How are you setting amplifier voltage?

[JBehrens]

(Warning, this will be more to the audio/electrical nerds out there) Ok so I installed my JL system, and was looking at different ways to tune the M600/6 amp. The goal is to get the most power out without distortion/clipping and make it idiot proof so if someone cranks the head unit to full power there will be no risk of damaging the system. Looking at JL's recommended method did not bring me much comfort as it allows for distortion at high levels and expects the user to not turn the head unit past 3/4 volume. Using a little bit of guessing, if JL was saying to sent the amp to 17.4volts as the upper limit then I would turn the head unit to max volume and set the amp to 17.4volts (I have zero distortion at full output on the Kenwood head unit, as verified with an oscilloscope) after setting the voltage hooking up the oscilloscope to the amplifier output showed a moderate level of clipping at 17.4 volts, with the scope hooked up, I backed the input sensitivity down to where the wave was no longer clipping and got ~16.3volts. This was kind of disappointing as ohms law would say that I am only getting ~65watts of undistorted power out of the amp and JL rates the M600/4 at 75watts for 4ohms.

So where do I go from here? Leave the amp at a lower level (showing no measurable distortion) or set it to JL's recommended and get more power with possible distortion? Or is there another way of tuning all together? Interested to hear how you guys have gone about setting the amps.

Thanks

 

[Mainah]

What is the voltage on the kenwood at 100%? Jl likes 4v input or less. If 4v input or less and the amp is not outputting rated power I recommend contacting JL. 0 line level out distortion at 100% from a headunit is rare.

The oscilloscope method with a calibrated oscilloscope is the best method to use.

 

[JBehrens]

I have the KMR-M325BT, the first time I measured it there was no line level distortion at 4volts on the outputs but I will measure again tonight to make sure.

I don't use my oscilloscope that often, is there an easy way to ensure it is calibrated correctly?

 

[Need A Vacation]

@JBehrens,

Which model amp is it? I don’t remember seeing a M600/4... unless it’s an older model.

Anyway, if it’s like the new M series models, at 12.5v output is 60w, but at 14.4v it is 75w.

What was the amp’s input voltage?

 

[ralphsmithiii]

I ended up biting the bullet and bought an SMD-DD1. With that, I set the head unit first to max distoration level (mine distorts at 90% volume, then set the gains. So far, it's been pretty money as expected.

 

[Mainah]

I have the KMR-M325BT, the first time I measured it there was no line level distortion at 4volts on the outputs but I will measure again tonight to make sure.

I don't use my oscilloscope that often, is there an easy way to ensure it is calibrated correctly?

I have the KMR-M325BT, the first time I measured it there was no line level distortion at 4volts on the outputs but I will measure again tonight to make sure.

I don't use my oscilloscope that often, is there an easy way to ensure it is calibrated correctly?

Calibration will vary depending on type and model. Basically need to measure highly accurate known voltages and signals across the spectrum.

 

[JBehrens]

@JBehrens,

Which model amp is it? I don’t remember seeing a M600/4... unless it’s an older model.

Anyway, if it’s like the new M series models, at 12.5v output is 60w, but at 14.4v it is 75w.

What was the amp’s input voltage?

My bad, I have the M600/6 running 1thr4 for the MX speakers and 5/6 bridged to the sub. Input voltage is a little low, around 12.3volts, that could be the problem here.

 

[JBehrens]

I ended up biting the bullet and bought an SMD-DD1. With that, I set the head unit first to max distoration level (mine distorts at 90% volume, then set the gains. So far, it's been pretty money as expected.

$150 is a lot for a single use tool... but it would be nice.

 

[Need A Vacation]

My bad, I have the M600/6 running 1thr4 for the MX speakers and 5/6 bridged to the sub. Input voltage is a little low, around 12.3volts, that could be the problem here.

Could be wrong, but I bet it’s the input voltage holding the amp back a little.

What size sub?

Other than trying to tune it, how does it sound? Are you happy with just one sub?

TY!

 

[JBehrens]

Could be wrong, but I bet it’s the input voltage holding the amp back a little.

What size sub?

Other than trying to tune it, how does it sound? Are you happy with just one sub?

TY!

It might be voltage but from what I am seeing, with a single stator charging the battery the voltage will probably just break 13volts with the engine running. So I may be limited with the performance if that is true.

I have the MX10IB sub, the whole system is 1 pair MX770's, 1 pair MX650's, 1 MX10IB sub, 1 M600/6.

I like the system so far, tons of clarity, everything sounds good but low end is currently leaving something to be desired. At first (playing country music) I didn't notice much difference between running the coaxials wide open with no sub to having the sub. This is probably more of an issue with the tune and the sub being underpowered at the moment then anything else.

 

[BrandonG]

I am looking at the JL IB subs and see you're running the MX IB sub I wonder if a pair of the the M series 10's are the way to go or bite the bullet and get the 12"

 

[JBehrens]

I am looking at the JL IB subs and see you're running the MX IB sub I wonder if a pair of the the M series 10's are the way to go or bite the bullet and get the 12"

I like 12's, just a deeper punch if that is what you want. 2x 10's will be louder but the 12 will be deeper. The 190's do not have a good spot to mount a 12" sub without giving up the port side helm storage (only spot I could see fitting a 12 w/box).

 

[BrandonG]

Where do you have your sub mounted at @JBehrens ?

 

[JBehrens]

Lower part of the helm wall