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instalher 06-07-2019 06:59 AM

Need R.E.W. help
 
2 Attachment(s)
Can someone help me decipher how to fix this curve?? I have a ms-8 and a Dayton 408 dsp. Been trying to smooth out that nasty 100-500hz range but to no avale.

JVD240 06-07-2019 07:29 AM

Re: Need R.E.W. help
 
Please use the "print screen" function rather than photograph you monitor.

Can you also share more information on the system configuration? What speakers? What crossovers? Etc.

timps67 06-13-2019 12:48 AM

Re: Need R.E.W. help
 
Measure each side separately to verify, it probably won't show up like it does playing in stereo. Usually I see people cutting frequencies around the null instead of trying to boost it. That frequency range is an issue in a lot of cars.

Truthunter 06-13-2019 07:29 AM

Re: Need R.E.W. help
 
Why so much boost on those eq filters? Looks like your just using 1/3rd center freqs and a Q of 4.8... why not make use of proper PEQ?
Cut those large humps between 200-500hz to bring them down to the rest of the response. What is your target curve? Lower it down so that the bottom peak of the null is like 1-3db below the target.

SkizeR 06-13-2019 07:55 AM

Re: Need R.E.W. help
 
Quote:

Originally Posted by Truthunter (Post 5712237)
Why so much boost on those eq filters? Looks like your just using 1/3rd center freqs and a Q of 4.8... why not make use of proper PEQ?

Cut those large humps between 200-500hz to bring them down to the rest of the response. What is your target curve? Lower it down so that the bottom peak of the null is like 1-3db below the target.

Yeah, over 12db boost on a budget processor is a recipe for a metric ton of clipping

Sent from my SM-G975U using Tapatalk

Lanson 06-13-2019 08:09 AM

Re: Need R.E.W. help
 
Well with the MS-8, I've had the best luck measuring in stereo (left first, then right) and averaging the response. You can get away with a fair amount of boost with it, but one thing the MS-8 can't do well is work with more or less than its intended house curve. I tried really hard to apply a more aggressive curve like Hanatsu's to an MS-8 and it sucked to even get close. I decided to give up, and re-assess the situation with the JBL curve and was able to get a nice response. I then bumped the midbass a bit with the amp gain related, and added a couple dB of boost here and there in the midbass region to get just a bit more liveliness out of it. The MS-8 really wants that JBL curve out of the box. Tuning an MS-8 with REW is possible but when it suggests changes with the auto-EQ, you sorta have to eyeball it, record your changes (I just take pics of the EQ profile with my phone along the way), measure again left to right and average, and rinse-repeat until you get somewhere. Polarity swaps also might be needed. Sometimes the MS-8 wants you to swap one side, sometimes both on the woofers, etc. You really just have to fiddle, measure, and see. Taking copious notes both on your REW files but also on a notebook (or word file or something) of each change helps you inch closer towards your goal.



I can't comment on the Dayton DSP, I assume just sticking with cuts and lowering your target to compensate would be a good call.

instalher 06-13-2019 11:34 AM

Re: Need R.E.W. help
 
thanks guys for your input..

Patrick Bateman 06-18-2019 10:38 PM

Re: Need R.E.W. help
 
https://www.diymobileaudio.com/forum...p;d=1559912385

You don't have a peak at 400Hz, you have a null at 150Hz. Look at your EQ settings - you have 12dB of boost at 180Hz. Don't do that; you have to fix the phase, that's the fundamental problem you're trying to fix with EQ.

So let's think about this:

What causes a null?

A null happens when two loudspeakers are not in-phase. For instance, if two loudspeakers are perfectly out-of-phase, you'll get a deep deep null.

If that makes sense to you, then the solution to your dip is to address the phase difference at 150Hz.

There are two ways to do that:

1) Try manipulating the slope of your crossover between midbass and subwoofer. For instance, if your subwoofer lowpass is 4th order, try 3rd order, and see if it improves things. If it does, great. If it doesn't, try 2nd order. Basically the idea is to change the slope of the xover, because changing the slope changes the phase.

2) If you have DSP delay for your sub, manipulate that to fill in the dip at 150Hz. Every time that you add five milliseconds of delay to your subwoofer, you are varying the phase at 150Hz by 22.5 degrees. If you added 40ms of delay, you would change the phase at 150Hz by 180 degrees.

If you want me to post the math for this, let me know.

The basic idea is to manipulate the phase until you get your midbass and your subwoofer in phase, filling in the dip at 150Hz.

Also, note that the process that I describe maximizes your power handling. Trying to address peaks and dips via EQ can kill your power handling if you're not careful, particularly if you're boosting frequencies.

If all of this makes sense, then you can see that once you address that dip at 150Hz, you will have the opportunity to LOWER the level on your midbass to flatten out that bump at 400hz. And when you get to that point, your power handling will be way higher, because you've addressed the phase issue at 150Hz.

Jimi77 06-18-2019 11:03 PM

Re: Need R.E.W. help
 
Mr Bateman is probably right about a null around 150hz and how to go about fixing it. Usually it's a cancellation problem when your EQ doesn't affect the dip in response. You can also vary the slope of the crossover to eliminate the null.

I think you also have cabin gain at ~300hz. Try taking ~250hz & 400hz down a few db. As another poster mentioned, this is a tough area in the response curve in car audio. The rest of the response curve looks pretty good.

jonah1810 07-09-2019 05:57 PM

Quote:

Originally Posted by Patrick Bateman (Post 5714375)
https://www.diymobileaudio.com/forum...1&d=1559912385

You don't have a peak at 400Hz, you have a null at 150Hz. Look at your EQ settings - you have 12dB of boost at 180Hz. Don't do that; you have to fix the phase, that's the fundamental problem you're trying to fix with EQ.

So let's think about this:

What causes a null?

A null happens when two loudspeakers are not in-phase. For instance, if two loudspeakers are perfectly out-of-phase, you'll get a deep deep null.

If that makes sense to you, then the solution to your dip is to address the phase difference at 150Hz.

There are two ways to do that:

1) Try manipulating the slope of your crossover between midbass and subwoofer. For instance, if your subwoofer lowpass is 4th order, try 3rd order, and see if it improves things. If it does, great. If it doesn't, try 2nd order. Basically the idea is to change the slope of the xover, because changing the slope changes the phase.

2) If you have DSP delay for your sub, manipulate that to fill in the dip at 150Hz. Every time that you add five milliseconds of delay to your subwoofer, you are varying the phase at 150Hz by 22.5 degrees. If you added 40ms of delay, you would change the phase at 150Hz by 180 degrees.

If you want me to post the math for this, let me know.

The basic idea is to manipulate the phase until you get your midbass and your subwoofer in phase, filling in the dip at 150Hz.

Also, note that the process that I describe maximizes your power handling. Trying to address peaks and dips via EQ can kill your power handling if you're not careful, particularly if you're boosting frequencies.

If all of this makes sense, then you can see that once you address that dip at 150Hz, you will have the opportunity to LOWER the level on your midbass to flatten out that bump at 400hz. And when you get to that point, your power handling will be way higher, because you've addressed the phase issue at 150Hz.

Not the OP. but could you post the math to finding the phase difference in delay at x frequency. I was unaware of a formula for this.

I'm just about to get into tuning my system up and i have no doubts it will prove useful

Many thanks!


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