# Adding another SVS for headroom...?



## Vader (Jul 8, 2006)

Hi all,

I am thinking about adding another sub for the additional headroom, and I am considering adding a PB12+ (especially since they are clearing out the piano black finishes!). I am currently running dual 20-30 PC+ cylinders, and my understanding is that the PB12+ is the box equivilent. What problems (if any) could this cause? I never thought I would run dual subs, much less three! My HT is about 3000 ft^3, and the duals are currently flanking the mains. The PB12+ (chosen because of the form factor, and price) would act as an end table (thus, it would be near field) next to the sofa. Thanx!


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## Warpdrv (Mar 3, 2007)

Wowsers bro... that should sound awesome... tuned the same they should incorporated quite well... I would imagine that nearfield you would just level it a bit lower. I assume you have a BFD or SMS. 
Maybe you should buy 2 of them to match the fronts...  Its all about BALANCE right...

I Also jumped on the Piano Black PB12+ Bandwagon... added it to my Plus/2..
My room is more then 2 times yours... I love the sound now... but I was thinking of Changing over to Dual Ultra 13's

Oh my aching wallet...


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## Guest (Jun 14, 2007)

Vader,

I've got the dual 20-39's now and can't imagine needing more headroom...but they're still new to me and I'm running them hotter than I should be. This may be a dumb question but have you tried co-locating for the db bump?


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## Vader (Jul 8, 2006)

Nick,

Yea, I started with them co-located at the side of the room (my only choice), and that resulted in a standing null around 42Hz at the sweet spot. Ed Mullen suggested I try placing them along the front stage, flanking the mains. That wiped the null out completely, and after EQ'ing with a BFD my FR is ruler flat. I also found that the null had thrown my calibration off considerably, so I was running it about 3dB too hot (my AVR trim is set 3dB lower when they are on the front, with the same calibration). In effect, I actually _gained_ 3dB headroom by moving them (less any headroom boost lost due to no longer coupling, of course).:T

After some troubleshooting and email exchanges, Ed and I figured out my problem (actually _Ed_ figured it out), and it had noting to do with "not enough sub". The first generation Toshiba players have a bug in the bass management. Specifically, the player fails to give the raw LFE the industry standard 10dB boost prior to mixing in the redirected bass (when using analog outs). If the AVR is then told to boost the entire mixture to compensate, the raw LFE will be OK, but the _redirected_ stuff will be 10dB too hot. The post-title explosion on "Revolutions" has full range bass in all channels, not just the LFE. As a result, while the raw LFE was correct, the redirected stuff buried the needle, so to speak. Until Toshiba fixes this in a frimware upgrade, I'm back to optical... I think I can live with full bitrate DTS...:devil:

Long story short, I have everything re-calibrated, and am back to peeling the paint off the upstairs walls, and my duals are more than enough to do it!


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## Guest (Jun 15, 2007)

EQ'ing with a BFD is my next task. I must addmit that it appears daunting but I've only started to read through the process recently. Just using a few of the Avia tones and the meter I can tell I'm all over the place. Glad to hear those 20-39's are doing the job. Still need to work on some calibration. Don't know for sure wether I want to run the mains small, even though we all know it should be the correct thing to do. This hobby is always a work in progress!!!


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## Vader (Jul 8, 2006)

Be careful if you run your mains large: There are several DVDs out there that have full range bass in the main channels as well as the LFE channel (for example, U-571 DTS). Remember that your mains will have to handle that as well, and they can blow out too. Also, if you run your mains on large, any bass in those channels that is below the rated FR of the speaker is effectively thrown to the netherworld, never to be "heard" from again (literally)...


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## Guest (Jun 15, 2007)

I'm running Def Tech bp30's in the front on a rotel 1067. Granted, Def Tech is usually very liberal when stating their speaker response, but I've never had a problem and I used to run them large before the 20-39's. Watch, if I change back they'll blow tomorrow. :wits-end: Also, my understanding is the rotel will deliver the full signal to the fronts and sub if set up that way...or maybe I'm remembering wrong. It just seems when I switched to small I lost some depth in the low mids. I know what you’re thinking. It's in my head, and you're probably right. This could also be due to the fact I replaced two subs that were all buzzing mid bass. The kind that won't deliver bellow 35Hz. I need to take the time to test some different xover points probably, but 80 should be the mark.


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## Vader (Jul 8, 2006)

> the rotel will deliver the full signal to the fronts and sub if set up that way...or maybe I'm remembering wrong


Nope, your memory is fine. My Denon will do the same thing (I think it's reffered to as 'LFE + Main' or something like that. The main reason (aside from lifting the LFE burdon) most people do't run their LFE through their mains, even if they are full range, is that it can make life miserable where the room response is concerned, and a pain in the wazu to EQ it (often times you also have to worry about relative phase, and stuff like that). Good luck with your BFD (I was intimidated at first as well, but the folks around here showed me how easy it really is once you start playing). You also might wanna read Wayne's article on House Curves. Let us know how it goes!


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## Blaser (Aug 28, 2006)

Vader...If I were you, I would wait for the PB13:R 

Ilkka, Is this sub planned soon in your tests?:T


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