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Discussion Starter #1
I just came back from Tweeter to get an estimate on a
sub installation, and one of the guys mentioned that
Scions have a problem with EMI (Electo-Magnetic
Interference). Basically, this means the
RCA/Path/Audio cables have to be twisted in a certain
pattern so they don't pick up interference from the
power/electrical system.

I've noticed a couple of other people have had custom
audio installs or installed something themselves. Is
this truely a problem? I already have some regular
patch cables I can use. I'm also having a problem
justifying spending $50 on Monster Cable (I have an
electrician friend who says Monster Cable is a waste
of money).

It would be nice to hear from someone who has had some
experience working with a tC and custom (and by that I
just mean, non-OEM) audio.

Thanks!
-Alan
 

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ok I have no clue about that.......so, heres my .02 on this. If there is no way for Tweeter to make money on what they are suggesting you do, then go for it because its obviously just free advice and they are looking out for you.

If they are telling you this, and suggesting a higher-priced install techniqe or better wires.......its bogus and ill put money on the fact that they are trying to squeeze you for every penny (its a business....) . - t
 

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From my experience, you need a ground loop isolator if you hear the motor through your speakers. You can pick one up at walmart or something and it'll eliminate the humming from the motor. But just install your system and if you do in fact hear any interference then get the GLI.
 

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there is a simple fix for most of your EMI troubles...

Run your RCA cables down the opposite side of the car from your Remote Turn on wire and your power wire going to the amp. That will significantly reduce any interference you may get. May make the install a bit more difficult, but depending on how large of a power wire you're using, it usually allows for a cleaner install so you don't have a 4 or 2 gauge power wire running along side RCAs... Just my .02
 

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Originally posted by alanthing@Sep 1 2004, 05:43 PM
I just came back from Tweeter to get an estimate on a
sub installation, and one of the guys mentioned that
Scions have a problem with EMI (Electo-Magnetic
Interference). Basically, this means the
RCA/Path/Audio cables have to be twisted in a certain
pattern so they don't pick up interference from the
power/electrical system.

I've noticed a couple of other people have had custom
audio installs or installed something themselves. Is
this truely a problem? I already have some regular
patch cables I can use. I'm also having a problem
justifying spending $50 on Monster Cable (I have an
electrician friend who says Monster Cable is a waste
of money).

It would be nice to hear from someone who has had some
experience working with a tC and custom (and by that I
just mean, non-OEM) audio.

Thanks!
-Alan
First of all, ask the guy who said that if he was paying attention during his JL Audio training!

Here's the deal: whenever current passes through a wire, a magnetic field is generated around it. If a wire passes through a manetic field, you generate current. This is how the altenator works except the wire is stationary and the magnet moves...but I digress.
The chassis of the car has been used as a negative return since the Model T. This means that there is as much current flowing through the chassis as there is flowing through the wires. This means that the whole car is a wire and there is magnetic fields being generated all around it (even extending beyond the vehicle). This happens with every vehicle, there is no special Law of Physics that apply only to the Scion.
That being said "Twisted pairs" are commonly used for noise rejection in signal cables. This doesn't mean that the wire can be routed anywhere with no worries about induced noise, sane installation practices still need to be observed even when using Elven cables.

If you have any questions, feel free to PM me.
BTW, Tweeter is really a great retailer to deal with.
If you really want to reduce EMI problems, there is a way, but it's not going to lower the cost of wire any.
Here goes:
Run power and ground the length of the car right next to each other. Connect the ground wire to the ground point created at the amp and the other end to the OEM ground point under the hood (where the battery grounds).
Here are the benefits:
Magnetic fields have polarity. The field generated around the positive wire will be opposite of the one around the negative wire. The net sum will be Zero! You would have created the quietest place in the entire vehicle to run a signal wire (right in between the cables).
You don't have to tear up both sides of the car.
The chassis of the car is worth only a 4 ga wire. If you were to put larger than 4 ga in the car it wouldn't matter because the return is only worth 4 ga. You can actually improve performace by shoring up the chassis this way (when using large gauge wire).
When magnetic fields break down, so does inductance. This means electrons flow easier which actually improves the performace of the wire and the efficiency of the charging system.


No one needs a capacitor. These items can never charge to a higher voltage than is available so they do nothing about helping an over-taxed charging system. Spend your money on something else
 

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Ding ding ding schools out.
 

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Discussion Starter #12
JLTD-

Are you saying that the best way to run cables would be to run both the postive and ground cables from the battery to the amp, and then put the patch cable inbetween them?
 

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Originally posted by alanthing@Sep 8 2004, 06:59 AM
JLTD-

Are you saying that the best way to run cables would be to run both the postive and ground cables from the battery to the amp, and then put the patch cable inbetween them?
First let me say that I am not asking you to buy anything, just try it on.
What I have posted really defies conventional installation wisdom, but the logic is there. I personally preach this and pactice it. Recently, I helped a co-worker install a system in his 2004 Corolla. We dragged two 2 ga wires down the middle of the car.
If you are planning to do a big system, so big that you plan to use wire larger than 4 ga, this is the only way to really get the performance out of your wire investment. You really don't have to do this if you are using 4 ga or smaller because in those cases, the chassis is a fine return.
I was trying to point out the folly of the statment "you need this cable because Scions have EMI problems". You could blow the guy away and say "can't I use the cheapest cables in the store, do this and actually get better performance????"
There is no silver bullet that is a replacement for good installation practice.
 

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JLTD seem's to know whats up, i would trust him over some doofus at Tweeter.....especially since JLTD is in theory telling oyu to spend LESS money!! - t
 

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Discussion Starter #15
I wouldn't be installating it though I don't think, so it would probably come down to whether or not the installer would throw a fit.

The guy who suggested it wasn't the guy I was working with, he was just some guy standing around (who worked there, of course).

What about a grounded patch cable? I heard of one of those today...
 

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JLTD has some good advice. I have a few more things to add.

IMHO, upgraded cables are a waste of money for what you actually get. Monster Cable does have a good product, but not that good. They actually have a great Marketing and Retail Training program. They teach the sales guys how to hook you. I had a friend that bought a Home Theatre In A Box for about $250 and they sold him over $200 in cables...WOW!!!

The mark-up on those cables is outrageous...3 to 4 times over. A $60 cable may only cost $15. This is why the sales guys always try to get you into the upgraded cables. They simply make more profit selling the cables than the hardware!!!

You can make your own Twisted Pair RCA cables very cheap and they will perform as well as the mega-buck Monster Cables, if not better, with excellent noise rejection.

Get some 24 awg stranded UTP (Unshielded Twisted Pair) CAT5 or better cable from your local computer store. Yes, ethernet cable. If it's good enough to reject noise on High Speed computer networks running hundreds of feet long, then it's good enough for a low speed audio signal 15 to 20 ft long in a car. Should cost less than 10 bucks for 15 ft. Do not use solid cable. This is an 8 conductor Unshielded Twisted Pair cable. You will be able to run front and rear RCA's w/ just one cable.

Get 4 pair of RCA solder type connector ends at your local Radio Shack or other electronics/car stereo store. RatShack P/N - 274-451 are $3.99 a pair for three pair X 2 = $8, and you'll have two extras in case you screw up the next step. Do not use the screw type or the solderless type connectors.

Strip back about 3 inches of the outer sheath on the CAT5 cable. Use about 1 inch of shrink tubing where you stripped the outer sheath to prevent the twisted pairs from untwisting. Solder each twisted pair to an RCA at each end of the ethernet cable, use the striped wire as ground. When you're done, you should have four RCA's at each end...Presto...Two sets (front/rear) of Twisted Pair RCA's for under $20! That's less than two 15 foot cheap-chili-bean rca's!!!

I've used these cables in countless installations and have never had any noise issues. Always use good installation practices. This is not a quick fix or an excuse to cut corners on the install.

Always run your signal cables at least 3 feet from your power cables and at 90 degree angles when the two paths cross. Always use the same guage ground wire from your amplifier as your power wire. Use a central ground point for all of your audio components, including the head unit and equalizers, to eliminate ground loops. Never use the factory radio ground when adding amps or replacing the head unit, disconnect that ground and run a 16-18 awg ground wire with the power cables to the central ground point. Upgrade the stock groung strap from the battery to the chassis at least one size larger than the largest power cable you ran to the amplifiers. 8 awg amp cable = 4 awg ground strap...4 awg amp cable = 2 awg ground strap, etc.

Following these proceedures will 99.99% guarantee you wont have EMI noise...AKA engine whine!!

Another long winded one, but hope it helps.

-G
 

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Discussion Starter #17
Wow, great idea! I never even thought of that. I'm taking a Networking class and we had just discussed why UTP cables are in fact, twisted- to reduce EMI! Brilliant! Thanks so much for the idea! Now I've got a reason to buy a soldering iron...

Your opinion on the markup of Monster Cable is what has always kept me from buying it. Go to Guitar Center, and you'll see that a 6" (yes, inch) Monster Cable to connect pedals is $20!! And the things the salespeople say are SUCH crap. The cables have an input and output end, and they tell you that Monster has engineered the cables to run one way to reduce noise. Whatever...

Your suggestion for the CAT5 cable sounds ambitious, but I like it. Especially since I think I want to mount my amp under the seat and therefore wouldn't need a 15-20 foot cable. My question now still remains about JLTD's suggestion.

You said to put the audio cable at least 3 feet away from the power cable. JLTD said to put the audio cable in between the ground and the power cable. What's the consensus here?
 

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I actually run the audio cable on the opposite side of the car, but you could run it down the center console. The idea is to keep it away from the EMI source...the power cable.
 
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