How To- Perfect Subwoofer Integration

Similarly to the OP, I have been able to properly integrate two subs using a measurement mic & rising frequency sweep at the listening position, in my case as part of a DEQX managed system.

However frequency, volume and phase are not the only factors - time alignment has an equally significant impact. Often the sub (s) will be further away in the room from the listening position and combined with longer ('slower') wavelengths, frequencies from the main speakers will arrive earlier without time alignment correction.

I choose a crossover frequency and slope (up to 72dB is possible), align phase between two subs/main speakers in a very similar fashion to that described above and then manually time align by viewing the outputs of step response measurements and 'delaying' the arrival of sound from both the nearest sub & the main speakers to align with the furthest away & 'slowest' sub.

As also mentioned in a previous post, treating room nodes is equally important and should also be addressed. When this is done and main speakers & subs are perfectly phase & time aligned in this way, the results can be quite breathtaking.

 

as long as you're happy and don't have the urge to go and crank on knobs every other song- that's all that matters!

 

good post. essentially the 0-180 continuous phase adjustment IS time alignment.

 

It is very possible. The response plot has no peaks. Peaks are killers when ou try to integrate subs- basically the system becomes a one note wonder at the response peak- when music contains that note- all you think is to turn down the sub level. unfortunately it lowers the entire output of the sub and it becomes useless.
get the response flat and it relays exactly what is in the music.

 

nice post. i may try to adjust the position of my main speakers to even out the response between 100Hz and 250Hz.
Even more benefits of RTA- measuring and adjusting the response just by moving the speakers!

 

EQ is a band-aid that will not lead to optimum results if you do not have proper crossover and phase relationship with the main speakers.
You should have seen some of the massive peaks and valleys in the response curve before I dialed things in. Trying to EQ those peaks and valleys would have destroyed the sound and put much more strain on the amplifier and affect the dynamic range as well as sound quality. A little EQ after you have the best possible phase / crossover is fine though.

 

Properly setup you do not need two subs. Frequencies below 100Hz are non directional.

 

Multiple subs do tend to smooth out room resonant responses though, so you can more easily get a better balanced sound across frequencies, and when moving away at all from the "sweet spot" listening position.

 

I have the 1/6 octave display. Not optimal but works well for me. High Q peaks and valleys are best left alone IME.

 

I will respectfully disagree; I have never heard a two-sub system that didn't sound remarkably better than a single-sub setup. I suspect it has more to do with the room response / resonances than the subs themselves... in the end I will go with my ears over theory or measurements.

 

It's not a matter of theory vs. ears. Ever seen those waterfall plots in the audio magazines like Stereophile? Room resonance and frequency response can be measured and you can see the results in graphic detail as well as hear.

 

Further proving my point.

I do have Room EQ Wizard, I keep meaning to pick up one of the mics they recommend to use with it. (I have plenty of studio mics, but I suspect they are not as appropriate for these measurements.) I'd like to see what my room actually is and is not, even if I make no changes.

 

Thank you -- that's very helpful. I'll explore from there.

 

Really ? I thought the ¨mark¨for that was 80 hz, and always felt kinda guilty for having my crossover a little over that mark (I'm guessing 100hz ?) The dial is marked 50 hz where it starts, 80 at its mid-position, and 150 at the end. When I listen bass to the right I'm always afraid it's directional but then I turn the sub off and voilá; bass guitar or kickdrum was recorded louder in that channel.

 

Buy an REL. Problem solved.

 

You may find the OCD fiddling solved after you know that is set up correctly, meaning much less fiddling.

 

I disagree. At 1/6 smoothing you are potentially hiding possible one note bass issues by averaging an octave, seven notes, into sixths.

 

Any sub needs to be measured to integrate correctly. The name plate does not change the physics of the room modes.

 

Also , frequency response is not as important as low end ringing under 300hz. That's why a waterfall is best here. It gives you the frequency response AND the decay of the low end.

And honestly,no pro.s would ever use 1/6 resolution when dialing in a room or integrating a sub,it's simply too rough. You should have no smoothing,or 1/24 at worst. You (the OP) say best leave peaks and valleys alone,that makes no sense. That's exactly what your trying to fix.

 

Agreed, the ringing is more important than the frequency response but wouldn't lots of ringing translate into more uneven frequency response?

 

or just get a better set of speakers so you don't have to go thru all this madness....

 

High Q (narrow peaks) are to be avoided as per a JBL / Harmann white paper and they cited 1/6 octave resolution as the way to measure.

 

I considered the REL T7i and they do have the ability to integrate well because of the adjustment capability as described in the procedure. However the controls are not factory pre-set to work with my room or speakers and some adjustment would be needed.
In the end I went with the JL audio dominion 110 because i heard it at my dealer and it was impressive in output, note definition and integration. Plus the fact that the JL has output nearly flat to 20Hz for my prog rock recordings! The T7i is 6db down at 30Hz in room response. The JL sounds awesome!
http://www.jlaudio.com/d110-gloss-home-audio-dominion-powered-subwoofers-96284

 

It's not the speakers, it's the room that usually causes the problem - so either treat the room nodes or get a better house!

Yes, this is what the DEQX people say too & because you can adjust eq in real time whilst listening to music, I can confirm that creating the reverse of a High Q peak basically has an unnoticeable effect.