Kenwood KAC-7204 Amplifiers

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lazybum

Member - Posts: 13

Joined: July 23, 2008

Location: Michigan, United States

Posted: July 23, 2008 at 3:00 AM / IP Logged

Alright, here's my deal... I have 2 ten inch rockford P3's, (400 watts RMS, 800 peak) and they're both being pushed by a kenwood KAC-7204 (bridged at 4 ohms, putting out 500 watts rms)

Kenwood KAC-7204 2-Channel Car Audio Amplifier

So, I realize i'm underpowering my subs, and i'm also trying to pull too much from that amp, because it's overheating and going into protect mode, then coming back on a few minutes later once it's cooled. I'm thinking about buying another of the same amp, and wiring one sub per amp. That *should* fix my overheating problem, as well as making the subs run louder, right? or wrong?

(i also have a SWX 1 farad capacitor installed, i don't think it matters, but i'm saying it just in case)

Thanks in advance,

-Chris

lazybum

Member - Posts: 13

Joined: July 23, 2008

Location: Michigan, United States

Posted: July 23, 2008 at 3:58 AM / IP Logged

Also, i would have to wire each sub to an 8 ohm load, so the amp sees it as a 4 ohm load, right?

aznboi3644

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This member consistently provides reliable information

Joined: May 01, 2006

Location: United States

Posted: July 23, 2008 at 4:11 AM / IP Logged

what coil config are the subwoofers??

How are they wired to the amplifier??

How is your gain set??

lazybum

Member - Posts: 13

Joined: July 23, 2008

Location: Michigan, United States

Posted: July 23, 2008 at 4:53 AM / IP Logged

Dual voice coil, 4 ohm subs

Bridged to amplifier

No idea about gain, cousin and i installed, he set the gain... I'll check on that once i go out to my car again.

DYohn

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Joined: April 22, 2003

Location: Arizona, United States

Posted: July 23, 2008 at 8:13 AM / IP Logged

lazybum wrote:

Your woofer wiring is wrong and you are not wired for 4-ohms, and/or your gain is way too high. How are the woofers wired?

Buying another amp is not the solution.

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lazybum

Member - Posts: 13

Joined: July 23, 2008

Location: Michigan, United States

Posted: July 23, 2008 at 8:34 AM / IP Logged

The woofers are wired to 4 ohms, but isn't the amp seeing it as 2 ohms? And i can't really wire 2 4 ohm subs to 8 ohms, so i have a bit of a problem seeing as the amp is only stable in 4 ohms...

haemphyst

Platinum - Posts: 5,054

Joined: January 19, 2003

Location: Michigan, Bouvet Island

Posted: July 23, 2008 at 9:53 AM / IP Logged

If the woofers are SVC 4 ohms each, wired in parallel, yes, that is 2 ohms, but your amplifier is bridged, presenting an effective 1 ohm load per channel - TWICE the rated load. This is why your amp is overheating. If the woofers are DVC, then your options are 2 ohms each (wired in parallel) or 8 ohms each (wired in series).

If you have them all paralleled, then you are showing the amp an effective .5 ohm load per channel.

For that amp, you must wire the woofer voice coils in series for 8 ohms each woofer, parallel the woofers for 4 ohms, then bridge the amplifier, for an effective 2 ohm load per channel.

If this is what you have, then you need to check your gain and/or your power supply, including all underhood wiring and connections.

It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

lazybum

Member - Posts: 13

Joined: July 23, 2008

Location: Michigan, United States

Posted: July 23, 2008 at 11:30 AM / IP Logged

Alright, so the amp is 4 ohm stable. Wire subs in series at 8 ohms, amp will see 4 ohms. Thanks alot man.

haemphyst

Platinum - Posts: 5,054

Joined: January 19, 2003

Location: Michigan, Bouvet Island

Posted: July 24, 2008 at 8:42 AM / IP Logged

Well, no. The amp is 2 ohm stable, which means the most you can bridge it to is a 4 ohm load.

One of us is confused. Here... You said you had two woofers, DVC each. That's four voice coils. Yes? Four, 4-ohm voice coils can give you 1 ohm (all parallel), 4 ohms (series-parallel), or 16 ohms (all series), which when bridged, present to the amplifier ½ ohm, 2 ohms, or 8 ohms per channel. It is still a 1, 4, or 16 ohm load.

Here's the diagram...

It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

i am an idiot

Platinum - Posts: 13,667

Joined: September 21, 2006

Location: Louisiana, United States

Posted: July 24, 2008 at 7:15 PM / IP Logged

Following is a picture of a 2 channel bridgeable amplifier. Notice that the left negative and the right positive terminals are connected together, and they are referenced to ground. A 4 ohm mono load is exactly the same as a 2 ohm stereo load. If you have a 2 ohm load on the left channel and a 2 ohm load on the right channel, it appears that you have 2 2ohm speakers wired in series which shows the amp a 4 ohm load across the bridged terminals of the amp. When someone says you bridge your amp into a 4 ohm load and that makes it see a 2 ohm load. They are trying to say that it will see 2 ohms per channel.

Kenwood KAC-7204 Amplifiers -- posted image.

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