# Question about the subsonic filter on PB13 Ultra



## tonyvdb (Sep 5, 2007)

On the back of the PB13 Ultra the subsonic filter setting is suposed to be used when plugging the ports, can this not also be used as a straight filter to avoid excursion below the subs ability meaning keeping it from reproducing anything below what you have the selector set for?
The reason I am asking is there are times in movies I have watched that there is some serious subsonic lows (below10Hz) that puts undue strain on the sub and was wondering if setting it to 10Hz would help control this.


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## JimP (May 18, 2006)

Hi Tony,

Glad you started this thread as I received my PB13ultra about 3 weeks ago and have had been tweaking since. Tough room, but who doesn't have one. 

You are correct in the presumption that subsonic filters provide a level of protection from over excursion. That's the simple answer. Where this gets to be a bit more murky is in finding the best combinations of 1)number of ports plugged 2)room size setting 3)subsonic filter setting and 4)SPL for a given room.

The best starting place is to tell us more about your room size and how loud you normally play your system.


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## tonyvdb (Sep 5, 2007)

I like my system at reference and is more than capable of exceeding that level. My signature has a list of what I own.
My room is large 16' wide by 37' long and has a 8.5' ceiling. I have really good acoustics and I need to try REW sometime but just have not found the time. Right now I'm running the PB13 Ultra with no bungs and a crossover in the receiver set to 80Hz


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## JimP (May 18, 2006)

Since you're not using any of the plugs and are playing at reference levels in a large room, your safe bet is to keep the subsonic filter at 20hz.

I don't play mine at reference levels, have one port plugged (15hz tune) and use the "sealed" subsonic filter selection. This give me a boost in the low frequencies. According to SVS, I would be at risk if I was playing the sub at full tilt as the subsonic filter would not limit the low frequency excursion. ....but sometimes you just have to color outside the lines.


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## tonyvdb (Sep 5, 2007)

I'm like you I like to push the envelope a bit. 20Hz, that seems high would I not be better off starting at 10 and work my way up as I do have my second sub (the A/D/S) also connected and its good down to 20Hz. Maybe I should plug up one of the ports?
I've thought of lowering my crossover to 60 or even lower as my mains can go down to 31Hz.


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## salvasol (Oct 31, 2006)

tonyvdb said:


> I've thought of lowering my crossover to 60 or even lower as my mains can go down to 31Hz.


I suggest you to use REW to measure the system response with different crossovers :yes:

YPAO setup the crossover at 65Hz; so I measured the response with 65Hz, 70Hz, 80Hz and 90Hz ...what I found out is that the best response in my case was using 80Hz, so is what I'm using.

My fronts are capable to 35Hz, I also measured using them as small and large ...better response was using them as large; so that's my set up ....80Hz crossover and large fronts :yes:


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## tonyvdb (Sep 5, 2007)

Thers that REW word again :hide: It seems like alot of time is needed to get it working and some quiet time, none of it I have much of in my house.
My issue is that I really do like how things sound and I worry that once I see a REW graph it will bother me to no end if its not looking right if you know what I mean.


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## JimP (May 18, 2006)

But it does give you a good excuse to buy more toys. 

I have to admit, I struggled to get it running right. Once you get there, its hard to not use it. Those waterfall charts are pretty interesting.


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