# Adding Pre-Amp / Line Driver will improve SQ



## SQ_lover

I've been suggested to use pre-amp / line driver to increase SQ. It's not regarding pumping the voltage since my HU is considered hi-voltage but adding it will enhance the signal quality. AFAIK, adding more device will add more noise thus degrading SQ. 

However, my book is open for any other thoughts.


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## St. Dark

You are correct in your suspicions. If you aren't having signal level related noise issues, or trying to run multiple amps off of one pair of RCAs, why add a line driver?


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## BowDown

Sounds like someone was looking to up-sell you.


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## evilbass

agreed with all of the above!!! You are correct, and it does sound like someone was trying to upsell you!


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## IBcivic

If your outout signal is "strong enough"....why would you need to add a "signal amplifier", before your amplifier.


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## Sulley

amitaF said:


> If your outout signal is "strong enough"....why would you need to add a "signal amplifier", before your amplifier.


What do you consider "strong enough"; .9v, 2v, 4v? 

do you mean strong enough as in able to properly drive the amplifier without introducing noise?


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## IBcivic

stockley.rod said:


> What do you consider "strong enough"; .9v, 2v, 4v?
> 
> do you mean strong enough as in able to properly drive the amplifier without introducing noise?





SQ_lover said:


> I've been suggested to use pre-amp / line driver to increase SQ. It's not regarding pumping the voltage since my HU is considered hi-voltage but adding it will enhance the signal quality. AFAIK, adding more device will add more noise thus degrading SQ.
> 
> However, my book is open for any other thoughts.


If th the h-u puts out an adequate line voltage(as claimed by the op in RED), to be able to drive his amps properly..then , yes...IMO a line driver is a total waste of money

2V, 4V , 5V or 9V is irrellevent. Those figures only look good on spec sheets


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## SQ_lover

The HU spec state: "Hi-Volt Preouts x 3 (4 v)". 
That's why I said "considered high".

I am wondering about the signal process inside the preamp.

here is quote from e-how.com:
_A preamp is used to improve the sound quality and power of your car stereo. It can increase the voltage to your system, add equalization and improve other areas of performance depending on which one you choose and how you set up the system. _


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## Cablguy184

I'm running a Linear Power PA2 / XO3 combo as mor of a "Linear Power" tradition ...
I couldn't tell you if it hurts or helps the system ... but I can tell you that it sounds and performs GREAT and excellent control of the system without going through the HU menu screens !!! Thanks ...


DIYMA ... Everyone, If you can, please go and vote for me on SMD System of the Month !!!
Please ........... thank you for your time, Randal ...

SMD FORUMS - SYSTEM OF THE MONTH Sponsored by MECHMAN Alternator! Win a High Output Alternator! - SMD Forum


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## Jboogie

Some line drivers actually "balance" the voltage going to your amps. The 4v the HU "says" it putting out is prolly not even 3.5 at all times. A good line driver will balance what your amps are getting allowing them to produce a cleaner signal. From what i remember a lower voltage signal will have more noise, by increasing the voltage, u will eliminate some of the noise. Thus, better SQ.

Just be careful and make sure your amps can accept higher voltages.


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## SQ_lover

wait, wait, 2v is not enough?

I don't have any audible noise issue in my current install.


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## IBcivic

Jboogie said:


> The 4v the HU "says" it putting out is prolly not even 3.5 at all


True...if all you listen to are test tones. Music is dynamic. It constantly fuctuates form 0v to Xv. X being your 2-3-4-5 volts.


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## TheKrellGuy

I used to use the Zapco line drivers on all my cars and systems with Symbilink back in the day and it worked amazing. I never did a system without an SP7_SLeq or the Line drivers it made the headroom scream but then again head units didnt have the output voltage of todays market so this can be something of a biased opinion.


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## t3sn4f2

TheKrellGuy said:


> I used to use the Zapco line drivers on all my cars and systems with Symbilink back in the day and it worked amazing. I never did a system without an SP7_SLeq or the Line drivers it made the headroom scream *but then again head units didnt have the output voltage of todays market* so this can be something of a biased opinion.


There's the clincher.


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## SoulFly

In general you don't need it. Though in my case I have the maxxbass, i love it except it puts out a lot of noise, i considered putting a LD behind it to push more voltage hoping i could keep the input/output levels below the noise, havnt tried it yet but i guess my only option


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## Salad Fingers

What head unit is it? At what volume does it ouput the 4 volts? Is bass/treble/bass boosts/eq curve/signal processing on or up? If so, how far? 

I don't know, I definitely think that line drivers have their place. Does everyone need one? No. However, like almost anything else, there is a time and a place. The last AudioControl Overdrive (2 ch line driver) I sold was last week. The guy had a "Hi-voltage 4 v" Kenwood head unit. He was using the power of the radio that went (I assume from others I have heard) high level in to the factory non Bose amplifier behind the glove box in his ~'02 Tahoe. The volume on his mids/highs is super loud at around 20, and he never turns it up past 22. He has some huge Hifonics amp on a couple of Kicker CVR 15's in a Pro Box (not exactly the epitome of sound quality, but I didn't sell it to him and he likes it, so whatever). The problem was that because he could only get the volume up three fifths of the way he had to crank the gain on the amp up really high and it wasn't sounding all that great (again, I understand the equipment issue). SO, I sold him an Overdrive to get the voltage up and the gain on the amp down a bit. It turns out that the voltage out of the radio at that volume was so weak (even with sub volume up to 15) that even with the Overdrive turned all the way up, it wasn't even getting the 1 volt LED to light up!! He brought it back because he thought it was defective. I took it to the back and hooked it up to our test bench, it worked just fine. That was also on a Kenwood "Hi voltage" out radio, and I notice I had to have the volume up above 30 and the sub volume all the way up for it to light the LEDs up (although the run is long and with crappy RCAs, so, that isn't helping). 

My point is that you can't just discount the line driver all together. It certainly has an application. Most modern day head units built with any level of quality (Kenwood, Alpine, Kenwood...) won't clip on the RCA level outputs even at full volume. However, the internal amps will distort horribly far before max volume, so it can help like in the above scenario. 

Also, the measurement of x preout voltage with the volume full tilt (and again, with whatever else is adjusted in the radio as well) is taken at the back of the radio. Let me tell you about an AudioControl demo I saw at a training we did at AutoSound some years ago. Alpine CDA-9887, volume at I think it was 25 before internal amp distorted, measured at the back of the radio was about 2 volts. At the end of 17 feet with a Stinger Pro Level 3 RCA, .8 volt. Then we hooked up an Overdrive and at the end of the 17 foot RCA without clipping, we had 8 volts. Many amps can accept up to 5 or even 8 volts of input and give full output with the gain literally all the way down. I don't know about you guys, but I like that. A lot. They aren't necessary, but I've never seen a good one properly installed hurt anything. In fact, in my experience if the amp is getting it's max input and the gain is all the way down, it has even LESS noise than before. I have had some repeat customers that want them in all of their installs after reaching the limit of their systems (within monetary practicality for them) and adding one in a car years before. They are also helpful when you need to split one RCA in to more (as previously mentioned) like in a multiple sub amp set up. They are also nice to be able to adjust your gain from the drivers seat where it really matters, like an active or bi amp set up through passives where getting gains to match desired output can be a very tedious task. Not to mention when using a head unit you like or can't afford to change out and it has a lower voltage output, like the Alpine iDA-X... units. Great pieces, but WEEEEEAAAK pre-out section. Same with some video units. 

I hate that I am on the opposite end of the argument from my good buddy amitaF on this topic, but I'm sure our friendship will survive... 

Also to Soulfly, a couple of things. First, Soulfly is a great band, and old Sepultura is even better . Second, those MaxxBass units can't take very much input. When those came out I had an Eclipse AVN 2454 that had a dismal .8 volts of advertised output, run in to an AudioControl Three.1 (in dash half din eq/line driver) and I went through probably literally 25 or more of the Maxxbass units. I was 18 and it did what I wanted it to do at that point in my life, but man I had a lot of issues. We came to find out that they can't take much more than a couple of volts of input or they'll fry. Just thought I'd give you my experience since it's not like you can just stop off and scoop up a new one or get it warrantied. 

In conclusion, I am in no way stating that I know everything, or that my stories are scientific fact. They are only my experiences working in a few high end shops over the last 5 years. My stories are anecdotal and not to be taken as scripture or anything. If anyone has had different experiences or some data to show otherwise, I'm always game to learn something new. However, again, I have always had positive results. I hope this was at least a little helpful for someone.


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## SoulFly

Salad Fingers said:


> Also to Soulfly, a couple of things. First, Soulfly is a great band, and old Sepultura is even better . Second, those MaxxBass units can't take very much input. When those came out I had an Eclipse AVN 2454 that had a dismal .8 volts of advertised output, run in to an AudioControl Three.1 (in dash half din eq/line driver) and I went through probably literally 25 or more of the Maxxbass units. I was 18 and it did what I wanted it to do at that point in my life, but man I had a lot of issues. We came to find out that they can't take much more than a couple of volts of input or they'll fry. Just thought I'd give you my experience since it's not like you can just stop off and scoop up a new one or get it warrantied.


i'll keep that in mind. thanks.
wish there was something i could do with the noise it puts out though. Its not bad at certain low in/out gain settings..but for it to work well it would be nice to crank it up a bit more.
and yes i think Sepultura was a bit better, both bands have similar sound.


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## envisionelec

Salad Fingers said:


> In conclusion, I am in no way stating that I know everything, or that my stories are scientific fact.


But...BUT....

You _measured it. _I've never had it mean anything in _any_ install or design. EVER. Unless you're talking about actual dBu - but they're not. It's just "VOLTS" which is absolutely meaningless.

You should feel good about your posts. At least it makes sense.


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## ECM

A line driver will improve the signal if it has a lower output impedance than the head unit. Especially in driving long interconnects.


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## t3sn4f2

ECM said:


> A line driver will improve the signal if it has a lower output impedance than the head unit. Especially in driving long interconnects.


That based on the assumption that a head unit has an output impedance that is TOO high, which I've never seen.

In fact, I have a soundcard with an output impedance of 600ohms and an input of 2.2kohms (way lower then the common 10kohms. That card measures flat and excellent in everything spec even with a 10 foot long $10 Hosa RCA. Hell even an iPhone's line out measure excellent into that difficult input.

http://www.diymobileaudio.com/forum/member-reviews-product-comparisons/77343-iphone-3gs-unloaded-headphone-out-measurements.html

IOW, a line driver won't help with that since that is not going to be a problem theses days.


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## atxtrd

This is a dilemma I have pondered recently myself. I'm going from an Eclipse CD8443 with 8v pre outs to a nav unit. Problem I see is most of todays nav units are 2-5v. I want as clean a signal as possible and the amps to work under ideal load conditions. I'll be losing lots of control by dumping the 8443 as well as the 8v pre outs, but I'm tired of having a radar detector and a Garmin gps stuck to my windshield all the time. I've also been told that some units reated a 5v are actually more like 2.5. Good stuff here on this subject. BTW I'm running Zed Gladius and Zed Deuce amps with Burr Brown converters in each.


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## mediumroast

My experience is line drivers or any device or even the wires in the audio chain will alter the sound in some way. You'll lose a bit of SQ but usually the gains of an LD far outweigh the loss. They all sound different when installed in your unique setup so even if you try one and it sounds bad there could a different one that sounds awesome. Only way to know is try it out.


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## DiMora

SQ_lover said:


> I've been suggested to use pre-amp / line driver to increase SQ. It's not regarding pumping the voltage since my HU is considered hi-voltage but adding it will enhance the signal quality. AFAIK, adding more device will add more noise thus degrading SQ.
> 
> However, my book is open for any other thoughts.


It makes an audible difference to me. I've run line drivers on every system I've had in the last 10 years. My first was a Phoenix Gold TBA-1, and now I run AudioControl Matrix drivers + AudioControl MAster Volume Controls.

Here's the deal: Let's say you have an 8 volt head unit (Like I do - Eclipse CD7100). 

When you are not listening to the system cranked up, you are not sending 8 volts. You are sending 1,2, 3, etc.

With a line driver (and an AudioControl Master volume control on the receiving end) your head unit puts out 8 volts all the time - at ANY volume level!. So...those long RCA cable runs from head unit to trunk are high voltage. That means more voltage above the noise floor, and therefore a much higher signal-to-noise ratio. A device like the MVC cuts the voltage down to the maximum that your amp can handle (Eclipse amps, which I run, also handle an 8 volt input). That means your amp gains can be turned all the way down - meaning, once again, less noise.

The difference I heard in the two systems I have had that featured both a line driver and an MVC was significant.

This Alpine Imprint I am trying excites me since the signal is balanced (kind of like the Phoenix Gold TBA-1) up to the Imprint module, which I will have in my trunk next to the amps. I may experiment with a Matrix / MVC on it as well to see if I can hear a difference or not.


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## Vital

I love when people complain about noise their line drivers and/or eq's bring to their system that didn't have that noise before ld/eq.
I'm sure there will be odd instances that will go against my theory here but those are odd instances, not a majority or even "good portion of" cases.

Here's the problem - your eq/ld is cheap, built cheap and made out of cheap components. When did you hear someone with Arc Audio or TruTechnologies or anything that's priced at "more then average" point complain on those noises due to equipment itself?? I didn't. Actually reason i mentioned both of these brands is because i've used Tru SSLD6i and now using Arc IDX/XEQ - both made a huge difference in my system and both never gave me a single issue.

My pos Kenwood hu is rated at 2V which means I never actually get it at my amps lol. 
With both of these LDs gains on my amps are literally ALL the way down, volume is very loud AND crystal clear, no noise, no issues of any sort. Take DL out (of my perticular system) - and i need to raise gains on my amp almost all the way up and at high volumes i can hear weird noise..not distortion or group loop, more like background noise, floor noise.


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## t3sn4f2

DiMora said:


> It makes an audible difference to me. I've run line drivers on every system I've had in the last 10 years. My first was a Phoenix Gold TBA-1, and now I run AudioControl Matrix drivers + AudioControl MAster Volume Controls.
> 
> Here's the deal: Let's say you have an 8 volt head unit (Like I do - Eclipse CD7100).
> 
> When you are not listening to the system cranked up, you are not sending 8 volts. You are sending 1,2, 3, etc.
> 
> *With a line driver (and an AudioControl Master volume control on the receiving end) your head unit puts out 8 volts all the time - at ANY volume level!. * So...those long RCA cable runs from head unit to trunk are high voltage. That means more voltage above the noise floor, and therefore a much higher signal-to-noise ratio. A device like the MVC cuts the voltage down to the maximum that your amp can handle (Eclipse amps, which I run, also handle an 8 volt input). That means your amp gains can be turned all the way down - meaning, once again, less noise.
> 
> The difference I heard in the two systems I have had that featured both a line driver and an MVC was significant.
> 
> This Alpine Imprint I am trying excites me since the signal is balanced (kind of like the Phoenix Gold TBA-1) up to the Imprint module, which I will have in my trunk next to the amps. I may experiment with a Matrix / MVC on it as well to see if I can hear a difference or not.


Sorry that's not correct. You lower the volume on the head unit to reduce the voltage the amplifier sees, so that it amplifies less, so that your speakers get less voltage, so that they playing lower in volume, so you hear the a volume level out of them that you want. 

Adding the line driver after you lowered the peak output voltage on the head unit from say 8 volts RMS to 1 will put you right back at 8 volts and negate the point of lowering the volume on the head unit. You then have to go to your amp or processor and lower the volume there so that the end of the signal chain (ie amp) is getting that 1 volt once again that gives you the volume from the speaker you wanted.

Noise and component quality aside, we are just multiplying and divided voltage levels with each component that we adjust the volume or gain pot of. 

And the output voltage is not constant either. Music is dynamic and typically varies by 15dB between transient peaks and average signal level through out the song. 0dB would represent a peak, -15db would represent the average volume of the track. In voltage, that is say ~8 volts peak and 1 volt average and if you lower the volume on the head unit to a comfortable setting, than that will typically lower the 8 volt peaks to ~1 volt and make the average level .1 volts.


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## minbari

DiMora said:


> *With a line driver (and an AudioControl Master volume control on the receiving end) your head unit puts out 8 volts all the time - at ANY volume level!. * So...those long RCA cable runs from head unit to trunk are high voltage. T..................


that is not true in the least. the HU will put out voltage based on music intensity and volume control. just turning the HU to 100% is not only a bad idea but will not solve anything. Not only that but with a line driver, it is garbage in, garbage out, only larger garbage out. if you have noise coming out of the HU it will be amplified. if you have a HU that is capable of 8volts like the eclipse, what is the point of a line driver that will boost it 1 more volt? pointless. most amplifiers have a 100mV to 10V adjustment anyway, so it makes line drivers a pointless part to begin with that is why amplifiers are adjustable..

A linedriver in 98% of installs is a waste of $100+. I would put it right up there with stiffening caps.


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## Vital

minbari said:


> that is not true in the least. the HU will put out voltage based on music intensity and volume control. just turning the HU to 100% is not only a bad idea but will not solve anything. Not only that but with a line driver, it is garbage in, garbage out, only larger garbage out. if you have noise coming out of the HU it will be amplified. if you have a HU that is capable of 8volts like the eclipse, what is the point of a line driver that will boost it 1 more volt? pointless. most amplifiers have a 100mV to 10V adjustment anyway, so it makes line drivers a pointless part to begin with that is why amplifiers are adjustable..
> 
> A linedriver in 98% of installs is a waste of $100+. I would put it right up there with stiffening caps.


Even if you are correct about everything you wrote you are still wrong on 98%. 

98% of installs do NOT have headunits with 8V. Actually i'd say it's the other way around.


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## t3sn4f2

Vital said:


> Even if you are correct about everything you wrote you are still wrong on 98%.
> 
> 98% of installs do NOT have headunits with 8V. Actually i'd say it's the other way around.


And how does that mattter?


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## mediumroast

This may not be true but to my understanding a Line-Driver is a pre-amp/op-amp designed to match impedance and or increase signal(voltage) for long cable runs. The change in impedance alone can do wonders for your sound so adding a line driver for an HU with 8v outs does make a lot of sense.

Also isn't the point of upgrading your amp's pre-amp/op-amp board to change the sound to something you like? I'd say it's much like adding a high quality line driver.

Lastly I don't think noise floor is too much of an issue if you use interconnects with a high level of noise rejection or shielding.


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## minbari

Vital said:


> Even if you are correct about everything you wrote you are still wrong on 98%.
> 
> 98% of installs do NOT have headunits with 8V. Actually i'd say it's the other way around.


I never said they do, i quoting this particular example. I will agree 98% do not have 8V pre-outs. even if all you have is 2V preamp output. that is still plenty for ANY amplifier to deal with. you still dont _need_ a line driver.


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## t3sn4f2

NwAvGuy: All About Gain


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## chad

mediumroast said:


> This may not be true but to my understanding a Line-Driver is a pre-amp/op-amp designed to match impedance and or increase signal(voltage) for long cable runs. The change in impedance alone can do wonders for your sound so adding a line driver for an HU with 8v outs does make a lot of sense.


I run a MICROPHONE LEVEL signal to a sub snake thru a 25' mic cable, then thru said 25'-50' sub snake to a stage head, where it runs thru a transformer and is split AT LEAST once. Then that goes down 250' of snake to FOH, along with about 20-40 of it's cousins. 


MICROPHONE LEVEL. running around dimmer packs and PWM power supplies, and ****.

Where on Odin's **** earth did anyone ever come up with the notion that you need 8 volts to make it to the damn trunk of a car.


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## minbari

chad said:


> I run a MICROPHONE LEVEL signal to a sub snake thru a 25' mic cable, then thru said 25'-50' sub snake to a stage head, where it runs thru a transformer and is split AT LEAST once. Then that goes down 250' of snake to FOH, along with about 20-40 of it's cousins.
> 
> 
> MICROPHONE LEVEL. running around dimmer packs and PWM power supplies, and ****.
> 
> *Where on Odin's **** earth did anyone ever come up with the notion that you need 8 volts to make it to the damn trunk of a car.*


lol, very colorfull............and complettely true!

I will make one observation, that your mic level signals are likely balanced, correct?


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## mediumroast

t3sn4f2 said:


> NwAvGuy: All About Gain


Excellent read. Thanks! t3sn4f2


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## gsdye

my old school Crystal Line Driver has served me well for over 10 years.

I've had an entry Clarion deck (2v), then a Sony C90 (4v)and now a Clarion HX-D10 (4v)

they've never been an issue for distortion, noise or clipping at any volume.

I think the piece of mind is knowing that the signal is clean out of that line driver.


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## chad

minbari said:


> I will make one observation, that your mic level signals are likely balanced, correct?


LOL shielded too, unlike a LOT of car audio UNBALANCED cabling.

My car is balanced and shielded, ironically that's what I used my AC Matrix for! it was in the rear, acting as a balanced line receiver.

It's unbelievably easy to do and cheap also as many amplifiers now accept balanced input!


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## todj

I say get a line driver. If you don't have a clean signal going into the amp the output side will sound just as bad. If you REALLY care about high quality SQ don't skimp on a cheap accessory that will make your overall sound better. You can upgrade slowly. It doesn't all have to be installed the same day.


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## t3sn4f2

Kill me now. I'm out.


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## minbari

todj said:


> I say get a line driver. If you don't have a clean signal going into the amp the output side will sound just as bad. If you REALLY care about high quality SQ don't skimp on a cheap accessory that will make your overall sound better. You can upgrade slowly. It doesn't all have to be installed the same day.


care to explain why it will make "high quality SQ"?




> Kill me now. I'm out.


me first me first!


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## chad

t3sn4f2 said:


> Kill me now. I'm out.





minbari said:


> me first me first!


Typing from Purgatory, not looking good for me.


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## chad

minbari said:


> care to explain why it will make "high quality SQ"?


that extra gain stage of noise and distortion.


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## DiMora

t3sn4f2 said:


> Sorry that's not correct. You lower the volume on the head unit to reduce the voltage the amplifier sees, so that it amplifies less, so that your speakers get less voltage, so that they playing lower in volume, so you hear the a volume level out of them that you want.
> 
> Adding the line driver after you lowered the peak output voltage on the head unit from say 8 volts RMS to 1 will put you right back at 8 volts and negate the point of lowering the volume on the head unit. You then have to go to your amp or processor and lower the volume there so that the end of the signal chain (ie amp) is getting that 1 volt once again that gives you the volume from the speaker you wanted.
> 
> Noise and component quality aside, we are just multiplying and divided voltage levels with each component that we adjust the volume or gain pot of.
> 
> And the output voltage is not constant either. Music is dynamic and typically varies by 15dB between transient peaks and average signal level through out the song. 0dB would represent a peak, -15db would represent the average volume of the track. In voltage, that is say ~8 volts peak and 1 volt average and if you lower the volume on the head unit to a comfortable setting, than that will typically lower the 8 volt peaks to ~1 volt and make the average level .1 volts.





minbari said:


> that is not true in the least. the HU will put out voltage based on music intensity and volume control. just turning the HU to 100% is not only a bad idea but will not solve anything. Not only that but with a line driver, it is garbage in, garbage out, only larger garbage out. if you have noise coming out of the HU it will be amplified. if you have a HU that is capable of 8volts like the eclipse, what is the point of a line driver that will boost it 1 more volt? pointless. most amplifiers have a 100mV to 10V adjustment anyway, so it makes line drivers a pointless part to begin with that is why amplifiers are adjustable..
> 
> A linedriver in 98% of installs is a waste of $100+. I would put it right up there with stiffening caps.


I can see how you would think my statement is inaccurate, so let me clarify - first off, of course there is no voltage when there is silence in the music. I am talking peak voltages during transients, or when setting up with a 1 KHz test tone at digital zero - (Car Audio 101 here guys).

Forget the line driver for a second.

Let's build system A: Let's say my Eclipse had unit, which DOES have 8 volt outputs...is fed into an AudioControl Master Volume control through an RCA cable run.

I turn the head unit as high as it will go without clipping. I use a 1KHz test tone at digital zero to set that level.

Then, I use my Master Volume control, which is in the trunk and is the last component pre-amplifier, to control my volume.

I get maximum S/N ratio.

Now...let's forget that system , and go to system B:

System B has a nice Clarion head unit, but , to our dismay, the Clarion only has a 1.8 volt maximum output.

So...we add a line driver.

Let's make it an AudioControl or Phoenix Gold PLD-1...doesn't really matter.

We then can go two ways: We can add something like an AudioControl Master volume control again, and keep the Clarion turned up all the way (well, as high as it will go without clipping). We then get an 8 or 9 volt signal in our RCA's running to the trunk (yes, when music is playing loud and intense...not when there is silence..I thought that fact would be obvious), and we decrease it pre-amplifier.

Again, we maximize our S/N ratio.

Finally, let's go with System C (without an AudioControl MVC):

Same Clarion head unit (1.8 volt output). In our trunk we use some Eclipse amps that can handle an 8 volt input.

We then turn up the Clarion as high as it will play without clipping, using a 1 KHz test tone at digital zero. Let's say it puts out a measly 1.6 volts clean. WE add the line driver. The line driver now pumps up our measly 1.6 volts to 8 volts...and now we get to turn the gains all the way down on the Eclipse amps.

We have maximized our S/N ratio. Any noise and hiss is almost inaudible.

Yes, when we turn the volume on our Clarion down - say to .5 volt (about a quarter of its peak capability)...our voltage decreases...the line driver still pumps up THAT voltage however...let's say the voltage transmitted on the RCA's is now 2 volts (again, about 1/4 of peak which would be 8)...the bottom line is we STILL have a better S/N ratio because we are transmitting 2 volts instead of .5 volts through our RCA's...our S/N ratio is improved above our noise floor.

I am speaking from experience here guys...I've been using line drivers since the Phoenix Gold TBA-1 came out. I have an AudioControl MVC in every car I have a system in.

It makes a huge, audible difference. This isn't theory, it is fact. These things have been used in Car Audio for years. Richard Clark had them in the Speakerworks Buick Grand National. They are used at every concert you go to...they are a Pro Audio piece...and for good reason.

If it didn't make a difference, why would I hassle with the extra two boxes?


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## chad

it still begs the issue, why are you having S/N ratio issues to begin with?

If it were bad enough that the noise was that noticeable then it's like putting a band-aid on a chainsaw wound while adding gain stages (more noise and distortion)

I'm speaking from experience too.


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## DiMora

minbari said:


> I never said they do, i quoting this particular example. I will agree 98% do not have 8V pre-outs. even if all you have is 2V preamp output. that is still plenty for ANY amplifier to deal with. you still dont _need_ a line driver.


True, you do not NEED a line driver.

Nor do I need a subwoofer with a thousand watts.

Nor do I NEED a nice component set and quality head unit.

But I choose to use all the above because it sounds better than NOT having it...just like a line driver in many systems.

You have obviously never had the opportunity to A/B a 2 volt output had unit before and after the installation of a line driver. It is a simple install, and you are really selling yourself short.

1) Add line driver. 

2) Determine max voltage head unit can output without clipping. Never turn head unit up past that point. Ever.

3) Determine max voltage amp can accept (Gains turned all the way down on amp).

4) Turn line driver output up to match amp max input level. Some line drivers use lights to tel lyou voltage output level, other method is test tone and a volt meter. To balance speakers levels, you turn DOWN any speakers that are too loud - with that channel on the line driver.

That's it...system is now optimized. When head unit is at max level, line driver is putting out max voltage amp can handle, and you have maximum S/N ratio at all time for a given volume level you choose to listen at.


----------



## t3sn4f2

DiMora said:


> I can see how you would think my statement is inaccurate, so let me clarify - first off, of course there is no voltage when there is silence in the music. I am talking peak voltages during transients, or when setting up with a 1 KHz test tone at digital zero - (Car Audio 101 here guys).
> 
> Forget the line driver for a second.
> 
> Let's build system A: Let's say my Eclipse had unit, which DOES have 8 volt outputs...is fed into an AudioControl Master Volume control through an RCA cable run.
> 
> I turn the head unit as high as it will go without clipping. I use a 1KHz test tone at digital zero to set that level.
> 
> Then, I use my Master Volume control, which is in the trunk and is the last component pre-amplifier, to control my volume.
> 
> I get maximum S/N ratio.
> 
> Now...let's forget that system , and go to system B:
> 
> System B has a nice Clarion head unit, but , to our dismay, the Clarion only has a 1.8 volt maximum output.
> 
> So...we add a line driver.
> 
> Let's make it an AudioControl or Phoenix Gold PLD-1...doesn't really matter.
> 
> We then can go two ways: We can add something like an AudioControl Master volume control again, and keep the Clarion turned up all the way (well, as high as it will go without clipping). We then get an 8 or 9 volt signal in our RCA's running to the trunk (yes, when music is playing loud and intense...not when there is silence..I thought that fact would be obvious), and we decrease it pre-amplifier.
> 
> Again, we maximize our S/N ratio.
> 
> Finally, let's go with System C (without an AudioControl MVC):
> 
> Same Clarion head unit (1.8 volt output). In our trunk we use some Eclipse amps that can handle an 8 volt input.
> 
> We then turn up the Clarion as high as it will play without clipping, using a 1 KHz test tone at digital zero. Let's say it puts out a measly 1.6 volts clean. WE add the line driver. The line driver now pumps up our measly 1.6 volts to 8 volts...and now we get to turn the gains all the way down on the Eclipse amps.
> 
> We have maximized our S/N ratio. Any noise and hiss is almost inaudible.
> 
> Yes, when we turn the volume on our Clarion down - say to .5 volt (about a quarter of its peak capability)...our voltage decreases...the line driver still pumps up THAT voltage however...let's say the voltage transmitted on the RCA's is now 2 volts (again, about 1/4 of peak which would be 8)...the bottom line is we STILL have a better S/N ratio because we are transmitting 2 volts instead of .5 volts through our RCA's...our S/N ratio is improved above our noise floor.
> 
> I am speaking from experience here guys...I've been using line drivers since the Phoenix Gold TBA-1 came out. I have an AudioControl MVC in every car I have a system in.
> 
> It makes a huge, audible difference. This isn't theory, it is fact. These things have been used in Car Audio for years. Richard Clark had them in the Speakerworks Buick Grand National. They are used at every concert you go to...they are a Pro Audio piece...and for good reason.
> 
> If it didn't make a difference, why would I hassle with the extra two boxes?


You're not maximizing signal to noise ratio, you're maximizing signal to assumed cable induced noise ratio. Since there shouldn't be any in a proper install all you are doing is playing with gain amounts at different points as well as assuming your amps input stage can't handle the standard input voltage of 2 volts.


----------



## DiMora

chad said:


> it still begs the issue, why are you having S/N ratio issues to begin with?
> 
> If it were bad enough that the noise was that noticeable then it's like putting a band-aid on a chainsaw wound while adding gain stages (more noise and distortion)
> 
> I'm speaking from experience too.


It's not an "issue"...it is that maintaining a higher S/N ratio sounds BETTER. 

That's all. There is an audible difference.

I can only hypothesize that you guys that are dissing line drivers have never used or heard one in a before / after comparison. 

They make your system sound better. Tighter. More dynamic. Less noise.


----------



## DiMora

t3sn4f2 said:


> You're not maximizing signal to noise ratio, you're your maximizing signal to assumed cable induced noise ratio. Since there shouldn't be any in a proper install all you are doing is playing with gain amounts at different points as well as assuming your amps input stage can't handle the standard input voltage of 2 volts.


Yes, you are maximizing S/N ratio.

Your noise floor is a _constant_, based on what cables you chose, what source unit you have, what radiated noise is picked up by your cable runs, etc.

By increasing voltage (AKA SIGNAL) our S/N ratio improves...since signal voltage is INCREASED and noise level STAYED THE SAME.


----------



## DiMora

Here...read this...start on page 3:

If you can't get it after that, I cannot help you understand.

http://autosound21.co.kr/shop/board_data/automanual/MVC_Owners_Manual.pdf


----------



## t3sn4f2

DiMora said:


> Yes, you are maximizing S/N ratio.
> 
> Your noise is a _constant_, based on what cables you chose, what source unit you have, what radiated noise is picked up by your cable runs, etc.
> 
> By increasing voltage (AKA SIGNAL) our S/N ratio improves...since signal voltage is INCREASED and noise level STAYED THE SAME.


Oh god. NOISE IS IN THE SIGNAL! It's component noise+recording noise. Noise is sound, sound is amplified by the line driver. Simple, I think.


----------



## DiMora

t3sn4f2 said:


> Oh god. NOISE IS IN THE SIGNAL! It's component noise+recording noise. Noise is sound, sound is amplified by the line driver. Simple, I think.


I disagree.

Recording noise you can do nothing about.

Component noise: That is a function of what components you choose. That is why you pay more money for an Eclipse deck or flagship Alpine head unit - better S/N ratio.

Did you read the AudioControl page I posted?

Do you not understand that a system has a noise floor that is based on what components you pick and what cables you choose, and what environment those components are installed in?

Do you not understand that increasing SIGNAL gives you a better RATIO of SIGNAL (IE the amplified music that you want to hear) to NOISE? _The line driver does NOT increase the noise floor._ That is what S/N ratio is!!!!!!!

*Have you ever used a line driver?*


----------



## chad

DiMora said:


> It's not an "issue"...it is that maintaining a higher S/N ratio sounds BETTER.
> 
> That's all. There is an audible difference.
> 
> I can only hypothesize that you guys that are dissing line drivers have never used or heard one in a before / after comparison.
> 
> They make your system sound better. Tighter. More dynamic. Less noise.


Cannot be tighter unless you have MAD impedance issues in the signal path, not happening in modern technologies without transformers on each end, even then you have HF attenuation in issues. Cannot be more dynamic ever, it's not an expander. Less noise I can buy, in a borked system. Let's not bring up Slew Rate.

If you are attenuating noise via driving a line, THEN attenuating it, then you have signal transfer issues, plain and simple. Like an old skool telco "dry line."


I think I have said a few lines up that I had an AC matrix that I used as a balanced line receiver  Look at the REAL numbers in terms of S/N, in reality, how many DB of noise floor are you really attenuating? Think about it.....


----------



## t3sn4f2

DiMora said:


> I disagree.
> 
> Recording noise you can do nothing about.
> 
> Component noise: That is a function of what components you choose. That is why you pay more money for an Eclipse deck or flagship Alpine head unit - better S/N ratio.
> 
> Did you read the AudioControl page I posted?
> 
> *Do you not understand that a system has a noise floor that is based on what components you pick and what cables you choose, and what environment those components are installed in?*
> Do you not understand that increasing SIGNAL gives you a better RATIO of SIGNAL (IE the amplified music that you want to hear) to NOISE? _The line driver does NOT increase the noise floor._ That is what S/N ratio is!!!!!!!


Yes I understand that, why don't you understand that your line driver, that you are putting after that noisy device CAN NOT increase JUST the music and leave that components noise un-driven. It doesn't discriminate.


----------



## t3sn4f2

DiMora said:


> *Have you ever used a line driver?*


Uh huh, always in fact. Every headunit I've ever owned came with one in it.


----------



## chad

ROFL.


----------



## chad

Here's an example of how I used a line driver. We send audio out of a radio station underground to a transmitter shack 200' away, said transmitter shack has 2 50KW FM transmitters in it and a 25KW am station that has a skirt antenna starting at ground level.

So from the plant I "kik up the jams," and the CMRR of these suckers are TIGHT AS ****. Then I send it to the shack, HUGELY different differential in RF potential, we have RF current big time, and AM to boot when you just need a dirty connection to DE-modulate. I receive it with a receiver that is TIGHT AS **** in CMRR, back down to +4dBu (common, lower than 8 flippin volts though) then into the processing that shoves the exciter composite RF. 

So.. if I do a "line driver" to make it that far, for insurance, under a cumulative 125KW of RF, why the **** do you need one to make it to the trunk of a car?


Average hobbyist signal transfer issues.


----------



## DiMora

t3sn4f2 said:


> Yes I understand that, why don't you understand that your line driver, that you are putting after that noisy device CAN NOT increase JUST the music and leave that components noise un-driven. It doesn't discriminate.


Have you ever uses some shorting plugs (RCA's with the positive and negatives soldered together) and installed them on the BEGINNING of a long RCA run (IE where the RCA's would normally plug into your head unit?

That test method will let you hear your systems noise floor - all you will hear is the amplifiers amplifying whatever noise your RCA runs are picking up.

I have done that.

You can also play a test track on a CD called "silence". 

That will also let you hear your systems noise floor, including the head unit.

I think I see where you are not getting it: Your line driver *CAN* increase just the music...because it is placed at the FRONT of the signal chain...right at the head unit's RCA outputs..._BEFORE where the majority of noise is picked up_...which is in the long RCA cable runs that go from the source unit to the trunk!

Answer this for me:

1) Why do pro audio engineers use a line drivers at concerts?

2) Why is a head unit that has a digital output desirable (obviously to be coupled with amps or a receiver in the trunk that has digital input) - such as Lanzars old Opti-Drive system or Pioneers ODR system? What is the advantage in such a system? I know the answer, but I would like to see your reply.


----------



## DiMora

chad said:


> Here's an example of how I used a line driver. We send audio out of a radio station underground to a transmitter shack 200' away, said transmitter shack has 2 50KW FM transmitters in it and a 25KW am station that has a skirt antenna starting at ground level.
> 
> So from the plant I "kik up the jams," and the CMRR of these suckers are TIGHT AS ****. Then I send it to the shack, HUGELY different differential in RF potential, we have RF current big time, and AM to boot when you just need a dirty connection to DE-modulate. I receive it with a receiver that is TIGHT AS **** in CMRR, back down to +4dBu (common, lower than 8 flippin volts though) then into the processing that shoves the exciter composite RF.
> 
> So.. if I do a "line driver" to make it that far, for insurance, under a cumulative 125KW of RF, why the **** do you need one to make it to the trunk of a car?


Because your car, without a line driver, would be tight.

Mine, with a line driver, would be TIGHT AS ****.


----------



## chad

DiMora said:


> That test method will let you hear your systems noise floor - all you will hear is the amplifiers amplifying whatever noise your RCA runs are picking up.


Wrong, it does not simulate the output impedance of the source  is ALSO does not derive a shield since the inputs of amps do not have the shield grounded to chassis.

Remember me taking about some amps having balanced inputs? that makes it even weirder.


It also allows anything leaking onto an unterminated (remember no ground, no screen) shield to be tied DIRECTLY to the input of the amplifier.

It is an incredibly flawed test, NOW if you did proper termination with decent 2 conductor+ shield cable, left the screen tied at the source, shorted the pin and shield of the AMPLIFIER WITH THE SCREEN LIFTED at the amp... we would have a notable test becuase it would show, remember? CMRR....


----------



## DiMora

chad said:


> Wrong, it does not simulate the output impedance of the source  is ALSO does not derive a shield since the inputs of amps do not have the shield grounded to chassis.
> 
> Remember me taking about some amps having balanced inputs? that makes it even weirder.
> 
> 
> It also allows anything leaking onto an unterminated (remember no ground, no screen) shield to be tied DIRECTLY to the input of the amplifier.


How about playing a test track of "Silence"?


----------



## chad

DiMora said:


> Because your car, without a line driver, would be tight.
> 
> Mine, with a line driver, would be TIGHT AS ****.


That's just not really how it works.

This is normally when common douche bags bring out credentials and **** they have done, but it's too much fun as it stands.
you understand CMRR correct?


----------



## DiMora

t3sn4f2 said:


> Uh huh, always in fact. Every headunit I've ever owned came with one in it.


----------



## chad

DiMora said:


> How about playing a test track of "Silence"?


pretty tough to do with shorting plugs installed


----------



## DiMora

chad said:


> That's just not really how it works.
> 
> This is normally when common douche bags bring out credentials and **** they have done, but it's too much fun as it stands.
> you understand CMRR correct?


Did you just call me a douche bag?

I am more of a fan of Godwin's law, if you are going to go down that road.

Yeah I understand CMRR. I have Teh Googles. :laugh:

Common-mode rejection ratio - Wikipedia, the free encyclopedia


----------



## DiMora

chad said:


> pretty tough to do with shorting plugs installed


 :laugh:


----------



## chad

DiMora said:


> Did you just call me a douche bag?


in ABSOLUTELY no way. please do not take it that way, I was speaking of common forum folk.... that's why I added that it was fun without it ! 

This is a good, but disagreeable conversation, normally they get uglier quicker


----------



## DiMora

Well, we'll have to agree to disagree. 

We can talk theory all we want, the fact of the matter is (for me personally) I have been using line drivers since I learned about them (starting with the Phoenix Gold TBA-1, which is a balanced line driver), and my systems have sounded better with them than without - and in the end, that is all that matters.

:beerchug:


----------



## t3sn4f2

DiMora said:


> Well, we'll have to agree to disagree.
> 
> We can talk theory all we want, the fact of the matter is (for me personally) I have been using line drivers since I learned about them (starting with the Phoenix Gold TBA-1, which is a balanced line driver), and my systems have sounded better with them than without - *and in the end, that is all that matters.*
> :beerchug:


Yup. But don't forgeeeeeeeeehhhhhht, you're talking theory, we're talking fact.


----------



## chad

t3sn4f2 said:


> Yup. But don't forgeeeeeeeeehhhhhht, you're talking theory, we're talking fact.


eventually..........


----------



## chad

when I ran a "line driver I noticed one thing. It made it a LOT easier to adjust the gain improperly. But without it, I got there, it just took a little more work in positions I really felt venerable in


----------



## DiMora

t3sn4f2 said:


> Yup. But don't forgeeeeeeeeehhhhhht, you're talking theory, we're talking fact.


Have YOU run a line driver before?


----------



## Salad Fingers

So lets say an amp has an input range of 5v-.3v... It getting 5 volts and the gain all the way down or .3v and all the way up, will sound and measure exactly the same? 

I feel like this is a really basic and day one question, but I've never really got a clear answer on it. My understanding of industry dogma is that the higher the gain, the higher the noise floor.


----------



## t3sn4f2

DiMora said:


> Have YOU run a line driver before?


You put too much emphasis on what people think about something. 
Do yourself a favor and learn how to put _yourself_ to the test. See what's real or not.


----------



## Salad Fingers

Salad Fingers said:


> but I've never really got a clear answer on it. My understanding of industry dogma is that the higher the gain, the higher the noise floor.


I should have said that I've never gotten an answer that I am willing to accept as fact, and that I try to question the "industry dogma" (meaning the universal rules and facts people throw around because that's what they heard) as much as possible.


----------



## DiMora

t3sn4f2 said:


> You put too much emphasis on what people think about something.
> Do yourself a favor and learn how to put _yourself_ to the test. See what's real or not.


I'll take that as " No, DiMora, I have never run one, and therefore I don't really have any real world experience on this topic, so all I can contribute to this thread is what I think, not anything factual"


----------



## t3sn4f2

DiMora said:


> I'll take that as " No, DiMora, I have never run one, and therefore I don't really have any real world experience on this topic, so all I can contribute to this thread is what I think, not anything factual"


Fine _with me_.


----------



## chad

I've used drivers and receivers, along with pre-emphasis and de-emphasis.


every day.

It really comes down to how old skool Dolby works... Without the noise reduction. Even RIAA phono EQ... without the EQ.


----------



## DiMora

Salad Fingers said:


> So lets say an amp has an input range of 5v-.3v... It getting 5 volts and the gain all the way down or .3v and all the way up, will sound and measure exactly the same?
> 
> I feel like this is a really basic and day one question, but I've never really got a clear answer on it. My understanding of industry dogma is that the higher the gain, the higher the noise floor.


5 volts with gains down sounds better than .3 volts and gains all the way up.

Why?

The 5 volts with gains down system has a better S/N ratio and better dynamics.


----------



## DiMora

chad said:


> I've used drivers and receivers, along with pre-emphasis and de-emphasis.
> 
> 
> every day.
> 
> It really comes down to how old skool Dolby works... Without the noise reduction. Even RIAA phono EQ... without the EQ.


Now your talking. I built a Hagerman bugle RIAA phono stage for my turntable.


----------



## t3sn4f2

So how does the background noise level in music factor in to all of this? I can't seem to find a track who's silent parts are less than ~60-70dB. What good is getting the noise floor down to -1googledB if -90dB still adds ~0dB to that "black background"?


----------



## ChrisB

Maybe I should add line drivers to my **thread**.


----------



## chad

DiMora said:


> 5 volts with gains down sounds better than .3 volts and gains all the way up.
> 
> Why?
> 
> The 5 volts with gains down system has a better S/N ratio and better dynamics.


Because the signal transfer is flawed.. now you are getting there...


Right back to running mic level (about phono level) down 300+ foot of cable and getting it there without any issues, got stacks of HDD's of recordings to prove it.


For a handful of simple coins and some simple thought you can improve your signal transfer and not need a line driver.


Dynamics CAN NEVER improve, that's the total constant in the equation, where most people miss it.

Now explain how dynamics improve....... In a scientific manner.


----------



## DiMora

chad said:


> Because the signal transfer is flawed.. now you are getting there...
> 
> 
> Right back to running mic level (about phono level) down 300+ foot of cable and getting it there without any issues, got stacks of HDD's of recordings to prove it.
> 
> 
> For a handful of simple coins and some simple thought you can improve your signal transfer and not need a line driver.


Yes. We agree. The signal transfer is flawed!

Let me try another way and see if you agree: The cable run from head unit to amp is indeed flawed (if analog).

A given audio selection that you play combines with the noise the cable picks up. That combined audio + noise goes into amp. Gains raise input voltage higher and audio + noise is amplified.

Now, add line driver.

Given audio selection that you play is amplified by line driver to higher voltage.

Higher voltage signal combines with noise the cable picks up. Audio + noise goes into amp. Gain on amp is all the way down. Amplifier amplifies both music and noise like before...but since the ratio of music to noise is higher, for a given listening volume, we hear more music and less noise vs. system with no line driver.


----------



## DiMora

When I use the term dynamics, I mean to highlight the differences between loud and quiet passages. 

When a lot of noise is present, a given peak volume will not seem as loud to the human ear as the exact same musical passage played at the same peak volume with no noise. The differential our ears picks up between quiet and loud is dynamics.

Go to YouTube and listen to "The Loudness Wars". Through compression in modern recordings, dynamics are being destroyed. The selection you hear without compression is what I mean when I say " more dynamic".

On the SAME recording, a system with a line driver and a great S/N ratio sounds more dynamic to my ears, even though the recording itself is a constant.


----------



## chad

We can agree there, totally, as with the broadcast analogy. 

But the question remains, why is that around 8' to your trunk more difficult with a low output impedance (of your headunit) and a high input impedance (of your amplifier,) at say, 2V.....

HARDER than a couple millivolts at a really high impedance out of your standard phono cartridge in an average cable length of 3 feet to a phono preamp at a similar impedance? We can even bring "damping factor" in here.......


Does that extra 5 feet really require what, off the cuff, 60 dB of gain?


How can I take a mic, or 5, put them in front of an orchestra, slam 42-48 dB of GAIN on it after a 200' run, and still make a great recording. without a "line driver" at the microphone? remember, mic level is about that as phono level, without RIAA.

Goes back to the band-aid on a chainsaw wound.. And the 90's... And a specific person that specified the wrong cable for the wrong app, then sold **** to make up for the noise gain.


Back to Dolby and RIAA.


----------



## DiMora

chad said:


> We can agree there, totally, as with the broadcast analogy.
> 
> But the question remains, why is that around 8' to your trunk more difficult with a low output impedance (of your headunit) and a high input impedance (of your amplifier,) at say, 2V.....
> 
> HARDER than a couple millivolts at a really high impedance out of your standard phono cartridge in an average cable length of 3 feet to a phono preamp at a similar impedance? We can even bring "damping factor" in here.......
> 
> 
> Does that extra 5 feet really require what, off the cuff, 60 dB of gain?
> 
> 
> How can I take a mic, or 5, put them in front of an orchestra, slam 42-48 dB of GAIN on it after a 200' run, and still make a great recording. without a "line driver" at the microphone? remember, mic level is about that as phono level, without RIAA.
> 
> Goes back to the band-aid on a chainsaw wound.. And the 90's... And a specific person that specified the wrong cable for the wrong app, then sold **** to make up for the noise gain.
> 
> 
> Back to Dolby and RIAA.


I see your point.

I swear Chad - if I couldn't hear an audible difference in my past systems using these things, I wouldn't be such a nutswinger about them. 

Here's my past experience and rationale for my argument:

On that little 8 foot run...in my past systems...that little run picked up a ton of noise. Why? Well - I think you are on track. Early RCA cables (like everyone used) were not twisted pair construction - so they picked up more noise. I remember spending big bucks in about 1989 for some Phoenix Gold RCA cables that had a shield around the signal wires, and that shield had a "dump" wire on one end only...you were to ground that to the vehicles chassis. They weren't twisted, but they were better than what I had before - straight RCA's.

Then a friend of mine used some home audio Kimber Cable in his car - and he had less noise...weird we thought...there was no shielding on it, but it was twisted pair construction. Hmmm...

So then we all started making our own interconnects - I would just buy some red and black 16 or 18 AWG and put one end in my vice and the other in a drill chuck and build my own twisted pair interconnects.

I still had audible noise, though (albeit not bad...and you could barely hear it when the engine was running, but I was seeking perfection and no hiss at all when listening while parked - for competition)...I figure the noise I had while the car was running was because there is a lot of electrical noise in a car...you have the power runs for the tail-lights, various seat belt tensioner power wires, power seats, power windows, fuel pump, alarm systems, plus the alternator, ignition coil / spark system, etc...and the low voltage signal out of a head unit run through those RCA's just loved to pick all that up like an antenna when the engine was running. When the engine was not running, the gain stages on my amps were the culprits. This was Soundstream Reference gear I had at the time, which back then was regarded as some of the best stuff you could get. Zapco was probably the very best, but few of us had the $$$ to get it, so most of us ran SS, Orion, or PPI.

Anyway, circa 1994 I read an article about the Phoenix Gold PLD-1 and TBA-1. $230.00 later I owned a TBA-1 and all that hiss and noise was gone. I was blown away, and became a line-driver / balanced transmission believer.

As to your orchestra / microphone question...mic cables are balanced and use an XLR connection. The good stuff uses a 4 wire twisted pair construction plus a shield. They still pick up noise, as you know, but the balanced design cancels out the noise at the receiving end.

I built and sold home audio cables for years (and XLR cables for guys with higher end balanced home gear) using Canare L4E6S microphone cable. 

In fact, many of my home-built interconnects now are made with Canare L4E6S - I ground the shield ONLY on the transmitting end, and solder the two twisted pairs (color matched) together for a cheap homemade twisted pair cable with good shielding.

I'm gonna try some pictures to try to clarity further. I used the AudioControl MVC owners manual diagram and did some photoshopping...here is my best attempt:

Here is a normal system. No line driver . Bottom squiggle is your noise floor, upper (rising) squiggle is the voltage increase you get when you turn up the volume on your head unit:










Those of you that don't understand line drivers seem to think that THIS is what happens when you use one...you think the line driver amplifies BOTH your noise floor and your music signal, like this:










In reality, a line driver, since it is installed at the head unit and BEFORE the long run from head unit to trunk, (the long run being where the noise is picked up) only amplifies signal and does NOT harm your noise floor. Like this:










*REMEMBER - When you amplify via the amps gain stage, the noise has already been picked up! The amp gain stage has no choice but to amplify BOTH noise and signal! Just like the second diagram above!*

You can see clearly, in that last diagram, that our signal to noise ratio is improved versus the first diagram (with no line driver).

That means that the quiet passages in our music are more quiet, and the loud parts, perceptively to our human ears, therefore seem to be louder (by comparison to the quiet). That is dynamics. Loud vs. Quiet. Contrast.

Since I am on a computer now and not my i-Pad, this little demo is a great explanation of dynamics (and also covers compression, which, IMHO, is destroying modern music. Anyone listened to Metallica's Death Magnetic? It sounds horrible. It clips even at low volume and has almost no dynamics left at all. It sucks):

"When there is no quiet, there can be no loud". That is what I mean by dynamics:

http://www.youtube.com/watch?v=3Gmex_4hreQ


----------



## t3sn4f2

Why do you keep on insisting that noise is always picked up along a signal run which would then benefit from a line driver at the source. How hard is it to understand that that only happens in a ****ty implemented cable run and boosting the signal away from that induced noise is not a fix, it is an expensive degrading rig job.

And you still have no clue just how much louder the background noise in a quality recording is when compared to component noise. It doesn't add any amount of perceived noise, so the recording is not gonna get any quieter.

Play a -96dB noise track (find my thread on it) with your volume setting all the way up. That will bypass your zero bit mute and give you the best possible noise result from a 16bit file as well as the true noise level of the entire system at max volume. Then lower the volume significantly and play a low noise music track. Notice how much louder the recording noise is even at a much lower volume setting. Try it at max for a sec. and see how it compares to the test file. 

:bash:


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## minbari

DiMora said:


> I get maximum S/N ratio.


I am not reading all that other crap. but this doesnt work. if you have 90dB signal to noise and add an amplifier, you still have 90dB signal to noise. you just have bigger signal and bigger noise.


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## DiMora

minbari said:


> I am not reading all that other crap. but this doesnt work. if you have 90dB signal to noise and add an amplifier, you still have 90dB signal to noise. you just have bigger signal and bigger noise.


Well if you won't read what I posted, I cannot help you understand. I dropped it down to the lowest common denominator with pictures. Diagram number two specifically addresses what you are stating. You are wrong.

Go read it. If you don't at least make the effort to understand, you will continue to remain lost...


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## DiMora

t3sn4f2 said:


> Why do you keep on insisting that noise is always picked up along a signal run *which would then benefit from a line driver at the source*.
> 
> :bash:


You may not realize it, but you just got it. That is what I have been saying all along! You benefit from a line driver at the source!

Most noise is picked up on the run from head unit to amps.

This is where a line driver helps. 

You just said so yourself.


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## minbari

dont need pictures. if you have 2v of signal and 100mV of noise. add an amplifier with a gain of 4. you will get 8v signal and 400mV noise. the amplifier doesn't magically know how to reject the noise. it amplifies everything.


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## DiMora

minbari said:


> dont need pictures. if you have 2v of signal and 100mV of noise. add an amplifier with a gain of 4. you will get 8v signal and 400mV noise. the amplifier doesn't magically know how to reject the noise. it amplifies everything.


_You DO need pictures, since you are failing to understand._

I am now going to add a line driver to your system:

I just put a line driver on your source unit. You now have 8 volts of signal. That 8 volts of signal now travels along your RCA cables with the same 100mV of noise.

The amplifier gain is turned down now from where you had it set. You set it at 4. I turned it down to 1. It didn't need to be at 4 because the signal was 4 times greater. 

I now get the exact same volume you had, but my noise is nearly inaudible. You had amplified the 100mV of noise by 4 at the amp gain stage. I amplified it at 1.

Here is your system before a line driver:










Here is your system after I added the line driver - your S/N ratio is improved.


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## minbari

thats is not how it works, but keep believing what you like...........I am done beating my head into a brick wall.

if you have 2volts of signal and 100mV of noise and you amplifier it by a factor of 4. you will have 8volts of signal and 400mV of noise. that is how amplifiers work. you cant keep the "noise floor" at 100mV, the amplifier cant know that the "noise" is unwanted. impossible.

I understand completely, but what you are describing doesnt exist without some sort of DSP to drop the low level signals (noise)off. as far as I know, line drivers dont have DSPs in them


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## t3sn4f2

DiMora said:


> You may not realize it, but you just got it. That is what I have been saying all along! You benefit from a line driver at the source!
> 
> Most noise is picked up on the run from head unit to amps.
> 
> This is where a line driver helps.
> 
> You just said so yourself.


I think you need to learn how to interconnect components in a mobile environment and save yourself some money on band-aids.

How many times around the same circle is this. Too many to count.


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## DiMora

Yeah, my head hurts from the brick wall too. I am done here as well. I've done the best I can to explain how it works.

I did enjoy the banter back and forth.

You (Minbari) said "if you have 2volts of signal and 100mV of noise and you amplifier it by a factor of 4. you will have 8volts of signal and 400mV of noise. that is how amplifiers work. you cant keep the "noise floor" at 100mV, the amplifier cant know that the "noise" is unwanted. impossible."

You missed this part... 8 volts of signal ( line driver) and 100mV of noise when amplified by the factor of four you insist on would be 32 volts signal and 400 mV noise. See the ratio difference?

Maybe someone else who understands line drivers can approach the explanation from a different angle and you guys will have an epiphany.


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## DiMora

t3sn4f2 said:


> I think you need to learn how to interconnect components in a mobile environment and save yourself some money on band-aids.
> 
> How many times around the same circle is this. Too many to count.


Nice...attack my install skills (or lack thereof) instead of discussing facts, voltages, providing a diagram, or otherwise trying to clarify your viewpoint.


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## t3sn4f2

DiMora said:


> Yeah, my head hurts from the brick wall too. I am done here as well. I've done the best I can to explain how it works.
> 
> I did enjoy the banter back and forth.
> 
> You (Minbari) said "if you have 2volts of signal and 100mV of noise and you amplifier it by a factor of 4. you will have 8volts of signal and 400mV of noise. that is how amplifiers work. you cant keep the "noise floor" at 100mV, the amplifier cant know that the "noise" is unwanted. impossible."
> 
> *You missed this part... 8 volts of signal ( line driver) and 100mV of noise when amplified by the factor of four you insist on would be 32 volts signal and 400 mV noise. See the ratio difference?*
> Maybe someone else who understands line drivers can approach the explanation from a different angle and you guys will have an epiphany.


No, I don't see it. It's the same ratio 

8/.1= 32/.4

8 volts= 20dBu
.1 volts= -17dBu

Differance of 37dB

32 volts= 32dBu
.4 volts= -5dBu

Differance of? 37dB

Here you go, play with it.......

The dBm calculator - conversion dBm to volt mW voltage V dB dBu dBV dBm conversion and calculation milliwatt milliwatts kilowatt power level power watts convertor converter audio engineering sound recording - sengpielaudio Sengpiel Berlin

Here's a clue why it's the same thing.


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## t3sn4f2

DiMora said:


> Nice...attack my install skills (or lack thereof) instead of discussing facts, voltages, providing a diagram, or otherwise trying to clarify your viewpoint.


That's not an attack. From my point of view, the only reason YOU can't have a system without needing a line driver is because you don't know how to correctly interconnect components without introducing noise. It's a suggestion, nothing more.

And using manufacturer's marketing documents isn't going to help _your case_, nor is relying on your biased and sighted comparisons for that matter.

http://www.diymobileaudio.com/forum/diyma-sq-forum-technical-advanced/86892-audiophile-banana.html

http://seanolive.blogspot.com/2009/04/dishonesty-of-sighted-audio-product.html


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## BuickGN

I think this is just a misunderstanding.

One person is saying if you add a line driver and your noise comes from the source it will make no difference.

One person is saying if you add a line driver near the source AND you're system picks up noise through the RCAs on it's way from the source to the amp, the one with a line driver at the source will have the lower noise floor since you're not amplifying it as much. That's assuming your noise is coming from the cables along the way.


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## minbari

DiMora said:


> *You missed this part... 8 volts of signal ( line driver) and 100mV of noise when amplified by the factor of four you insist on would be 32 volts signal and 400 mV noise. See the ratio difference?
> *
> Maybe someone else who understands line drivers can approach the explanation from a different angle and you guys will have an epiphany.


8 / 4 = 2
32 / 4 = 8
400 / 4 =100

its all 4:1 ratio. maybe a brushup on a math class?


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## DiMora

minbari said:


> 8 / 4 = 2
> 32 / 4 = 8
> 400 / 4 =100
> 
> its all 4:1 ratio. maybe a brushup on a math class?


It is you who fails math.

Lets back up. You said: * "if you have 2volts of signal and 100mV of noise and you amplifier it by a factor of 4. you will have 8volts of signal and 400mV of noise. that is how amplifiers work. you cant keep the "noise floor" at 100mV, the amplifier cant know that the "noise" is unwanted. impossible.*"

Using your numbers: 

2 volts signal + 100 mV noise and multiply by four = 8 volts/400 mV. Your ratio is 8/400. That is a ratio of .02

I add line driver.

8 volts signal + 100 mV noise. (Line driver does not increase noise! Only voltage! It is at the source unit!) Multiply by four (amp gain) = 32 volts signal / 400mV noise. That is a ratio of .08.

.02 and .08 are clearly different ratios.

Try again.


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## minbari

I dont ussualy flame on here, but I am beginning to believe you are retarded.

2 to 8 is as .1 to .4

those are the two ratios. both are 4:1.



> 8 volts signal + 100 mV noise. (Line driver does not increase noise! Only voltage! It is at the source unit!) Multiply by four (amp gain) = 32 volts signal / 400mV noise. That is a ratio of .08.


you are 100% wrong. how does an amplifier know the difference between noise (which is just a voltage level) and the actually signal voltage? they are not seperate! the noise is integrated into the signal. the amplifier will amplify the whole thing together.


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## minbari

I dont ussualy flame on here, but I am beginning to believe you are retarded.

2 to 8 is as .1 to .4

those are the two ratios. both are 4:1.



> 8 volts signal + 100 mV noise. (Line driver does not increase noise! Only voltage! It is at the source unit!) Multiply by four (amp gain) = 32 volts signal / 400mV noise. That is a ratio of .08.


you are 100% wrong. how does an amplifier(line driver) know the difference between noise (which is just a voltage level) and the actually signal voltage? they are not seperate! the noise is integrated into the signal. the amplifier will amplify the whole thing together.


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## DiMora

minbari said:


> I dont ussualy flame on here, but I am beginning to believe you are retarded.
> 
> 2 to 8 is as .1 to .4
> 
> those are the two ratios. both are 4:1.
> 
> 
> 
> you are 100% wrong. how does an amplifier(line driver) know the difference between noise (which is just a voltage level) and the actually signal voltage? they are not seperate! the noise is integrated into the signal. the amplifier will amplify the whole thing together.



Flame away. I can't get through, so any further attempts are futile.


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## DaveRulz

I think post # 98 needs to be read by both DiMora and Minibari. 

Minbari: you're missing how DiMora is describing the line driver's use. If the 100mv of noise is induced in your RCAs, and you add a line driver BEFORE the rca run to the rear, where the 100mv of noise is induced, you do in fact get a better signal to noise ratio. 

Lets see if this clarifies so people can stop calling each other names. 
HU(2v signal) -> RCA(100mv noise) -> Amp Gain 10 (20v signal and 1000mv noise) *Signal to noise ratio of 20:1*
HU(2v signal) -> RCA(100mv noise) -> Line Driver 4 (8v signal and 400mv noise) -> Amp Gain 2.5 (20v signal and 1000mv noise) *Signal to noise ratio of 20:1*
HU(2v signal) -> Line Driver 4 (8v signal and negligible noise due to short run from HU to LD) -> RCA(100mv noise) -> Amp Gain 2.5 (20v signal and 250mv noise) *Signal to noise ratio of 20:0.25*

The important thing to note, is that we're not talking about the signal to noise ratio of the HU, we're talking about the ratio of the signal coming out of the hu to the noise induced through the RCAs

A line driver can in no way improve the signal to noise ratio of your source, but it CAN improve the overall signal to noise ratio of your system as described above. This is the reason for the push to have higher voltage preamp outputs on HU's. A 2v signal (what you'll typically get out of a 4v HU if you're lucky) will overcome 100mv of noise much easier than a .5v signal. I think that's pretty plain to see. 

Again, we're talking about induced noise, not the S/N of your source. If you don't know the difference, then this discussion is not going to get any further. 


And to get at what chad was hinting at with the mic on a 300ft cable....this would all be moot if someone early on had decided to use a balanced signal to begin with.


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## DiMora

DaveRulz said:


> I think post # 98 needs to be read by both DiMora and Minibari.
> 
> Minbari: you're missing how DiMora is describing the line driver's use. If the 100mv of noise is induced in your RCAs, and you add a line driver BEFORE the rca run to the rear, where the 100mv of noise is induced, you do in fact get a better signal to noise ratio.
> 
> Lets see if this clarifies so people can stop calling each other names.
> HU(2v signal) -> RCA(100mv noise) -> Amp Gain 10 (20v signal and 1000mv noise) *Signal to noise ratio of 20:1*
> HU(2v signal) -> RCA(100mv noise) -> Line Driver 4 (8v signal and 400mv noise) -> Amp Gain 2.5 (20v signal and 1000mv noise) *Signal to noise ratio of 20:1*
> HU(2v signal) -> Line Driver 4 (8v signal and negligible noise due to short run from HU to LD) -> RCA(100mv noise) -> Amp Gain 2.5 (20v signal and 250mv noise) *Signal to noise ratio of 20:0.25*
> 
> The important thing to note, is that we're not talking about the signal to noise ratio of the HU, we're talking about the ratio of the signal coming out of the hu to the noise induced through the RCAs
> 
> A line driver can in no way improve the signal to noise ratio of your source, but it CAN improve the overall signal to noise ratio of your system as described above. This is the reason for the push to have higher voltage preamp outputs on HU's. A 2v signal (what you'll typically get out of a 4v HU if you're lucky) will overcome 100mv of noise much easier than a .5v signal. I think that's pretty plain to see.
> 
> Again, we're talking about induced noise, not the S/N of your source. If you don't know the difference, then this discussion is not going to get any further.
> 
> 
> And to get at what chad was hinting at with the mic on a 300ft cable....this would all be moot if someone early on had decided to use a balanced signal to begin with.


Yes! Exactly! I agree 100% with everything you just said.

Yes, Post #98 is correct. On my end, I am not misunderstanding anything...I know what MnBari is saying, but I can't seem to get him to see what I am saying regardless of how I describe it or what diagrams I post.

One of the items we have NOT discussed is head unit output impedance. Many head units, although they have a great S/N ratio, have a high output impedance - which often leads to noise.

A device like an Audio Control Overdrive or Matrix line driver has a 45 Ohm output impedance and adjustable ground isolation (ground, float, or 200 Ohm), so when add one immediately after a head unit, you can break a ground loop if that is the cause of noise you have.

Here is thread with a gentleman who has a real-world problem. He has noise. He has used a high quality RCA cable (Monster MPC I304 4C-6M Extra Low Noise 4-Channel Car Stereo RCA Cable) which is a $70.00 cable and still has noise.

Now, we could say that his head unit is at fault, as it probably has a really high output impedance, or it may be his cable routing, but I think I have a simple solution for him which will allow him to keep his Retrosound source unit - add a line driver.

Here is the thread: http://www.diymobileaudio.com/forum...speakers-while-engine-idling.html#post1494027

MnBari, Chad, t3sn4f2, put your installer skills to the test. Help that gentleman out. 

We can have him add ground loop isolators to the head unit, run power wires from the head unit to a star-ground configuration where the amps are grounded, isolate his head unit, use a toggle switch for head unit power instead of car's ignition power, add a relay to his ignition to provide isolated power to the head unit, change RCA cables, re-route his RCA etc.

_*t3sn4f2 says, and I quote: "From my point of view, the only reason YOU can't have a system without needing a line driver is because you don't know how to correctly interconnect components without introducing noise".*_

Well, go help that gentleman in that thread. Let's see your troubleshooting and your "correct interconnection of component" skills.

Real world test. Fix his problem with the least amount of time and money spent.

I gave him a few ideas, and then told him to put a line driver on it.

Flame away.


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## chad

I agree with Dave in that I think people are looking at 2 different things, kinda why I bowed out a bit. It CAN help induced noise, but with proper signal transfer it should not be needed, it, again, WILL NOT help dynamics. and should not have to help with impedance matching. THE AC matrix is badass for running a metric ****load of amps off of one send.

It even goes along the lines of "Noise can never be eliminated, just attenuated" and again, I used my "line driver" as a balanced receiver.. in the boot. The Matrix does that.


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## mediumroast

Chad,
What is this "AC Matrix" you speak of. Very interested but is it costly?
I used to use line drivers and they did reduce the induced noise on my monster cable interconnects. Switching to streetwires zn5 helped a lot but now I use twisted pair magnet wire interconnects which seems to reduce enough noise to make the line driver unnecessary.


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## chad

Audio Control Matrix....


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## mediumroast

Yes AudioControl is good stuff and built in line driver to boot.


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## chad

you will need to "modify" the source to balance the impedance. IT WILL HAVE SOME CMRR with proper wiring but the modification assures that both lines are matched in impedance, this DOES NOT mod for balanced differential.


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## DiMora

I don't want to "whack the hornets nest again" on this topic; I've had my say and we can agree to disagree minbari and Chad and the others...

I very much enjoyed our banter. It makes you think critically, and that is never bad...but I had to share:

I was in CarTunes in Detroit listening to Focals with Deviate2112 two days ago...and look what they had on their soundboard:

Yep...that's an AudioControl Matrix - the very piece I have recommended in this thread.

I love that piece. Their head units feed the Matrix, then it feeds the amps.


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## chad

how many amps is it feeding?


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## t3sn4f2

edit


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## DiMora

chad said:


> how many amps is it feeding?


Don't know, Chad. I *think* three.

What I was listening to only used the far left ""gain" knob...one head unit, the switching board, the matrix, one amp, another switching board...then to some Focals.

They probably have it set so two more channels from the Matrix feed their sub amp, then to another switch board, then the subs.

The point was the gain was all the way down on the amp I was listening to, and they simply tweaked The Matrix to optimize input voltage. The salesman said that amp liked a peak 5 volt input and The Matrix was adjusted accordingly.


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## chad

they make fantastic distribution amps, that's what it was being used for as opposed to noise floor reduction... if you wanna do it at home look into Henry Engineering.


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## t3sn4f2

:inout:


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## Lars Ulriched

So is it really needed for SQ? Will this make your system sounds better after all?


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## chad

Lars Ulriched said:


> So is it really needed for SQ? Will this make your system sounds better after all?


LOL dirty bastard......


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## minbari

chad said:


> LOL dirty bastard......


:hanged::z:


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## DiMora

chad said:


> LOL dirty bastard......





minbari said:


> :hanged::z:


:knife:


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## SQ_lover

I feel so bad for being a hit and run on this thread. 

I just want to update that I ended up bought the line driver. I tried for a couple of days, heard no difference and gave it to a friend who admired it.

Maybe my install is too bad to hear the difference or it's just my ear or indeed there is no audible difference. Now, running my HU to MS-8 in the trunk with 20ft RCA. works just fine.

Sorry for bumping this old thread.


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## minbari

sometimes first hand experience is worth more than someone telling you how it will turn out.

line-drivers have very little uses, as you found out


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## cobretti

I don't believe you gain anything in amplifying an amplified signal. The best phonically sounding head unit I ever owned was an old Alpine that had no power of its own. Amps were required to produce any sound. IMO too much gear equals muddy music. Buy quality and keep it simple. I have yet to meet many folks with "pitch perfect ears" to appreciate high priced "Audiophile" gear. Just sayin.


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## mikechec9

cobretti said:


> ...IMO too much gear equals muddy music. Buy quality and keep it simple. I have yet to meet many folks with "pitch perfect ears" to appreciate high priced "Audiophile" gear. Just sayin.


Agreed. I have a very sensitive ear coupled with a case of severe OCD when it comes to sound. Mosconi 6to8 and mosconi one series amps...still forced to compensate for the low voltage HU w the matrix. At least until someone makes a dash adapter for the Infiniti G. Still waiting for an import version of Krass and Bernie to come out too though, so...


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## CrossFired

I've always notice when running a low/normal volt out(<2 volt), that I can never get the full potential of an amplifier. I've heard systems come alive, with more bass slam and smoother highs, all from added a higher volt supply. Given my findings, I'd say all a system needs is a minimum of 4 volts per channel, and your good to go.


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