Calibration is frustrating

I have stacked the subwoofers again, and in a different position.

And I've taken som new measurements, with correct axis:

Rlp15"

Rlp18"

Both:


If I've done things right now, it finally seems like I got some lowend..! (On each subwoofer that is. not together!)

Only problem now, is how to get rid off that decrease below 26hz, when they are both on. Is phase the answer here? Just play around with phase on one of them, until I find some sweet spot?

Integrating the 2 subwoofers is really hard.

I manage to get some lowend by setting one of the subwoofers to "inverse". But then I get a bad decrease in SPL from 30-45hz... Adjusting the phase gives minor changes only.

So im going over to plan B... placement!



If you look at the ports, - is there any "theory" of what is optimal for different tuned subs? Im not sure if I should go for A or B.

Each subwoofer weights like 100kg each, so I want to stack them correctly.

Any inputs on how to place them?

Yeah, your thread title about says it all. We continually warn people off trying to mix two different subs, whether it be two different commercial models or simply two subs of a different tune. It's quite difficult to get a smooth and extended response.

Sure, some people get lucky and they use their sample of one to poopoo all the naysayers and recount how simple it is, but it's a **** shoot and you have to work at it.

It's easy enough to see that if one sub extended flat down to 15Hz, and the second sub was down 20dB at 15Hz, what happens when you combine them. We like to say it dumbs down the better sub to the challenged subs poor response. It's simple math.

Certainly you'll have to do your work with the listening position in mind and do all your measuring and tweaking with the goal of getting the listening position flat. I think your planB of placement is the only way to go with mis-matched subs. Use them against each other in finding the best spots. To make it easier, I would move one sub to my listening position and move the mic around to find a good spot for it (using RTA is best since it's dynamic, then when you find the spot, take a response measure). Then do the same with the next sub and place both responses on the Measured tab to compare. It's easy math to see what the resultant sound will be.

brucek

I have been stubborn thinking it wouldn't be such a big deal to integrate two subs (with different tunings). I was wrong!

I have stressed a lot today, with different positions. I can get a good flat freq. response on each sub, but NOT both subs together. I actually don't think it is possible for me to achieve a flat response when they are stacked. I can't place the subs wherever I want them either, since they are HUGE. So im very limited on where to place them.

I guess I have 3 options:

1) Play some more with the subs stacked, and see if I can get some "compromised" freq. response
2) Place each subwoofer in it's opposite corner. But this means that the RLp18" will be placed nearfield- and last time I had it placed nearfield I had problems setting the delay correctly, not to mention the bass was very easy to localise. BUT I didn't use REW then - so I think I would be able to integrate it better this time!
3) Sell one of the subs.. so that I can build one more sub, and have 2 identical subs

I'll report back when I manage to get something decent out of this!

Thanks for your advice and help Bruce! Much appreciated.

Edit: I actually manage to get it somewhat flat (by using the EQ on the DCX2496.. But when I then play music, it just doesn't sound good to me. It may be because I've gotten used to "car bass" where the area from 30-50hz has been boosted. Or maybe I have just measured things wrong somehow. I also get very flat response like 1m away from the listening position,.. problem is though, that's not where I sit .. hehe