Replaced front speakers with component set - sound is worse
 

I am in the process of doing an audio build. I have a set of Polk Audio MM6501 Components from my old car that I decided to re-use in my BRZ.

The plan is to use my Alpine PDX-F4 to power the components (as was my old setup), but as a first go I wanted to power them off the stock amp to see how they would sound first.

I purchased a set of door spacers and tweet mounts off subaru audio DOT net. The tweet mounts looked a little too rough cut and so I decided to fabricate some tweeter mounts from sheet metal. I purchased a bunch of weatherstripping foam from Lowes and ensured a good seal between the door, the spacer and the speaker.

I purchased Metra speaker connector adapter for the door speakers (Metra 72-8104) and routed them along with the Polk speaker wires through the door grommet. This is a really tough job and you will likely have to remove the tape on the hose between the door, peel back the upper hose and poke a hole for the wire. I used a coat hanger, some packing tape and grease to guide the wires through.

Finally I mounted the cross overs under the dash. To the left of the steering column on the driver's side (tie raps) and behind the glove box (velcro tape) on the passenger side.

Here are some pics:
http://i995.photobucket.com/albums/a...psc5478f8e.jpg

http://i995.photobucket.com/albums/a...psb94d3ecc.jpg

The result:

First off, when having completed the driver's side and not yet touched the passenger side. I sat in the car and turned on the stereo. The OEM speakers were considerably louder. I don't know if that's a result of the passive crossover from the Polks component set sucking up the juice? The second thing I noticed is that the front stage was less present.

I played with the fader switching between FL and FR only and it was obvious that the polks were just not as good present as the OEM. I proceeded anyway to install the Polk MM6501 set on the passenger side as well. Once everything was put back together I sat inside with both doors closed for a listen.

Immediatly it sounded a lot less bright and in your face. I had to turn up the volume to 75% to match the OEM level of 40%. Also, the rears were now too loud so I had to set the fader forward a little to match the fronts with the rears. Also, the Polks didn't seem to like the low frequencies very well, so I loaded the equalizer and dropped the first two bars down to hide the lows.

The sound does seem more clear in the mids, but I feel like I lost a bunch of high and lows. I dont't know if it is even worth running them to an aftermarket LOC and amp to see if it gets better.

I am thinking that I should put the OEM tweeter and 3.5 back in place and power the polk 6.5 directly to the door speaker connector and see if that gets the best of both worlds.

Do you guys have any thoughts on the matter. I would like to point out that I am planning on putting in an 8 or 10" subwoofer down the line, so I don't really need long term a load of bass from my doors, but I think it's nice to have.

I am left feeling really confused about what I need to do here. I definitely feel like right now my audio experience has taken a step back in my BRZ.

I put a set of polk components in my old tc (along with polk 6.5 full range in the back and 4 inchers in the front as well) and had the same issue with stock power. I actually also had the alpine pdx-4 and once that was installed it was absolutely insane. Just be sure to get your equalization right and the levels right. I had the best luck with it with all levels on the amp set right around the middle. It was LOUD. like deafening loud.

So you're saying that once I amp it up with the PDX-F4 everything will get up to par?

Also do you recommend installing 4" speakers in the dash as well?

that amp will do wonders for those speakers. If you do put in 3.5's or 4s as well in the dash, try to find something without a tweeter. I made the mistake of using the polks with the tweeter and the highs were out of control. It took a lot of work to get it sounding right cause of that. Once i got it right it was unbelievable. I also had 2 8inch bazooka subs which made it more complicated but in the end gave it a nice full sound. Of course once i got it sounding right, hurricane sandy hit and took away all my hard work :(

The stock speakers were (are) 2 Ohm and you've replaced them with a 4 ohm set. They will not be as loud on the factory amp since that amplifier's power output is matched to a 2 ohm load. You've basically halved the power output.

When you replace the amp you will get much better sound.

That is also true. you're probably getting like 6-10 watts rms to the speakers on the stock power. With the pdx-4 it's 100 watts rms per channel which will make a huge difference.

Nice. Did not know that the stock speakers are 2ohm.

For those of you wondering about the math... Given that V=I*R and P=I*V, then P=V²/R. So power is inversely proportional to resistance given the same voltage. Double the resistance = half the power!

Do you think I am damaging my Polks in any way by powering them with the original amp?

No, the amp running at 2ohm will get less hot with 4ohm speakers vs the 2ohm, it's an easier load on the amp.

Also I'm sure the polks aren't as sensitive as the factory speakers, that's also why they are not as loud.

Most people's hearing is tricked with factory systems that are heavy in the mid range, so even with the new amp running them it will sound very different than stock, that's a good thing, but a lot of people don't notice/realize that at first.

Edit: To add to the first comment, running an 8ohm receiver/amp on 2ohm speakers, that'd be bad, to the receiver/amp. It could blow the speakers also if it introduced clipping which is very possible once the amp starts straining too hard.

as long as you don't turn it up to high it should be fine. Generally, you want to get as close to the optimal power rating of the speakers as possible. So say these speakers are rated for 100 watts as the set i had were and you power them with only 10 watts, it will work but if you turn it up too high, the sound waves square off and cause clipping which can ultimately fry the voice coils. You'll hear it if it starts clipping though... it'll make distorted farting noises. with the 100watt rms amp you have, you'll be at ideal power and can crank it up to max and have a clean sound (from outside the car at least; inside will be too loud to tolerate)

I like that tweeter mount a LOT better than what I make. If everybody was as handy as you are I'd never make the dash adapters. Your version is clearly better, but people don't tend to want to DIY like that and I could never mass produce them, as every tweeter has different requirements.

The door adapter looks great in the car as well.

May I re-host and post these pictures? I'd like to recommend that people try to make your tweeter mount in the DIY writeup that I did.

No problem Pat. I work in an environment with a lot of skilled fabricators. I sort of outsourced the job to them :) Was not planning on it!

Thanks again for the door spacers!

Not exactly. If you turn the volume up all the way, you will (most likely) push the factory amp into the range where the signal is clipped. The reason clipping is bad for speakers, is they move less, so there is less cooling airflow to the voice coil. However, to use your example, if you're running 10w of power to speakers rated for 100w, they really shouldn't be in any danger of overheating, no matter how badly the signal is clipped, though they will certainly sound terrible.

To the OP, yes, the factory speakers are 2 ohms, and the speakers you installed are most likely less sensitive than the factory speakers. Since you already have everything (I assume), hook your amp up and see how it sounds!

Amp those bad boys. Running Polk anything without the appropriate amp is doing yourself an injustice. Also, doesn't your factory radio have 3 sets of pre-outs? Why would you need an LOC? I would do an amp bypass, to bypass the factory amp, install the 4 channel using speed wire and RCAs.

I'm assuming you don't have the pleasure of driving the Subaru BRZ. The standard Fujitsu FA601US equipped on all USA cars does not have RCA outputs like the FR-S does.

I will be using an Alpine PDX-F4 to power them as soon as my LOC gets in. My amp is already wired!

I am hoping so, but I keep having this itch to want to maintain a 3 way setup. I love how present the stage on the OEM speakers are. Do you think that there is a point there to maintain a 3 way setup when upgrading speakers if you don't want to loose that aspect of your sounds response?

No such pleasure. Mine happens to have 3 sets of preouts and in preparation for a hiccup down the line I have an x940bt sitting on the shelf. Now I understand your reference to the LOC...it sucks but I understand nonetheless.

A disclaimer: I'm still waiting on my BRZ so I haven't been able to spend much time in one listening. However, I would think that the fact that the mid and high are mounted at the corners of the dash/windshield is what really brings the stage up front. With a larger tweeter, you may be able to achieve decent staging with a two-way setup. Not sure where the crossover point is on your particular components, or how low your tweeters can play without failing.

With most three-way systems, the mid affects the staging more than anything, as that is the range of sound our ears/brains are most effective at locating, and I would expect it to be the same with the factory setup.

Quick question for you guys, if I installed components can I just remove the oem amp and replace it with an after market one? Would that work?

Yes.

Thanks! Didn't feel like doing extra work and run wires from the front to the back.

Sorry, I misunderstood. You can replace the oem amp but it isn't plug-n-play. You'll need to run the wires.

So to clarify on this, you can grab your front speaker signals from the harness that plugs into the rear OEM amplifier.

Look up the wiring manual on the forum to understand which wires are what. The connector is a Metra 70-1761 that you can get from ama zon.

Further clarification

http://i46.tinypic.com/1zv4n6u.jpg

Just to be clear, The front door speakers are powered by the stock amplifier right. The rest of the speakers in the car, the two speakers and tweeters on the dash and the rear speakers are all being powered by the head unit?. Right now i am running jbl p66s speakers in the doors and infinity reference speakers on the dash. The jbl's are 2ohms and have 55 watt rms. Does the stock amplifier have enough juice to power the jbl speakers?

I am thinking of getting the alpine power pack to boost the head unit's power output. the alpine power pack is good in that it can be tucked away behind the head unit, a much cleaner install.
http://a248.e.akamai.net/pix.crutchf...power-pack.jpg

The stock amp probably has enough power for your JBLs at low to normal listening levels. However, like the OEM speakers if you turn up the volume there will be distortion and this will be a strain on the JBLs.

So the amps just power the door speakers right?

Yes. Kind of unfortunate.

wow, the head unit powers the rest of the 4 speakers and the tweeters. Any one know the rms rating for the stock amplifier

Correct headunit drives all but door speakers. It may be enough power, you would just have to give it a try.

Also, last time I checked the power pack doesn't work unless you have an alpine HU.



Nvm the KTP-445U works with any HU now. I would say do that if you have an fr-s and ditch the factory amp.
To go a step further pick up that and a minidsp and control your whole frontstage, it would stay clean and sound good.

My brz already comes with pioneer avic 930bt installed. Does it really need a digital sound processor? would that change the sound quality a lot, because the cheapest one that i am able to find is jl audio cl441dsp clean sweep.

clean sweep only de-eqs. if you have the pioneer, you can hook up the amp and try out the auto-eq. it may be good enough for you.


minidsp is ~100$ but you prolly wont need it after doing autoeq, its good enough for most.

Polk's are my favorite neutral speaker but I was afraid of this because the factory setup is so complex. Aftermarket is going to be hard to improve over stock.

It really isn't Subaru did not design the car for optimal audio- just look at the rear speaker selection!

A good setup- either good 3.5 coaxials in the dash with the bass limited and good 6.5" midranges or coaxials in the doors OR a nice 6.5" component setup and you are far ahead of what Subaru put in the car.

I went with Polk 3.5" coaxial in the dash & rear with bass blockers. Also replaced the door speakers with Polk components and placed the Polk tweeter in the factory location. Added an amp & the sound improvement over stock is amazing.

thats a lot of work for an improvement over stock. stock sounds good enough for me.

Even without the amp that would be a huge step up.

Cheap Fix
 

After reading that the OEM plus system leaves all the factory speakers, except the tweeters, in place but changes the amplifier and adds a subwoofer. I decided to change out the factory amp. FYI, the factory amplifier only powers the door speakers. The head unit powers the tiny dash and rear speakers. The factory amp, located in the trunk, is the apparent culprit for the boomy sound of the BRZ. I never heard the stereo in the FRS but I suspect it may be similar. Anyway, the amplifier harness is the same as the head unit and therefore the Metra 70-1761 harness can be used to avoid cutting into the factory wires. However the configuration of the pins are completely different. After reading the Service Manual (page 322), I reconfigured the pins. Basically the 6 pin connector supplies the ground and power to the amplifier while the 10 pin connector has the amplifier input, output and remote turn on. I disconnected the factory amp and hooked up an old Sony Xplod amp I had laying around and the sound is way better. The cheap boomy sound is gone. Before I had to turn the bass all the way down on the equalizer and it still sounded boomy and muddy. I'm assuming the factory amplifier has a bass booster. Now the bass sounds clean. I'm thinking about buying a Kicker DX125.2. If anybody has any knowledge of this amp, your input would be appreciated.
I uploaded pictures of the harness after reconfiguring the pins. The white and gray wires are the input and the green and purple wires are the output. The blue wire is the amplifier turn on.