# 25-31PCI 20Hz Need help!



## Guest (Aug 15, 2008)

Ey guys, im new to this forum. I hope someone out there can help me with a problem I have with my new 25-31 PCI custom tuned to 20Hz.

I have a very small room which is about 130 square feet. I replaced a new REL T1 because I wanted the DEEP bass a lot of SVS customers are raving about. Ordered a 25-31PCI and had it tuned to 20Hz without knowing the pros and cons. After my Audyssey set up and using a SPL meter, I was ready to go. I noticed a lot of bass and mid bass LFE from 25Hz up are missing. Bass is only present from 20Hz below and a lot of LFE materials are lost.

My question is, is there a DIY route to fix this problem and bring it back to the default 25Hz or 22Hz setting?

Any help will be appreciated.

Thanks!


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## Sonnie (Apr 11, 2006)

Hi Lance and welcome to the Shack.

Can you take a measurement sweep from your main listening position with REW (Room EQ Wizard) and post the graph? This may be more appropriate in the REW Forum, but we can start out here and see where we need to go. It will be easier to help you if we can see what the response is doing. Also tell us about your room and where the sub is located. The tuning may have nothing to do with your issues.


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## Guest (Aug 15, 2008)

Hi Sonnie, thanks for your reply.

To be honest with you, I do not know how to make a measurement sweep with a REW. Is it a program or a device I need to buy? I am interested to learn just so I can get help from you and other people in the forum so I can solve this problem.

I appreciate your help.


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## Mike P. (Apr 6, 2007)

REW is Room EQ Wizard, a free program that will measure your in room response. There is a link at the top of the page. You'll need a computer and a full duplex sound card to use it.

Since you already have a SPL meter, you can download and burn test tones to a CD. Play the tones and measure each ones SPL. This will show if there are any peaks and dips in your response. Which make and model SPL meter do you have?


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## Guest (Aug 15, 2008)

Mike P. said:


> REW is Room EQ Wizard, a free program that will measure your in room response. There is a link at the top of the page. You'll need a computer and a full duplex sound card to use it.
> 
> Since you already have a SPL meter, you can download and burn test tones to a CD. Play the tones and measure each ones SPL. This will show if there are any peaks and dips in your response. Which make and model SPL meter do you have?



Thanks Mike. I have an old digital Radio Shack SPL meter. It is the same as the digital meter picture on the help menu of REW. Not sure about the exact model though.


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## Mike P. (Apr 6, 2007)

You'll have to apply the right correction file for your meter to get a more accurate reading of the lower frequencies. 

http://www.hometheatershack.com/forums/downloads-area/19-downloads-page.html


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## Ed Mullen (Jul 28, 2006)

Switching from the 22 Hz tune back to a 25 Hz tune will not help your situation. The short tube PCi subwoofer is amp limited (not woofer limited), and slightly lowering the system tune has almost no influence on available headroom in the mid-bass regions. 

The most the 22 Hz tune gives up is about 1 dB of max output at 50 Hz and they are otherwise virtually identical in max output and FR from 25-100 Hz. The deeper tune will provide a few Hz deeper extension and more clean output capability <25 Hz, but it does not result in a noticeable headroom loss or an FR difference >25 Hz. 

Your problem is likely a poor FR at the listening position due to room acoustics, standing waves, and a null. Small rooms are notorious for nulls which are smack dab in the typical listening locations, and having limited subwoofer placement options doesn't help the situation either. 

I definitely recommend plotting the FR at a few listening locations with REW and trying to find the least offensive subwoofer placement/listening position combination.


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## Guest (Aug 17, 2008)

Thank you, Ed! It was a placement issue all along. After I tucked my subwoofer in a corner, things improved 100 times. I got worried at first but all doubts came into mind about my SVS are resolved. You are correct, my sub was at a null location before hand. Again, thanks for your help.


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## Ed Mullen (Jul 28, 2006)

Fantastic, Lance. The three things real estate and subwoofers have in common are location, location, location.


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