niebur3

After I did an install last weekend and had major issues with noise taking the pre-amp signal and wiring directly to an AudioControl Matrix, I decided to do some research.

First of all, the Matrix DOES have a jumper setting inside that may need to be adjusted to help with/eliminate ground loop noise.

Now, with that said, I asked Bing (simplicityinsound on DIYMA) who is a top installer and he knows the car very well. He says to STAY AWAY from the AudioControl Matrix. He has nothing but issues with noise when using them. Not to say, everyone will have noise, but there is a high percentage you will.

He also confirms the balanced out are a NON-ISSUE when going to an amp because of the lack of voltage from the factory Head Unit. You guys will need a line driver. Just not the Matrix.

Anyway, just trying to help!

Trunk Monkey

iTrader: (1)

Well that's not good. I know a few on here have used the Matrix with good results. If he says our HU's balanced out is a non-issue due to lack of voltage, why would a line driver be needed? Serious question lol. He saying that a line driver could be the reason for noise?

I haven't touched my setup all week. Just depressing. I need to figure it out though

stevemk07

Good to know.

niebur3

Because of the lack of voltage. You need the line driver to increase the voltage so you can actually obtain full power from you amplifiers. He says he hates AudioControl line drivers because of their noise.

Aftermarket amps don't need to accept balanced inputs if you go directly in from the HU (pre-factory amp) due to the crazy low voltage our HU puts out. Again, the whole reason you would need an amp that accepts balanced is because balanced is typically higher voltage, and in some cases as much as 16 volts. Many amps can't handle that much. All amps can handle the fraction of a volt out HU puts out. Once you put a line driver in line, the signal is no longer balanced (in most cases) and therefore again, the amp being balanced isn't important.

Opel

I've been running the new matrix plus with absolutely no issues right out of the box. It is configured for isolated ground in factory form, and I never even bothered changing anything, because it simply worked fine from the get go.

Trunk Monkey

iTrader: (1)

Interesting. Thanks

pohljm

Thats kinda crappy news for audiocontrol! But in reference to the other part of the discussion I do not believe that a line driver is necessarily required for our HU due to the low voltage.

I can vouch for the JL amps being able to play nicely with the low output voltage. I have no noise and still have headroom on my gains. Most every professional I discussed this with thought a line driver would be necessary. It just is not true with the JL. I have no experience with any other amp.

My RCA runs are very short to get under the seat, so there is less opportunity for noise to creep in.

Opel

There's a lot of amps that will work with the low voltage input, yours being one of them, and mine as well. But they will not run at their potential. You do need a line driver if you want to keep your amp gains down while still getting their potential maximum amplifying output. This however, doesn't apply to everyone. Some people will be happy with minimal output, and some wont, so they will crank up their amp gains, and that's when system starts to sound like crap. A line driver will keep your gains low. I ran the system with and without a line driver...it makes a big difference

DiamondJoeQuimby

iTrader: (2)

You can damn near stick a kitchen funnel in the RCA input of a JL amp, talk into it, and it will work. The input side of those amplifiers is just fantastic.

Trunk Monkey

iTrader: (1)

All you're doing is matching voltage here....

Line driver just makes the amp work less hard thus lowering amp gains, heat, THD, etc.

niebur3

Sorry, but the line driver will help noise and let your amp reach its full power (or full power sooner) but will not help heat or THD. If the amp is making 300 watts, its doesn't care about the input voltage (as long as its enough to make the 300 watts) and works just as hard either way.

cacicgt7

How does this compare with all the other AudioControl stuff?

Is the AudioControl LC6i still considered a really good LOC post factory amp? Just wondering if the rest of their lineup isn't as strong as well.

Trunk Monkey

iTrader: (1)

Sorry...THD+N. Seems like 99.9% of the time in car audio the N is included, but left out of the equation. THD is just a measure of the distortion within the FR. You obviously lower the gains if increasing the voltage also. Would heat not be lowered though?

niebur3

No, heat would be the same, if the amp is making the same watts.

so cal eddie

I've done about a dozen or so of these cars, my own car included when I had it, and I never had any issues with the matrix. I took the signal from the back of the deck, added rcas, and went straight to the matrix. In lower budget installs, I used sni-35s off of the stock amp with no problems either. The only time I had noise was with a pos rockford fosgate unit.

Trunk Monkey

iTrader: (1)

what pos rockford unit? BLD, 3sixty.2, etc?

jda123

I have never used a matrix or any kind of line driver and I can tell you that the HU signal will still cause issues being balanced differential even at less than a volt. I have several .2v input amps which can make full power with a .2v signal (even balanced differential) that still had noise from the HU. How does this guy confirm that balanced differential signals are not an issue at low voltage? I can confirm that is is an issue with the ELS head unit. What equipment did he use? Does he still have the ELS head unit? I can post my equipment and maybe we can track down the difference. Heck, most line drivers will convert balanced diff, so maybe he has something doing a conversion that he hasn't though about.

There is more to a balanced signal (differential, or not) than just voltage.

Gains just try and normalize the input signal. THD+N is product of the output, not the input. Low gain on a high voltage signal will have the same THD+N as high gain on a low voltage signal, assuming the same output. Remember, it is not a volume knob. If your amp can accept an input signal in the range that the HU puts out, then you gain nothing with a line driver - what you boost in signal, you take away in gain... but not all amps can do this, so line drivers are needed for some (or most for all that I know).

The JL amps are fantastic for our cars and should make most people very happy. They are easy, cheap (considering all factors) and reliable. I don't like the SQ or any of them as much as most of the bipolar amps, but most of us are still using the ELS HU which is not stellar in SQ... so this is mostly a moot point. I have switched to all Zapco and Audison, but I would use a Jl amp again in my TL in a heartbeat if one of these amps went out. If anybody wants a no-headaches install, then get a JL amp for this car. If you can find some older zapco ref amps (or DC), they are no-headache install amps too.

so cal eddie

I honestly don't remember. It was probably about 6,7, or 8 years ago when I was doing some of these cars, so whatever rockford offered at that time. I do remember switching to the pac sni35s, though, and the problem was solved.

I hate cars

All I can say is I've run non balanced input amps off of the HU and I had no noise but also not enough volume on most. Some amps can deal with the super low input voltage, some can't. None I've dealt with have had noise.

The line driver does reduce or eliminate noise that is picked up on the way to the amp (actually it amplifies the "good stuff", drowning out the "bad stuff". The amp's gains amplify the entire signal. If that signal is full of noise, the noise along with the music gets amplified. If that signal is amplified first, before the noise gets in the system, the amp's gains do not need to be as high which will amplify the noise less. Or said another way, a line driver placed up front will amplify only the good signal while the amp will amplify everything. Boost the clean signal before the amp and you have a better signal to noise ratio by the time it gets to the amp.

Or said ANOTHER way, say you have .8v from the HU and the RCA picks up .2v of "noise" along the way to the trunk. Amplify that .8v to 5v and send it to the trunk mounted amps and you don't notice that .2v of noise anymore.

Keep in mind, the HU puts out a MAX of .8v. What do you think it puts out at normal listening levels? It's destined to pick up noise along the way with the amount of amplification needed to get decent output.

Output causes heat and noise, not gains.

I'm pretty sure some MECA events have been won with the stock HU. The only thing I dislike about it is a sort of loudness curve that goes on as the volume is raised.

pohljm

Cant you use your processor to eliminate that loudness curve?

I hate cars

I'm not sure. Not the one I'm using. If I run the setup CD, the one that flattens and sums the factory signal with the HU at 30, the highs and subs are a little boosted at low HU volumes. If I do it with the HU lower, the sound is more normal at low volume but thins out a lot when you crank on it.

The processor would have to somehow boost the subs and somewhere in the midrange/treble as the volume knob goes up to compensate. I'm sure someone somewhere has done it. I know there's a product made just for newer factory headunits that does just that but only on the subs, never seen one that does the treble as well.

cacicgt7

Can you run a JL amp, say the XD series straight to the headunit? Or is it best to run one of these after the stock amp with an LOC?

DiamondJoeQuimby

iTrader: (2)

All of the current line JL amps (even the entry JX) will accept a balanced differential input.

The only ones that didn't were the original "e" series amps from ~2004ish. Once they switched to the "a" series all amps were balanced diff input capable.

I don't remember if the original J2 did or not (TMA rebadge). But honestly if you are buying a TMA, J2, or e amp used, just don't.

pohljm

Its never better to run after the stock amp! Current JL amps work perfect with the TL Headunit.

cacicgt7

Right but I'm talking strictly no line driver, just running from the H/U spliced into some RCA's and connecting them to the XD amp.


I thought like 70% of this board ran after the OEM amp with an LOC to whatever amp they chose? No? Many without any problems? I'm just referencing the above scenario with the JL amps to see if you can just cut out a step and additional expenses.

jda123

You can run either signal into the XD without any line driver or LOC. It is fine either way. You will get better sound with the pre-amp signal.

Trunk Monkey

iTrader: (1)

This car is a PITA. Some guys are saying line driver is needed to reduce noise on the run to the amp(s) while others say there's no need for it. Some people get noise using certain amps and others don't when they both accept balanced, etc.

We need to come to a conclusion and then make a sticky

cacicgt7

That's what I'm saying! Too much info in the long run. I think a lot has to do with SPECIFIC amps that people use, or it seems that way at least.



1.) From what I've gathered most of the newer JL amps work really well. And by what others are saying, if you have one of the newer ones you "can" run straight from the head unit (pre OEM amp signal) to a JL amp with speaker level inputs (make your own to RCA's or use something from crutchfield) and then from the amp to speakers. Then keep the OEM amp on the center channel all by itself.


I looked up the XD specs, and it says: Input Voltage Range @ RCA Inputs 100 mV - 4 V RMS

Which means the .8 volts the stock h/u outputs (someone confirm the voltage please) will work with the xd series JL amps.


2.) Run a line driver if you have other types of after market amps. Thus head unit to line driver, then from the line driver to new amp. Keeping stock OEM amp for center channel again.

3.) Run an loc AFTER OEM amp signal, then from loc to new amp. (This may have the worst potential sound and signal from everything I've tried to read here.)




Someone tell me if I'm WAY off lol. Option 1 I haven't tried but sure sound the easiest, with the only risk of potentially running gains higher (not confirmed)

jda123

I got .9 something on the front pre-amp signal. I did not see the voltage drop much from 10 to 30 and my thought was that wattage changed on the volume and the voltage stayed constant like most electrical systems... however, I did not test wattage and these thoughts are just anecdotal at best. You cannot just test this with a DMM, you need an oscilloscope... music is dynamic and DDMs are not.

I don't think that anybody has ever had an issue with a modern JL amp in this car.

I have run JL Slash amps, Audison LRx (the black ones) and Zapco amps with nothing but a RCA cable spliced into the headunit output (preamp). No noise, no problems and loud enough to deafen you with excellent sound quality.

I have used older Audison LRx (the blue ones), Fosgate Power (the good ones), Fosgate a-series and some others that accept voltages down to .2 and they all have had noise until I used a Zapco balanced to unbalanced converter - this is not a line driver, just a converter and the noise went away. Again, just a RCA spliced into the radio output.

I have made my conclusions:
1). Plan ahead and buy an amp that accepts either signal with voltages in the range that the HU puts out.
2). Why would I use something by Audiocontrol, Fosgate or the like in front of several-thousand-dollar components as well as thousand dollar amps designed for SQ when I can already tell the difference in a mosfet and bipolar amp? ...so no line driver or anything for me. In a least-common-denominator system, a Fosgate BLD (while nice for what they are) is not worth the risk of killing my sound. I already hate it enough that the ELS headunit is not all that great in sound quality... and one day will get replaced.

cacicgt7

^ Great post. Did you keep your center channel on the stock amp for navi prompts?

jda123

My center and rears are still on the stock amp. I have the center turned off, though - I hate it being part of the mix. However, I have the navi prompts off... "you are now entering an unknown area, proceed with caution."

I hate cars

ANY super low level signal will always be more suceptable to noise picked up along the run. In some installations it might be a problem and in some others it might not but it's never a bad idea to boost it early on. Type of wire (RCAs or speaker wire) can affect this just as much or more than the type of amp. This isn't just a TL thing, it's with any car.

I had a little noise pre-amp at one time and swapping to a slightly higher quality RCA fixed it, still using the same routing and everything else staying the same.

Post amp you don't have to worry about picking up noise along the way because the stock amp boost the signal enough that it does the same thing as a line driver with the difference being it's a dirty signal and you get hiss.

So basically pre-amp picks up noise along the signal path to the trunk and post amp starts with a dirty signal and your aftermarket amps amplify it even more. If you boost the pre-amp signal early on with a line driver you get the benefits of post and AND pre-amp. You're no longer on the verge or past the verge of noise entering the system, you have a much larger safety margin.

I hate cars

A bit off topic but I didn't realize until a few months ago that some of the beeps from pushing buttons on the navi are actually from the navi itself and not coming from the center speaker. I've heard the beeps but just recently remembered that I have no center speaker installed.

niebur3

Matt, you shouldn't be having any eq differences since you are going pre-amp....the curve is built in the amplifier. Also, if you did have an eq curve, you could tune to a specific number on the factory HU and then use the volume dial on the MS8.

What I believe you are hearing is the EQ boost the JL HD amps have built in. Yes, those amps are not flat. They have a built in curve (one reason I don't care for them) and you are probably experience this undefeatable "feature" of the amp. It may change based on voltage or something.

I hate cars

I surely hope you're wrong but probably not. Everything definitely thins out at higher volumes, I'll try and dig up that old test that's on DIYMA. I'm 90% sure it was on the HU, not after the amp but my memory isn't always the best. Still going to get rid of the MS8 as I believe that's 90% of my problems.

I'm going to be hitting you up about some MW182s pretty soon. I just got forced into selling a bunch of my land so I might be going on a spending spree soon.

DiamondJoeQuimby

iTrader: (2)

Where did you get this information? Did you bench one and check it? I have NEVER heard this before.

I'll hook one up on the bench after lunch and report back.

DiamondJoeQuimby

iTrader: (2)

I used Autosound 2000's CD102, track 18 20Hz-20kHz un-correlated pink noise.

First pic is RCA signal from the POS Sony H/U pictured in the test bench, all loudness and boosts off or flat

Second pic is the front right output from an HD600/4. Ran the output through a 10:1 voltage divider b/c I didn't figure the RTA would like that much input signal.

Also, first pic is on the 70dB range, 3dB step, second is on the 90dB range, 3dB step.

The first pic is obviously a bit "flatter", but keep in mind the pink noise track bounces around quite a bit and what you are seeing is literally a snapshot. Watching them both in real time they are both pretty damn flat. Plus, I don't know how much the voltage divider is affecting things.

By no means is this a lab grade measurement, but to me, if there is any eq in there I don't see it.

If I could find my disc w/ straight tone and not pink noise, I'd guess they'd be even a little closer.

cacicgt7

Looks like the same picture twice. But it's good to hear from your tests that the amp is flat.

niebur3

I actually heard that from several industry people. I noticed I experienced a similar boost in the midbass frequencies when I played around with one myself before becoming a dealer. I wonder how much production variance they have.

With that said, that seems like a shitty FR if you are using 3dB steps. With what looks to be a nice boost at 50Hz? I have eq'd my car flatter then that looks.

DiamondJoeQuimby

iTrader: (2)

Based on everything else I have seen with them, there is likely next to 0 production variance.

Like I said, watching in real time, they are both pretty flat. I have never experienced a mid-bass boost from their amps. If anything, the mid bass is the area that is the most consistent between the pics. The sub-bass gets wonky, and it looks like the top end ramps up a bit, but mid-bass into mid range looks similar. Plus I don't know what loss/noise/junk is from my super high end voltage divider. It's like 4 bucks in resistors and some left over terminal parts, so mils-spec it ain't.