Non identical subs

[Asere]

Guys I'm a little confused. I just bought the PSA S3000i sub to go along with my duo dxd 12012 subs. I have subeq ht on my avr. I ran Audyssey using the dxds as one sub stacked with a Y splitter on sub output 1 and the s3000i on output 2 of course. When done I got a trim in the DXDs of -9 and the s3000i -4.
When I played some content the s3000i seemed to be low so I went up on the gain and now it sounds like it blended in well with the DXDs.
What I did notice with the s3000i when I changed the phase from 0 to the highest setting it sounds better and digs even lower then on 0.
Can you have one sub at 0 phase and the other at the highest setting?
The DXDs sound about the same on either phase setting but the s3000i is night and day with phase change.
I am new to this and maybe I'm over thinking but need to make sure that's ok.

 

[Matthew J Poes]

Guys I'm a little confused. I just bought the PSA S3000i sub to go along with my duo dxd 12012 subs. I have subeq ht on my avr. I ran Audyssey using the dxds as one sub stacked with a Y splitter on sub output 1 and the s3000i on output 2 of course. When done I got a trim in the DXDs of -9 and the s3000i -4.
When I played some content the s3000i seemed to be low so I went up on the gain and now it sounds like it blended in well with the DXDs.
What I did notice with the s3000i when I changed the phase from 0 to the highest setting it sounds better and digs even lower then on 0.
Can you have one sub at 0 phase and the other at the highest setting?
The DXDs sound about the same on either phase setting but the s3000i is night and day with phase change.
I am new to this and maybe I'm over thinking but need to make sure that's ok.

Hi Asere,

Tuning phase by ear is very difficult. To answer your question, yes it is possible that you might have one sub at 180 degrees out of phase with another and get better performance. This is because acousticaly the waves may in fact align better, be more in phase. At such low frequencies absolute phase tends to be more important than incremental differences in phase as LF's are largely steady state (what hits your ears has already bounced off numerous walls before hitting your ears).

My strongest suggestion is to get a measurement microphone and download REW. Real measurements will show you what is going on and why one sounds better than the other. While Audyssey should be able to address relative phase with dual subs, many of us have found that manual measurements and adjustment are critical. It's also important to remember that Audyssey can't correct for placement problems such as SBIR.

See my article for some real measurements and examples of placement and orientation problems. None of that could be addressed by EQ, no matter how sophisticated.

https://www.avnirvana.com/threads/sbir-matters-for-subs-too.2269/

 

[Asere]

I'll have to measure but time is against me as I'm busy most days. Was hard for me to use Audyssey as is.
When I use Audyssey it will set the phase for both subs regardless if they are identical or not yes?
Also is there such thing as having one sub at 0 and the other set different if it sounds better doing so after Audyssey?
Lastly I notice when I turn off my kks the PSA seems to work better yet combined with the KKs it seems like less output. Is this normal what I'm hearing?

 

[Asere]

What is better GAIN match or LEVEL match non identical subs? There is a lot of debate on this from what I've read?

 

[Wayne A. Pflughaupt]

Well, the SPL levels need to match. That might require different gain settings on the individual subs.

Regards,
Wayne

 

[Matthew J Poes]

What is better GAIN match or LEVEL match non identical subs? There is a lot of debate on this from what I've read?

Yeah I'm not sure what the debate is. The typically way to setup multiple subs is to first set one sub so that it is about 2-3 dbs below where you want your final sub level. Then slowly bring up the second sub (while the first still plays) until you are where you want to be.

The notion of gain matching subs really makes no sense. Not sure who is debating that but I don't think they have read the numerous papers on multiple subs nor understand how LF's work. Especially with similar subs.

With similar subs placed symetricly. I could see gain matching identical subs as a means to assure maximum contribution of bass to the room, but that would only make sense for the subs placed in the front of the room. The closer the subs are to you or behind you the quieter you want them so as to avoid localizability.

 

[Asere]

Gain from I've read is not a volume knob. Yet when you raise it the gain volume goes up. I can see when you go up and down the trim you either raise or lower the volume that way but...Doesn't gain do the same thing?

 

[Matthew J Poes]

Gain from I've read is not a volume knob. Yet when you raise it the gain volume goes up. I can see when you go up and down the trim you either raise or lower the volume that way but...Doesn't gain do the same thing?

Gain and volume are not the same thing, but on a subwoofer like this, they will work the same way. Raise the gain and the volume will go up. It is not important to separate these ideas for this discussion. Ideally you would set the gain such that the preamplifier's output is able to drive the subwoofer to full volume without clipping the amplifier input at all. That isn't something you can do by ear and without knowing the specs (nor having measurement capabilities) is not something you could calculate either. Instead it is better to just use the gain like a volume knob and not worry about the rest.