# Preamp voltage secret



## takurofromjapan (Oct 19, 2009)

Hi , 

I was just told by this engineer of soundstream that when a head unit says "4 volt preamp voltage" , that voltage is devided by 3 channels ( front, rear, and sub) and they are actually 1.33V per preout channel ( 4volts/3channels) .

Is this true? 

Also , I read somewhere that if the gain is matched correctly ,an amp should be able to produce its maximum output power regardless of preamp input voltage ....is that correct?

If that is true, the maximum volume level of the system will not improve by using one of those preamp boosters ,meanwhile it will help the sound quality by being able to keep the gain low , is that right? 

I might be way off ....I don't know . People in the know, please help!!


----------



## spork (Jul 1, 2008)

if your preout voltage falls within the amps sensitivity range, then yes, it can make full power if it is set correctly.

However, higher voltage ALWAYS has the benefit of keeping your gains lower and reducing noise / interference - a line driver should never be used to increase the volume of the system, because althought technically it can, that would mean that your gains are set way too high. When you boost your preamp voltage, you would reduce your gain accordingly.


----------



## Mooble (Oct 21, 2007)

Is that true of all head units? Certainly not. Many HUs do put out their rated voltage per channel. Many Alpines test higher than their rated voltage in fact. Some are also a little light in the loafers. I suspect my Pioneer doesn't put out the stated 5v, but I haven't tested it to be sure.


----------



## stereo_luver (Oct 30, 2007)

Your 880PRS does or should put out the 5v but it doesn't reach that until WOT.
WOT = Wide Open Throttle.

When setting up my system I checked voltages as well as clipping on my HU and found no clipping at full volume and I just hit the 5v (4.96v). At first I tried to set everything the old school way of 3/4 volume and then set your amp gains. I did this since I didn't have an Oscope. When I had trouble getting EVERYTHING set-up properly I went and got a new Oscope. I couldn't get my 3sixty.2 to hit the clipping signal when setting the gains on the unit on the center/sub channels at 3/4 HU volume.


----------



## ncv6coupe (Oct 25, 2009)

This is a very interesting thread and response u got from soundstream to the OP


spork said:


> if your preout voltage falls within the amps sensitivity range, then yes, it can make full power if it is set correctly.
> 
> A line driver should never be used to increase the volume of the system, because although technically it can, that would mean that your gains are set way too high.


I don't think this statement is 100% correct. I will add to your post that I think it may be equipment dependent, for ex. Amplifiers with regulated vs. Non regulated power supplies. There are some non regulated amplifiers that will benefit from high input voltages at say 12.5 volts vs 14.4++ volts. I think that this may get too scientific because your statement is right but equipment matters. On another note how would we go about testing the voltage of our headunits if anyone knows? Would cutting a set of rca's and hooking them up to a DMM on AC voltage work? I want to do this to my kenwood kdc-x792 and I also have a 5 volt line driver in my system but it has voltage lights so you turn the knob and forget about it. afterwards.


----------



## spork (Jul 1, 2008)

We're talking about signal voltage, not voltage from the car's charging system.

My statement above is assuming that the input voltage from the charging system is unchanged.


----------



## ncv6coupe (Oct 25, 2009)

I know that you were talking about signal voltages but I'm kinda thinking about amplifier efficiency effecting what power we get from what signal the amplifier receives, classic argument I've seen somewhere is the rockford fosgate t10001bd vs the jl audio 1000/1. The fosgate has greater efficiency than the 1000/1 but u would have to have ur gains much higher to get there off of 12.5 volts versus the jl and I don't know if u would get that 1000 watts from it in that scenerio versus whatever jl does in their amps to regulate the load. What do u think? IS this invalid against the line driver theory?


----------



## spork (Jul 1, 2008)

Well, if you have an unregulated power supply and you are at 12.5v but the amps specs are all written out at 14.4v - there is no way you will get to the amps specs. Line driver or not.

With a lower input voltage, the amp is only capable of a lower output. So, your gain should still be set _relative_ to your signal voltage. The line driver still will not increase the overall "volume" without setting the gain higher than it should be.


----------



## SoundChaser (Apr 3, 2009)

ncv6coupe said:


> This is a very interesting thread and response u got from soundstream to the OP
> 
> 
> I don't think this statement is 100% correct. I will add to your post that I think it may be equipment dependent, for ex. Amplifiers with regulated vs. Non regulated power supplies. There are some non regulated amplifiers that will benefit from high input voltages at say 12.5 volts vs 14.4++ volts. I think that this may get too scientific because your statement is right but equipment matters.
> ...


Yes, that would work, but there is no need to cut the rca's. Just measure on the tip and sleeve. I made a couple of test cables by cutting junk rca's that came with my vcr, a long time ago. If you have cheap crapy rca's then go for it.


----------



## ncv6coupe (Oct 25, 2009)

spork said:


> Well, if you have an unregulated power supply and you are at 12.5v but the amps specs are all written out at 14.4v - there is no way you will get to the amps specs. Line driver or not.
> 
> With a lower input voltage, the amp is only capable of a lower output. So, your gain should still be set _relative_ to your signal voltage. The line driver still will not increase the overall "volume" without setting the gain higher than it should be.


Ok, I hope u don't think I'm badgering you because I really find this interesting but I guess I'm comparing different amplifiers which is why my thoughts on this are a little blurry. And I also have in mind where u stated earlier that although line drivers can be used for volume they shouldn't, what do u think about those spl guys that burp there systems? I know it may be just .2 db increase but do u see where I'm coming from, it seems we are more focused on music listening than squeezing out little to no sound with high input voltages? Thanks for your input.

And to SoundChaser that's what I meant, LOL if I'm gonna sacrifice my shiny nickel plated rca's for this test, reason I rather cut is to avoid the probe slipping and shorting out and blwoing something in my radio.


----------



## t3sn4f2 (Jan 3, 2007)

Electrical system power fluctuations do not change _overall_ volume, they only affect the maximum wattage possible. If your system is set up to put out 1000 watts at 14.4 and you hit a note that pulls the voltage down to 12 volts, the only thing that will happen is that the peak of that note will be compressed by a dB or so. Output at 1 watt will still be 1 watt, 2 will be 2, 4 will be 4, and so on till you hit the new lower wall brought on by the reduced voltage (ie a compressed peak not a overall compressed output).


----------



## ncv6coupe (Oct 25, 2009)

t3sn4f2 said:


> Electrical system power fluctuations do not change _overall_ volume, they only affect the maximum wattage possible. If your system is set up to put out 1000 watts at 14.4 and you hit a note that pulls the voltage down to 12 volts, the only thing that will happen is that the peak of that note will be compressed by a dB or so. Output at 1 watt will still be 1 watt, 2 will be 2, 4 will be 4, and so on till you hit the new lower wall brought on by the reduced voltage (ie a compressed peak not a overall compressed output).


I knew this in a sense but you know rms values and so called "PEAK" amplifier power are sometimes not published or misstated by manufacturers. This is where I'm a little off track, but I can almost swear that on the music I listen to, mostly 70's-80's acoustic reggae, drum strikes are sooo much more impactful with the line driver than without?? Guess this is just dynamic headroom??


----------



## spork (Jul 1, 2008)

it is possible that headroom is part of it.

however, another possibly could be that your pre-outs without the line driver don't fall within your amp's sensitivity range. I really doubt that is the issue, but it is a possibility.

For a good comparison, you would have to know for certain that your gain is _properly_ set to the voltage of your line driver then try again without the line driver while making sure the gain is _properly_ set to that voltage.


----------



## ncv6coupe (Oct 25, 2009)

I set everything with my meter/test tones, the headunit says it puts out 4 volts, the line driver I set at 5 volts right until it overloads then back it down, the amps can accept up to 8 volts, I also have a dsp in the signal path with ONLY .5 volt output stinking pioneer, so I adjust the amplifier to compensate when I run without the line driver but with the line driver transients sound flat out better/louder, maybe a mental illusion fpr spending $160? I hope u guys don't think I'm the moron that is saying that you magically get 10 increased db? I wish I had a spl meter. I'm gonna do some quick test after I find some junk rca's to cut and measure and run them straight from the head unit. Thanks for all the input, hopefully others who was wondering may pick up this info.


----------



## t3sn4f2 (Jan 3, 2007)

spork said:


> it is possible that headroom is part of it.
> 
> however, another possibly could be that your pre-outs without the line driver don't fall within your amp's sensitivity range. I really doubt that is the issue, but it is a possibility.
> 
> For a good comparison, you would have to know for certain that your gain is _properly_ set to the voltage of your line driver then try again without the line driver while making sure the gain is _properly_ set to that voltage.


Their is no headroom in this case. If the voltage going into the amp is at a level that makes the amp put out its maximum voltage (ie expected wattage) then any extra preamp gain will simply cause the amp to clip. You could use extra preamp gain (ie preamp headroom) for other purposes though like leaving some clean gain available on the head unit knob for lower recordings. Or to lower the gains on the amp and use the line driver's clean hiss free gain (if that's an issue).


----------



## spork (Jul 1, 2008)

If he were to use the line driver and he left the amp's gain in the same position that it was in without the line driver, there would be no headroom?


----------



## ncv6coupe (Oct 25, 2009)

t3sn4f2 said:


> Their is no headroom in this case. If the voltage going into the amp is at a level that makes the amp put out its maximum voltage (ie expected wattage) then any extra preamp gain will simply cause the amp to clip.
> (ie preamp headroom) is what I meant


This is where I think my amplifiers may be where I get the loudness illusion?? Variable resistance and variable voltage power stability so I'm getting more constant power even though the speaker resistance is fluctuating when playing?
Does amplifier power underrating or peak power come into play anywhere because the amps don't say what they are MAX capable of. I could meter it and convert, just never have. The amps are JL audio if you are wondering supposedly 150 watts per channel.


----------



## t3sn4f2 (Jan 3, 2007)

spork said:


> If he were to use the line driver and he left the amp's gain in the same position that it was in without the line driver, there would be no headroom?


With regard to the increase in dynamics that he mentioned he observed? No. That would no be "headroom" it would be more gain for low recording or more preamp/linedriver "gain headroom" but the amp would not be able to put out more then its max wattage just becasue the signal is stronger and the gain are set the same. The extra gain headroom would just go to clipping the inputs on the amp.


----------



## t3sn4f2 (Jan 3, 2007)

ncv6coupe said:


> Does amplifier power underrating or peak power come into play anywhere because the amps don't say what they are MAX capable of. I could meter it and convert, just never have. The amps are JL audio if you are wondering supposedly 150 watts per channel.


It's irrelivent since you are setting the gains on the amp based on what you hear to be the most it can go, whichever powe rating goes to it is just placing a number on what is heard. Once you driver the line you then reduce the gains and the output and numbers sent out the amp are still the same.


----------



## ncv6coupe (Oct 25, 2009)

t3sn4f2 said:


> It's irrelivent since you are setting the gains on the amp based on what you hear to be the most it can go, Once you driver the line you then reduce the gains and the output and numbers sent out the amp are still the same.


I actually don't adjust by ear. I go by the procedure JL says, which is by the reactive load of the speakers, like 2 ohms 30 volts, 4 ohms 50 volts and so on and again they JL does not state max power but I think the amp is cleanly putting out more stable power when I have a strong input signal, I can't sit in the car to measure by ear, 4 6.5" up front. Earbleed mahn.


----------



## sqshoestring (Jun 19, 2007)

An amp multiplies the input voltage to get rail voltage to apply to the speaker. Lets say an amp takes 12v and makes 24v (+/-) rails, it can apply +/-24v to the speaker at peak output above that it clips. On 14v input it can apply 28v (if unregulated). However the gains kind of follow this I'd guess, because I've never had a need to adjust gains due to car on or off. There should be a little fudge factor in your HU volume if you must have the last bit. Not really an issue at all unless you are doing SPL. Amps are so cheap just go buy a bigger one.

The last issue with setting your gains for this, is that most all recordings are at different levels anyway....so you really can't make it perfect only for one source of music. Setting a particular voltage gets you close.

HU RCA voltage should be on every RCA, but yes you need a 0db tone and to max the HU out, there will be far less than half that voltage at half volume because it is an audio taper. You will get the voltage in the last 10% or whatever, that is why 2v HU work fine for most things....unless you have an amp that does not gain that much and I have run into them.

I have seen amps that come alive with drivers, but mostly 1-2v HUs and certain brand usually older amps or the ones that don't gain up as much. Another issue is having another thing inline could degrade signal quality, I like KISS when I can use it.

The input section if an amp is not really directly connected to what comes out the big end. A line driver can't change what the amp can do that much, unless the amp is designed to have more input. Once it has enough input/gain, it can make up to rail voltage and thats it.

Yes this is an SQ forum mostly.... but I personally don't care so much what people ask.

I'd say put a line driver in there if you really want to know if it will help. If you have a 4v or more HU they often don't do much unless you are trying to get rid of line noise, but you never know for sure unless you try. You will have to figure out how to measure it properly, you really need a scope to see when it clips. I think in most cases they don't do much for you in SQ with newer equipment, but some people swear by them. Maybe some just want to run one, and that's ok I guess.


----------



## ncv6coupe (Oct 25, 2009)

i just hunted down a review I saw months ago talking about the JL power supply of this amp in question i'm using, Look at page 3 where they put the final pros and cons of the amplifier> 

http://www.caraudiomag.com/testreports/caep_0203_jl_audio_amplifier/performance.html

("The other issue with this design was when we were driving 2 ohm loads. The amplifier would not drop the supply voltage to match this load unless the power reached 157 watts per channel. If we listened to the system at moderate levels, the amplifier would operate with excessive headroom, causing excessive current draw and heat. JL claims that this is a feature - that this feature will increase headroom for real-world speaker loads. Maybe."
The Amp comes up in 4-ohm mode every time on power up and will be inefficient at low-level signal with low impedance loads until load sense circuit activates)

That quoted paragragh is probably where i'm getting my thoughts about the mysterious transient impact my mind says is there. What do u guys think about what those reviewers said?


----------



## slomofo (Mar 30, 2009)

spork said:


> if your preout voltage falls within the amps sensitivity range, then yes, it can make full power if it is set correctly.
> 
> However, higher voltage ALWAYS has the benefit of keeping your gains lower and reducing noise / interference - a line driver should never be used to increase the volume of the system, because althought technically it can, that would mean that your gains are set way too high. When you boost your preamp voltage, you would reduce your gain accordingly.


this is exactly what i was saying about 2 weeks ago but people apparently thought i was saying that more voltage makes more power and then some argument insued about basic math and some other crap but....
you are absolutely correct, the more voltage the better. it will lower induced noise and allow for cleaner power with less effort. my xtant's accept up to 9V unbalanced and 28V balanced. my soundstream says it only takes 5V but I know it takes way more than that and will also run 9V balanced with a BLT4 
with that said, the new Soundstream made by Power Acoustik very well may have ****ty preouts that say 5V split over 3 outputs but my Eclipse puts out 8V at 55ohms over all 4 of it's preouts. the Alpines and Nakamichi's also do this. I'm skeptical of most Pioneer's claims but I wouldn't be surprised if the 880prs and 990prs do what they say they do.


----------



## t3sn4f2 (Jan 3, 2007)

slomofo said:


> this is exactly what i was saying about 2 weeks ago but *people apparently thought i was saying that more voltage makes more power* and then some argument insued about basic math and some other crap but....
> you are absolutely correct, the more voltage the better. it will lower induced noise and allow for cleaner power with less effort. my xtant's accept up to 9V unbalanced and 28V balanced. my soundstream says it only takes 5V but I know it takes way more than that and will also run 9V balanced with a BLT4
> with that said, the new Soundstream made by Power Acoustik very well may have ****ty preouts that say 5V split over 3 outputs but my Eclipse puts out 8V at 55ohms over all 4 of it's preouts. the Alpines and Nakamichi's also do this. I'm skeptical of most Pioneer's claims but I wouldn't be surprised if the 880prs and 990prs do what they say they do.


:laugh: Where'd you get that from? 

Here's the thread for anyone to read more on the same topic.

http://www.diymobileaudio.com/forum/diy-mobile-audio-sq-forum/66672-adding-line-drivers-beneficial-overkill-4.html


----------



## sqshoestring (Jun 19, 2007)

ncv6coupe said:


> i just hunted down a review I saw months ago talking about the JL power supply of this amp in question i'm using, Look at page 3 where they put the final pros and cons of the amplifier>
> 
> http://www.caraudiomag.com/testreports/caep_0203_jl_audio_amplifier/performance.html
> 
> ...


That has nothing to do with line input voltage. What they are talking about is the power supply changing voltage to run different loads. If you match loads, you reduce voltage for lower loads like 2 ohms and can increase it for higher loads like 4 ohms. The alpine PDX rates same output for both by doing this as well. What they might do is leave the high voltage that could make more output until the amp seems significant output of the 157w. So if you ran it under than as most will for music, it could peak for a moment without switching and you would get a higher than rated peak, or more headroom. If you thrash it on a sub it will switch down. Does not really matter, though it may sound different when it switches if anyone noticed the change in output. I know the newer JL are hybrids and this would not happen, some are anyway.


SS made by Power Acoustik? Oh man.


----------



## slomofo (Mar 30, 2009)

t3sn4f2 said:


> :laugh: Where'd you get that from?
> 
> Here's the thread for anyone to read more on the same topic.
> 
> http://www.diymobileaudio.com/forum/diy-mobile-audio-sq-forum/66672-adding-line-drivers-beneficial-overkill-4.html


and I stand by my statement. It's okay though, Zapco never liked high volt in through their balanced ins, neither did Soundstream. David Navone and Richard Clark never used line drivers in their cars either. If you don't know who they are, do a google search and look at the speakerworks built car of Clark's. first competition waveguides, first high volt out 33 band eq's, and the list goes on. Don't forget Wayne Harris who created the Symmetry EPX and EPX2 for Rockford, it's preout voltage was 9Volts, why, to do just the things I said high voltage does. Don't worry though, these guys probably never did anything to advance car audio. 
okay, that's enough threadjacking for me. just go out and get a half volt preout deck, hook it up to your class A amp, and bury those gains (which induces noise) to get your stereo loud enough to hear over the noise of your car driving down the road. preout voltage is irrelavant........


----------



## Qicker306 (Oct 2, 2009)

The JL HD amps can make rated voltage below 10V, as the voltage drops, the amp increases it's current draw in order to create the rated power at all voltage levels. It's been demonstrated and proven, I heard at one demo it went almost below 8V before it reduced rated output power. Nothing to do with pre-outs, oops...


----------



## slomofo (Mar 30, 2009)

Qicker306 said:


> The JL HD amps can make rated voltage below 10V, as the voltage drops, the amp increases it's current draw in order to create the rated power at all voltage levels. It's been demonstrated and proven, I heard at one demo it went almost below 8V before it reduced rated output power. Nothing to do with pre-outs, oops...


i see at the end you figured out that we were on 2 different pages, but that is pretty cool, i know they said that with the regulated power supplies they could go pretty low in B+ voltage and still make good power but that's damn cool. I prefer unregulated high current myself.


----------



## Luke352 (Jul 24, 2006)

slomofo said:


> and I stand by my statement. It's okay though, Zapco never liked high volt in through their balanced ins, neither did Soundstream. *David Navone and Richard Clark never used line drivers in their cars either. Don't worry though, these guys probably never did anything to advance car audio.*
> just go out and get a half volt preout deck, hook it up to your class A amp, and bury those gains (which induces noise) to get your stereo loud enough to hear over the noise of your car driving down the road. preout voltage is irrelavant........


Thats because the head decks those guys had available were .5 volt or less pre-out, so in that case the extra voltage will help, but I'm not sure if you noticed but technology has kinda moved forward since the mid 90's and you can buy Headunits off the shelf with in most cases 4v or greater pre-outs. I'd hazard a guess that if those guys had the type of headunits available that we do now they probably would never have bothered with line drivers.


----------



## ncv6coupe (Oct 25, 2009)

t3sn4f2 said:


> :laugh: Where'd you get that from?
> 
> Here's the thread for anyone to read more on the same topic.
> 
> http://www.diymobileaudio.com/forum/diy-mobile-audio-sq-forum/66672-adding-line-drivers-beneficial-overkill-4.html


holy deja vu batman??? this is like a replay of the same thread up top, i have a matrix like that guy does, I think I know that the weakest link in my signal chain is the Pioneer DSP because it ONLY has 500mV/22k ohms input and 500mV/1k ohms output impedance with a low 91db SN ratio *but* it has a volume control and they give instruction as what to set the volume to considering the head unit is providing input of 500mV but I set this by ear level with the head unit about halfway until i hear tweeter distortion which i think is quickest audibly to me. The reason why i got the Matrix in the first place is coming from mostly home audio/live band setups, I'm a overpower to be safe junkie. That post touched on low output impedance, balanced inputs vs unbalanced, 1 guy on there actually used an audio control line driver just to drop the output impedance on his signal and for the supposed noise rejection of a line driver HELP I have to find someone with an O scope, I will be doing the RCA voltage test and running the head unit straight to the amplifiers and doing alot more late night listening when the outside noise is less to see if I didn't just spend a day debating about Nonsense with you guys. I'll let you guys know as i get to some testing later on.


----------



## ncv6coupe (Oct 25, 2009)

sqshoestring said:


> What they are talking about is the power supply changing voltage to run different loads. If you match loads, you reduce voltage for lower loads like 2 ohms and can increase it for higher loads like 4 ohms. So if you ran it under than as most will for music, it could peak for a moment without switching and you would get a higher than rated peak, or more headroom. If you thrash it on a sub it will switch down.


I knew what the reviewers meant, maybe my questions i ask are too vague because I'm posting through my phone so its sort of rush rush before i get a call and it deletes my message. The JL amplifier is not just a normal amplifier with all of its LAZY OWNER POWER LEVEL MATCHING ABILITIES:laugh::laugh: although u probably already know that, its the automatic power supply switching along with reactive loads/ working speakers not resistors that the amp (sees) that has me asking all these questions and thinking that the amp at low volume sounds more crisp to me because I'm talking about midrange and tweeters in my system with 2 ohm midbass drivers. I am gonna go through a serious system component choice analysis, I'm giving myself a headache,:laugh: gonna go for the KISS approach next time. may have some stuff for sale soon.


----------



## Luke352 (Jul 24, 2006)

ncv6coupe said:


> holy deja vu batman??? this is like a replay of the same thread up top, i have a matrix like that guy does, I think I know that the weakest link in my signal chain is the Pioneer DSP because it ONLY has 500mV/22k ohms input and 500mV/1k ohms output impedance with a low 91db SN ratio *but* it has a volume control and they give instruction as what to set the volume to considering the head unit is providing input of 500mV but I set this by ear level with the head unit about halfway until i hear tweeter distortion which i think is quickest audibly to me. The reason why i got the Matrix in the first place is coming from mostly home audio/live band setups, I'm a overpower to be safe junkie. That post touched on low output impedance, balanced inputs vs unbalanced, 1 guy on there actually used an audio control line driver just to drop the output impedance on his signal and for the supposed noise rejection of a line driver HELP I have to find someone with an O scope, I will be doing the RCA voltage test and running the head unit straight to the amplifiers and doing alot more late night listening when the outside noise is less to see if I didn't just spend a day debating about Nonsense with you guys. I'll let you guys know as i get to some testing later on.


In your case with only .5v pre-out voltage a little extra wouldn't hurt, if you already had 4v + output though I would have said your wasting your time.

Those people who claim they use the line driver to aid in noise rejection, again this is old technology since they were used for these purposes in the days of low pre-out voltage, in this day in age with high pre-out voltages and high quality RCA's if you need a line driver to increase noise rejection then you actually have other system wiring issue's you should be rectifying first, since a line driver will actually just amplify any source unit noise floor, so your actually increasing any existing noise from the source.


----------



## Luke352 (Jul 24, 2006)

ncv6coupe said:


> I knew what the reviewers meant, maybe my questions i ask are too vague because I'm posting through my phone so its sort of rush rush before i get a call and it deletes my message. The JL amplifier is not just a normal amplifier with all of its LAZY OWNER POWER LEVEL MATCHING ABILITIES:laugh::laugh: although u probably already know that, its the automatic power supply switching along with reactive loads/ working speakers not resistors that the amp (sees) that has me asking all these questions and thinking that the amp at low volume sounds more crisp to me because I'm talking about midrange and tweeters in my system with 2 ohm midbass drivers. I am gonna go through a serious system component choice analysis, I'm giving myself a headache,:laugh: gonna go for the KISS approach next time. may have some stuff for sale soon.



The JL system is just a compromise so that they can get away using a smaller power supply which would normally be undersized in a proper regulated design which should double power with a halving of speaker load 4 ohm > 2 ohm.


----------



## trebor (Jun 30, 2008)

Luke352 said:


> Thats because the head decks those guys had available were .5 volt or less pre-out, so in that case the extra voltage will help, but I'm not sure if you noticed but technology has kinda moved forward since the mid 90's and you can buy Headunits off the shelf with in most cases 4v or greater pre-outs. I'd hazard a guess that if those guys had the type of headunits available that we do now they probably would never have bothered with line drivers.


The deck in that car was a Alpine 7909, the first deck to have high output voltage pre-outs (4V). Even so, in THAT car mentioned, the deck was modified and was nothing more than a CD transport.


----------



## slomofo (Mar 30, 2009)

don't worry, no one ever used line drivers on DRX's, 7909's, or CDXC-910's, all of which have high volt preouts. 
I'm sorry for threadjacking but i've been doing this since 1994 and I've always seen beneficial results so when people try to prove another point, I call ********.


----------



## chad (Jun 30, 2005)

Lets say that it's obvious that I work in other facets of audio, and in those facets of audio, if i have a bit of noise on my line or a tad bit of RF I don't think "Hmmm lets kick the signal up." I look to see WHERE the noise is getting in and take care of the problem the PROPER way. The money spent on a line driver as a bandaid can easily be spent on, oh, about 750 feet of PROPER wire with a low capacitance and proper shielding. IF I have to do it electronically I immediately look at the receiving end of the chain, because, as stated 2 weeks ago, that's the most important link. 

Ironically I can get audio, NOISELESS audio 250 feet while it's at a level of the TENS OF MILLIVOLTS at 600 ohms. And you are trying to tell me that this industry is so flipping incompetent that they can't get 2 volts to a fuggin trunk of a car?


----------



## ncv6coupe (Oct 25, 2009)

slomofo said:


> no one ever used line drivers on DRX's, 7909's, or CDXC-910's, all of which have high volt preouts.
> i've been doing this since 1994 and I've always seen beneficial results so when people try to prove another point, I call ********.


Ok if I didn't know better I would think you are against them, so for a REAL noob, not just us with low post counts who may not understand all this electrical jargon, slowmofo actually *LIKES* line drivers in sarcastic terms simplified!!!!!


----------



## chad (Jun 30, 2005)

because they have good profit margins.


----------



## slomofo (Mar 30, 2009)

Chad, 
I was waiting for you to chime in. I'm glad you did. Now, I'm not an electronics engineer, never claimed to be, I only took Electronics Manufacturing Technology for 1.5 yrs so yeah, I dropped out, but let's talk about this. Let's not discuss ANY regulated power supply amplifiers that are full range class D because they don't count. Let's talk about sound Q amps like class A/B or class A. If you give a ****ty signal to your amp, how much harder does it have to work to reproduce that sound accurately while drawing massive amounts of current to do so. Now if you supply more than is needed, the amp draws less current to do the same job. Isn't that what its all about. Efficiency leads to cleanliness.


----------



## slomofo (Mar 30, 2009)

chad said:


> because they have good profit margins.


only ever sold one actually. there's always more profit margin in cheap decks with bells and whistles. the Eclipse's Nak's, and high end Alpine's never carry the same margin. As the price goes up, the margin goes down. did i ever tell you that my car scored a 34 on the RTA back when 40 was perfect, that was using the Coustic RTA1000. That was with all the eq settings at flat. That was with a Pioneer deck with a 1v preout, but with a RF crossover that bumped the signal to 10volts. It would also do 141db which back in 96 was pretty good for a 2 amp system.
experience ftw over e-thuggin any day


----------



## t3sn4f2 (Jan 3, 2007)

slomofo said:


> Chad,
> I was waiting for you to chime in. I'm glad you did. Now, I'm not an electronics engineer, never claimed to be, I only took Electronics Manufacturing Technology for 1.5 yrs so yeah, I dropped out, but let's talk about this. Let's not discuss ANY regulated power supply amplifiers that are full range class D because they don't count. Let's talk about sound Q amps like class A/B or class A. If you give a ****ty signal to your amp, how much harder does it have to work to reproduce that sound accurately while drawing massive amounts of current to do so. *Now if you supply more than is needed, the amp draws less current to do the same job.* Isn't that what its all about. Efficiency leads to cleanliness.


I have a feeling this is completely wrong. "I got ah feelinnnnnnnn'"


----------



## chad (Jun 30, 2005)

slomofo said:


> Let's not discuss ANY regulated power supply amplifiers that are full range class D because they don't count. Let's talk about sound Q amps like class A/B or class A.


Cool.



slomofo said:


> If you give a ****ty signal to your amp, how much harder does it have to work to reproduce that sound accurately while drawing massive amounts of current to do so.


The amplifier cannot differentiate between noise and music, if the signal to noise ratio is such that at low volumes you can hear noise but at high volumes you cannot then the power wasted amplifying said noise is only wasted until the signal overcomes the noise. 

This is also why amplifiers are EXCELLENT at amplifying a clipped signal, which can be WAY worse than actual clipping of the amplifier. Final sections of amplifiers clip WAY more gracefully than op-amps. One reason where I WILL CONDONE the use of a line driver, I owned one, it's been posted. My amp, even with the gains up, would not use the full potential of my headunit which is of a model that plays some "tricks" to prevent itself from clipping. I used the line driver to give myself about 3-5dB of gain AND, More importantly, provide me with a great differential receiver, I used the line driver in the trunk as more of a preamp and line receiver I guess. :blush:



slomofo said:


> Now if you supply more than is needed, the amp draws less current to do the same job. Isn't that what its all about. Efficiency leads to cleanliness.


The amplifier is simply a stout gain stage, think of it that way, it merely makes small volts into bigger volts. If you provide the amplifier with one volt and it makes 10 volts on the output then it's drawing the same amount of current than it would if you provided it with 10 volts and it's makes 10 volts on the output, given the impedance does not change that it's driving. The difference is that in scenario A you are using the "line driver" built into the amplifier to get the extra gain that you are not getting in scenario B where the amplifier is being used as a buffer stage.

This was mentioned in the line driver thread where one person mentioned that his line driver was actually replacing the first gain stage of the amplifier.

Often times we see this internally in amplifiers, the finals, the last stage of amplification, is damn near a 1:1 situation, the drivers see full rail voltage and have the job on ONLY turning off and on the final stage that can handle the current. All gain staging happens at the pre drivers for the most part, where the interface is merged from the bipolar low voltage section to the bipolar high voltage section. 

Another time I will condone the use of line drivers is when driving a BUTTLOAD of amplifiers from one output, you will need some buffering to prevent losses, generally in my world I would use a DA amp which basically provides X number of outputs, Individually buffered from one input. I believe the audio control Matrix does this also (that's the one I used for a while)


----------



## slomofo (Mar 30, 2009)

see, I knew we could find a common ground somewhere. for the record, I don't use a line driver, I have a deck that has 8v @ 55ohms and it doesn't clip so I don't need one, even though I would like to get a balanced rca setup because my xtant's accept up to 28V balanced in. or i guess i could just buy the new Pioneer that has the optical out like my MobileES did. no induced noise there.


----------



## chad (Jun 30, 2005)

hang on... let me find something for you


----------



## chad (Jun 30, 2005)

http://www.jensen-transformers.com/an/an003.pdf

Figure 2.4... a light might come on... I use this method and it works rather well.


----------



## t3sn4f2 (Jan 3, 2007)

chad said:


> http://www.jensen-transformers.com/an/an003.pdf
> 
> Figure 2.4... a light might come on... I use this method and it works rather well.


http://www.audioxpress.com/reviews/media/AE600HA.pdf


----------



## cubdenno (Nov 10, 2007)

I don't think adding a line driver is going to increase the amps efficiency. The amp is supposed to do what its name implies with the signal received. If you feed it a dirty noisy signal it will output the same noisy signal albeit with more power than it received said same signal. 
Edit: Chad answered before I could post.
Now, on the other hand, I like the way my system sounds with a line driver added after the Alpine H701. I was able to turn down the gains significantly. 

Chad, would you say the the preouts on pro equipment are better than what is found in the car audio market? I seem to remember that the pro and even home audio seems to follow a set of standards that never seem to apply to the car audio market. 

The last part I am curious about. I always thought it was funny how home/pro audio preouts were so abysmally low compared to car audio.


----------



## ncv6coupe (Oct 25, 2009)

Can I just chime in, i like that you guys are both Electrical Giants willing to use logic, ok let me make this quick and then watch on.



chad said:


> The amplifier cannot differentiate between noise and music, if the signal to noise ratio is such that at low volumes you can hear noise but at high volumes you cannot
> 
> Final sections of amplifiers clip WAY more gracefully than op-amps. One reason where I WILL CONDONE the use of a line driver, I owned one, it's been posted. *I used the line driver to give myself about 3-5dB of gain AND, More importantly, provide me with a great differential receiver*, I used the line driver in the trunk as more of a preamp and line receiver I guess. :blush:
> 
> ...


thats just it with me, the pioneer is not the quietest equalizer/dsp ever made, 91 db S/N ratio and 150 ohm output impedance so it was pretty classy in 1998 when it was mfg.

The Matrix does indeed buffer all six outputs from just 2 input channels, I'm running 7 channels of amplifiers in my system. 6 midrange, 1 sub, it has 110 db S/N ratio not to mention jumpers to switch grounds, balanced vs unbalanced inputs and a low 50 ohm output impedance

you said given the impedance doesnt change, thats exactly it, we know about speakers and impedance when they are actually playing music not sitting on a test bench.

what are your thoughts on this?? the pioneer has a 500mv input with volume control, the head unit is a high voltage unit so I use the volume control as an input _CHOKE_, then i run into my matrix drop the impedance on the line, boost it back to 5 volt levels with *NEWER TECHNOLOGY CLEANER LINE DRIVEN LEVELS* to the balanced input of my class A/B amplifiers which has a voltage range switch that i use as a _CHOKE_ again so as to not have the gains but only cracked to give me my power readings, am i wrong for this, its only a flip of the voltage range switch and i can adjust for the 5 volt input that i have available but to my ears i don't think its wasted at all hence, NOISE FREE probably where earlier i was saying better transients, i listened to that newest mariah carey cd, its track 14 or 15 i think, just for her *HIGH PITCHED SQUEALS* and there is a song on there that almost made my eyes water the first time i heard her go up that HIGH, WOW is all i could say, ok my rant is over, I'm staying tuned for some more of this discussion, its good to see that CHAD is not just a doubter on line drivers and SLOWMOFO both of your guys were users at the point in time, this is the in-depth electrical class that you never wanted to sit it, just more Adrenaline friendly here, Thanks


----------



## chad (Jun 30, 2005)

t3sn4f2 said:


> http://www.audioxpress.com/reviews/media/AE600HA.pdf


Don't even need an isomax to do truly impedance balanced


----------



## ncv6coupe (Oct 25, 2009)

chad said:


> This was mentioned in the line driver thread where one person mentioned that his line driver was actually replacing the first gain stage of the amplifier.
> 
> Often times we see this internally in amplifiers, the finals, the last stage of amplification, is damn near a 1:1 situation, the drivers see full rail voltage and have the job on ONLY turning off and on the final stage that can handle the current. All gain staging happens at the pre drivers for the most part, where the interface is merged from the bipolar low voltage section to the bipolar high voltage section.


Again here, this JL Audio amplifier is such a DUFUS its gain staging is still moderated (if thats a good way to use the word) at the outputs, no matter the impedance 1.5 to 4 ohms to beyond for whoever knows??? doesn't matter whats the load, u get full RMS stable power.


----------



## chad (Jun 30, 2005)

cubdenno said:


> Chad, would you say the the preouts on pro equipment are better than what is found in the car audio market? I seem to remember that the pro and even home audio seems to follow a set of standards that never seem to apply to the car audio market.
> 
> The last part I am curious about. I always thought it was funny how home/pro audio preouts were so abysmally low compared to car audio.


Ugh, don't get me started on the lack of standards  Standardazation would make things so much easier while dispelling myths, can't sell **** doing that man .

I would not say that they are that much better in other facets but I can say that the implementation of signal transfer is light-years better. Truly balanced is a plus, the lack of mythology of UTP cabling being better, in fact our twisted PAIR IS indeed shielded, as it should be. The adherence of practice in interconnection is important and when said standards are adhered to then things just work. When I made my tens of millivolts comment I was referring to a microphone down a snake, no preout, just physics.



ncv6coupe said:


> *NEWER TECHNOLOGY CLEANER LINE DRIVEN LEVELS* to the balanced input of my class A/B amplifiers



A, the matrix outputs unbalanced, it just receives balanced.
B, you would **** yourself if you knew how archaic the components and technology inside the matrix really are compared to today's standards. Simple little commonly used inline BA4560's IIRC. just set up as a simple gain stage on a decent simple bipolar power supply.

Damn thing does not even have a pixie dust storage vessel!


----------



## sqshoestring (Jun 19, 2007)

That old Pioneer .5v auto stuff was the biggest PITA. I would not use it. Sure it worked fine when the car was off, then it always had noise. You near had to run the input up the center of the car away from any other wires to get it to work. Some people loved it, but I was installing and hated it.


----------



## chad (Jun 30, 2005)

sqshoestring said:


> That old Pioneer .5v auto stuff was the biggest PITA. I would not use it. Sure it worked fine when the car was off, then it always had noise. You near had to run the input up the center of the car away from any other wires to get it to work. Some people loved it, but I was installing and hated it.


psst, hey buddy, your age is showing  :laugh:

Now the cars run everything down the center 

I got burnt by that one


----------



## slomofo (Mar 30, 2009)

Chad, thanks for the diagram for the balanced outs, unfortunately I'm unwilling to mod the board of my deck because i may want to use it for something else later and have to reverse all of it. i will just get some rockford bld-1 balanced adapters. 
SO, has the original poster even responded since or did we blow him out of the water.....


----------



## chad (Jun 30, 2005)

slomofo said:


> Chad, thanks for the diagram for the balanced outs, unfortunately I'm unwilling to mod the board of my deck because i may want to use it for something else later and have to reverse all of it. i will just get some rockford bld-1 balanced adapters.
> SO, has the original poster even responded since or did we blow him out of the water.....


if you can get you "box to balance" close enough to the headunit you can do it externally as long as you can get the schematics or get into the headunit to see what the existing components are.


----------



## ncv6coupe (Oct 25, 2009)

slomofo said:


> SO, has the original poster even responded since or did we blow him out of the water.....


he may be asleep from the aspirin he had to take to see straight after the migraine he got from reading our *conflicting at first but now:dRESOLVED* ideologies. That was Very Refreshing. With *MY* equipment the line driver i have is beneficial but beware not all line drivers are created EQUAL with the features they come with, in your cases they _might_ help but you know enough about electronics to not support experimentation, lol, I'm in the process of redesigning my system and i'm repositioning my speakers so I'm gonna try to eliminate the DSP and use as minimal as possible equalizer on the kenwood radio. 



chad said:


> A, the matrix outputs unbalanced, it just receives balanced.
> B, you would **** yourself if you knew how archaic the components and technology inside the matrix really are compared to today's standards. Simple little commonly used inline BA4560's IIRC. just set up as a simple gain stage on a decent simple bipolar power supply
> Damn thing does not even have a pixie dust storage vessel!.....


I was talking about my amplifiers having balanced inputs also, another thing is the matrix you can switch the jumpers and have the inputs unbalanced. Believe me I found it damn hard to spend $160 for the line driver. now to see that i probably would have jimmy rigged up some components for may $75 and hid them in the glove box makes me want to PUKE. KISS 40% Had money to burn at the time 60% lol


----------



## 14642 (May 19, 2008)

I love it when all of these technical posts have phrases like "amp works harder", "effortless sound", "more forceful transients" because those are code for "my science is a ruse".


----------



## ncv6coupe (Oct 25, 2009)

Andy Wehmeyer said:


> I love it when all of these technical posts have phrases like "amp works harder", "effortless sound", "more forceful transients" because those are code for "my science is a ruse".


Whats your input will all the tough reasoning we just subjected each other to come to final judgement, I'm very curious because u don't seem to have much supporters around these parts. On another note i LOVE my infiniti kappa tweeters when run in an active setup on its own channels to keep the levels down, some call them harsh but i call it headroom need be i get loose on my volume knob,


----------



## chad (Jun 30, 2005)

ncv6coupe said:


> Again here, this JL Audio amplifier is such a DUFUS its gain staging is still moderated (if thats a good way to use the word) at the outputs, no matter the impedance 1.5 to 4 ohms to beyond for whoever knows??? doesn't matter whats the load, u get full RMS stable power.


It's GAIN STAGING is not "moderated" it uses stepped power supplies to produce the same APPROXIMATE power output under different load conditions. 

Rest assured that if you get a JL amplifier to make 10 volts out with X volts in at 4 ohms it will make 10V out with X Volts in at 1 ohm. The GAIN does not change, the maximum voltage out indeed does change. Gain is MUCH different than maximum voltage output, gain is expressed in voltage gain, not power gain.

I think JL makes a damn fine amplifier, unfortunately people doubt their capabilities. This is because of people believing the the RIPS principle in that the amplifier simply brick-walls at X watts, it does not, you don't lose "headroom" it's just on a different set of voltage rails. voltage gain indeed stays the same.


----------



## chad (Jun 30, 2005)

FWIW there are VERY FEW things Andy and I could disagree upon, which is not bad considering I'm a jaded, bitter old road dog


----------



## slomofo (Mar 30, 2009)

Andy Wehmeyer said:


> I love it when all of these technical posts have phrases like "amp works harder", "effortless sound", "more forceful transients" because those are code for "my science is a ruse".


hey, snakeoil me sideways!!


----------



## ncv6coupe (Oct 25, 2009)

chad said:


> It's GAIN STAGING is not "moderated" it uses stepped power supplies to produce the same APPROXIMATE power output under different load conditions.
> 
> Rest assured that if you get a JL amplifier to make 10 volts out with X volts in at 4 ohms it will make 10V out with X Volts in at 1 ohm. The GAIN does not change, the maximum voltage out indeed does change. Gain is MUCH different than maximum voltage output, gain is expressed in voltage gain, not power gain.
> 
> I think JL makes a damn fine amplifier, unfortunately people doubt their capabilities. This is because of people believing the the RIPS principle in that the amplifier simply brick-walls at X watts, it does not, you don't lose "headroom" it's just on a different set of voltage rails. voltage gain indeed stays the same.


didn't know another word to use so I had to keep most of my science like a "ruse" lmao Well since you REALLY know what your talking about, i guess it's safe to come out of the closet with some of my amp porn,









 i needed justification as to why my amp rack is stuffed with this (non-essential) equipment,

Cheers


----------



## chad (Jun 30, 2005)

They have differential inputs too


----------



## 14642 (May 19, 2008)

ncv6coupe said:


> Whats your input will all the tough reasoning we just subjected each other to come to final judgement, I'm very curious because u don't seem to have much supporters around these parts. On another note i LOVE my infiniti kappa tweeters when run in an active setup on its own channels to keep the levels down, some call them harsh but i call it headroom need be i get loose on my volume knob,


I'm far more interested in beneficiaries than in supporters. I'm not running for office, just trying to help out here. Granted, I make an occasional jerky post, but all I care to do here is provide the benefit of my considerable experience to forum members in the interest of steering people toward efficient success in making their cars sound good instead of hours and hours of BS trial and error based on some marketing garbage or keyboard-commando advice from snake oil salesmen. 

What do I get in return? I get to know what kinds of products to build to make this easier for interested consumers.


----------



## ncv6coupe (Oct 25, 2009)

Is that a 13w6v2 i see stuffed in the spare tire enclosure??


----------



## Sulley (Dec 8, 2008)

If i have a 2V preout, Is that peak 2 Volts or 2 Volts RMS? peak, correct? i know most DMM's are RMS voltmeters. So if I measure my preouts with a sine wave i'll never see that 2Vs but only .7071 of it (if read with RMS DMM). Correct?


----------



## chad (Jun 30, 2005)

depends on the frequency response for the DMM, some less expensive ones are rather narrow banded and that bandwidth is centered at 60 cycles


----------



## chad (Jun 30, 2005)

ncv6coupe said:


> Is that a 13w6v2 i see stuffed in the spare tire enclosure??


Dayton RS265HO, Don't have the room for a JL.


----------



## sqshoestring (Jun 19, 2007)

chad said:


> psst, hey buddy, your age is showing  :laugh:
> 
> Now the cars run everything down the center
> 
> I got burnt by that one


Lot of people had pristine 70s/80s summer cars, many RWD like camaros/montes/dueces/etc, some you had to take the seat out and stuff like that it could be a major renovation then it still had noise. We were sticking caps on stuff all the time, noise filters, etc. Yeah I was a kid then. I'd also guess cars were noisier electrically back then. I still would not use that stuff, but would use a PA2 I have sitting here if I didn't have all that in the HU now. That old pioneer stuff about drove us nuts back then, left a bad taste if you can't tell. I did like the HUs for budget stuff, good tuner in them. They would have been great if they would have gone along with everyone else with more line voltage, and they did work well once you got them clean.

I've been told the JL amps are nice (from techs), but I've never run one.


----------



## chad (Jun 30, 2005)

I have a bad taste for fryanear due to the pico fuse thing, but you have to admit, back in the day, they had KILLER tuners (my age is showing )

The JL amps do well, they, damn I can't believe I am saying this, have WON A LOT of comps. Even though I was turned off at first by idiots on the phone and e-mail who could not explain the RIPS on a 300/4, I then bought my 500/5. It has been flawless, even after the Indy 500 incident. I'm happy with it. People get confused by the terminology and thus drawing conclusions.

The fact that they express tutorials in detents of a pot and the pot is accurate enough to do that is testimonial. This testimonial is echoed with our "home subs" we use in our mastering studio at work, take the phase, divide it by detents and it's remarkably spot on, even between 2 subs  There's some pride in that that cannot be overlooked, and QC.


----------



## takurofromjapan (Oct 19, 2009)

slomofo said:


> SO, has the original poster even responded since or did we blow him out of the water.....


Hi , everyone , I am surprised how this forum is so active. 


By the way, maybe I should jump back in with more detail to get some opinions I was hoping to get originally. 

This meeting with a soundstream engineer happened because I recently installed RUB5.800 to replace my stolen Directed 450d5. RUB was way outperformed by 450D5 both in volume and SQ ,although everything on spec suggest this was an upgrade for me. 

A local dealer took me out to this event of 12V peeps in Oakland to help me meet guys from SS directly . I had them listen to my setup.. They admitted it sounds ****ty , but the solution I was offered was to buy SS's Preamp booster. I kind of understood how it can be beneficial in terms of SQ with lower gain on amp.But I felt that will not solve the problem of RUB pumping out so much less volume compared to lower-rated 450D5,which was making me open up the gain of RUB so much just to get that sorry volume, and it of course attributed to the bad SQ to begin with. And more than anything 450d5 didnt need such an aid of extra booster at all, and it still would have laughed at RUB ...... Something isnt making sense...is it?? so, I continued to ask questions to this SS guy. 

He proudly says that RUB can handle up to 8V input signal( what amp doesn't these days?) ,and this booster will lets me bring up the preamp voltage up to either 5v or 10v....

I was like , wait a minute, so I can only use 5V boost then????? My H/U is Sony GT-705DX ( sorry sony haters....) and it says preamp voltage is 4V...???? I can only get 1v boost per channel , instead of 6V or it would go beyond sensitive range , wouldn't it??

He explained that the booster's voltage rating is a sum of 3 channels ( front rear and Sub) . so in reality you are going to get 3.33V per channel with it set at 10v...( btw at this point I realized that this booster only has 1 input channel) 

so are you suggesting that I need to change preamp signal from 4V x3ch to 4v x 1ch boosted to 10v and divide that into 3 channels of 3.33V each? how good is that??? 

His answer was that all the H/Us use the same method of rating their preout voltage , and my H/U for example says 4v preout and its signals are actually 1.33v per channel..

I couldn't believe it and asked a guy at clarion section, and he says "no way. At least I know that we do not rate our products misleadingly like that" 

And the SS guy's answer was , he doesnt know what he is talking about....

I am sorry to say this , as Chuck Kenney from SS( not the engineer guy I am talking about here) treated me with a lot of respect ...but is SS actually a full of **** ? 

Their RUB5.800 sounds like a ****...at very least I know with my experience....

What do you guys think?


----------



## wwjdato (Dec 1, 2010)

spork said:


> if your preout voltage falls within the amps sensitivity range, then yes, it can make full power if it is set correctly.
> 
> However, higher voltage ALWAYS has the benefit of keeping your gains lower and reducing noise / interference - a line driver should never be used to increase the volume of the system, because althought technically it can, that would mean that your gains are set way too high. When you boost your preamp voltage, you would reduce your gain accordingly.


I have a question and maybe you can help. My pioneer head unit has 3 sets of preouts they are suppose to be 4v preouts. I am installing a total of 5 amps 4 for mids and 1 for sub. So I need 5 sets of preouts 4 of them going to my mids. The sub out will plug straight into the amp. but the others i only have two? can i splice these with y adapters? Or will that hurt my sound quality? Are there any other options? thanks


----------



## ncv6coupe (Oct 25, 2009)

wwjdato said:


> I have a question and maybe you can help. My pioneer head unit has 3 sets of preouts they are suppose to be 4v preouts. I am installing a total of 5 amps 4 for mids and 1 for sub. So I need 5 sets of preouts 4 of them going to my mids. The sub out will plug straight into the amp. but the others i only have two? can i splice these with y adapters? Or will that hurt my sound quality? Are there any other options? thanks



Great Ancient thread You can use Y-cables but the resistance changes and *you lose line level voltage*. Does your amp not have pre-amp outputs so that you can daisy chain them back to back instead? That way you would only need to run 2 sets(front and rear)+sub from head unit then 1 set from each amp and get full voltage across all of the inputs. The radio will handle 2 inputs per channel but don't try anymore or you might let the white smoke out.


----------



## Ianarian (Dec 20, 2010)

OH, the horse lives! This is my favorite topic, I've been banned over this debate. ... Haha, to those who think that the outputs from the source are the best signals they can make prior to amplification. Well, I am done trying to convince. Some people are using gain to adjust volume levels from front to rear on 4ch amps. Especially when channels 3/4 are bridged for a sub. How many set their F+R gains both the same? Then they flip a switch and go through the amp's manufacturers versions of what 80Hz is. Now, mind you, this is a XO on a network inside this current and voltage dwelling device. I like to propose a lame scenario that I do because I am stupid OK? Hows about setting those gains down low, both at the same level. The internal XO in the amp sets to flat. The amps done, leave it be. Now the control is in the external XO. Signal Level, Hz, slopes, boosts, active options on and on, blah haha. Ya I asked a judge at MECA once if all his extra gear helped out the sound at all..... He looks at me seriously and just utters, "Naaaa, nooo, found all that in Grandma's basement."


----------



## chad (Jun 30, 2005)

ncv6coupe said:


> Great Ancient thread You can use Y-cables but the resistance changes and *you lose line level voltage*.


the input impedance of the amp will be high enough that you really don't need to worry about this being even close to negligible off of a simple Y connector.


----------



## sqshoestring (Jun 19, 2007)

When I get an amp that will not gain enough off a 4-5v HU that it needs a line driver, I get rid of it.


----------

