Audiophiles: Touring factory EQ curve doesn't change with volume!

[FaintReality]

Images of the EQ tab.

Looks like they just set to flat giving you a good platform to tune with. If the fix-86 is capable, try changing polarity on individual speakers to see if it makes a difference. I know you can check all this with REW, but I have not yet dove into that as I just started messing with the program.

As for the flat frequency response, what's flat on paper is not flat to the human ear. Most prefer a little more low end and the top end dropped a bit. Check out some of the house curves from this post and give some a try: http://www.diymobileaudio.com/forum/showthread.php?t=131029

I have also attached a pic of various house curves to give an idea on what many prefer.

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[Trey]

Images of the EQ tab.

 

[josby]

As for the flat frequency response, what's flat on paper is not flat to the human ear. Most prefer a little more low end and the top end dropped a bit. Check out some of the house curves from this post and give some a try: http://www.diymobileaudio.com/forum/showthread.php?t=131029

Definitely this! No midbass and too much treble is usually how people describe hearing a flat EQ profile in a car. The reason for devices like the FiX being able to flatten an OEM EQ curve isn't to have a flat output from the speakers - it's to have a flat signal to use as the starting point for your own curve on the output side.

 

[cestjoel]

Looks like they just set to flat giving you a good platform to tune with. If the fix-86 is capable, try changing polarity on individual speakers to see if it makes a difference. I know you can check all this with REW, but I have not yet dove into that as I just started messing with the program.

As for the flat frequency response, what's flat on paper is not flat to the human ear. Most prefer a little more low end and the top end dropped a bit. Check out some of the house curves from this post and give some a try: http://www.diymobileaudio.com/forum/showthread.php?t=131029

I have also attached a pic of various house curves to give an idea on what many prefer.

Thank you for this! didnt know the science behind this. But as you can see, i was already naturally EQing the Fix86 with less highs and more lows haha. I really should get the Twk so i can have more control over the EQ.

 

[FaintReality]

Thank you for this! didnt know the science behind this. But as you can see, i was already naturally EQing the Fix86 with less highs and more lows haha. I really should get the Twk so i can have more control over the EQ.

Try tuning with what you have first. Also, check out the mini dsp. It's amazing for the price.

 

[Whitest Russian]

Can someone summarize what these graphs mean? Car audio is a whole new world for me so I don't really know what I'm l seeing here.

 

[cestjoel]

Can someone summarize what these graphs mean? Car audio is a whole new world for me so I don't really know what I'm l seeing here.

They represent an EQ curve. Right are higher frequencies and left are lower frequencies. We try to tune (boost up and cut down frequencies) until we achieve the sound we want

 

[PaulD]

I can give you an initial impression, the car has ZERO center imaging, even with a center channel speaker on the 2018 coupe Si .. that's a classic symptom of out of phase. Did you guys tap into the rear outputs or the front outputs for input into the Fix86 ?

 

[PaulD]

The lowering of the bass curve at higher levels and a little of the treble curve is a classic fletcher munson loudness curve.

 

[cestjoel]

I can give you an initial impression, the car has ZERO center imaging, even with a center channel speaker on the 2018 coupe Si .. that's a classic symptom of out of phase. Did you guys tap into the rear outputs or the front outputs for input into the Fix86 ?

The Fix86 has 6 inputs, If I’m correct. They used both the fronts and rears on mine.

The Fix86 doesn’t have phase or delay corrections. You would have to add the Twk88. However, JL Audio just released a new set of amps that come with all in one. They seem pretty cool.

 

[PaulD]

@josby do you have the wiring scheme for the Si built in amp ?

 

[DANANDME]

I improved the measurements I did previously by using a voltage divider circuit to avoid clipping, and I measured the front tweeter signal this time too. Most importantly, I measured at different volume levels (15, 20, 25 and 30 @makemerush). That's because a lot of Honda vehicles have been found to have volume-dependent EQ, presumably to reduce the bass going to the speakers as you turn the volume up since they use crappy speakers that can't handle it.

Raw results, measured at 1/48th octave resolution then smoothed to 1/6th:

(note that these are line VOLTAGE measurements, not speaker VOLUME measurements)

I added the sub, mid, and tweeter curves together using REW's A+B trace math to make it easier to compare the shape of the curve at each volume level:

So, no wonky EQ that varies with the volume setting like many Hondas have! This is great because it means if you use one of the many OEM integration DSP products that measure and correct the output of factory headunits (e.g. JBL CleanSweep), you won't have the problem of the curve changing as you increase or decrease the headunit volume. Flat output is possible at all volume levels!

Note: no conclusions should be drawn from this for the lower trim stereos (the ones without a factory sub)! It's possible (and in my opinion likely) that they do not work the same way.

Hi ,

Amazing info ,thank you very much for sharing this.
so actually you measure the elecrical signal and not the acoustical output from the speakers ? is that correct ?

 

[josby]

Hi ,

Amazing info ,thank you very much for sharing this.
so actually you measure the elecrical signal and not the acoustical output from the speakers ? is that correct ?

Correct, that is a measurement of the electrical signal on the wires going to the speakers.

But, read post #9, because I later discovered that my initial conclusions weren't quite right.

 

[DANANDME]

Correct, that is a measurement of the electrical signal on the wires going to the speakers.

But, read post #9, because I later discovered that my initial conclusions weren't quite right.

thats what i thought also - make sense- they need to protect the low quality speakers and provide a more "whigther" sound at low levels.

i have a 1.5 T CIVIC HATCHBACK made in englend - SPORT model - do you think it will measure the same ?

what kind of equipment you used to measure it ?

many thanks

Dan

 

[Fountainhead]

they're using what's called a "sliding high-pass" filter on the low end to conserve headroom at high volumes.

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