Just starting with REW & MiniDSP

[Pandaman617]

So I’ve been taking some measurements with REW for a few weeks now and the MiniDSP I ordered will be here tomorrow. I’ve always had a dip at 90-100hz roughly and tonight I tried different crossover points, distance setting and eventually multiple locations for one of my 4 subs and my Mirage towers and finally got rid of it. I had to move my Mirage OM-10’s (the OMD-28’s I usually run are both having the crossovers “upgraded” for free my one of my areas local audio gurus for helping him fix his Subaru I don’t think it will make an audible difference but I wasn’t going to turn down free better quality components) 34.5” away from my rear walls, 20” from the side walls and move one of my front 1/4 length location subwoofers out another 15”. I’m excited to get the MiniDSP as I know you’re not supposed to mix sealed and ported subs but it’s what I have at the moment so two of my subs are sealed dual driver 12” BPS-400’s and two are SVS PB-1000’s and from what I’ve been reading adding a shelf filter can help smooth out their response better? Anyways here’s the before and after.

 

[shadyJ]

A shelf filter will not smooth out the response. It will just take uniformly down the level of a specified band.

Per the response, I would try to move one of the subs to shore up the response at 60hz and above where it seems to sag. After that, I would apply EQ to take out the peaks in the response.

 

[Pandaman617]

A shelf filter will not smooth out the response. It will just take uniformly down the level of a specified band.

Per the response, I would try to move one of the subs to shore up the response at 60hz and above where it seems to sag. After that, I would apply EQ to take out the peaks in the response.

Thanks for the input! Moved the 15” sealed sub a bit further into the room and my response is way flatter across my 3 seats. My current room is relatively small and not very ideal but with proper placement and tons of trial and error I’ve gotten it about as close to “good sounding” as my current setup allows. MiniDSP was really a piece of the puzzle I ignored for so long. I’m glad I took the multisub route and did some research on here instead of listening to some of my local AV guys who wanted me to bass trap and treat the hell out of my room which would have actually cost me exponentially more than MiniDSP, a Mic & another sub.

 

[PENG]

Agreed with Shady's suggestions. You can do a lot with the peaks but much more difficult to tackle the dips with EQ such as the minidsp/REW. You can tried and it might improve somewhat (that sharp dip near 90 Hz), and keep in mind such a narrow dip is likely to be audible either.

 

[Pogre]

Yup. I always start by cutting peaks first, then remeasure. Sometimes a few cuts is all you need.

 

[diskreet]

I have two 12" subs, and an 18". To get really good response in my room I did the following. I completely agree that getting rid of peaks is easy, so focus on reducing dips first.
This process might not be perfect for you, but my recommendation is to start with position of the subs. Next, tweak phase and delay. Then apply EQ. You can do things like I did with filters and EQ on specific outputs, but it's not necessary.


The very long version of what I did:
Baseline
First, I disabled all EQ on the miniDSP to start with a clean slate. I ran sweeps in REW with everything on and no correction/EQ for a true baseline. I then ran Audyssey on my receiver, and used the app to stop Audyssey EQ on the subwoofers.

Correct for dips with Phase and Delay
I then ran sweeps with only one sub enabled at a time. In MiniDSP I adjusted phase (inverted or not), and adjusted the delay 1ms at a time, until I found the best response for each sub. You can then run them all enabled when you're done to confirm the response looks much better than your baseline. Note: I used this to get the most flat response, not the biggest peaks at random frequencies.
This made an enormous difference, getting me close to a relatively flat response without any EQ. I can't stress enough that this made a far bigger difference than EQ. In fact, results after this step had been drastically better than just using Audyssey or just using EQ in MiniDSP (I know, because I tried that first and wasn't happy).

Protect my little guys
Next I put a high pass filter on the 12" subs with a steep roll off under 20Hz. The 18" sub can handle all of that.

Reduce the Peaks
Because the 18" sub had a significant bump in mid-bass, I used REW's EQ generation tool to flatten it. Note that I did this before global EQ across all subs because it was the one major problem and it was isolated to one subwoofer. So I took sweeps of only that sub again, used REW to generate a filter file, and applied it to this sub's output. This is an EQ on that specific sub only, not the input signal to the MiniDSP.

From here I followed the typical REW auto-EQ process that I just used on the 18" sub: https://www.minidsp.com/applications/auto-eq-with-rew
I had to play with the Filters and target curve to get what I wanted. I added a couple manual filters because the purely auto EQ still left one significant peak that looked higher than I wanted, but talking true fine tuning at this point.

Hope that helps.

Edit: my results from the above steps (I got it a bit better, smoothing 70-90Hz, with the last round of EQ adjustments but forgot to save the last runs in REW.)

 

[Pandaman617]

I have two 12" subs, and an 18". To get really good response in my room I did the following. I completely agree that getting rid of peaks is easy, so focus on reducing dips first.
This process might not be perfect for you, but my recommendation is to start with position of the subs. Next, tweak phase and delay. Then apply EQ. You can do things like I did with filters and EQ on specific outputs, but it's not necessary.


The very long version of what I did:
Baseline
First, I disabled all EQ on the miniDSP to start with a clean slate. I ran sweeps in REW with everything on and no correction/EQ for a true baseline. I then ran Audyssey on my receiver, and used the app to stop Audyssey EQ on the subwoofers.

Correct for dips with Phase and Delay
I then ran sweeps with only one sub enabled at a time. In MiniDSP I adjusted phase (inverted or not), and adjusted the delay 1ms at a time, until I found the best response for each sub. You can then run them all enabled when you're done to confirm the response looks much better than your baseline. Note: I used this to get the most flat response, not the biggest peaks at random frequencies.
This made an enormous difference, getting me close to a relatively flat response without any EQ. I can't stress enough that this made a far bigger difference than EQ. In fact, results after this step had been drastically better than just using Audyssey or just using EQ in MiniDSP (I know, because I tried that first and wasn't happy).

Protect my little guys
Next I put a high pass filter on the 12" subs with a steep roll off under 20Hz. The 18" sub can handle all of that.

Reduce the Peaks
Because the 18" sub had a significant bump in mid-bass, I used REW's EQ generation tool to flatten it. Note that I did this before global EQ across all subs because it was the one major problem and it was isolated to one subwoofer. So I took sweeps of only that sub again, used REW to generate a filter file, and applied it to this sub's output. This is an EQ on that specific sub only, not the input signal to the MiniDSP.

From here I followed the typical REW auto-EQ process that I just used on the 18" sub: https://www.minidsp.com/applications/auto-eq-with-rew
I had to play with the Filters and target curve to get what I wanted. I added a couple manual filters because the purely auto EQ still left one significant peak that looked higher than I wanted, but talking true fine tuning at this point.

Hope that helps.

Edit: my results from the above steps (I got it a bit better, smoothing 70-90Hz, with the last round of EQ adjustments but forgot to save the last runs in REW.)

Thanks so much all of you! I’m actually going to start over today and see if following these instructions nets me better performance.

 

[Pandaman617]

After a bit of tweaking I’m making progress here! My mains and surrounds are crossed over at 80hz with front and rear top speakers at 100hz. I’ve been using this pair of Def Tech BP2004 TL’s I got for cheap as I’ve always wondered about them but they’ve ended up crossed over at 80hz as well and I can’t even imagine how they can claim these towers go to 18HZ. This measurement is from 8 different points 18” from my MLP in somewhat of a circular formation using a single Mirage BPS-400 & Atlantic Technology BPM372.

 

[Pogre]

That's looking pretty good! Tho I'd adjust the vertical scale for 5 dB increments instead of 10. It's not as pretty but larger scales can hide things.

 

[Pandaman617]

That's looking pretty good! Tho I'd adjust the vertical scale for 5 dB increments instead of 10. It's not as pretty but larger scales can hide things.

Thanks a lot! I just did that and I have some more work to do

 

[Pogre]

Thanks a lot! I just did that and I have some more work to do

You know, I have that same notch right around 80 hz. I don't think it's even audibly perceptible but drives me nuts. It's easy to get carried away striving for perfection, lol.

 

[Pandaman617]

You know, I have that same notch right around 80 hz. I don't think it's even audibly perceptible but drives me nuts. It's easy to get carried away striving for perfection, lol.

Hahahh! I’m with you there! I was so excited when I got to this point and watched a few bass heavy UHD Blu-Ray scenes I showed a few of my non audio friends and the general consensus was “So…you made this line straighter? Is that what you’ve been doing for the last week?”

 

[Pogre]

Hahahh! I’m with you there! I was so excited when I got to this point and watched a few bass heavy UHD Blu-Ray scenes I showed a few of my non audio friends and the general consensus was “So…you made this line straighter? Is that what you’ve been doing for the last week?”

Ha ha! Oh yeah. I'm feeling you man. My wife has only recently started appreciating the stuff I do for good sound and we've been married for over 20 years! She still thinks I'm nuts when I bust out the mic and and boom stand.

 

[Pandaman617]

Ha ha! Oh yeah. I'm feeling you man. My wife has only recently started appreciating the stuff I do for good sound and we've been married for over 20 years! She still thinks I'm nuts when I bust out the mic and and boom stand.

That’s a great wife though!! Every girl I’ve dated ever has more or less just said “Are you spending more money on things that make noise again?”

 

[Endaar]

That’s a great wife though!! Every girl I’ve dated ever has more or less just said “Are you spending more money on things that make noise again?”

What...like jewelry?


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[Mr._Clark]

That’s a great wife though!! Every girl I’ve dated ever has more or less just said “Are you spending more money on things that make noise again?”

What...like jewelry?

My relationship with my spousal unit (AKA "wife") is transactional in nature. If I want to drop $ on audio equipment, she complains unless we spend an equal amount of money on something she wants (AKA "useless crap for her")(hereinafter "UCFH").

This is good because I can ultimately get most things I want, but it's bad because everything costs twice as much.

Also, be forewarned, once you offer to buy your spousal unit UCFH of equal value after she complains, the spousal unit will learn quickly to complain loudly about every audio purchase in order to get a reward (see UCFH, supra). Also, the old "But honey, it's not for me, it's for us" ploy doesn't work for very long because the spousal unit will figure out quickly that she can get the both the "for us" item and the UCFH by complaining. Once you take this path there is no turning back.

The above is tongue in cheek, but I'd have to admit there's a fairly large grain of truth to it.

 

[Pogre]

My relationship with my spousal unit (AKA "wife") is transactional in nature. If I want to drop $ on audio equipment, she complains unless we spend an equal amount of money on something she wants (AKA "useless crap for her")(hereinafter "UCFH").

This is good because I can ultimately get most things I want, but it's bad because everything costs twice as much.

Also, be forewarned, once you offer to buy your spousal unit UCFH of equal value after she complains, the spousal unit will learn quickly to complain loudly about every audio purchase in order to get a reward (see UCFH, supra). Also, the old "But honey, it's not for me, it's for us" ploy doesn't work for very long because the spousal unit will figure out quickly that she can get the both the "for us" item and the UCFH by complaining. Once you take this path there is no turning back.

The above is tongue in cheek, but I'd have to admit there's a fairly large grain of truth to it.

Indeed. My wife got a new tablet when I bought towers to go with the bookshelf speakers I found. She got a new phone when I got the bookshelf speakers...