Creating my first house curve

[lovingdvd]

After equalizing my sub I agree with the consensus that it makes the sub sound pretty dull, and that defining a house curve is in order!

After reading through the stick and REW help files I have a few questions please:

1) In the sticky it talks about the approach of using the -15dB filter at 366Hz to create a house curve. However this seems like a different approach compared to the "house curve" functionality built into REW. Which approach is best used under which circumstances?

2) Its obvious to me how the -15dB 366hz shelving filter works. But I don't readily see how the REW house curve function gets translated to the BFD.

I see how you set up the house curve file for REW. But what exactly is REW doing with this information when it imports it? Does it create additional filters at various points that create the necessary cuts or something?

3) There seems to be three different types of house curves. On type is a fairly linear drop off from the 20-100hz range. The other type is more curved as shown with the 366hz filter. And yet another approach I've seen posted is where bass from say 20-35 hz is several dB higher, and then it drops several dB but flattens out from there (rather than sloping away as the frequency gets higher).

Is there a consensus for what tends to work best or what type most peopel prefer? I am interested for MOVIES only - do not care how music sounds except of course for music that plays as a movie soundtrack. What types of sound characteritics do these various house curve styles have?

[brucek]

In the sticky it talks about the approach of using the -15dB filter at 366Hz to create a house curve

I would forget this idea. We used to use this method before REW when the tones and excel spreadsheet was all we had to work with. It's far easier now with REW to create appropriate filters...

Don't read more into the house than it is. It is simply modifying the standard REW target line with your own ideas of what you want the response to look like. That's basically it. Realize that this extra lift you are programming in doesn't usually come for free. Unless you have some fortunate room gain, then you will have to raise the wholesale subwoofer level with the sub amplifier and then cut the response down to the house curve. You can lose lots of headroom.

Look at this plot of a standard target and then one where I add a housecurve.txt file with the simple parameters shown. The yellow shows the extra output I am going to need from my sub to pull it off. Where is that gain going to come from? Are you going to add gain filters? No, that's a bad idea (that a lot of people haven't figured out yet).

You will need to turn up your sub amplifier 5dB and then use filters to cut down to the target..


house_combined.jpg


brucek

[lovingdvd]

OK, I was thinking that you get your normal target done, then apply a house curve, and then it somehow transformed the existing filters.

So do I have this correct in that basically what I need to do is to start over, except this time I alter the target using the house curve before I start applying filters. Then I have it apply the filters, optimize them, and tell it to adjust the gains to the target. Before I get started turn the sub up so that it measures 80dB at say 25 hz, and run the Measurements and adjustments from there.

Do I have this right?

The other question is what level do you then use when you calibrate your sub to fit with your mains? I assume you aim to have say 50hz to be at 75dB while letting the lower end run hot?

[brucek]

Do I have this right?

Yeah, pretty much, except you need to make a small text file with notepad (called housecurve.txt or whatever) that you point to with the settings icon in the housecurve tab. The file will alter the standard target you choose with the parameters in the file. You can play around with a bunch of different curves to end up with the one you want. Do this before you even start measuring. The housecurve will load every time you start REW just like any cal file.

In my plot above I used two entries. I started the house curve at 80Hz (the crossover) with a zero. Then I raised the level by +5db up to 30Hz. That's it. You can do anything you want with as many entries as you want. Play around with it.

The other question is what level do you then use when you calibrate your sub to fit with your mains? I assume you aim to have say 50hz to be at 75dB while letting the lower end run hot?

Hehehe, that's up to you. If you're a normal guy, you will have the mains meet the sub at an even level and then the house curve rises from there. You can be a maniac (like myself) and run the sub hot. I listen at very reasonable levels, so I like a hot sub....

Wanna see it? I like how it sounds, but that's just me. My point is, there is no correct answer.


FULL_RANGE_WITH_FILTERS.jpg

brucek

[lovingdvd]

Interesting. What is your xo point? What params did you use to create this house curve?

Also am I correct that the option that says something like "apply PK gains" in the filters part of the window is what will force REW to bend the response to follow the target (even if there are no peaks there)?

[brucek]

What is your xo point?

60Hz with an 80dBSPL target level and a housecurve of:
30 5.0
40 3.0
50 1.0
60 0.0

Also am I correct that the option that says something like "apply PK gains" in the filters part of the window is what will force REW to bend the response to follow the target (even if there are no peaks there)?

No. REW acts no different when there is a housecurve - it's still just a target. Use the standard Find Peaks, Assign Filters, etc etc.

brucek

[cyberbri]

For my situation, room gain gave me a natural rise in the low frequencies:
(this graph shows response with bass traps in the room, sub + mains, sub near front right corner along right wall)




So I cut down the peaks up higher and let the room gain give me a nice curve below 30Hz. I listen to a lot of music, probably more than I watch movies (although TV and video games figure in as well), so I didn't want the bass to be boomy and over-powering for music. Most bass in music is above 30~35Hz, so this curve gives me a nice rise in the deeper bass.

[Wayne A. Pflughaupt]

lovingdvd wrote:

2) Its obvious to me how the -15dB 366hz shelving filter works. But I don't readily see how the REW house curve function gets translated to the BFD.

You can see in cyberbri’s graph that the equalization he needed played nicely into a house curve. But this isn’t the same for everyone. Some people end up with somewhat flat response once a few peaks and valleys are dealt with. This is the situation that brucek devised the shelving filter for, as an easy way to introduce a house curve when a sub had been equalized to flat.

As brucek notes, with REW people now tend to equalize along the target line. However, if you happen to have relatively flat response above the point where the target line drops, it makes more sense to apply the shelving filter than add a bunch of filters between 30 and 100 Hz.

For instance, referring to cyberbri’s equalized graph – notice how flat his response is between 30-80 Hz. If he decided he wanted a steeper slope, it would make the most sense to apply a single shelving filter.

lovingdvd wrote:

3) There seems to be three different types of house curves. On type is a fairly linear drop off from the 20-100hz range. The other type is more curved as shown with the 366hz filter. And yet another approach I've seen posted is where bass from say 20-35 hz is several dB higher, and then it drops several dB but flattens out from there (rather than sloping away as the frequency gets higher).

Is there a consensus for what tends to work best or what type most peopel prefer?

As others have noted, it’s largely what sounds best and most natural to you.

Regards,
Wayne