Do I need a line driver??

[5.9Limited]

Hey all, a lot of you are already familiar with my new set up... Im running a 600.2 Ti with 2 RSDC 10's bridged @2 ohms... I heard in another thread that Ti's really benefit from using a line driver, and I read in the manual that its reccomended so you can keep the sensitivity down on the amp..

how much benefit is there to using a PLD?? will I notice an increase in power and SQ??? One or the other?? Any input is appreciated.

[dBincognito]

You are jacking up the input signal....and the "gain" on your amp is really input sensitivity.....so when you jack up the input signal...you don't have to turn the "gain" up as much

[GX3]

if properly used the LD will add (some one correct me if i'm wrong) head room and help the amps run more efficiently

[dBincognito]

if properly used the LD will add (some one correct me if i'm wrong) head room and help the amps run more efficiently

Yes...the EQ's do the same thing as well....you don't need a LD, if you are using a EQ215 or EQ230 they already jack up the signal and give you plenty of headroom....but you can still use 1 for looks...like me

[Eric D]

I don't think headroom is based on input sensitivity. From what I have learned, headroom is an amplifiers ability to play beyond its rated capacity. If you bought a 25W amp which really does 100W, it would be underrated by 75W, and therefore I suppose you could say it has 75W of headroom.

But a better way to describe it would be when an amp has the resources to play beyond a rated range, but not necessarily sustain it. If you had a 25W amp, and it would cleanly output 100W for a fraction of a second, but not maintain a test tone at 100W into load, then it would be said to have 75W of headroom. You would only be able to ever utilize this additional power when playing music.

The voltage amplification built into line drivers, EQs, and other processors is specifically for improved signal to noise ratio. Since a wire in an analog situation will always pick up some measure of noise, if you can keep your original signal as large as possible, you minimize the noise you hear in the end.

A 100W amp will always be a 100W amp, if you have a 2V input signal or an 8V signal. But, with an 8V signal, you will hear much less noise in your speakers than with the 2V signal.

I suppose it would make sense for someone to develop a deck with say a 50V output signal, and then your amplifier would simply be current gain, not any voltage gain. There are probably plenty of reasons not to do this though, such as killing people with the output, or frying the deck if it shorted.

[dBincognito]

Here is what I understand headroom to be

http://www.audiomasterclass.com/arc.cfm ... ou-need-it

[Eric D]

That is a great explanation of headroom, but I don't know if it applies here. They seem to be talking about recordings, and how to use headroom to anticipate the threshold of clipping.

In our case of audio playback equipment, we want headroom so we can play the music louder, and still maintain clarity.

[Eric D]

Maybe I can explain this better if I use an example.

I have a ZX450v2. Now, the ZX450v2 is rated at 75W a channel into 4 ohms. If you use a formula for power, V = sqrt (P x R), it would mean this amp does 17.3V output (sqrt (75 x 4). When I adjust my gain control on my amp, and the gains on my EQ or linedriver, my target would be to get 17.3V measured at the amplifiers speaker output terminals.

Does this make sense so far? I think I found a topic elsewhere on the forum which mentioned gain setting with a DMM, so I figure many of you have that idea down.

Now here is the really cool part. My ZX450v2 actually does 24V output, prior to clipping. Using the same math in reverse this comes out to 144W a channel into 4 ohms. For an amp rated at only 75W, that is pretty killer.

But here is the problem…

If I play a test tone into a 4 ohm set of speakers on that amp, it will not do 24V of output. It will fall short significantly. I do not have a power supply large enough to verify it, but my best guess is it can indeed do the 17.3V it is rated at.

Now we know music is dynamic, be it a cymbal crash, or a bass hit, the dynamic parts typically last for a fraction of a second. So, we can still set the gain of the ZX450v2 to do 24V of output, and hopefully it will not clip, or if it does, not clip by much. This is where the rail capacitance of the amplifier comes into play as it tries to keep the output section fed with the energy it needs.

Now I personally would use all of the above and say, "My ZX450v2 has 69W of headroom". If that is the proper use of the term headroom, I don't know, and never have really been able to find a solid answer.

[dBincognito]

I like what you said....here it is short and sweet

Definition: Dynamic Headroom refers to the ability of a receiver or amplifier to output power at a significantly higher level than normal for short periods to accommodate musical peaks.

Dynamic Headroom is measured in Decibels. If a receiver/amplifier has the ability to double is power output for a brief period to accommodate the conditions described above, it would have a Dynamic Headroom of 3db.

[dBincognito]

Eric D

"My ZX450v2 has 69W of headroom"

Do the conversion to dB...and that would be the amount of headroom

[Eric D]

Hey all, a lot of you are already familiar with my new set up... Im running a 600.2 Ti with 2 RSDC 10's bridged @2 ohms... I heard in another thread that Ti's really benefit from using a line driver, and I read in the manual that its reccomended so you can keep the sensitivity down on the amp..

how much benefit is there to using a PLD?? will I notice an increase in power and SQ??? One or the other?? Any input is appreciated.

Sorry for my other tangent, just trying to give some background on this.

In answer to your question, a line driver will not give you an increase in power or SQ. It will however lower the noise (hiss) you hear in your speakers, which I suppose could be called an improvement in SQ.

It can give you an increase in power when you are in a situation in which your deck does not have enough voltage to drive the amplifier even when the amplifiers gain is at maximum setting. I highly doubt you have this problem as it is quite rare (shows up with ZPA amps a lot).

dBincognito is right in that adding a line driver means you don’t have to turn up your gain on the amp as much, and this will lower your noise floor.

I personally don’t see much need for line drivers these days, as decks often have a high enough output themselves, and most modern amps have differential inputs which cancel out a good part of the noise on their own.

[Eric D]

I like what you said....here it is short and sweet

Definition: Dynamic Headroom refers to the ability of a receiver or amplifier to output power at a significantly higher level than normal for short periods to accommodate musical peaks.

Dynamic Headroom is measured in Decibels. If a receiver/amplifier has the ability to double is power output for a brief period to accommodate the conditions described above, it would have a Dynamic Headroom of 3db.

That description works for me, and it takes up a heck of a lot less text.

[5.9Limited]

thanks guys for all the help. I wasn't really sure if a pld would be worth my $$ or not...sounds like probably not.. I know my HU has 4v pre outs that seem to be doing fine...and to be honest...I've had my "sensitivity" i.e gain at 50% or less so far...i guess I didn't pick up on that the sens. and gain were the same thing... makes sense now that i think about it...

[stipud]

Don't trust your headunit's voltage rating. I've tested 4v decks that put out only 1v RMS when you hook up a DMM.

On just subwoofers though, there's not much to gain by lowering your noisefloor, since it's so hard to hear distortion in bass anyways. People are much more sensitive to distortion in midrange and treble, so if you decide to amp your components, that would be when I would start recommending an LD.