# REW with miniDSP 2x4 and UMIK-1



## thyname (Oct 25, 2017)

Hi there,

Brand new to this. 

I have a miniDSP 2x4 (not the HD version), and a UMIK-1 mic coming in the mail. 

Already downloaded REW for windows.

This is going to EQ my two subs only, on a 2.2 channel setup, 100% music only.

Preamp is Halo P5, and dual PSA s1500 subs

I tried to read everything, but can someone please help me cut to the chase and just do the EQ for the two subs?

Thank you!


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## Wayne A. Pflughaupt (Apr 13, 2006)

Measure one sub from the listening position with the main speakers turned off, in each potential placement location, to determine which has the best frequency response – i.e., the least severe peaks and troughs. Often this will be in a corner with uninterrupted wall lengths in both directions. Dual subs will perform best if co-located at that position in the room.

Next measure from the listening position with both subs playing, again with the main speakers turned off.

Use the equalizer to bring down the worst peaks and raise (within reason) the worst troughs (not to be confused with nulls, which are deep and narrow and can’t be equalized away). Generally, the sum of boosted and cut filters should be no more than about 8 dB, although with subs that are way overkill for the room you can get away with more severe cuts and peaks. The idea is to smooth out the worst anomalies, not remove every little ripple in response. Refer to my “Minimal EQ” article for more detail.

That’s the best I can offer without seeing a graph.

Regards, 
Wayne


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## thyname (Oct 25, 2017)

Wayne A. Pflughaupt said:


> Measure one sub from the listening position with the main speakers turned off, in each potential placement location, to determine which has the best frequency response – i.e., the least severe peaks and troughs. Often this will be in a corner with uninterrupted wall lengths in both directions. Dual subs will perform best if co-located at that position in the room.
> 
> Next measure from the listening position with both subs playing, again with the main speakers turned off.
> 
> ...


Wayne:

Thank you very much! Very informative.

The UMIK-1 and the miniDSP arrived yesterday.

I realized I needed a third USB cable to connect my PC to my preamp. The other two would be used to connect the PC to Mic, and to the miniDSP. Will grab one later today.


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## thyname (Oct 25, 2017)

Wayne A. Pflughaupt said:


> Measure one sub from the listening position with the main speakers turned off, in each potential placement location, to determine which has the best frequency response – i.e., the least severe peaks and troughs. Often this will be in a corner with uninterrupted wall lengths in both directions. Dual subs will perform best if co-located at that position in the room.
> 
> Next measure from the listening position with both subs playing, again with the main speakers turned off.
> 
> ...


Wayne:

A couple of questions if you don't mind, as this is very confusing:

1 - Since I am not EQ-ing the mains, I don't set the high pass filter / crossover on the miniDSP for the speakers, right? As a matter of fact, the speakers are NOT going to be connected to miniDSP at all.

2 - Since my preamp can do active crossover on board (Parasound Halo P5), I still plan to high pass my speakers at about 70-80 Hz with the P5 (my speakers are Sonus Faber Olympica I)

3 - Are you suggesting that I put the two subwoofers on the same location (side-by-side)?

Thanks!


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## Wayne A. Pflughaupt (Apr 13, 2006)

I assumed the speakers weren’t connected to the miniDSP - you said you wanted to EQ just the subs, right? The typical signal chain is: Receiver sub output -> equalizer (miniDSP in this case) -> subwoofer. Typically the receiver does the crossover filtering, not the miniDSP.

You’ll get the best performance (fewer peaks and troughs and higher SPL output) with the subs either side by side, or stacked. However, separate placement can work in some rooms, if you’re willing to live with less output. Just be sure and take a measurement at the second location to make sure frequency response is not abysmal. Once you’ve decided on your two locations, take measurements with both subs playing, and equalize with a single set of filters. Do not try to equalize each one separately, that never works.

Regards, 
Wayne


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## thyname (Oct 25, 2017)

Wayne A. Pflughaupt said:


> I assumed the speakers weren’t connected to the miniDSP - you said you wanted to EQ just the subs, right? The typical signal chain is: Receiver sub output -> equalizer (miniDSP in this case) -> subwoofer. Typically the receiver does the crossover filtering, not the miniDSP.
> 
> You’ll get the best performance (fewer peaks and troughs and higher SPL output) with the subs either side by side, or stacked. However, separate placement can work in some rooms, if you’re willing to live with less output. Just be sure and take a measurement at the second location to make sure frequency response is not abysmal. Once you’ve decided on your two locations, take measurements with both subs playing, and equalize with a single set of filters. Do not try to equalize each one separately, that never works.
> 
> ...


Nothing connected to DSP yet. When I do, just the subs will be connected, as I will only EQ and crossover the subs.

Do you recommend I use the Auto EQ on REW?

This is a two channel setup (2.2 rather) with Parasound Halo P5 as a preamp (two channel preamp)

This is the first time I hear the subs need to be next to each other or stacked. Everything I have read recommended placing in various locations. For example:

https://www.svsound.com/blogs/svs/75040195-why-go-dual

Thoughts?


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## Wayne A. Pflughaupt (Apr 13, 2006)

Sure, you can use REW’s Auto EQ. Just keep in mind it may go a bit overboard with filter recommendations. Filters with small amounts of boost or cut (say, 3 dB or less) or more narrow than about 1/4 octave (5.8Q) aren’t readily audible so there’s no point in using them. It’s generally accepted that using multiple filters to chase every little ripple in response ultimately doesn’t sound as good as just eliminating the worse peaks and troughs with a few filters.

Keep in mind that SVS wants to sell subwoofers. For instance, the recommendation for mid-wall placement – the one time I tried that, measurements showed response was so abysmal it was beyond the help of equalization.

Basically, two subs co-located in the same corner will get 6 dB greater output than the one. Best case scenario when separating the two subs is a 3 dB increase in output.

However, separating can offer other benefits, such as more even frequency response in a greater number of seats.

Here are a couple of good articles in the subject.

http://www.audioholics.com/subwoofer-setup/multiple-subwoofer-setup-calibration-1
http://www.acousticfrontiers.com/2013109multiple-subwoofer-case-study-af-demo-room/

This is mainly a room matter. For instance, when I’ve lived in places with high cathedral ceilings and open floor plans (i.e. highly irregular room boundaries), I’ve had acceptably linear frequency response in all seating located away from boundaries, with only a single subwoofer located in the optimal corner.

Contrast that to a common rectangular, shoe-box home theater room, where there bass is strongest at the room boundaries and diminishes as you move away from the wall, culminating in a sort of “bass hole” in the dead center of the room where the lows are audible reduced compared to near the walls. Every seat in a room like that is going to get different levels of bass. Multiple subwoofers reportedly can help that situation and room. 

While the articles linked above are good reads, keep in mind that they are only relevant to you if you have a similar room. 

Regards, 
Wayne


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