amp loads

neomagus00
neomagus00 Posts: 3,899
edited September 2004 in Car Audio & Electronics
aight, quick question: what happens if you drive an amp to a too-low impedance? say if it's designed for a minimum of 2 ohms / channel and you put 1 ohm on a channel? i know that the voltage will ramp up twice as fast, so you can't turn the volume knob up as far (though you will get the same dBs out of it with that reduced travel)... are there any other effects? if so, a technical explanation would be appreciated, if it's available...
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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  • mbdyer12
    mbdyer12 Posts: 220
    edited September 2004
    From past experience, it gets REALLY hot and fries like throwing a box of garbage bags in a camp fire. Ohh that was fun.

    Of course, this was with a DHD amp. Haha...
    2005 Subaru Impreza WRX
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  • exalted512
    exalted512 Posts: 10,735
    edited September 2004
    from my understanding...amps that are not made to go down to 1 ohm has everything to do with the materials used inside the amps
    theyre not made to handle that kind of load...so if you put a load on them that they cant handle...stuff breaks
    as far as my technical explanation
    "**** breaks"
    -Cody
    Music is like candy, you have to get rid of the rappers to enjoy it
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  • Joelsbass
    Joelsbass Posts: 637
    edited September 2004
    it's a realy good way to let the magic smoke out of the amp....
    MacLeod: I guess youre lucky Polk has such lax hiring standards.

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  • dougie07
    dougie07 Posts: 53
    edited September 2004
    By decreasing the resistance (2 ohm load to 1 ohm load), you increase the current flow (amperage). And when you try to increase the current flow through wires, and other parts in the amp that can't handle that much current flowing through them, they start to heat up. When they heat up, stuff starts to burn, melt, etc. I know Cody said the same exact thing, I just thought I'd throw a few technical terms in there to expand on his technical explanation a bit. :D

    Doug
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  • neomagus00
    neomagus00 Posts: 3,899
    edited September 2004
    awesome - the stuff before dougie's post saved a good amp, and dougie explained why I have to spend more money... thanks guys (gals? are there any here?)...
    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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  • LittleCar_w/12s
    LittleCar_w/12s Posts: 568
    edited September 2004
    in addition... even if you ran the amp at the say, 1ohm vs the rated 2ohm, and only turned it up half way so that it outputted out a wattage within it's limits, the lowered impedance will create havoc with the feedback circuits in tha amp and the THD become very bad.
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  • MacLeod
    MacLeod Posts: 14,358
    edited September 2004
    Thats evident even when running at 2 ohm loads. Most amps THD distortion triples at a 2 ohm versus a 4 ohm load so you can imagine what a 1 ohm load would be like. 6% THD?

    This is the reason I dont like bridging 4 channel amps to run as 2 channels.
    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
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  • PoweredByDodge
    PoweredByDodge Posts: 4,185
    edited September 2004
    as stated... if an amp is rated (lets speak more practically) at 4 ohms bridged... and you run it at 2 ohms bridged...

    now the amp is rated at 300 watts x 1 bridged at 4 ohms... and u run it at 2 ohms, but stay at or below 300 watts of power output.

    so you're not going to HURT anything... but...

    damping factor is cut to 1/4 or something aweful like that... thd goes up - random bad ****.... etc etc
    The Artist formerly known as PoweredByDodge
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  • Jstas
    Jstas Posts: 14,804
    edited September 2004
    Originally posted by MacLeod
    Thats evident even when running at 2 ohm loads. Most amps THD distortion triples at a 2 ohm versus a 4 ohm load so you can imagine what a 1 ohm load would be like. 6% THD?

    This is the reason I dont like bridging 4 channel amps to run as 2 channels.

    It actually depends alot on the amp. D class and T class (new) seems to be more resilient at lower impedance levels. It's the A and AB class amps that have troubles with low impedances the most.

    Consequently, you see massive power house D-classers with thousands of watts avaiable at 2 ohm and below impedances but THD rathings in the 1-2% range. That's pretty good for such a large amount of power. Class A and AB amps will get decidedly ugly the lower you go. That is mainly because of the way the power supplies and circuits are designed. D class is beefy and often over built by most companies for what the amp will be doing. A and AB amps are not always as big and powerful but rely more on finesse than brute force. The T class amps are very much like D-class but with a wider frequency band.

    I realize it seems rather sophomoric to use such general terms to describe something so specific but without diagrams and an understanding of circuits, it's difficult to get the idea across accurately.
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  • MacLeod
    MacLeod Posts: 14,358
    edited September 2004
    Originally posted by Jstas

    I realize it seems rather sophomoric to use such general terms to describe something so specific but without diagrams and an understanding of circuits, it's difficult to get the idea across accurately.

    Dont sweat it bro, youre speaking my language; slow and with small words! ;)
    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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  • exalted512
    exalted512 Posts: 10,735
    edited September 2004
    is this the reason why most component speakers are 4 ohms and not 2??
    -Cody
    Music is like candy, you have to get rid of the rappers to enjoy it
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  • neomagus00
    neomagus00 Posts: 3,899
    edited September 2004
    jstas - i do have a bit of understanding on this, and it interests me, so pm me if you've got anything like that (and we can save mac the headache :D)
    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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  • jamas33
    jamas33 Posts: 89
    edited September 2004
    If you do that.. you can save alot of money.. instead of buying a George Foreman Grill you can just use the AMP. Make sure bring some sauces for marinating
    Equipment List:
    Head Unit: Kenwood Excelon XXV-005
    Planet Audio P13.3
    Ipod 60 GB
    XBox
    AMPS:
    Kicker KX1200.1
    Kicker KX850.4
    Speakers:
    Front: Kicker RS65
    Rear: Kicker RS65
    Rear Deck: Pioneer 4x10 (AAARGH)
    Subs: 2 Kicker 15L7

    my car: http://www.cardomain.com/ride/571313
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