My system's response

[Bose(o)]

Hello all.

You may have seen my post in the systems&pictures thread or, you may not have seen it. Either way, you'll see it
Some info. System is in my basement which is unfinished, I have a large carpet that "defines" the area. I removed a coffee table for the measurement. I also have concrete walls up to about a metre then it becomes drywall. Digital Radioshack SPL metre. I used a CD with MP3-sine waves creation program...really neat and the demo allows for a 3 second long file. Not bad. Now onto the neat stuff: Sub-woofer is a 12" Shiva in a 53L enclosure with a SUB-100 plate-amp from Solen. I have two open-baffle enclosures (If you can call 'em that), using a 6.5" P17RCP-08 and a Seas 19TNF08 tweeter. For the OBs, they have a cap that reduces sound from 90Hz. and below, thus reducing excursion and decreasing non-linear distortion. Anyway, here's the graph and your comments are welcome. I'm still waiting to take a picture of the system. Also, if you want me to measure something else...like @1m. etc, I can...

[tiroth]

Are you getting cancellation from the sub? Because that huge 20dB suckout is occurring right at crossover.

You could take measurements of just the mains and just the sub and see if that s illustrative.

[Bose(o)]

I have a graph of the Shiva @ the cone. I'll measure just the sub@ listeing pos. and the panels after posting this.

[Bose(o)]

Alright, I've got some measurements: All at the listening position. I didn't go all the way up as I didn't think it was important for the suck-out problem.

[Bose(o)]

And...

[Bose(o)]

Also...changed the x-over to 160Hz.

[GRollins]

As I've noted elsewhere, that's pretty much typical response for a Shiva. You will not get deep bass out of Shivas/Titanics/et. al. without eq. or other tail-twisting.
At least in the case of the Titanics, a 6dB/oct lowpass at about 20Hz or so will give you pretty flat response up to about 100-150Hz, at which point the response begins to roll off at something approximating a 12dB/oct slope. Looks in this case that the Shivas will begin to tip downwards at about 50Hz, plus or minus a bit if you go that route. Your choice. You can live with the response or try to coax it into doing flat response.
As for the dip ca. 100Hz or so, you can try taking the cap off the mids and see what happens. Another thing to try is to reverse the phase of the subs or mids--you might have a phase cancellation problem at the crossover point.
You can also try moving the speakers back and forth in the room. If it's a room cancellation problem, the dip will change with the position of the speakers, both in severity and frequency.

Grey

[Bose(o)]

Thank you for the info: I shall try using the 180 phase switch and your other recommendations. Also, there is an EQ +6dB. @ 35Hz. on the amp...that would explain the bump. I will also be adding TL enclosures which will run from 150Hz. and down so, this may fill the gap as I definintly want to keep the caps as the Seas like to hit their maximum excursion fairly quick on bass passages.

Thank you Grollins..and Tiroth.