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Using GG with true balanced

  • Could help sound

    Votes: 2 66.7%
  • Won't help a bit

    Votes: 1 33.3%
  • Might help if it wasn't an OEM HU

    Votes: 0 0.0%
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Discussion Starter · #1 ·
OK, I know that most folks on here are NOT believers in the "cables-sound-different" concept. Bear with me for a moment.

In my experience, inducted noise, while rare, is always the biggest fear in car audio. For this reason, I have always used tightly twisted pair, for its excellent inducted-noise rejection properties.

A few years ago, I tried some Ixos 700 series in a BMW X5. I was pitched the cable due to its lower capacitance and inductance since the physical cable properties were different. Regardless of the snake oil, I know that adding capacitance or inductance to the signal path DOES change the sound, so I decided to give it a try.

I had trouble with inducted noise and finally determined that the Gamma Geometry cable is not tightly twisted enough to be "twisted pair" as far as audio frequencies are concerned. (I experimentally determined that it was indeed inducted noise, and even found some of the sources.)

So I removed that Ixos and replaced it with some Directed Expert series RCAs and the noise was gone.

So I still have these two lengths of Gamma Geometry RCAs. I am doing a system in my BMW 3-series. The 3-series uses true balanced preamp outs to the OEM amp. I plan on running these outputs into the true balanced inputs of a Zapco DSP-6.

In production installs, many installers chop the wires at the OEM amp in the trunk. For this system, I am thinking of cutting the balanced wires at the back of the HU, and inserting a M and a F 4-pin disconnect (letting things go back to OEM easily in future). These OEM wires are tightly twisted.

Now, with a true balanced signal out and a true balanced signal in, a tight twist should be irrelevant, right? As long as the signal + and the signal - are routed together - so that both signals pick up the same inducted noise - there is no need to use twisted pair. I *think* that the Symbilink cables use a signal pair inside the cable which is not tightly twisted, for example.

So... I am thinking of using these Gamma Geometry cables WITHOUT the RCAs, to carry the balanced signal. Since they are not tightly twisted, they should have less inductance and capacitance. Since they have the Gamma Geometry, any effects from proximity should be reduced.

Anyone think it will make a difference? I'm gonna do it anyway, just wondering who thinks it will help, who thinks it is stupid, and who thinks that it doesn't matter with an OEM HU.
 

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OK, I know that most folks on here are NOT believers in the "cables-sound-different" concept. Bear with me for a moment.

In my experience, inducted noise, while rare, is always the biggest fear in car audio. For this reason, I have always used tightly twisted pair, for its excellent inducted-noise rejection properties.

A few years ago, I tried some Ixos 700 series in a BMW X5. I was pitched the cable due to its lower capacitance and inductance since the physical cable properties were different. Regardless of the snake oil, I know that adding capacitance or inductance to the signal path DOES change the sound, so I decided to give it a try.

I had trouble with inducted noise and finally determined that the Gamma Geometry cable is not tightly twisted enough to be "twisted pair" as far as audio frequencies are concerned. (I experimentally determined that it was indeed inducted noise, and even found some of the sources.)

So I removed that Ixos and replaced it with some Directed Expert series RCAs and the noise was gone.

So I still have these two lengths of Gamma Geometry RCAs. I am doing a system in my BMW 3-series. The 3-series uses true balanced preamp outs to the OEM amp. I plan on running these outputs into the true balanced inputs of a Zapco DSP-6.

In production installs, many installers chop the wires at the OEM amp in the trunk. For this system, I am thinking of cutting the balanced wires at the back of the HU, and inserting a M and a F 4-pin disconnect (letting things go back to OEM easily in future). These OEM wires are tightly twisted.

Now, with a true balanced signal out and a true balanced signal in, a tight twist should be irrelevant, right? As long as the signal + and the signal - are routed together - so that both signals pick up the same inducted noise - there is no need to use twisted pair. I *think* that the Symbilink cables use a signal pair inside the cable which is not tightly twisted, for example.

So... I am thinking of using these Gamma Geometry cables WITHOUT the RCAs, to carry the balanced signal. Since they are not tightly twisted, they should have less inductance and capacitance. Since they have the Gamma Geometry, any effects from proximity should be reduced.

Anyone think it will make a difference? I'm gonna do it anyway, just wondering who thinks it will help, who thinks it is stupid, and who thinks that it doesn't matter with an OEM HU.
It could matter if the not so twisted wire happen to run over a noise source and one of the hot leads happens to land on top of that noise source and have more noise induced onto it versus the other hot lead over it that is being shielded by the directly exposed one. Causing an imbalanced that cannot be fully canceled at the end of the circuit.
 

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Discussion Starter · #3 ·
As long as the signal + and the signal - are routed together - so that both signals pick up the same inducted noise
I guess the question in this instance would be, if the two conductors are on top of each other - 1-2mm apart - will the difference between the amplitude of the noise on the and on the - be above the audible noise floor? (SOME will get onto the other line, come on : )

You forgot to vote :)
 

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Gee, thanks :)

Yeah, it will be some work, and I'm trying to make myself feel better about it...
When talking RCA's, I currently have 2 sets i bought form the RF online store for like 11.99 for 2 10' cables, not a bad price, which are a fairly good AWG so that cuts down on resistance and are twisted as well which helps the noise reductions. I know this because I had horrible wine in the car after installing the cables and fully hooking up the system with horrible, horrible whine which only went away when i manage to pull a bit of slack out of the cables and moved it like 6 inches away from the fuel pump harnes/panel located under the back seat (kia spectra 03) that short distance is all it took to cut out the induced noise. Now either the moving it cut it out, and i didn't move it far, or my belife is the twisted pair had soemthing to do with.


what's more interesting to note is that I only got the noise when I a combonation of 3 or more RCa's plugged into the amp. My guess is the twisted pair was able to cancel all the induced noise up to a point. And moving it may put it at a point where it was able to cancel that noise.

Or maybe i'm completely off topic b/c i misunderstood the thread b/c my reading comprehinson sucks, as well as my spelling most likely....
 

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Discussion Starter · #7 ·
I know this because I had horrible wine in the car after installing the cables and fully hooking up the system with horrible, horrible whine which only went away when i manage to pull a bit of slack out of the cables and moved it like 6 inches away from the fuel pump harnes/panel located under the back seat (kia spectra 03) that short distance is all it took to cut out the induced noise. Now either the moving it cut it out, and i didn't move it far, or my belife is the twisted pair had soemthing to do with.
Well, they were already twisted, so if you were picking up a horrible whine from the fuel pump, which stopped when you moved the cable, I don't have to be Socrates to posit that moving the cable solved the issue.

Anything whining that much scares me... might be incipient failure. Then again, my dad taught me that clutches are always about to blow up, and the same may be true of the FP in an '03 Kia..
 

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Well, they were already twisted, so if you were picking up a horrible whine from the fuel pump, which stopped when you moved the cable, I don't have to be Socrates to posit that moving the cable solved the issue.

Anything whining that much scares me... might be incipient failure. Then again, my dad taught me that clutches are always about to blow up, and the same may be true of the FP in an '03 Kia..
I think I might of stated that not so clearly, LoL. Anywho, I meant my speakers were picking up a whine or ground loop and when the sound was way low you could hear a wine that increased or decresed in pitch with the engine.

Any other time i can't hear the fuel pump LoL. And if I could hear it that good I def would have replaced it. Again i may be WAY off topic of what your discussing LoL
 

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you need to twist, especially for RFI type induction. the twist also assures that both conductors are more likely to receive the same amount of induction as opposed to the one closer to the source of the noise.

Twisted pair is unacceptable in purely unbalanced installations. it never was acceptable and outside of car audio and certain sects of high-end home audio UTP is a laughable alternative.
 

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My vote would be skip Gamma and go for a true twisted pair, shielded with a 100% foil shield attached at the sending end only.
 

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My vote would be skip Gamma and go for a true twisted pair, shielded with a 100% foil shield attached at the sending end only.
I got to looking and really researching the issue myself out of curiosity and I kind of find it funny to. Imo you probably would be better off like you said with the true twisted pair wrapped with foil. I currently have my subs hooked up with a set of monster RCA's that are done this way. I got lucky and found them at a Radio shack for like 15 dollars for 13 feet. They run right over the fuel pump, which where my front and rear RCA's were running, and they do not induce ANY noise at all.

Really the only true way for you to know is to set up a test, which is something I've actually seen done before in article somwhere but I can't remeber where. Either way they tested all the high and low end stuff using the same set of test equipment since anything can really cause problems. Personally I would like to see this kind of test done the cables to see if they really live up to that standard.

Although the best I would agree with chad. A farady, that's the term I'm familiar with, cage around the twisted pair would probably be more than enough. Ideally copper, however, you couldn't honestly say that copper would be better than Aluminum without lab testing you really can't see to be honest.
 
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