Well, I recently realized I can a bone-head at times...the connector that connects the mid/woofers to the amplifier is accessible from the little panel at the front middle area of the door panel...so no need to remove the entire door panel! You can get to what you need through this panel.

I estimate that this will take about 30 minutes per door. What you are doing is installing a 220uF capacitor (a 150uF, 200uF or 270uF would work as well) in series with the mid-woofer. This capacitor creates a high-pass filter that filters out frequencies that are about less than 200 hertz to the mid-woofer, thereby reducing the amount of bass coming from these speakers. This allows the bass control to be raised by about five to seven increments to get the bass from the subs at a higher volume while not overloading the mid/woofs. As I stated before, this little modification does wonders to the low frequency through the lower midrange frequency band. It was enough of an improvement for me to not go out and purchase an entirely new system. Since it will cost less than $5 and only about an hour total, it really is a great modification. You can purchase the caps (2) at Radio Shack for less than $2 apiece.

This is the procedure:

1. Pop off the panel with a screwdriver.
----> Use a small flathead screwdriver and with a little finesse, the panel will pop right out.

2. Reach in and disconnect the rear connector (the one with two wires, not five!).
----> Squeeze in the two tabs on each side, and pull the connector downwards. When it disconnects, there is enough play in the wire to pull it out of the door panel several inches. You will have to pull back the black cloth sleeve that protects the wires inside.

3. Install the capacitor.
----> I have two different procedures for this. Cut one wire and splice in the capacitor using either 1) wire nuts or 2) crimp connectors.
----> The capacitor can be wired in series with either the red or the black wire. It doesn't matter.
----> Capacitor values in this range are usually polarized. This means that one end has to be connected to the more positive voltage side of the circuit. In our case, this is a don't care and it doesn't matter which way the cap is oriented. This is because there is no DC voltage level at the amplifier output (actually there is always a few millivolts of DC, but never enough to worry about).
----> In summary, the capacitor is put into series with either the black wire or the red wire, and it doesn't matter which way the cap is "pointing" in this series connection.

4. Reconnect the plug and pop the panel back into the door. Done! Enjoy your great "new" stereo!

For my tastes, Before the mod, I usually had the bass control set at -7, -8 (or sometimes even -9) to prevent the front speakers from over loading and distorting from too much bass. After the mod, the bass can be put all the way up to around -5 to about +2, depending on the material.

I will state that however easy and safe this procedure is, I am not responsible for any damage incurred by anybody performing this to their Crossfire, either to their person or to their vehicle and/or other property.

Good Luck and have fun!

 

One of the best written "how to's" I have ever seen. Thanks a bunch.

 

~ indeed a great write up. thanks!

 

Thank you so much...have been waiting for this. One question from the unknowing here...by using a 150uF or 200uF, does that allow somewhat more bass than the 220uF to the speaker...and 270uF less bass? Just trying to figure out which way the numbers run for custom tailoring to individual likes.

Thanks again for coming up with this mod and posting for us.

 

Increasing the capacitance value will lower the cutoff frequency for a highpass filter and allow more bass through.

The formula for calculating the cutoff frequency is...
Fco = 1/(6.283 x R x C)

So for 220 uF capacitor and a 4 ohm speaker (I am guessing about the speaker)...
Fco = 1/(6.283 x 4 x .00022) = 181 Hz.

For a 270uF capacitor, Fco = 147 Hz.

Here's a link...
http://www.qrp.pops.net/filter1.htm

 

Thanks, I had it backwards (as usual)! I think I am going to try the 200uF initially and go from there. I'm excited to give this a try and see how it works out.

 

Thank You, fantastic !

 

Thanks for the replies.

I just glanced through Digi-Key online and noticed that there is no 200uF capacitor value. There is a 180uF and a 220uF...so the values in the range that would be most effective for reducing the bass coming out of the fronts are 120, 150, 180, 220, 270 and 330uF. Doing the math for these results in this (trobertson7 shows the formula):

120uF = 331 Hz
150uF = 265 Hz
180uF = 221 Hz
220uF = 181 Hz
270uF = 147 Hz
330uF = 121 Hz

The reason I am bringing this up is that the difference between the successive values really aren't that much; the audible difference probably would be only slight, but the difference between the 120 and 330 values should be really obvious.

It would be interesting for somebody to try some of these values and see if one value is much better than another. I only ever tried the 220uF and was very satisfied with it, so I didn't try the others. My gut feel is that different people would like different values, so it would be interesting to hear what people are experiencing.

 

I ordered two 200uF 100V capacitors from amazon.com for $2.40 ea, which according to their specs are good for up to 200 watts. I wanted 200uF to get as close to the 200hz cutoff as possible. What I did notice was that the capacitors from Radio Shack were 35V which makes me wonder if they are only rated to 70 watts...much less than the amplified wattage. I don't know enough about this obviously, but the capacitors that I ordered seem to be much more in line with the equipment. But I could be all wrong again...just throwing it out for discussion.

 

yes, yes, can't wait to see your info on this install... hurry!

 

Good point!
It is important to match the capacitor's working voltage with the system wattage. However, only part of the output from the amplifier is seen by the capacitor, so the capacitor doesn't have to be able to handle the total power. Plus, you (or I) don't normally listen to our system at the maximum power level...so the 35V working voltage should handle the output of the stock Crossfire system for most people. If you have modified the stock system then you probably want a higher voltage cap (and you probably aren't looking at this $2 mod anyway).

 

I have talked with an engineer friend of mine (Masters degree in electronics engineering) on this subject, and he convinced me that I gave out some misinformation. The misinformation is that a polarized capacitor can be used as an AC, (i.e., music) filter element. I had incorrectly assumed that because audio amplifiers do not have a DC offset at their outputs, and that the average value of sinusoidal AC is zero, then using a polarized cap is ok. The fact is that because the AC signal does spend an equivalent time on the positive side as well as the negative side of ground, the capacitor will see a reverse voltage for half of the signal, regardless of the fact that the average value is zero.

I will say, however, that I have done this mod on both of my Crossfire's with no apparent change in sound quality, which would be an indirect method of determining if the electrolytic capacitors are ok or not. My feeling is that because I only occasionally crank up the volume to real loud volumes, the average AC signal voltage is low enough to not blow the capacitor. Here is an example: The average wattage at mild volume levels are probably around 1 watt, and 1 watt rms (average) into a speaker (4 ohms) calculates to a rms voltage of 2 volts. I am speculating here, but maybe this just isn't enough reverse bias voltage to blow the cap. What would probably happen if the caps started to fail is that they would become leaky on the reverse bias side of the AC signal and begin to "rectify" the AC signal…basically as the capacitor starting going bad, it would start to appear non-linear on the reverse biased side of the signal at the lower frequencies and would probably sound like a distortion in the bass portion that the capacitor is supposed to filter out.

Regardless, I will have to state that only NON-polarized electrolytic caps should be used for this mod. The capacitors at Amazon.com that danimal recommended are ideal, and I am going to change mine as soon as I get a chance:

http://www.amazon.com/gp/search/ref=...0&Go.y=0&Go=Go

Amazon stocks a good variety of values of non-polarized caps: 120, 150, 200, 220, 250, 320, 330, and 400uF.

Sorry about the bad info...and really long post...good luck to all!

 

So the question remains...

When the factory amp eq circuit changes based on speed and volume settings what is the result of the modification?

If you have not taken that into your calculations then your modification is not 100% on target. Not to mention the additional capacitive load you are suggesting here is at what slope?

There is more than meets the eye here and the old school fixes (while they work on some systems) will not deliver the results expected across the volume range or vehicles speeds.

Essentially if you want to weed out the bump in the response around 100 hz drop the bass control -3 and it will work, and all of the other settings in the factory EQ will work as normal.

While products such a Clean Sweep are available for adding aftermarket amplification and negates the effects of the eq, they do not take into account all of the delay and compression limiter circuits either making them minimally effective. Sure they look good at 1/3 octave RTA measurement, but that is not sufficient resolution to see the problems that are heard by people (in this case our ears are better) moving to 1/12th or better yet 1/20th of an octave measurement lets you see the problems. Additionally they do not take into account spatial averaging which is critical in ensuring that each location in the car maintains the same level and quality of sound (we should see products like these hit dealers showrooms in the next year).

 

Okay, I just finished installing the capacitors (I used 200uF) and pelked1's directions are impeccable. It took 1 hour total from start to finish. Afterward, I spent another hour checking out FM and various CDs at different settings. WHAT AN INCREDIBLE DIFFERENCE --- I AM COMPLETELY SATISFIED WITH THE FACTORY RADIO NOW!!! I can actually run the bass as high as +5 or +6 on some material, at +35 volume, with NO DISTORTION. Did any of you know that the subs will VIBRATE your teeth and THUMP you in the back, without distortion in the mid and high range? I actually had to decrease treble to 0 to even it out. I'm actually excited to pump up the volume again instead of groaning over the muddled mess from before.

Thank you so much pelked1!!! I have NEVER spent a better $5 in my life. If you want to enjoy your music, BASS included, instead of running it in attenuated mode, then you must install the capacitors. YOU WILL NOT BE SORRY!

 

Ya, those two little subs back there really can put out some serious bass. I couldn't believe it at first myself either. They can really rock.

I am ecstatic that you found the mod to be so effective!

I agree with what you have found...and that is that the factory stereo system is actually quite a little powerhouse...without a real need to upgrade. Sure, the Becker head unit isn't the best quality sounding unit out there, but it really cleans up a lot that is wrong with it with just this little mod.

If you are a real car stereo enthusiast, you will still want more, but for the rest of you interested in better performance without much time/money investment, you should really go for it.

Here is another source for the capacitors. These are marketed as "Bass Blockers" and can be found at several sources. These are nothing more than a capacitor prewired for you. This link from Crutchfield would be the model best for our application:
http://www.crutchfield.com/S-sYBvcdB...bass+blocker
This Bass Blocker model is a 250uF capacitor. At $10 a pair, it still is a relatively inexpensive way to go, although you could go to Amazon and get a pair of 250uF's for $6.

Good luck to all!

 

OK, I have officially joined the Pelked Party and let me tell you, the difference is AMAZING!! It's like having a whole new stereo! Folks, if you have the stock stereo, this is a no-brainer mod. It took me a grand total of about 15 minutes to do. I got two 220uf electrolytic capacitors form Partronics here in Richmond for a grand total of $.90 each.

It seems to me that the stereo separation got better, the audio cleaned-up a whole lot, and the best part is that the rear-view mirrors no longer vibrate when you have the volume is cranked-up. Danimal is right too. Those sub woofers really add a nice kick to the bottem end if you give them a chance to work. Don't believe me? If you're in the Richmond, VA area, I will be happy to meet-up with you and let you have a listen.

Along with HDDP's SRT-6 brake mod, this goes on my list of "must-have" mods for the Crossfire.

Bob.

 

Pelked,

Which frequency from Crutchfield would you suggest? They sell 150, 300, 600 and 800 hz models.

 

You want to get the 150 hz model (they call it the "brown" wired model)...it is a 250uF cap for those of you who want to buy the equivalent directly from an electronics parts outlet. Also, make sure you get a non-polarized capacitor if you go that route. The Amazon.com caps are of the correct type:
http://www.amazon.com/gp/search/ref=...0&Go.y=0&Go=Go


Here is the Crutchfield link to the correct model bass blocker. I am unsure why the previous link I posted didn't work, but I am going to try it again.
http://www.crutchfield.com/S-vOKvTf1...h=bass+blocker

 

This sounds like BS to me.

 

The amplifier is underneath the carpet in the passenger foot area. No need to remove the seat to access it, removing the cover on the console and the door jam will allow access to it.

Did you find out what the scoop is on the duplicate pins?

BTW, AUDIO SYSTEM CIRCUIT DIAGRAM goofed up in another way. The fuse (23) in the underhood accessory fuse block is HOT AT ALL TIMES. I found this out the hard way when I dug into the fuse block (I like my stereo to work without the key in, so I needed to keep the power amp HOT AT ALL TIMES). I am assuming it powers down when the antenna signal is disabled.

I replaced my head unit because I want to use a remote CD changer that will play MP3s (the stock head unit apparently will not).