Getting sub phase set right with active/balanced speakers

[highstream]

I have a pair of ATC SCM19A active floorstanders that take balanced ICs and a pair of JL Audio e-110 subs I'm setting up. The apparently best method for manually setting the JL's phase dial is to reverse the polarity of the main speakers and then adjust that channel sub's phase dial for the least amount of bass while playing a test tone around the crossover point. With active, balanced main speakers that take an IC, and without a polarity switch on the preamp, that's not as obvious. Any ideas? There is a polarity switch on the sub. Would that accomplish the same thing?

If so, what do I listen for to tell the minimum point? Ear to speaker or from listening position? This is manual operation, no mikes, except for a iPad decibel app, and the subs and mains are adjacent to each other. Thanks,

 

[Ian Eales]

Playing a test tone at the crossover point is most assuredly not the way to proceed.
IMO, unless you have sophisticated tools and the know how, the best way is by ear listening to program.
This is how I did it before I had tools: ieLogical SubterraneanHomesickBlues
Read the whole page for background on sub design, problems and integration.
Also consider rolling the bottom from an octave above the mains' -6dB point [maybe 80-100Hz] with a first order filter and possibly invert the sub polarity. Unfortunatley, the e110 only has fourth order filter.
IGNORE what the knobs say and keeps adjusting in small increments over several program types. When you hit the sweet spot, you'll know!

 

[JStewart]

To Ian’s point, there are more accurate ways, meaning you’ll know it’s correct, to to this, but in the spirit of using the tools you have at hand, here goes...

Before you start you should set distances/delays to what they actually are because the procedure you wish to use will align the phase of mains and sub at the chosen frequency, but will not ensure they are on the same cycle. Setting actual distances/delays beforehand should keep that from happening.

There is a polarity switch on the sub. Would that accomplish the same thing?

It’s supposed to.

If so, what do I listen for to tell the minimum point? Ear to speaker or from listening position? This is manual operation, no mikes, except for a iPad decibel app,

Use the app. Set for “C” weighting.
Use the app at the listening position.

 

[AJ Soundfield]

I have a pair of ATC SCM19A active floorstanders that take balanced ICs and a pair of JL Audio e-110 subs I'm setting up.
no mikes, except for a iPad decibel app, and the subs and mains are adjacent to each other.

Isn't that > $13k retail speakers???
For <$100, you could get a UMIK-1 and https://www.minidsp.com/applications/acoustic-measurements/using-the-umik-1-with-audiotools-on-ipad

 

[VinceHoffman]

Isn't that > $13k retail speakers???
For <$100, you could get a UMIK-1 and https://www.minidsp.com/applications/acoustic-measurements/using-the-umik-1-with-audiotools-on-ipad

LOL! That was pretty much what I was thinking. Btw, I use a JL Audio CR-1 subwoofer crossover to really dial in seamless integration between my closely related ATC SCM20ASL Pro actives and four Seaton Submersive HP subs.

 

[Buttecreeker]

I have a pair of ATC SCM19A active floorstanders that take balanced ICs and a pair of JL Audio e-110 subs I'm setting up. The apparently best method for manually setting the JL's phase dial is to reverse the polarity of the main speakers and then adjust that channel sub's phase dial for the least amount of bass while playing a test tone around the crossover point. With active, balanced main speakers that take an IC, and without a polarity switch on the preamp, that's not as obvious. Any ideas? There is a polarity switch on the sub. Would that accomplish the same thing?

If so, what do I listen for to tell the minimum point? Ear to speaker or from listening position? This is manual operation, no mikes, except for a iPad decibel app, and the subs and mains are adjacent to each other. Thanks,

It sounds like the method you are describing is one described by Soundoctor Barry Ober. In a nutshell he states; add 12 more feet to your subwoofer distance setting than you have for your front Main channels. Then reverse the polarity of the Main speaker that is closest to the sub and disconnect all other speaker channels. Using a test tone playing at the crossover frequency, place your head equidistance between the Main and the closest sub, start adjusting the Phase Knob, Phase Switch, and Level Control Knob on the sub to fine tune your sub to achieve the deepest null or possibly complete disappearance of the tone. Then, do the same procedure for the other Main and its closest sub.

Since you have balanced IC's to your Mains, and you stated you don't have any other processor/speaker switching capabilities, you might want to make a balanced connector "pigtail", that has the polarity reversed. You will only need to build one since you are adjusting one Main to sub at a time.

I've used this method in the past, and it worked very well to adjust for the "Group Delay/Latency" of my OHM Walsh 4.5000 to Velodyne DD-18 sub. However, now I have OHM Walsh F-5015's as my Mains, and they have a down firing 15" active sub integrated into the cabinet of each Main speaker. I tried performing this procedure yesterday by placing my SPL mike mid way up the cabinet to find the lowest SPL between the 15" driver and the CLS driver, and started adjusting my sub delays, in my processor, back down in real time, and the result is that my Left Main speaker+sub are identical to each other in delay distance settings, and the Right Main speaker+sub delay distance setting diference is 2' 2". I need to do serious listening to see how everything sounds comparing these settings, to the settings I've come up with using REW.

 

[highstream]

Thanks for the ideas. For a couple of reasons, including practical given my room, I've located the subs immediately to the inside of the mains. Putting my head between the two is what I did while adjusting. However, since I'm still auditioning a couple of ATC active versions, the final set up awaits.

 

[Mike-48]

Since the subs and mains are the same distance and orientation from your listening position, it will work to put your microphone -- i.e., your head -- in between them when doing this.

I agree with the suggestion by @AJ Soundfield and @VinceHoffman to buy a measuring mic and see what frequency response (FR) you actually are getting. I've had better results that way. That also lets you move the subs around (to the degree that aesthetics allows) and see when the FR is best. In that case, measure response at the main listening position.

"Super Sliders" (teflon glides under your subs' feet) are your friend when repositioning.

An active crossover (analog or digital) can help get the best blend. I've always used one, but its necessity is a matter of opinion, like so many things audiophile.

Have fun!

P.S. I just saw, I'm about 3 weeks late to this thread. If you aren't done (@highstream), I hope this helps. If you are, I hope you're happy with the results.

 

[highstream]

Thanks, Mike. Given the room and space available, as shown in the attached photo, the subs can't really go anywhere but next to the main speakers (there's now also an upper matching bass trap in the back). They actually sound good there with a preliminary set up, pending a decision on which main ATC speakers (19A or 40A) I'm going to keep.

 

[Mike-48]

the attached photo

The asymmetrical and open layout of your setup should decrease strength and number of troublesome bass nodes. I have a sealed, symmetrical room, which is great for imaging, but to get smooth bass, I have to use tons of acoustic treatment and DSP.

 

[highstream]

The catch is the bookcase, closed area and sofa on the left do wonders, but the open area on the left — front entry, stairway and unused wood stove brick area — means a significant dB difference left over right, and sound typically centering a bit to left center (per the recording of course). Doesn’t seem much I can do about it. My preamp has a balance knob, but any gains come with loss of focus, etc.

 

[Mike-48]

A friend uses some kind of acoustic screen to fill the opening in his room when he's listening. He say it helps a lot. His system does sound good to me, but more than that, I can't say.