Linedrivers? Good or bad for spl?

[1200 bandit 2]

Hi guys, I need some feedback on linedrivers for spl. Some say that linedrivers kill subs and some thinks it makes you louder do to up to 13v outs?

Edited November 3, 2008 by loud by design

[///M5 2,833]

If you have enough voltage they do nothing. Perhaps it would be better to talk about your specific application instead of a general one.

[1200 bandit 2]

If you have enough voltage they do nothing. Perhaps it would be better to talk about your specific application instead of a general one.

My set up is a Alpine 7995 head unit, runnning to my saz 3000d, my sub is a T3 tss 15. I have a audiocontrol overdrive sitting off to the side in a box I'm not going to use it if it's not going to help for spl.

[fritosaregood 0]

If you have enough voltage they do nothing. Perhaps it would be better to talk about your specific application instead of a general one.

My set up is a Alpine 7995 head unit, runnning to my saz 3000d, my sub is a T3 tss 15. I have a audiocontrol overdrive sitting off to the side in a box I'm not going to use it if it's not going to help for spl.

the sundown amp's line input voltage is only 6 volts. i dont think puttin 13 volts to it would be good, and don't those alpines have a 4 volt output already?

[johnecon2001 82]

When people refer that they kill subs, its due to overdriving the line level and clipping the amp. This sends a square wave (DC) to the sub and smokes it. 9 times out of 10, this can be avoided by setting your gains with an oscilloscope.

[///M5 2,833]

As long as the amplifier puts out its rated power, which as John stated should be measured with an Oscilloscope, there is no benefit for stepping up the input voltage.

Personally if I were you and really wanted to know, I'd measure the output of my headunit for clipping with the o-scope and then do the same for the amplifier. If you hit power, there is nothing left to be gained. (pun intended)

[95Honda 486]

The (original) intention of a line driver was to do the following-

#1 Be able to drive the required voltage levels into the low impedances that are created by driving the inputs of multiple amps at the same time. Early head units could not source the neccesary current to keep the drive voltage up in these cases. All they (line drivers) really are is a current buffer, they really aren't meant to boost voltage, they are intended to drive the lower impedance loads at adequate voltage levels.

#2 (and a distant #2) Improve sound by operating further above (higher drive voltage/less amp sensitivity) the noise floor than the headunit could do on its own.

The (missconception) that line drivers are for SPL come from the fact that the only way to drive say 20 amps with one head unit is with a line driver, because they are able to source the neccesary current. If you have one amp, you never need a line driver. If you have 2 amps, more than likely, you never need a line driver.

They don't help with clipping, in fact, they make it easier to overdrive your system.

Clipping is not DC, does not behave like DC and doesn't heat voice coils up any faster than a sine wave. This is a HUGE missconception. Too much power blows speakers. Period. Amplifiers (attempt) to put out a constant voltage into varing impedances. If you ask an amplifier to produce Y voltage of a sine wave it is equal to X watts. The same amplifer puts out 2X watts with Y voltage with a theoretically perfect square wave. The speaker doesn't care what it gets, as long as it is below it's thermal rating. And if you can sit in a car and listen to music so distorted that the amplifiers are driven into full clipping, you are a tool and shouldn't be able to complain about anything.....

Setting your gains with a scope is a waste of time, especially if you have only one sub amp..... If you blow subs, no scope, DMM, "Online tutorial" or shop can help you....

[///M5 2,833]

Setting your gains with a scope is a waste of time, especially if you have only one sub amp..... If you blow subs, no scope, DMM, "Online tutorial" or shop can help you....

I would disagree with condition. Considering there is no gain in output by running a clipped signal there is no reason to do it and considering most people cannot hear distortion it is of a huge benefit to them to make sure that they are within the levels that their amplifier can put out. Not a mechanism to protect the speakers, but one to make sure that you aren't introducing excess noise/distortion into the signal when you aren't trained to hear it.

All that being said, I set mine by ear but that is pretty easy since the sub gain is basically off in my car & truck.

[95Honda 486]

I guess what I am trying to say is that clipping will not induce overly high average power levels untill it is very, unquestionably, without a doubt audible. And if you still play your system at this point, you are without help....

It's tough for me. I have been building speakers for almost 20 years now, I have been designing and building amplifiers, crossovers and power supplies from scratch for over 15 years. I use scopes, spec-anys, distortion meters, function generators on a daily basis. I know intrinsically what they do. I ahve installed maybe 100 or more complete car audio systems, and for the life of me, I have never once drug out my bench scope, or my Fluke handheld work scope for that matter, to set the gain of an amplifer. I can't comprehend how some people swear by using this equipment when I know they have 1/100th the experience with it I have (not meant twards you M5 )....

Maybe I am just biased and think people should use common sense 1st, thier ears right after 1st and an oscope somewhere near 73rd on that same list....

I think the problem lies where alot of people think the scope is some sort of golden parachute keping them from ruining all thier brand new equipment they payed and arm and leg for.....

[KU40 173]

Isn't the use of an oscope also at times dependent on other information to ensure that a typical volume will not blow a sub? For instance, if you have a 2000 watt amp on a 500 RMS sub, setting the amp with an oscope for 2000 watts will look like a perfect sine wave, but you'll still kill the sub because of the thermal limits. So you'd still need to clamp the speaker wire to monitor the actual power output of the amplifier. This also goes for mechanical limits, as well, and you'd need to know the characteristics of the box and how the woofer reacts in that box for that. A 1000 watt amp with a perfect oscope readout can still kill a 1000 watt sub if the box is too large and allows the sub to go over xmech. So then you'd need to depend on some modeling software or a good eye/ear to know when mechanical limits have been reached.

I've always set mine by ear, too.