? about alpine cda-9813

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Kadetheus

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Joined: January 15, 2003

Location: United States

Posted: June 23, 2003 at 10:57 AM / IP Logged

i was wanting to know a little about the alpine cda-9813. i know that it pushes 4v to the amplifiers and all. but can anyone tell me the ohm level that it sends to the amp. is it low or high?

Velocity Motors

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Joined: March 08, 2002

Location: Manitoba, Canada

Posted: June 23, 2003 at 12:32 PM / IP Logged

Alpine HU's put out 4 ohm & the ratings reflect this.

Jeff

Velocity Custom Home Theater

Mobile Audio/Video Specialist

Morden, Manitoba CANADA

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Kadetheus

Member - Posts: 36

Joined: January 15, 2003

Location: United States

Posted: June 23, 2003 at 12:39 PM / IP Logged

i was talking about the ohms for the rca wires that go to the amp. on most radios i think that it's like 250ohms and on some radios i've seen it go as low as 55ohms on the eclipse radios. but i appreciate the response. sorry for not being specific.

thanks again

Velocity Motors

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Posted: June 23, 2003 at 1:12 PM / IP Logged

Just curious why you need to know the ohms of the RCA's? If your planning to do a line level setting all you need to know is the voltage output of the HU & the input voltage of the EQ & amplifier.

Jeff

Velocity Custom Home Theater

Mobile Audio/Video Specialist

Morden, Manitoba CANADA

Kadetheus

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Joined: January 15, 2003

Location: United States

Posted: June 23, 2003 at 1:50 PM / IP Logged

because the way that i understood it is that the lower the impedance the lower the chances for radio and other electrical interference. and in that case it would have been good for me because the radio that i have now (jvc kd-sh707 (2v rca outs)) has interference when i connect it to amp (mtx 4244) i called the mtx tech support dept. and we talked for at least an hour and we still didn't get rid of the interference. so i ended up buying a ground loop isolator which nearly got rid of the noise completely, but it also took a lot away as far as the sound quality goes. i'm basically trying to avoid that situation again.

esmith69

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Joined: November 26, 2002

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Posted: June 23, 2003 at 6:32 PM / IP Logged

This quoted from the Basic Car Audio Electronics page:

Output Impedance:

Some head units (or other devices that have an audio output signal) rate the output impedance of their pre-amp lines. These specs will tell you how robust the output signal is. Since all decks have more than a zero output impedance (50-500 ohms) and all other devices have something less than an infinite input impedance (10,000-100,000 ohms), the input circuit will affect the signal from the previous piece of audio equipment. A lower output impedance (50 ohms) will be affected less than one with a higher output impedance (500 ohms). The most common (and least degrading) effect on the signal is the slight reduction in the signal level. This slight reduction is generally never noticed and is completely normal. A bigger problem appears when some piece of equipment does not have a purely resistive input circuit. This is generally from a ultrasonic filter on the input. These will cause the high frequency part of the signal to be attenuated more than the rest of the signal. Equipment with higher output impedances will have more high frequency roll off than those with a lower output impedance.

Anyways, the only info I could find for your particualr head unit was in the owner's manual, at the end where it lists the specifications, under the "General" section, it says "Maximum Pre-Output Voltage: 4 V/10 k ohms". Not exactly sure what they mean by that, and it might not help you but i thought I'd bring it up just in case.

Ethan

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Velocity Motors

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Location: Manitoba, Canada

Posted: June 23, 2003 at 10:26 PM / IP Logged

ground lops isolators are not the answer to noise in a system ( in my books ). Look for other ways to elimate or reduce the noise that is induced into the system. Look at teh amp gains on the amplifier. Using high voltage RCA's ( 4 volts or higher ) will lower the amp gains so this in itself will help you reduce the noise. Another thing to check for is to isolate the power and ignition wires of the deck from possible electronic distortions like AC. fan motors or lights / wiper's. Using a relay to isolate the power source is another possibility.

Jeff

Velocity Custom Home Theater

Mobile Audio/Video Specialist

Morden, Manitoba CANADA

Kadetheus

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Joined: January 15, 2003

Location: United States

Posted: June 24, 2003 at 7:31 AM / IP Logged

thanks. you two told me exactly what i needed to know plus a little more.

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? about alpine cda-9813

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