Anonymous
Anonymous asked in Cars & TransportationCar Audio · 1 decade ago

How many ohms stable in bridged?

I have a Kenwood KAC-829 amp and I want to know how many ohms it can take in bridged mode. I know its 300 rms bridged but in how many ohms? its 100 x 2 at 4ohms and 150 x 2 at 2ohms. I cant find anything that tells me the output/ohms in bridged mode.

Also, what kind of protections does this amp have? Like overheat shut off? Too much power shut off? Anything else really? I want to know as much as I can about it. It also has this "gain" nob with numbers from like 1.0 to like 0.2 or something. Whats with the numbers?

10 points to the person who helps me out most. (especially on the main question) answer well cuz someone might out do you :D

Update:

That manual was great and had all the information I was looking for. The amp is supposed to draw 28 amps but it is supposed to have 2x 20 amp fuses. The owner before me put 2x 15 amp fuses in it and the only way I could blow them was by running 2 ohm bridged. Why would they put fuses totaling 50 amps when it can only use 28 amps? why not make it have 2x 15?

4 Answers

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  • Jody
    Lv 5
    1 decade ago
    Favorite Answer

    The best way to know is to go to Kenwoods website and look up the amp's manual. However, following with a simple general rule that if it's a 2 ohm stereo stable amp, the most it will do is 4 ohm bridged.

    Back in the days (circa 80's, early 90's) before anyone was really running low impedances it was normal for cheaper amps to be only able to run 4 ohm stereo and 8 ohm mono.

    Now it's standard for a amp to do 2 stereo/4 mono. High current amps are able to go even lower, but are rarely used in daily drivers.

    Even the rca outputs of back then would not reach too high like as of now. Those numbers you see on the gain is volts to millivolts. Nowadays 1 volt isn't much, but back then it was. It wasn't uncommon to have a deck only putting out about .5 volts (500 millivolts) or even as low as .2 (200 millivolts) if it was cheap. If you run that amp from a newer head unit it is very possible you will have to run a set of these:

    http://www.partsexpress.com/pe/showdetl.cfm?&Partn...

    These will lower the inputt voltage on the amp's rca jacks to a acceptable range. Over driving the amps input won't be a good thing as it can cause early clipping and sound bleed-thru at very low levels to almost no volume at all, even with the amp's gain all the way down.

    I take it you have an old Kenwood? Still nice amps if you can use it.

    http://inform3.kenwoodusa.com/manuals/KAC829.pdf

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  • 1 decade ago

    Most 2 channel amps are 4 ohm stable while bridged. I'd imagine the Kenwood is no exception.

    Most newer amps have thermal protection and short circuit protection. They will protect your amp from being fried from overheating, or wiring the amp to too low of an ohm load. For example, if you bridge the amp to 2 ohms, the amp will not power the speaker to keep the internals from burning up under the extra stress.

    The gain knob is a whole 'nother story. It adjusts the amp to the output of your head unit. It isn't a volume knob. For example, if your CD player's preout voltage is 2 volts, and you set the gain to the 1 volt sensitivity, the amp will be driven into clipping, thus making your speakers distort and sound bad. If you set the gain to the 4 volt sensitivity, the amp will not be making as much power as it could be making. Ideally, you want to set the gain as close to the output of your CD player. To do this properly, you'll need a disc with test tones and a Digital Multimeter.

    Check out this tutorial on the JL Audio website that explains it very nicely:

    http://mobile.jlaudio.com/support_pages.php?page_i...

    The easier, but riskier way to do it, is to set your head unit to about 3/4 volume, and ease the gains up until you hear distortion, and then backing the gain back down a hair. While this method works, you're more prone to inducing distortion, because it's difficult to distinguish lower levels of distortion.

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  • 1 decade ago

    Basically, that's all the options you have. Because it's a 2-channel amp, it won't be 1-ohm stable...or at least 99.99999% of the time.

    You can either run 2 - 4 ohm speakers, or 4 - 4ohm speakers....

    Or, 1 - dual 4 ohm speaker, or 1 - dual 2 ohm speaker,

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  • 1 decade ago

    Features

    Protection circuitry:

    Speaker output contacts ground

    Speaker wire short

    Unit malfunctions and DC is sent to speaker output

    Thermal: when internal temp is high

    Loss of ground of head unit or amp

    Controls:

    Filter control switch: may be set to "off" or "LPF" (for 80Hz low pass operation)

    Operation control switch: can be set for stereo or mono (L channel)

    Input sensitivity control: rotary control that is continuously variable from 0.2 to 5V

    Inputs and Outputs

    Right Side of the Amplifier

    GND: philips head screw for RCA signal ground

    Speaker-level input: gold plated screw terminals (0.24" wide)

    Line in jacks: gold plated RCA inputs

    Left Side of the Amplifier

    Fuses: two 20 amp fuses

    BATT (power): gold plated screw terminal (0.335" wide)

    GND (ground): gold plated screw terminal (0.335" wide)

    P.CON (remote turn-on): gold plated screw terminal (0.335" wide)

    Speaker outputs: gold plated screw terminals (0.335" wide) for left and right loudspeakers (bridged = Left+ and Right-)

    Additional Specifications

    Specifications:

    Rated power output at 2 ohms: 150 watts x 2 (1 kHz, 0.8% THD)

    Max power output at 4 ohms: 200 watts x 2

    Max power output at 4 ohms, bridged: 600 watts x 1

    Input impedance: 10k ohms

    Operating voltage: 14.4 V (11-16V allowable)

    Current consumption (1 kHz, 10% THD): 28 amps

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