[Early B.]

For years, many of us have been confounded by the various subwoofer plate amp settings. Lots of folks have been asking for instructions on how best to dial in their subs.

Let's use this thread to help one another get guidance, insight, and input on determining the optimal settings for the subwoofer plate amps commonly used for GR Research subs, with and without use of room measurement devices.

Here's a link and the instructions that come with the A370 Rythmik Audio amps:   

https://www.rythmikaudio.com/amplifiers.html



There's some good info on page 33-34 regarding the phase setting in this thread: https://www.audiocircle.com/index.php?topic=141060.msg1748693#new

OK, guys -- please chime in. Tell us what you're learned about the various settings and how to apply them. Let's talk about the low pass setting, rumble filter, bass extension filter, delay phase, crossover level, etc., and how the one setting change affects the others.

[AKLegal]

Some random tips:

For those of us with asymmetric rooms, you will probably need asymmetric settings on each sub amp.  The crossover point and volume on my left speaker are lower than my right but they measure almost exactly the same. The left side of the room has a wall with a normal door sized opening.  The right side is one large opening.     

If you can use REW, use it to confirm what you are hearing.  If you use REW go very slow, one or two clicks on the crossover and volume will result in big changes if you are getting close to a room mode.  I will quite literally take a measurement for each click on the crossover potentiometer watching the frequency response move up and down in order to find the point where it all goes haywire.   

In setups where I have had stereo H-frames that are under the mains, adjusting phase has been a bad idea.  I get wild swings in frequency response from minor adjustments and inexplicable nulls and peaks. It might sound great with one song and awful with a bunch of others. This has confused me a little because the voice coils on the subs are much further back than the voice coils on the NX-Ottica MTMs, the Super 7, and even the Super V.  So it seems like a fractional adjustment should work but it doesn't. I guess bass wavelengths are too long to make any real difference here.  I tend to leave phase on zero. 

I know some folks have had success with phase adjustments but an "expert" explanation might be in order. 

[mlundy57]

Some random tips:

For those of us with asymmetric rooms, you will probably need asymmetric settings on each sub amp.  The crossover point and volume on my left speaker are lower than my right but they measure almost exactly the same. The left side of the room has a wall with a normal door sized opening.  The right side is one large opening.     

If you can use REW, use it to confirm what you are hearing.  If you use REW go very slow, one or two clicks on the crossover and volume will result in big changes if you are getting close to a room mode.  I will quite literally take a measurement for each click on the crossover potentiometer watching the frequency response move up and down in order to find the point where it all goes haywire.   

In setups where I have had stereo H-frames that are under the mains, adjusting phase has been a bad idea.  I get wild swings in frequency response from minor adjustments and inexplicable nulls and peaks. It might sound great with one song and awful with a bunch of others. This has confused me a little because the voice coils on the subs are much further back than the voice coils on the NX-Ottica MTMs, the Super 7, and even the Super V.  So it seems like a fractional adjustment should work but it doesn't. I guess bass wavelengths are too long to make any real difference here.  I tend to leave phase on zero. 

I know some folks have had success with phase adjustments but an "expert" explanation might be in order.

That may have something to do with your room. I find with the phase set to 0 with my 'Otica MTMs/dual subs there is a suckout at the crossover point. Adjusting the phase control corrects this. My room is fairly symmetrical but there is a door on one of the side walls even with the listening position. The result is slight differences on most of the dial controls between the two subs.

Here's another thread that is helpful.

https://www.audiocircle.com/index.php?topic=159295.20

Discussion of phase adjustment starts with Reply #25

[Early B.]

Yeah, I'd like to learn more about setting the phase. I get the cleanest and most detailed level of bass when the phase is set to 0. Yesterday, I was at my friend's house who has a pair of triple 8's and when I dialed down his phase from the 8am position to 0, it sounded much cleaner. The phase probably depends on the other settings, as well. I wonder if there's a hierarchy of settings. Hmmm....

 

[mlundy57]

Yeah, I'd like to learn more about setting the phase. I get the cleanest and most detailed level of bass when the phase is set to 0. Yesterday, I was at my friend's house who has a pair of triple 8's and when I dialed down his phase from the 8am position to 0, it sounded much cleaner. The phase probably depends on the other settings, as well. I wonder if there's a hierarchy of settings. Hmmm....

I've found there to be interaction between the different settings so I have to keep moving back and forth between the settings until I reach a point where things remain stable. It's an iterative process that can be hair pulling at times. It takes patience and repetition. I'm still pretty slow at it. It takes me around four to six hours to get to a point I'm happy with.

Everythig comes with trade-offs. The more flexibility, the more complicated it is to use. The simpler it is to use, the more limited the results.

[e_biz80]

With the NX-Treme’s the woofers are wired out of phase. Does that mean I should start with the phase dial on the subs at 180 degrees?  I get more output at 180 vs 0