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Discussion Starter · #1 · (Edited)
2011 GT-E – Clean Sub Install – w/ Bose & Volume control

This will be my journal on the install of my amp and subwoofer.
The goals of this install are, clean, do no damage to the car, removable (for more trunk space or when I no longer wish to have this), stealth and have a volume control.

Step One – Power
The hardest part of any Sub install is getting the power wire through the firewall. Thanks to ptcary (http://mazda3revolution.com/forums/2010-mazda-3-audio-electronics/11866-firewall-help.html) for the tip, it was very easy.
I removed the battery, tray and other stuff attached to it.


Using a coat hanger I made a tool to poke the power wire through the hood release cable grommet located to the outside of the ABS controller. I just poked it through, and used soap to lube the wire for easy pulling.



Once the wire was pulled through, I coved the wire in black wire loom and zip tied it all neat. Installed the battery box and ran the power wire into the box from the bottom through an unused hole. Installed fuse holder and terminal. I attached the terminal to the unfused side of the distribution block.




KEEPING THE FUSE OUT, I ran the wire to under the driver’s seat, still using the same coat hanger tool.



Power wire complete!

Step Two – Audio signal and Volume control
One of the features I wanted in this install is the ability to control the volume of the Subwoofer. My old head unit had a sub volume right on the face, I have gotten use to that and now really enjoy having the control. I wanted to be able to turn down the subs depending on the music I am listening to or turn the amp off.
My amplifier does not have a remote gain or boost like some (it does but I need a Kenwood Head unit to control it). Therefore, my plans are to add a simple volume control in the audio signal path and add a switch to turn off the amp when I have it turned down all the way (no sense having the amp on when not in use).
This is what I need: This is a 10k ohm log variable resistor, with a 1 amp switch. The kind on the volume of a radio when you turn it down all the way it clicks and shuts down.


I split my RCA to only have one channel (I’m only running mono) then spliced in the pot about half way along the RCA. Also connecting the amp remote wire



Seeing other installs of having the sub control in cigarette lighter, I decided to do my own take on that.
I removed the center console where the cigarette lighter is and separated it from the shifter bezel (or whatever it’s called).


After removing the cigarette lighter assembly, I realized that it would have been easier to remove the metal from the black ring before remove that black ring. I just pushed it out from the back.


Now I need to install the pot into that hole, an idea I had was to have two rings of plastic that could be sandwiched in the hole and be held tight by the pot assembly.
I found the perfect plastic, a DVD case, its strong enough and matches the colour and texture of the lighter assembly. Now to make the rings, I found a hole-drill that would make the perfect rings with the right diameter outer and inner hole.


I cleaned them up with some sand paper then installed the pot. I also added some 2-sided tape just to hold the back in place and stop the whole assembly from turning. Some zip ties and labels to keep things strait.






I wished it turned out a little better, but it still looks really good!
Ran the wires to both sides under the seats, input to the passenger and out the driver.


Then reassembled the console. Looks good and very easy to operate.




Now to get the signals. Removed the passenger seat. And accessed the Bose amp to get at the head units out puts (Bose input). I chose this way since the Bose amp, plays with the signal. And spliced in my wires, using Pin G and H. H is positive so that goes to the center of the RCA, G is negative that that goes to the shield. I never liked those slicing plastic clips, so I soldered mine in. Then cleaned it all up and installed the seat back in.







Part two done! That was the hard part.


Step Three – Ground

My original plan was to attach the ground to seat bolts. I still think it would have been my best option, but I had some difficulties that I don't care to discuss.

I found a good ground in the "B" pillar in the seat belt assembly. I have my reasons. :argh 1:




Cleaned up the paint with a Dremel and bolted down the terminal. Ran the wire and reassembled





Ground Done!

Step Three – The Box and Speaker


I found a nice wedge sub box on Kijiji for really cheap, so I swiped it up really fast. It was a JL box with a volume of about a cubic foot (~0.96ft^3)
Since it was used and I don’t have the same screws, some of the holds are striped. So I had to install some “T-nuts”.
Pre-drilled the holes larger, and using some washers to spread the force I tightened down the t-nuts.





Once they were all in I needed a speaker grill. I could not find a nice grill for a reasonable price! SO… I made one!
I used ¼ inch SS tubeing bent into U shapes three 12” and two 9.5”.





Measuring out the holes, one right trough for the skrews and one like an 1/8 inch to counter sink the rods. Looks good!






So once the first one turned out nice I did the rest, counter sinking and securing them from the back with flat head self-tapping screws. Wired the speaker and installed it all together!






Box DONE!

Step Four – The Amp

I bet you all have been thinking I’m going to put the amp under the driver seat… You happen to be wrong… Not that I did not want to, I tried! My amp is too large to fit under the seat. There is just a bit of interference from the seat and it blocks the air from the back. So I’m forced to change my plan. I was thinking about attaching the amp to the box and have quick connects to pull the whole box out, but again the amp is too large. So I have to place it under the BACK DRIVER Passenger’s feet. I needed a way to protect the amp so I made this box. It has room for air to move around, it also has a fan so I am not worried about heat.



Some Industrial strength Velcro on the amp and the speaker box to keep it in place.


I wired it all up, set it up, and cranked it up! ITS ALIVE!





Done!
 

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you said you where doing this with the bose system still installed? are you using a LOC? or taping the preamp wires??
 

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Discussion Starter · #4 ·
Updated,

I'm tapping into the Bose amp input, I don't like LOCs. see updated fist post.
 

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Great work! I heard a 'bass knob' that cuts RCA voltage works better then a remote gain amp. I want to switch mine over to your style. Tell me how it works out.
 

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dammit I couldnt find the cable release gromet -_- Now I see it.
 

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Discussion Starter · #7 ·
Updated!

The volume control pot in the RCA will prevent me form over-driving the system. The max volume will be set my the amp and input will be a combo of the HU and volume control. :walkman:
 

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Discussion Starter · #8 ·
dammit I couldn't find the cable release grommet -_- Now I see it.
I'm glad I can help... I'm doing this for the people!!!! :tongue:

I had many questions when I started this, I just wanted to share the knowledge I gained.
 

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Updated!

The volume control pot in the RCA will prevent me form over-driving the system. The max volume will be set my the amp and input will be a combo of the HU and volume control. :walkman:
You'll find yourself changing the bass on the HU alot, or atleast I do. To add or take away mid-bass.
 

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Discussion Starter · #12 ·
Updated!

And Finished!

But I seem to be having some low volume issues. The inputs are set right, at 2.5V, I even measured the output of the head unit at 75% volume at 60hz to be 2.53volts.

There might be something wrong with the amp, or a grounding issue. The voltage is reading fine about 40volts to the speaker but its only drawing 3amps. If you do the math with voltage I'm running 800watts. The math with the amps I'm only running 100watts. it sounds more like 100watts.
 

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Discussion Starter · #13 ·
Its not the ground. I got 0.4ohm from the ground wire terminal (amp side) to any random bolt in range. I also got 0.4ohm from the -ve battery terminal to any bolt in range. The DMM reads 0.3ohms when the leads are touched.
 

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Discussion Starter · #15 ·
That is the same conclusion that most ppl come to, bad speakers. But they are DVC, 1.8ohms (2.1ohm[speaker]-0.3ohm[DMM]) in parallel and 7.9ohms (8.2-0.3) in series. The speakers move about 60% with a 9V and in the right direction.
I'm sure its not the speakers. The amp and speakers make noise but I have to turn the gain way up. This is a 919RMS amp into a 300RMS sub, at normal gain this speaker should be maxing out.

But since ppl think it is I will look very closely at it and might hook up my spare. If the spare is the same I might send the amp for testing, to check its output.
 

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Try another input on the amp. I had that issue when I changed amps. No clue what I did. But after the HU install I had RCA's

If you have anything that puts out sound wire it up to the amp. I had to hook my amp to my truck's RCA's(tons of extensions). But it showed me that it was the car's rca not the amp.

So if someone you know has a system back the cars upto each other and plug his RCA into your amp.
 

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any updates to your problem? I am interested in how using the bose inputs works with an aftermarket amplifier for a subwoofer
 

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Discussion Starter · #18 ·
Well, the more I poke around and ask questions, the more I find nothing wrong. The Low volume of my amp is starting to look more and more like high volume of the bose amp, the bose is just over powering my amp set up.

I wish I had an O-scope to learn more...

I'm not giveing up I have more testing to do and I still have a back up plan :thumbup1 1:
 

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Well, the more I poke around and ask questions, the more I find nothing wrong. The Low volume of my amp is starting to look more and more like high volume of the bose amp, the bose is just over powering my amp set up.

I wish I had an O-scope to learn more...

I'm not giveing up I have more testing to do and I still have a back up plan :thumbup1 1:
What did you use as your signal again? I still couldnt understand from your pictures, the stock HU outputs had good signal.

any updates to your problem? I am interested in how using the bose inputs works with an aftermarket amplifier for a subwoofer
The bose inputs/ headunit outputs work GREAT. A little low so you'll have to turn the gain on up but the signal is clean, and useable.
 

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Discussion Starter · #20 ·
What did you use as your signal again? I still couldnt understand from your pictures, the stock HU outputs had good signal.
I used the Bose head unit outs, same as you and every one else. Its not the signal coming in. I'm sure its the amp. I think the some out put MOSFETs are not working properly.


The bose inputs/ headunit outputs work GREAT. A little low so you'll have to turn the gain on up but the signal is clean, and useable.
I'm trying to get my hands on a O-scope to find the problem. Also I might just pull the fets out to check them.
 
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