Bass crawl using two subs

[Ryan Laposky]

Hi all,

Have read about using the bass crawl method using one sub, but how can you do this with two? After you find the sweet spot with one sub, how do you find the second sweet spot? Do you place your first sub in the sweet spot, then do the crawl again with the second sub at the main listening seat? Hope this makes sense. Thanks!

Ryan

 

[WaynePflughaupt]

The sub crawl is outmoded 20th century technique that’s crude and inaccurate at best. Everyone these days takes scientific room measurements with a program like Room EQ Wizard.

Regards,
Wayne A. Pflughaupt

 

[Ryan Laposky]

Ok, but how would I go about this without the software? The bass crawl method is on the audioholics website so it must work... thanks!

 

[WaynePflughaupt]

With two subs you’ll spend literally days doing what could be accomplished in a couple of hours with measurements, but get a track like Basia’s “Ordinary People” that features a bass line that spans two octaves. The goal would be for all bass notes to sound like they’re at the same volume – i.e. no “hot” notes, no “dead” notes. I'd say "good luck" but I'm not holding out much hope for success...

Regards,
Wayne A. Pflughaupt

 

[Ryan Laposky]

I'm willing to try software. Is it fairly easy to use (Room EQ Wizard)? What mic do you purchase? Also, does the software hookup to a laptop and somehow to your receiver? Or do you just run test tones from your receiver and adjust based on the readings on the laptop? Thanks for your help

Ryan

 

[WaynePflughaupt]

Assuming you already have a laptop, the REW software is a free download at Home Theater Shack. The only expense is a calibrated USB mic such as the miniDSP UMIK-1 or Dayton UMM-6, which you can get from Cross Spectrum Labs for $100.

If that makes you balk, consider past alternatives. I paid $500 back in 1996 for a hardware-based AudioControl real time analyzer - what would that be, $12-1500 today? - and it won’t do half of what REW will.

There will be a learning curve for someone with no experience with room measurements, but basically you connect an audio output from your computer (3.5 headphone jack or HDMI) to an input on your receiver. The program (through the computer) will generate test tones that your speakers (or sub in your case) will audibly play. The audio signal will be picked up by the mic, and you’ll get a display on your computer screen showing the frequency response. HT Shack has a helpful forum dedicated to helping REW users, if you run into problems.

After using measurements to determine the best locations for your two subs, you’ll probably need an equalizer to completely take out the peaks and troughs in response.

Regards,
Wayne A. Pflughaupt

 

[fuzz092888]

I'm willing to try software. Is it fairly easy to use (Room EQ Wizard)? What mic do you purchase? Also, does the software hookup to a laptop and somehow to your receiver? Or do you just run test tones from your receiver and adjust based on the readings on the laptop? Thanks for your help

Ryan

What Wayne was explaining to you is that the subwoofer crawl helps identify the best location for a single subwoofer. However, with two subs the peaks and valleys of the FR response shouldn't be in the same place. The second sub should have have peaks where the other sub has valleys to create a situation where, like Wayne said, all frequencies should sound equally loud. Trying to do this by ear could be a complete nightmare. Using REW, and even using REW before you get a mic, can really save time carrying or sliding the subs around. If you measure out your room, REW has a room simulation option where you can get a rough idea where the best place for the two subs would be before ever placing them. Then you can use the mic when you get to to confirm the accuracy of the results and make adjustments as needed.

 

[herbu]

Do you place your first sub in the sweet spot, then do the crawl again with the second sub at the main listening seat?

Ryan,
Don't over-think this. You can spend hours and $$$ to find the perfect sub positions.
or
You can use a more pedestrian approach, (like I did).

First, I only have 4 or 5 places a sub will fit with our furniture in our room. I tried one sub in each of the places and finally picked the one that seemed to best suit both aesthetics and sound. It was the front right corner. There was a clear peak at my lazboy and a clear null at my wife's. But I like bass and she doesn't care, so it was OK.

Then I got a second sub. I tried it in the remaining places, starting at the rear of the room because my first sub was in the front. Luckily, the first place I tried was the winner. Both the peak and the null went away, (to my ears), after balancing the volume w/ Audyssey. Surprisingly, even the wife said it sounded better.

Now it's possible there are other peaks & nulls in the room somewhere, but I don't care. There aren't any at our listening positions. If I had 6 or 8 seating positions and wanted to be sure each was optimum, I'd do the REW thing. But I don't, and Audyssey worked great for our 2 seats.