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Discussion Starter #1
06 Mazda 6i Non-bose stereo
First off, yes this is the first amp installation I've done

Second, I searched and found the head unit harness diagram and also found that I needed the Orange wire for the amp acc turn on wire.

I can't seem to get my damn amp (Kenwood DAC-7252) to turn on, all I get when I turn on the car is silence. I have the battery terminal hooked to the inline fuse then to the amp, a negative cable from the amp to a bolt for my seat, the speaker wires ran from the head unit harness to an LOC to the amp, then back to the speakers wires.

I've spent all night working on this, have it near professional looking considering I'm an amateur, and am exhausted. I saw on the diagram that there is "supposed" to be a blue/black wire for remote amp turn on, but I don't have that wire on my car; actually I have 2 wires that are not listed on the diagram for a non bose stereo there. Can ANYONE help shed some light on this?
 

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06 Mazda 6i Non-bose stereo
First off, yes this is the first amp installation I've done

Second, I searched and found the head unit harness diagram and also found that I needed the Orange wire for the amp acc turn on wire.

I can't seem to get my damn amp (Kenwood DAC-7252) to turn on, all I get when I turn on the car is silence. I have the battery terminal hooked to the inline fuse then to the amp, a negative cable from the amp to a bolt for my seat, the speaker wires ran from the head unit harness to an LOC to the amp, then back to the speakers wires.

I've spent all night working on this, have it near professional looking considering I'm an amateur, and am exhausted. I saw on the diagram that there is "supposed" to be a blue/black wire for remote amp turn on, but I don't have that wire on my car; actually I have 2 wires that are not listed on the diagram for a non bose stereo there. Can ANYONE help shed some light on this?
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Honestly diagnosing Car Audio is very hard from text. If you had some pictures it would be extremely helpful. From what I gather from the quote it seems to me that you may possibly be "grounding out" your speakers. This would occur when the + and - wires are touching for lack of a better discription. I think your main problem is that you haven't seperated the Speaker wire going to the LOC from the returning speaker wire behind the stereo. I know this sounds weird but if you take a look at the crude drawing made in paint (would be much better if I only had CAD). Hopefully this helps. If not shoot me a message and we'll work this thing out. But once again if you have pictures or can get them it would be most helpful.

 

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Discussion Starter #3
I do have to check my +/- wires tomorrow, but I have at least figured out why it would not work at all - my grounding point was a little too painted (happened due to a short grounding cable and trying to do a quick fix).

I did the "classic" reroute the front speakers to the rear via amp since I have the crappy non bose deck and didn't want to pay for a metra kit and steering wheel control modifier. Basically, I cut all four channel outputs, connected the left and right fronts to my 2 channel amp, and then hooked 2 wires to each channel - one for front, one for rear. It should be more than enough output power, considering I have 4x45 watt RMS speakers and the amp is rated for 2x170 RMS.

Also, I noticed that the left side sounds lower in pitch than the right side - could be the songs, or could be a slight short in the speaker wires, hence why I have to check them. I'm hoping it is a short, the right side sounds so much more full in comparison - harder hitting bass and higher highs.

Thanks for your help, I did exactly what you had on the diagram (soldered + heat shrink wrapped each line after cutting and adding the wires).
 

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Sounds like you need to run your remote wire. You can use any +12V acc wire to get the signal from, you just need something that only has power when the car is in the ACC and ON position. Then run that wire to the remote place on the amp.
 

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Discussion Starter #7
Didn't explicitly say it, but had hooked up the remote (or power controller in the case of my amp) to the orange wire (12v acc).

Also, had already stated I got it working just have to make sure the levels are correct.

Thanks for all the help though, I do appreciate it.
 

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Discussion Starter #8
Fixed the levels - the LOC makes the right channel more powerful for some reason (I suspect it is leeching from the left channel since it works with only one wire plugged in out of the +/- on that channel), so I just lowered the output via the turn screw.
 

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Sweet Glad you got everything working properly. That ground problem would have been my next guess.
 

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Discussion Starter #10
While this is still up, does anyone have an answer to this question:

Since my amp puts out 170 watts RMS to each of it's 2 channels, and I'm only using 2-45 watt RMS speakers *PER* channel (for a total of 4x45 watt RMS), am I in effect overpowering my speakers? At least in theory, wouldn't 2-80 watt RMS speakers per channel sound better?
 

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Discussion Starter #12
Although I hate to, I'm assuming 4 ohms since it is the stock head unit and stock speaker wire (minus the wire I had to add from amp to stock speaker wire).

The gain goes from 4 (min) to .5 (max), and I have it set between 2 and 1 right now. Offhand I think I set my remote between 60 and 70 hz and +3db -> +4db.

Eventually, I'll run new speaker wire so it all matches and isn't spliced+soldered together like it is now.
 

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So your putting 85W RMS to each 45W RMS speakers?

Ya, that would be overpowering quite a bit, and I wouldn't except those speakers to last too long if you turn the volume up. And RMS isn't a good tool to measure sound quality, you gotta actually listen to the speaker. I know quite a few 40W RMS speakers that sound better than some 75W RMS speakers.
 

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Hi all, maybe a bit of electrical theory would help to clarify a few misconceptions. It is not a bad thing to have an amplifier capable of delivering more power than the power rating of the speaker.

Power rating of amplifiers: this is what an amplifier is capable of delivering, if the load it is driving tries to draw that much. Try to draw more than that and the amp will start to clip, which means "curvy" sine waves (music signals) get chopped off and start to look like direct current. Clipping and direct current is bad for speakers. It creates excessive heat which will eventually melt the thin layer of insulation (really a coat of varnish) on the wire in the voicecoil, causing failure of the speaker. Depending on where the insulation fails the amp may suddenly see a drastic drop in impedance (iel short circuit), causing the output stages to blow.

The amp does not "push" this power into the load. The load draws from the amp. The volume of the speaker is adjusted by varying the voltage across the speaker. As the voltage increases (by turning up the volume knob), the load (in this case the voicecoil of the speaker) will draw more current.

This is basic Ohms Law: Voltage (V) = Current (A) x Resistance (Ohms)
Readjusting the equation gives: Current = Voltage/Resistance
and for Power, Power (W) = Voltage x Current

Power doesn't really exist, while Voltage, Current and Resistance are real and measurable. Power is a way of quantifying how much work a certain combination of Voltage and Current will create across a certain Resistance (load).

For the sake of this discussion we will talk about continuous, constant sound level, like a constant test signal is being put through (as opposed to a musical signal, which varies greatly in sound intensity and duration due to the nature of music).

Try some numbers in the above equations to try to see what I'm saying:
Say you have a 4 ohm speaker. At a certain volume setting of the stereo the amplifier is applying 8 Volts across the speaker terminals.
8Volts/4 Ohms (Voltage/Resistance) = 2 Amps. The speaker is drawing 2 amps of current out of the output stages of the amplifier.
Power = Volt x Current. 8Volts x 2 Amps = 16 Watts.
The amplifier is providing 16 Watts to the speaker.
Now you turn the volume control up on the stereo. This corresponds to a voltage fo 20Volts across the 4 Ohm speaker.
20Volts/4Ohms = 5 Amps. The 4 ohms speaker wants to draw 5 amps of current out of the amp.
Power this corresponds to: 20Volts x 5 amps = 100 Watts of power. The amplifier needs to be able to deliver 100 Watts of power to maintain the 5 Amp current flow demanded by the 20Volts across the speaker.

What happens with a 2 Ohm speaker? Using same example as above:
8Volts/2 Ohms = 4Amps. The speaker is drawing 4 amps of current out of the amplifiter.
8 Volts x 4 Amps = 32 Watts.
Turn up volume control:
20Volts / 2Ohms = 10 Amps
20Volts x 10Amps = 200Watts.

The same amplifier, going into a 2 ohm load, is drawing twice the power out of the amplifier that the 4 ohm load was, at the same voltage levels across the speaker.This is why most amplifiers that are capable of driving both 2 Ohm and 4 Ohm loads are usually always rated for double the power at the lower 2 Ohm load.

In essence what that rating is saying is that the amplifier can maintain the same voltage levels across the speaker because it can provide the necessary doubling of current when going into a 2 Ohm load.'

What happens if the volume level you set results in a voltage across the speaker that the amplifier cannot maintain the necessary amount of current? For example, to maintain the 20Volt level, a 4 ohm speaker is drawing 5 amps of current. If the amplifier is only rated to 50W at 4 Ohms, it cannot deliver 5 amps at 20V (equiv to 100W). Both the voltage and current signals will start to clip, creating a really ugly, distorted signal to the speaker that will cause it to overheat. Result if left at this level for any period of time? Blown speakers and blown output stage in the amplifier.

How does all this relate to the power rating of the speaker? The power rating of the speaker is just a reflecton of the amount of heat the voicecoil assembly can dissipate. The bigger the voicecoil, and the bigger the magnet around the voicecoil (it acts as a heat sink), the more heat it can dissipate. The power rating of a speaker is typically the CONTINUOUS CLEAN power it can handle. IE. a speaker rated at 60W can handle 12V at 5amps (as an example) forever, as long as it's clean (undistored sine wave).

How many of you listen to a continuous test tone? I don't. The music I listen is composed of notes that vary immensely both in strength and duration. A momentary spike equivalent to 100W of power won't blow the 60W speaker, if it's clean and undistorted signal. You're not playing that 100W signal continously.

Synopsis: If you can afford it, always get the amplifier capable of delivering tremendous amounts of current when needed. This will prevent cliipping and distortion, which is what blows speakers and output stages. Because car amps dont' tell you how much current they can actually deliver, you have to go by the power rating.

You do not need to worry about matching the power rating of the speaker to the amplifier unless you're competing and doing SPL tests with contiuous test tones. Persoally I would err on the side of caution and get an amplfiier more powerful than the rating of the speaker, if I could afford it.

Anecdote:
When I owned a high end stereo store (2 decades ago now) we'd take small bookshelf speakers (PSBs if I remember correctly, about 12" tall) and I'd hook them up to a 200W per channel Krell amplifier. You would not believe how good those speakers sounded, and how loud they could play, when driven by an amplifier that could effortless deliver 200W of power. The Krells were rated to be able to deliver momentary bursts of current up to 50Amps. Power rating of the PSBs? About 60W. Did we ever blow the speakers, driving them with a 200W amp? Never. But boy, did we have to do repairs for people who bought the small PSBs and tried to drive them with a 20W amp. They'd try to play them loud, beyond the capabilities of the amp, and blow something (usally the amp). Yet these customers would always wonder why, when they were only using a 20W amp and the speakers could "handle" 60W.
 

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Discussion Starter #16
Looks like some good information, thanks for the insight. The only time I have really noticed it could be better, I was using an LOC to convert from the head unit to amp input, the I discovered I had speaker level inputs and it sounds much better. With the first, the bass sounded terrible (too bangy for the music) but with the latter everything sounds much more crisp.
 
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