M Series input voltage question

[HoseHead]

I'm building a system using M Series amplifiers. The published input sensitivity spec for the amps is 200mv - 2V.

I have a Pro Line Driver and a TBA line amp combo. Both of these devices will drive 8 volts out.
I'd like to use one of these two line drive options for their intended purpose.

Will the M Series be able to manage anything above 2V input? PG was infamous for under specifying. Is that the case here too?

Thanks for your time.

HH

[holmis]

The M-series can handle 8v...

[kg1961]

The M-series can handle 8v...

I too have heard this but i heard also it can damaged them? were is Eric or Val?

[Shinju]

From personal experience they do not like anything over 6v.

[Eric D]

8V will overdrive a M series amp.

But, you have plenty of options...

-Run the line driver at less than 8V
-Change the resistors on the M amp's inputs to handle the 8V
-Don't use the line driver

If it were me, I would turn the gains all the way down on the M amps, hook the line driver too them, and then use the DMM method to set the output of the line driver so the amps just clip. It will probably be around 4V or so.

It is still good to use the line driver, as I know you have about 20 M amps, and if you need to drive a lot of inputs at once, that is where the line driver will perform. It can source more current than a deck can, so with multiple amps connected the voltage will not drop.

[HoseHead]

Thanks for all the input.
I'll run it up on the bench.

HH

[Lowcountrypsulion]

8V will overdrive a M series amp.

But, you have plenty of options...

-Run the line driver at less than 8V
-Change the resistors on the M amp's inputs to handle the 8V
-Don't use the line driver

If it were me, I would turn the gains all the way down on the M amps, hook the line driver too them, and then use the DMM method to set the output of the line driver so the amps just clip. It will probably be around 4V or so.

It is still good to use the line driver, as I know you have about 20 M amps, and if you need to drive a lot of inputs at once, that is where the line driver will perform. It can source more current than a deck can, so with multiple amps connected the voltage will not drop.

Eric D,

Thanks for the information. I too recently connected a first generation PLD1 (powder coat w/blue & gold graphics) between my Apline 9884 and my M44. I used the instructions found in the .pdf of the original owers manual I found on this site. I turned the gains to their lowest possible level, adjusted the volume on the 9884 to 2/3rds, and started adjusting the PLD1 pot till the red clipping light started blinking. At that point I turned the PLD1's pot down slightly so that it's at maybe 60%, definitely not the whole way to the right.

In short, I was blown away with the difference. Obviously, the M44 runs cooler now and the system sounds as if it can get louder than it did before it starts to clip. I guess this makes sense because, with the gains at their minimum, the M44 is providing the best ratio between power output and distortion.

By the way, what function is the PLD1 performing, technically-speaking? I realize that saying, "it's amplifing or boosting the low-level output back to the amplifier" is probably wrong. I think I read somewhere on this site that it has something to do with "raising the noisefloor".

Thanks,

LowcountryLion

[tonym]

not sure if I know what Im talking about here.....but my 2cents is signal loss from the head unit....not enough ass to push the signal 16-20 feet of cable.....kinda like usb on the head units...take a IDE 2.5 laptop drive if you plug it right in to the usb off the head unit (the head unit will power the drive up)if you add an extension to the usb off the head unit it will no longet power up the IDE drive...you would need a second power supply

this is with what I have installed right now....not sure if thats the same for all head units...

[Eric D]

Let me make this very clear, adding a line driver will not make your amp run cooler.

It also will not make it sound better.

If it does either of them, you are either using it wrong, had your system setup wrong prior to using it, or have some other really strange issue with your system.

What a line driver does is boost the signal to noise ratio (when used like it should be used). This will reduce the "hiss" in your system. Otherwise known as lowering the noise floor.

If you listen to a loud song which has a moment of silence in the track, that hiss (or lack there of) is the noise floor of your system. Most systems these days do well with this due to improvements in the amps themselves, and the vehicles. Back in the day this was a much bigger problem.

One other use for a line driver is if your deck cannot supply enough voltage to get your amp to full power. I have found that 2V will drive any amp I have ever tested, which includes ZPA amps that supposedly "require" a line driver. Not true, ZPAs can run fine with 2V of input.

If your stereo sounds fine on silent tracks and does not have much hiss, then you don't need a line driver.

I should also add, SPL guys use line drivers to run many amps. They can source more current than a deck can, and with say 24 amplifiers installed in a system, you need more current to supply all those inputs.

[Lowcountrypsulion]

Let me make this very clear, adding a line driver will not make your amp run cooler.

It also will not make it sound better.

If it does either of them, you are either using it wrong, had your system setup wrong prior to using it, or have some other really strange issue with your system.

What a line driver does is boost the signal to noise ratio (when used like it should be used). This will reduce the "hiss" in your system. Otherwise known as lowering the noise floor.

If you listen to a loud song which has a moment of silence in the track, that hiss (or lack there of) is the noise floor of your system. Most systems these days do well with this due to improvements in the amps themselves, and the vehicles. Back in the day this was a much bigger problem.

One other use for a line driver is if your deck cannot supply enough voltage to get your amp to full power. I have found that 2V will drive any amp I have ever tested, which includes ZPA amps that supposedly "require" a line driver. Not true, ZPAs can run fine with 2V of input.

If your stereo sounds fine on silent tracks and does not have much hiss, then you don't need a line driver.

I should also add, SPL guys use line drivers to run many amps. They can source more current than a deck can, and with say 24 amplifiers installed in a system, you need more current to supply all those inputs.

Eric D,

Thanks for the clarification and the additional information. I've read a lot of your posts and I respect your opinions and information because I'm not a very technically-inclined person. I've been enjoying car audio since I was 19 in 1992. I actually just got back into the hobby and am currently assembling a nice, small collection of old PG gear that I plan to install soon.

I realize that the amp won't "run cooler", but since the gains are at the lowest level, it doesn't get as warm as fast as it would if I weren't using and adjusting the PLD1. As far as the system "sounding better", there was just a noticeable difference in the overall performance of the system. It didn't necessarily sound better. I don't now how to properly describe the difference, but it was noticeable.

Thanks again for the info! Ltr, LowcountryLion

[Eric D]

If you noticed a difference, then my best guess is this...

Considering you wanted a line driver for the reason of having your gains all the way DOWN, this clearly shows you are interested in good sound and not a moron who turns all the knobs all the way up.

I am willing to bet you actually had your gains a bit too low prior to the installation of the line driver. In this case you were not getting the full output of the amp, but it was not distorting either, and still sounded great.

Now with the line driver you have increased the output of the amp closer to its optimum capability, and this additional power will manifest itself as sounding much better (hence the reason I like to run bridged 4-channels on my components, the extra power reserve keeps anything from ever choking)

[Lowcountrypsulion]

If you noticed a difference, then my best guess is this...

Considering you wanted a line driver for the reason of having your gains all the way DOWN, this clearly shows you are interested in good sound and not a moron who turns all the knobs all the way up.

I am willing to bet you actually had your gains a bit too low prior to the installation of the line driver. In this case you were not getting the full output of the amp, but it was not distorting either, and still sounded great.

Now with the line driver you have increased the output of the amp closer to its optimum capability, and this additional power will manifest itself as sounding much better (hence the reason I like to run bridged 4-channels on my components, the extra power reserve keeps anything from ever choking)

Eric D,

Thanks for assuming that I'm not a moron! My fragile ego appreciates it. I am indeed interested in good sound quality. In fact, I only run a single 4-ohm 12 in a 1.2 cu/ft sealed enclosure and a now-12 year old set of Quart 5 1/4" Reference components. As I mentioned earlier, I just bought the last two pieces of equipment I was looking for (first gen. AX204A and old LPL44) and will probably start my simple false-floor design this weekend.

You mentioned in your reply that you bridge 4-channel amps for your components. This has me considering doing the same thing. Let me explain in greater detail:

This is the signal chain in my design: Alpine CDA9884 to PLD1 (1st gen) back to an EQ215 (1st gen) then split out to an AX204A and AX406A (both 1st gen). Next will be a Series II M25 bridged to power the sub and the M44 running the Quart components. I was going to use the front channels of the M44 to power the components and the rear channels to power the factory rear speakers utilizing the bandpass feature of the AX204A.

However, your comment regarding bridging 4-channel amps got me thinking about doing the same for my setup. After reading the description of my setup, do you think I should do the same and bridge both pairs of channels on the M44 to power the Quart components?

Have a good one,

LowcountryLion

[Eric D]

I would really consider bridging the M44 into the components, and not running any rears at all. The additional power will help the components, and you should stay well below clipping with this much power.

Besides, if you don't like the setup and really want rears, or less power on the components, you can easily change things around.

[ttocs]

why not run the componants and m44 fully active? by taking the cross over out you save a significant amount of power that it would usually eat up, as well as the ability to tune them better.

[Eric D]

The M44 is a pretty low powered amplifier. If you go active with it you have so little power running the 4-channels at only 4 ohms stereo, plus you are effectively throwing away two channels as well.

For the audio purist it would be great, but I doubt the system would even be loud enough to overcome road noise. In this instance a typical user would turn it up more, which would then enter the realm of clipping, thereby defeating the all benefit gained going active in the first place.

Now if it were me and I wanted an active system, I would consider a pair of M44s, one bridged for the mids, another on a sub, and the tweeters. Quite often tweeters need to be attenuated anyway, so running at only 1/4 of the power in this case would probably still be optimal.

[The Golden One]

their is one thing that need's to be accounted for and that is rca line voltage drop, if you have really long or low quality rca's then you will have some loss in voltage. believe it or not you wont have as much signal voltage as you have at the radio or line driver at your amp. that can probably be helpful in your case if you use a line driver some of the voltage may not end up at your amp anyway.