ~ USACi 05 Southeast AutumnFest 1st

    polkaudio SR6500 --- polkaudio MM1040 x2 -- Pioneer P99 -- Rockford Fosgate P1000X5D
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  • PoweredByDodge
    PoweredByDodge Posts: 4,185
    edited November 2005
    not so true... mtx 500D's had 3 25 amp fuses = 75 amps...

    - assume 85% effiency (rough)
    - 500D's actually did between 775 and 850 x 1 into 2 ohms.
    - rated at 14.4 V.

    that's 69.4 amps (70A) at the 850 watt number. only 5 amps below the fuse rating.
    The Artist formerly known as PoweredByDodge
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  • MacLeod
    MacLeod Posts: 14,358
    edited November 2005
    Were they really that effeceint? I wouldve thought more around 65%.
    polkaudio sound quality competitor since 2005
    MECA SQ Rookie of the Year 06 ~ MECA State Champ 06,07,08,11 ~ MECA World Finals 2nd place 06,07,08,09
    08 Car Audio Nationals 1st ~ 07 N Georgia Nationals 1st ~ 06 Carl Casper Nationals 1st ~ USACi 05 Southeast AutumnFest 1st

    polkaudio SR6500 --- polkaudio MM1040 x2 -- Pioneer P99 -- Rockford Fosgate P1000X5D
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  • PoweredByDodge
    PoweredByDodge Posts: 4,185
    edited November 2005
    class D amplifiers are all betwen 80 and 85% efficient unless they're junk. that's the whole purpose of class D... efficiency.

    class AB's can be anywhere from 60 to 75% efficient.

    ex... mtx thunder 404 (newer model - circa 2 yrs ago or so)... 50 (2 25's) A fuse.
    200 x 2 into 4 ohm load at 14.4...

    say 45 amps (5 less than the 50 fuse rating) * 14.4 = 648 ...
    400 / 648 = 62% ... it's probably better than that... but its around 65% ... some can be as efficient as 70 or 75 ... but it's not the norm.
    The Artist formerly known as PoweredByDodge
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