How close does a line driver need to be?

[vwdude]

I know that the line driver needs to be close to the source. Are we talking inches or can it be like 2 feet away?

Trying to plan my next phase of the install.

[captainobvious]

It doesn't necessarily need to be close to the source, but it's better for it to be from a signal strength standpoint. Part of the benefit of keeping it closer is to avoid reducing the S/N ratio over longer runs of signal wire by ramping up the voltage. That said, if you had very well shielded cables that aren't introducing noise into the signal, then you could place the line driver at the back of the car if you wanted...no big deal.

[Bchester6]

My rule of thumb has always been no more than 18 inches away from the head unit. Audiocontrol recommends "as close to head unit as possible" to ensure that the source pre amp voltage doesn't decay over extended distances and the line driver may send maximum output voltage down the wire.
http://www.sound-better.net/Support/Man ... Manual.pdf

[ttocs]

I too have mine about 18 inches away from the deck. In a perfect world you could put it directly in front of the amp and it would not hurt anything but then again if this were a perfect world the amp would already have the driver built in, or would not need it from the decks output being high enough. The closer the better and also try not to mount it to the chassis as I have had noise issues with that as well.

[Drock]

@Scott. Just curious, are you not using the elite amp? Why would you need a line driver? The elite can make full power at 200mv.
My h/u is 4v out but the ms8 knocks signal down to 2.4v. I wanted to use a line driver to bump it back up, but Morgan said there was no need.


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[captainobvious]

Good point Drock. Plus, a gain stage is a gain stage. Whether you're increasing with a line driver or with the amp input gain.

[ajaye]

@Scott. Just curious, are you not using the elite amp? Why would you need a line driver? The elite can make full power at 200mv.
My h/u is 4v out but the ms8 knocks signal down to 2.4v. I wanted to use a line driver to bump it back up, but Morgan said there was no need.


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Besides s/n which was already covered, feeding a hotter input signal allows you more flexibility to maximize your system's output from a recording-to-recording standpoint. If you have no gain overlap, chances are good you are missing out on some power with some recordings, and generally speaking its the better sounding recordings because they've not been bricked or pushed to digital zero as is common practice now for pop music.

Now talking specifically about the Elite amps, being a few db down is probably only the difference between your ears bleeding and your skull imploding. For some of us with more modest equipment, it offers a much bigger benefit.

[Kirghiz]

Now talking specifically about the Elite amps, being a few db down is probably only the difference between your ears bleeding and your skull imploding.

LOL

The only instances I could see using line drivers on Elite amps would be if you had 2V preouts, or if you have to split the signal to multiple amps. Even then it may not be necessary. That said, there may be some SQ benefit from it, but as clean as those amps are, it's probably splitting hairs.

[zeropoint0.5]

as close as technically possible..........

nomatter witch amp it is, it will always give a better result feeding an amp with it max input signal

then with it's min input signal.......

you'll have a much cleaner and dynamic sound then playing without it.....

only on the M series i would not use them because they can't handle more then around 3V rms.....

but for the zx/zpa/ms series for sure !!!!

no experience with the new elite amps, but i suppose it will be the same story............

[ttocs]

I am not using a line driver to get more power out of the amp, that is not what it is about. Its all about signal too noise and any time I have the chance to increase that # for the cheap price of a line driver, I will make that purchase.

[Drock]

Ok I understand that the line driver is not an amp gain.
But I have a question ,
If I put a line driver before my ms8 or my bit one processors, and then try to set them up it won't work because the signal is to noisy it says. If I remove the line driver then everything sets up as it should.
As for line drivers I have tried the pld1, tld66, eq215ix. Always the same result.
I have not tried the line driver after the processor though.
But if I put a line driver before the processor it sounds like absolute shit.



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[ttocs]

I doubt the processors are actually measuring the signal to noise ratio and saying they are high/bad as much as just complaining about too hot of a signal but I have not worked with them personally. I know that they do a number of different digital eq/signal gain/volume processes and I have no idea why it would not like a higher power input.

[ajaye]

I doubt the processors are actually measuring the signal to noise ratio and saying they are high/bad as much as just complaining about too hot of a signal but I have not worked with them personally. I know that they do a number of different digital eq/signal gain/volume processes and I have no idea why it would not like a higher power input.

This would be my guess as well, input signal is beyond the processor's least sensitive input capability so the input section is being over-driven. It should give you a sensitivity range on the spec sheet. I doubt the MS8 is attenuating either though. With a "4 volt" headunit, with a music signal you are probably in the 1.5-1.8 volt RMS range with the volume up, give or take and depending on the record. IF you are happy with your noise floor and the overall output of your system I wouldn't worry about it anyway.

[Bchester6]

I too have mine about 18 inches away from the deck. In a perfect world you could put it directly in front of the amp and it would not hurt anything but then again if this were a perfect world the amp would already have the driver built in, or would not need it from the decks output being high enough. The closer the better and also try not to mount it to the chassis as I have had noise issues with that as well.

It was a perfect world at one time... once upon a time Xtant made amplifiers with an "Input gain jumper" module which was essentially functioning as an on board line driver. No preamp voltage coming from head unit, no problem!! Can't quite understand what happened to the evolution of that sort of forward thinking technology...

[Bchester6]

Furthermore, I have only had nothing but positive experiences with line drivers (Audiocontrol only) but at one time I did subscribe to traditional installation schematics that didn't include "extra" components that may impede clean signal. The problem that I struggled with was that I wasn't convinced that head units were capable of doing this along with all of it's other "responsibilities". Initially, I lessened the burden by adding line drivers during my Xenon phase because we all know how stubborn those gains are and I have implemented them in every installation thereafter as they provided me with the sonic fidelity that I'm looking for. Personally, I like working on the other side of the gain knob, 6-12 o'clock, which allows all of my equipment to run noticeably cooler under my passenger and driver seats. Ya I know this is not optimal but wetsuits and surfboards don't mix well with amplifiers!!

[ttocs]

I too have mine about 18 inches away from the deck. In a perfect world you could put it directly in front of the amp and it would not hurt anything but then again if this were a perfect world the amp would already have the driver built in, or would not need it from the decks output being high enough. The closer the better and also try not to mount it to the chassis as I have had noise issues with that as well.

It was a perfect world at one time... once upon a time Xtant made amplifiers with an "Input gain jumper" module which was essentially functioning as an on board line driver. No preamp voltage coming from head unit, no problem!! Can't quite understand what happened to the evolution of that sort of forward thinking technology...

The xtant amps were cool and had some neat functions, how ever the usability of them meant they are still to this date the only amp I NEEDED the manual to install. Count the little jumpers, be super careful not to get a stray piece of wire on the board....

[Bchester6]

AGREED but once you did the first one... smooth as eggs after that.

[LowandLoud]

Now that you guys mention it, it does seem rather odd PG (or anyone else) has not incorporated a line driver into their amps. It seems like it would be a rather easy thing to do.
Maybe it's strictly the lure of grabbing a few extra bucks from the people who know their value in a system.

LL

[Eric D]

Putting a line driver inside an amplifier is high on the list of useless features for an amplifier. Installing a line driver is not to make your system louder, it is to reduce the noise floor that exists on the long (often 16ft or so) RCA cables from the front of the vehicle to the rear.

The RCA cable will pick up some amount of nose. If you only have 2V of signal on it, the ratio of noise will be higher than if you have 8V on it.

A system with a 2V head unit and a quality amplifier should be just as loud as a system with an 8V line driver installed, and that same amplifier, the difference being there will be a lot less noise (hiss for example) in the quiet portions of music on the 8V line driver equipped setup.

If you install an 8V line driver in the rear of the vehicle (after those 16ft RCA cables), then your system will be no louder, and have just as much noise as the 2V head unit system would have. In this case the line driver would be serving no real purpose, as it would be boosting the noise that has gathered up on the RCA.

If someone's system is louder with a line driver than without, then they are likely just using the line driver to send an amplifier further into clipping, or they did not have the gain properly set prior to installing the line driver.

[trickyricky]

Thanks Eric. You read my mind....was going to say the same thing. Absolutely no use for a line driver in the rear or in the amps

[captainobvious]

I too have mine about 18 inches away from the deck. In a perfect world you could put it directly in front of the amp and it would not hurt anything but then again if this were a perfect world the amp would already have the driver built in, or would not need it from the decks output being high enough. The closer the better and also try not to mount it to the chassis as I have had noise issues with that as well.

It was a perfect world at one time... once upon a time Xtant made amplifiers with an "Input gain jumper" module which was essentially functioning as an on board line driver. No preamp voltage coming from head unit, no problem!! Can't quite understand what happened to the evolution of that sort of forward thinking technology...

The xtant amps were cool and had some neat functions, how ever the usability of them meant they are still to this date the only amp I NEEDED the manual to install. Count the little jumpers, be super careful not to get a stray piece of wire on the board....

Heh, I've actually got 2 x604's and an x1001 in the closet

They are fairly easy to setup in my opinion. The quirky thing about the jumpers is there is no knob for input sensitivity adjustment. The jumpers and board are very easy to see and understand though so it's a piece of cake.

[captainobvious]

Now that you guys mention it, it does seem rather odd PG (or anyone else) has not incorporated a line driver into their amps. It seems like it would be a rather easy thing to do.
Maybe it's strictly the lure of grabbing a few extra bucks from the people who know their value in a system.

LL

There's no need to do it. The amps have input gain controls and most amps are able to reach full output with a relatively low input signal.

[Kirghiz]

You would however think that HU's would just come with 8v preouts (go ahead and call it a line driver if you wish) and be done with it. That's where the line driver needs to be.

[ajaye]

If someone's system is louder with a line driver than without, then they are likely just using the line driver to send an amplifier further into clipping, or they did not have the gain properly set prior to installing the line driver.

I have to respectfully disagree with you guys, though your theory is spot on. I don't go driving around listening to sine waves though. I had an ipod w/ lossless files going straight to my amps for a while. Technically, the ipod output signal was capable of driving the amps to full power no problem. There were countless records that were nowhere near loud enough for me though, and were certainly not pushing my amps close to max. Added a gain stage in the way of an eq, problem solved. Will things clip with a source that peaks just before 0db now? Probably. I have a volume nob and I know how to use it though. Just saying, quoted output voltages mean nothing without defining your source/input signal. I agree with the not putting it in the back part though, that just doesn't make sense.

[Drock]

Well put Eric. Thanks


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