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running RCAs by power

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=65069
Printed Date: August 18, 2022 at 5:08 AM


Topic: running RCAs by power

Posted By: Poormanq45
Subject: running RCAs by power
Date Posted: October 26, 2005 at 6:40 PM

In short, running the RCA wires next to the power wire does NOT cause ANY interference whatsoever.  The power wire is carrying a DC current, which has a frequency of ZERO, and the RCA cables are carrying a frequency from 0~40khz.

These two wires will NOT cross talk as is the misconception.  How could they?  The power wire is putting absolutely NO interference due to the fact that its frequency is zero. 



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Replies:

Posted By: boulderguy
Date Posted: October 26, 2005 at 7:52 PM

Interesting.  So the electromagnetic field it generates doesn't actually produce any interference?  Can you explain more about the "frequency of zero?"

I've never bought into the idea that power wires had to be run seperate from RCA's b/c I've never solved a noise problem by seperating the two.  Good to hear I wasn't just lucky.





Posted By: dwarren
Date Posted: October 26, 2005 at 9:09 PM

I recently read a similar article about this as well. And there were other points brought up too. Here is some of it...

There is no where on the chassis/floor of the car that will be isolated from noise.

Electrons flow from negative to postive. There is NO way to isolate anything going down the power wire from anything laying on the chassis/floor. Because anything that is going down the wires is also going down the chassis.

You do NOT get noise (or any audible noise) from running power wires and RCAs together.

You do get noise from bad grounds, poorly designed equipment, or a pinched cable.

Running power wires and low level signal wires together will not have an effect on noise. there is no statistically reliable evidence to show that it does matter, but there is a lot of evidence available to show that it doesn't.



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Posted By: stevdart
Date Posted: October 26, 2005 at 9:15 PM
You wanna credit the source of those quotes, dwarren?

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: boulderguy
Date Posted: October 26, 2005 at 9:17 PM
I'd be interested in seeing the whole article.




Posted By: fingaz22
Date Posted: October 26, 2005 at 9:22 PM
me too i would like to get a look at that article. thankx

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JUST ONE MORE AMP!!!
hu,alpine cva 1005/dva 5205
sound processor,symmetry(first one).
sub amp,power 1000 the terminator.(1992).
subs,spl comp dual 1 ohms.
punch 150hd on a 10" ev.
alotofhighs




Posted By: dwarren
Date Posted: October 26, 2005 at 9:25 PM

Meposted_image

It was discussed at work, however I am not necessarily agreeing or disagreeing with the given info. For me to buy this, I might have to try it.

Unfortunately some of this info was pulled from Rcichard Clark and David Navone, which in my book are circus clowns.



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Posted By: stevdart
Date Posted: October 26, 2005 at 9:31 PM
dwarren wrote:

Meposted_image

It was discussed at work


You used the wrong smilie.  It should have been a posted_image.                   posted_image



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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: dwarren
Date Posted: October 26, 2005 at 9:40 PM

No, stevdart I was graceful in my choice of smilies... Your purple guy was the wrong one!

To me it seems there are flaws to both arguments. But there shouldn't as these really are mathematical and technical expressions.



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Posted By: geepherder
Date Posted: October 26, 2005 at 9:46 PM

I have to disagree here.  Alternators produce rippling DC voltage because it can never be flattened out completely.  If you view this on an o-scope, it will look like a sin wave and will have a frequency.

I will agree that most of the time power wires will not induce any noise, but I, as well as others on here I'm sure have run into cases in the past where moving RCA's away from a power source solved a noise problem.



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My ex once told me I have a perfect face for radio.




Posted By: dwarren
Date Posted: October 26, 2005 at 9:53 PM
Right, so here is the other side... "In a vehicle, the ground plane is the ground plane. Floorpan, chassis/frame, negative battery terminal...all the same (for all intents and purposes) electrically, the path of the positive current is different.

An alternator produces "dirty power." It's not filtered or smoothed like say, a laboratory-grade power supply. Running a low-level signal (RCAs) near a cable that's essentially connected directly to the alternator CAN result in a plethora of different noises being picked up. "Static", "ticking noises" etc."

I've experienced this myself. I have even run all the cables down the same side, experienced the noise, then simply moved the RCAs over a foot or so just to experiment and the noise went away.



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Posted By: KarTuneMan
Date Posted: October 26, 2005 at 10:12 PM

Its not that technical, audio cables WILL pick up electrical noise from ANY sorce, including the little bit of factory wiring it might come in near proximity too.

As dwarren stated....move the RCA's and the noise problem is solved. Its really that simple. no need for "o-scopes" or scientific mumbo jumbo chat.



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Posted By: DYohn
Date Posted: October 26, 2005 at 10:15 PM
OK, who told you that DC does not induce a magnetic field?  They are wrong.  Who told you that DC-produced magnetic fields cannot induce EMI into other wires around them?  They were wrong.  EMI can be just as bad in a DC system as it can be in an AC system.  It's called physics.  Now it is true that most good quality RCA cables use sufficient shielding to be relatively immune to EMI and that noise from ground loops is generally a far more significant problem than EMI, but thinking that DC power, because it's not AC, does not induce voltages into adjacent cables is just plain wrong.

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Posted By: haemphyst
Date Posted: October 26, 2005 at 10:55 PM
OK... here comes Dave.

The DC COMPONENT, IN AND OF ITSELF, WILL NOT, AND CAN NOT, CAUSE NOISE. That is the physics, DYohn. The AC ripple ON the DC, caused by the alternator, CAN cause noise, so everybody that has posted so far is correct, to an extent.

Imagine a transformer. All a tranformer is is two (or possibly more, but lets keep this simple) wires wrapped around a core, right? If you put an AC current into the one side, you get a corresponding AC current output on the other side. This is simply putting EMI to work for us. If you feed DC into that same transformer, do you get a corresponding DC on the other side? No, because the DC sets UP a magnetic field, but because there is no collapse of magnetic field, there is no EMI coupling - there can't be.

Additionally, the DC component cannot cause noise UNLESS THERE IS A CURRENT FLOWING THROUGH THE POWER CABLE. The current is what makes the magnetic field, and causes the noise. Since this is the case, there will not be, and can not be, noise induced when the system is idling - there is simply not enough current in the power cable to induce the noise onto the RCA cables. A static voltage, cannot ever produce a magnetic field - current is required. Take the same transformer discussed above, and disconnect the AC neutral from the one side. There is still POTENTIAL (the voltage component of power) in the coil, but because there is no CURRENT in the coil, there is no alternating magnetic field, therefore no EMI, and no primary magnetic field or secondary output...

As you turn the system up, the current demand will increase, causing a stronger magnetic field to be produced around the power cable, potentially inducing a voltage on the RCA signal wire.

I have RARELY, if ever, had luck in separating the power cable from the RCA, and in the few times I DID have a little bit of luck - i.e. a slight reduction in noise level - it was discovered that the battery (a big ol' noise filter, people) needed replacing or the alternator was in some way defective.

There's MY two cents again...

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: dwarren
Date Posted: October 26, 2005 at 11:11 PM

haemphyst wrote:



it was discovered that the battery (a big ol' noise filter, people) needed replacing or the alternator was in some way defective.


Yes, so I have heard the battery acts as a filter, and can be biggest problem in a system. This is where most of the nosie is created.



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Posted By: boulderguy
Date Posted: October 26, 2005 at 11:15 PM

haemphyst wrote:

Take the same transformer discussed above, and disconnect the AC neutral from the one side. There is still POTENTIAL (the voltage component of power) in the coil, but because there is no CURRENT in the coil, there is no alternating magnetic field, therefore no EMI, and no primary magnetic field or secondary output...

I was following everything fine until we got here.  Think I'll politely excuse myself now...





Posted By: DYohn
Date Posted: October 26, 2005 at 11:31 PM

As the current flow through a cable in a DC circuit changes, the magnetic field it generates changes.  It is the changing magnetic field that can cause EMI in an adjacent circuit, just like in an AC circuit.  Of course there is no changing magnetic field as a system is "idling," as there is no changing current flow (or no current flow at all.)  But in an active car audio power system, the DC current draw is changing constantly.  This causes constantly variable (expanding and collapsing) magnetic fields around the DC power cables, which can induce noise (EMI) into other circuits.  It's been more than 20 years since college but I believe I still remember applications of Faraday's Law.....



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Posted By: KarTuneMan
Date Posted: October 26, 2005 at 11:38 PM
Hey when you guys figure it out......make sure you let the rest of us know.....Kposted_image

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Posted By: haemphyst
Date Posted: October 27, 2005 at 12:16 AM
The changing of the magnetic field in the power cable is always a positive - sometimes a little more, sometimes a little less - but ALWAYS positive. There is never a SWING from positive THROUGH zero, to negative.

DYohn... Of course you are right, but why is it, then, that when there is the LEAST amount of (desired) sound, the noise (undesired sound - the alternator whine) is at it's highest? Yes, the undesired sound WILL be eventually covered up by the desired sound, but while this is happening, the current through the DC power cable is increasing, but the undesired noise is NOT increasing at a constant level (and this I HAVE demonstrated with an o-scope) - if it were, the noise would be as loud as the music, or potentially louder, at some frequencies...

There is simply not enough change in magnetic field with MUSIC signals to produce the necessary magnetic fluctuations required to induce a voltage high enough to go to the effort of tearing apart the entire car to run power down one side, and the signal down the other. There ARE fluctuations, but they ARE always POSITIVE. There is NEVER a negative swing - required to cause a total collapse of the magnetic field, inducing the voltage on the secondary - in this case the positive signal wire contained in the RCA wire.

In my experience, ALMOST ALL noise induced into signal wires does not come from amplifier power cables, but from other electronics in the car - ECUs, fuel pumps; things like that.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: dwarren
Date Posted: October 27, 2005 at 1:02 AM

haemphyst wrote:

In my experience, ALMOST ALL noise induced into signal wires does not come from amplifier power cables, but from other electronics in the car - ECUs, fuel pumps; things like that.

Perhaps I missed the explanation for this, but why then would it matter if the electrical component is not an amp, rather an ECU or fuel pump, how does it vary?



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Posted By: DYohn
Date Posted: October 27, 2005 at 8:25 AM

Dave, a magnetic field does not have to swing negative in order for it to collapse.  Indeed, if the current flow goes to zero, it collapses.  If the polarity swings negative, the field reverses polarity.  But "collapse" literally means it goes from some value to zero, and it will certainly do that in a DC circuit.  Faraday (and Maxwell) showed that anytime a magnetic field is moving in relation to a wire, an EMF is induced.  It does not matter the polarity.

The magnetic field change I am talking about is in the power cable for an amplifier, not in the signal cable.  This field change can be very radical as the amplifier draws more or less current, and this field is certainly more than sufficient to induce a voltage into adjacent wiring.

You are correct of course that the LARGEST contributors to EMI and other induction effects is more likely a noisy system (rippled DC, arcs and sparks in the alternator, other mechanical and magnetic devices, etc.) than from pure induction through magnetic field interaction.  But you cannot say it does not happen.  That was my only point: that it is certainly possible and in some cases very problematic.  Poorman's theory that it is a "misconception" is simply wrong.



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Posted By: Tegpilot
Date Posted: October 27, 2005 at 9:32 AM
I'm already in the car on my way to ABC to pitch this one as a Reality TV Show. 

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99 INTEGRA LS 4DR Forest Green.Alpine CDA9857 Deck. JBL 755.6 AMP, Kappa 50.7cs Front, Kappa 6x9's Rear, 4 JBL GTO804 subs




Posted By: dwarren
Date Posted: October 27, 2005 at 9:36 AM
Sounds...boring, but there could be some great "drama" especially from the Dave's.

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Posted By: Tegpilot
Date Posted: October 27, 2005 at 9:48 AM

Oh come, we'll give em each a glass room, Some wire, goggles, a big ol battery and a six month supply of Doritos. 

Then we just see who cracks first.  "or proves the theory first"  



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99 INTEGRA LS 4DR Forest Green.Alpine CDA9857 Deck. JBL 755.6 AMP, Kappa 50.7cs Front, Kappa 6x9's Rear, 4 JBL GTO804 subs




Posted By: haemphyst
Date Posted: October 27, 2005 at 10:28 AM
Tegpilot wrote:

Oh come, we'll give em each a glass room, Some wire, goggles, a big ol battery and a six month supply of Doritos.

'cept mine'd hafta be jerky... I'm on Atkins!

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: Mad Scientists
Date Posted: October 27, 2005 at 12:20 PM

haemphyst wrote:

The changing of the magnetic field in the power cable is always a positive - sometimes a little more, sometimes a little less - but ALWAYS positive. There is never a SWING from positive THROUGH zero, to negative.

There is simply not enough change in magnetic field with MUSIC signals to produce the necessary magnetic fluctuations required to induce a voltage high enough to go to the effort of tearing apart the entire car to run power down one side, and the signal down the other. There ARE fluctuations, but they ARE always POSITIVE. There is NEVER a negative swing - required to cause a total collapse of the magnetic field, inducing the voltage on the secondary - in this case the positive signal wire contained in the RCA wire.

Looking specifically at "There is NEVER a negative swing - required to cause a total collapse of the magnetic field, inducing the voltage on the secondary"

explain how an ignition coil (which is nothing but a step-up transformer) works in this situation.. and why diodes are used on relay coil leads.

Jim





Posted By: haemphyst
Date Posted: October 27, 2005 at 3:16 PM
Perhaps my statement translated to needing AC. While this is NOT true, a pulsed DC is a minimum. This is what is fed to the primary side of your ignition coil. ON, then OFF - the cycle of your ignition points (or in the case of most of today's cars, the solid state switching circuitry)... The OFF is when the spark occurs.

Diodes in relay coils are there to prevent the back EMF, produced when the field collapses, from feeding back into the driving circuitry. The diode is placed in opposite polarity of the driving voltage so it is "invisible" to the driving circuit.

When the field collapses, the back EMF produced is an opposite polarity of the voltage that produced the field to begin with. This is why the diode is placed the way it is... it will short the back EMF across the terminals of the relay coil, preventing the high voltage spike produced from being sent back into the driving circuitry.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: haemphyst
Date Posted: October 27, 2005 at 3:18 PM
Tegpilot wrote:

Oh come, we'll give em each a glass room, Some wire, goggles, a big ol battery and a six month supply of Doritos. 

Then we just see who cracks first.  "or proves the theory first"  




...and I think he's talking about us, DYohn... you ready? posted_image

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: tcss
Date Posted: October 27, 2005 at 3:43 PM
WOOOOOOSSSSSSSSHHHHHHHH. ( The sound of most of that going over my head ) Deep stuff guys, I'm going to go bang my head on a dashboard.........

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There is no such thing as free installation!




Posted By: DYohn
Date Posted: October 27, 2005 at 3:50 PM
haemphyst wrote:

Tegpilot wrote:

Oh come, we'll give em each a glass room, Some wire, goggles, a big ol battery and a six month supply of Doritos. 

Then we just see who cracks first.  "or proves the theory first"  




...and I think he's talking about us, DYohn... you ready? posted_image

I'd rather work with you than against you, my friend.  We could cook up some pretty good Frankenstein monsters if we wanted too.  I see large open frame plasma drivers.....  and plenty of Doritos and jerky...  posted_image



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Posted By: dwarren
Date Posted: October 27, 2005 at 5:25 PM

I decided to investigate this matter further. I went to a physics professor today and brought the situation to him.

He said that yes AC current does produce EMF. However will we hear the noise, no. It is dependant on what the amperage the wire is pulling. The higher the number the more it will produce.

As far as the swing of polarity, negative doesn't necessarily mean it goes negative, rather it is a drop from one poin to another. So DYohn Faraday's theory is applicable but the magnitude of what we are dealing with (relatively small numbers) EMF will not have and effect on low voltage signal cables.  



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Posted By: stevdart
Date Posted: October 27, 2005 at 5:52 PM
I'm sure that I'm not the only one to notice that poormanq45 started another controversy (number 594, I believe) and then ducked into the shadows to let DYohn and haemphyst do the heavy lifting...

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: DYohn
Date Posted: October 27, 2005 at 5:57 PM
dwarren wrote:

, rather it is a drop from one point to another. So DYohn Faraday's theory is applicable but the magnitude of what we are dealing with (relatively small numbers) EMF will not have and effect on low voltage signal cables.  


... assuming the low-level signal cables are properly shielded.  If they are cheap 99 cent unshielded cables, the EMF induced from the changing magnetic field around a power cable can create audible hum, buzz or thumps.  I know, I've heard it.  posted_image



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Posted By: boulderguy
Date Posted: October 27, 2005 at 6:01 PM

I can't believe y'all are still going at this!  Interesting theories even tho they're beyond my understanding level.

So to bring this to a more practical level, how many of you have actually solved noise problems by seperating RCA's & power lines?  Those who have, how often, out of say 100 noisy systems, would you say that the power lines were responsible?





Posted By: Mad Scientists
Date Posted: October 27, 2005 at 6:20 PM

haemphyst wrote:

Perhaps my statement translated to needing AC. While this is NOT true, a pulsed DC is a minimum. This is what is fed to the primary side of your ignition coil. ON, then OFF - the cycle of your ignition points (or in the case of most of today's cars, the solid state switching circuitry)... The OFF is when the spark occurs.

Diodes in relay coils are there to prevent the back EMF, produced when the field collapses, from feeding back into the driving circuitry. The diode is placed in opposite polarity of the driving voltage so it is "invisible" to the driving circuit.

When the field collapses, the back EMF produced is an opposite polarity of the voltage that produced the field to begin with. This is why the diode is placed the way it is... it will short the back EMF across the terminals of the relay coil, preventing the high voltage spike produced from being sent back into the driving circuitry.

It was a rhetorical question... my point was to show that it's certainly possible to run a transformer off DC.. you have to pulse it, yes, but even though there's no zero crossing, it'll still work.

to go a step further, if you accept that the higher the current flow the stronger the magnetic field, a current change from 400 amps to 50 amps in a wire would change the magnetic field enough to generate a current in another nearby wire... yes?

Jim





Posted By: dwarren
Date Posted: October 27, 2005 at 6:48 PM
DYohn] wrote:

QUOTE=dwarren]

, rather it is a drop from one point to another. So DYohn Faraday's theory is applicable but the magnitude of what we are dealing with (relatively small numbers) EMF will not have and effect on low voltage signal cables.  


... assuming the low-level signal cables are properly shielded.  If they are cheap 99 cent unshielded cables, the EMF induced from the changing magnetic field around a power cable can create audible hum, buzz or thumps.  I know, I've heard it.  posted_image

[/QUOTE]

Shielding (the foil wrap) in rca's acts an amplifier for noise here, so they may make things worse, not better.



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Posted By: stevdart
Date Posted: October 27, 2005 at 7:13 PM

C'mon, let's not make DYohn do all the research too!  Here's one answer from a source we all know well (https://www.bcae1.com/rcacable.htm):

RCA Cable Construction
The RCA cable, which is used in virtually all car audio installations, is a specialized cable which is designed to transmit audio while preventing noise from entering the audio stream. As you can see in the diagram below, the center conductor is "shielded" from noise by completely enveloping it in a braided copper shield conductor. The shield is connected to the reference terminal of the audio source. You remember that every measurement has to have a reference. The same is true when you are sending a signal (audio in this case). This is so because the next device in line must "measure" the level of the incoming signal. If it does not have a good reference, the signal quality will suffer. I will explain "audio grounds" in a section to come. 

posted_image



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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: geepherder
Date Posted: October 27, 2005 at 7:41 PM

That's funny, I went to sleep after posting yesterday.  I wasn't going to get as indepth as Dyohn or Haemphyst because I wanted to make my point in a somewhat easy-to-read manner.

Steve, I like the comment about stirring up the nest and leaving (594).



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My ex once told me I have a perfect face for radio.




Posted By: haemphyst
Date Posted: October 27, 2005 at 10:11 PM
dwarren wrote:

Shielding (the foil wrap) in rca's acts an amplifier for noise here, so they may make things worse, not better.

There's one I have never heard before...

The shield is called a shield, because it shields. ANY noise induced in the shield SHOULD be shorted to ground. As long as the components (or at least one of them) has an appropriate ground plane within, the signal should be shortd to ground, where it CANNOT cause any problems.

If both have ground planes connected to the RCA's outer connector, this is where proper grounds become even more important. If there is a voltage potential between the ground planes of the devices, there WILL be noise induced in the signal, caused by the current flow over the braid.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: fingaz22
Date Posted: October 27, 2005 at 10:58 PM

well i love it when everybody gets techanical . it shows the knoldedge we are all capable if we apply ourselfs. well i was just going through my symmetrys handbook and this is how fosgate solved this problem in the early 90's,  they used a missing link transmitter for the signal processor system, witch i believe is one of the best systems ever designed. just my opinion though, so here it is, most systems use low voltage,unbalanced cables to transmit audio signal from one end to another. unfortunately,these unbalanced lines are very suscepible to ignition noise,fan motors,and alternator whine. to alleviate these problems the missing link transmitter comes into play.

it takes unbalanced lines witch are immediatly converted to fully balanced,differentially driven output.these outputs,witch are similar to the ones used in recording studios,are amplified to 30 volts peak to peak and then routed to preamplified module(pam) via db25 multiconductor cable (computer cable) the (mlt) is designed to be mounted as close to the source unit as possible to obtain the lowest possible noise figure.since the output of the (mlt) is fully balanced,any noise introduced into the cable between the (mlt) and the (pam) will be eliminated due to common mode rejection.in addition,by amplifying the signal at the (mlt) and then reducing it back to unity at the preamplifier, any noise that escapes the common mode rejection will be reduced at the same time the signal is reduced to unity at the preamplifier.

so there you go you can have all that for the 500 to a 1000 dollars they are selling for today. oposed to the 2500 dollars when they came out in 1992. i personaly own one and love it the options are endless but thats my opinion and just thought i would add that to this topic. they are not for evryone.



-------------
JUST ONE MORE AMP!!!
hu,alpine cva 1005/dva 5205
sound processor,symmetry(first one).
sub amp,power 1000 the terminator.(1992).
subs,spl comp dual 1 ohms.
punch 150hd on a 10" ev.
alotofhighs




Posted By: dwarren
Date Posted: October 27, 2005 at 11:26 PM

haemphyst wrote:

There's one I have never heard before...

I am here to entertain! and something else, just can't remember.

Again this was gathered info from a physics professor. Your explanation is sound, however in your previous responses it was stated that AC current does produce a EMF, but the magnitude of this will not affect low level signal, but a metal wrapping in an RCA will amplify this interference. Yes a shield is used to block things so to speak, but after all it is a conductor.



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Posted By: youngone
Date Posted: October 28, 2005 at 12:26 AM
alright out of everybody's comments it seems that there is a current drop in a line that is carrying a dc or ac both currents make noise. ac makes more of a noise than dc because of its set hz. but in a dc current there is always a very small amount of noise because of a alternater or a fan or something. i now that a power cord can interfear with the signal going to the speakers.(if the speaker wire/rca is close to the power. sometimes it can be loud sometimes it can be quiet it all depends on the setup. if you have the problem with it you gust try what you think it is. all cars are different and stuff happens.

i think that all you have to do is gust try to keep the wire as far away from the power cord. preferbly on the other side of the car. no need to have an argument over it.

but hay it is interesting to hear the advansed and technical answers that people have and there points. keep it up guys it is a extreamly helpful topic.posted_image posted_image posted_image

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Posted By: KarTuneMan
Date Posted: October 28, 2005 at 1:39 AM

Oh MY GOD..........come on "boys"...where is all of this taking us? And yes I said "BOYS".    You kids babble off this crap that is supposed to impress us, honestly it just makes the rest of us just want to "walk away with our tails between our legs" How many people do you think understand HALF of the crap you kids are spewing......and does it really help ANYONE. It's like the main objective has been forgotten....to help, and assist...the "not so experienced"

I would think this would be a perfect topic for you guys to PM the living crap out of one another over...........



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Posted By: dwarren
Date Posted: October 28, 2005 at 2:09 AM

Well Kar TuneMan you sure like to spoil other people's fun! Perhaps this topic is a little beaten, but at least it hasn't been reduced to name calling and other juvenille behavior (yet). Just because you can't join in doesn't mean you have to condemn it. (this should be read with a humorous inflection)

I for one have learned a lot from this thread, and am quite happy to have participated in it. It may take some time to figure this stuff out (there are some things I am not totally clear on) but there are answers to questions here. Be patient, this is after all a DISCUSSION forum...



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Posted By: Mad Scientists
Date Posted: October 28, 2005 at 7:37 AM
KarTuneMan wrote:

Oh MY GOD..........come on "boys"...where is all of this taking us? And yes I said "BOYS".    You kids babble off this crap that is supposed to impress us, honestly it just makes the rest of us just want to "walk away with our tails between our legs" How many people do you think understand HALF of the crap you kids are spewing......and does it really help ANYONE. It's like the main objective has been forgotten....to help, and assist...the "not so experienced"

I would think this would be a perfect topic for you guys to PM the living crap out of one another over...........


If nothing else, use this to recognize things you don't know about and read up on them. Try to learn more. Is it surprising that DYohn and Hamfisted (sic) know stuff like this?.. they are two of the most knowledgeable people on the board. Do you think they ever stop trying to learn?

Jim 





Posted By: Mad Scientists
Date Posted: October 28, 2005 at 7:43 AM

Heh.. here's a post from another place I read..

"My Marks Manual lists the simplified final velocity of a rocket as delta V = I(s)*g*ln(w(i)/W(f)). This means that the specific impulse ( the I(s) term) times the natural log the final weight over the intial weight. Modern rockets often have a final weight of 10% of their initial weight (90% fuel), which gives about 2.2 for that part. I can not find the specific impulse of gun powder, but we can assume it is fairly low, which is why no one uses it and therfor it is not listed in my book. The lowest specific impulse listed is for hyrdazine, at 110 seconds. That give a maximum speed of 7,734 feet/sec. Escape velocity is around 33,000 feet/sec, so there is no way it could have reached orbit. If they fired it at a 45 degree angle, it would take about 170 seconds to reach its highest point, and another 170 seconds to hit the ground again. With a horizontal velocity 5468 feet/sec, that gives a max distance of 352 miles, which makes things at least possible."

Jim





Posted By: haemphyst
Date Posted: October 28, 2005 at 7:49 AM
WOW, and rocket hobbiests too! We do have an assortment of people here, don't we?

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: geepherder
Date Posted: October 28, 2005 at 8:19 AM

Dwarren, just a quick correction.  This professor is telling you the braid would make more noise because in his mind it is like an antenna, paralleled with the center conductor.  The only problem with his view is the "antenna" is grounded at both ends.  Haemphyst's assessment is correct.



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My ex once told me I have a perfect face for radio.





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