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SVS sub question (1 Viewer)

werty7777

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Martin
Alright pros,

I have made the plunge on the SVS PC12 Plus. It wasn't really all that much of a plunge being I got it used, in perfect condition, for only $450. It replaced my Martin Logan Dynamo. Now my setup, in case it matters, is as follows:

Onkyo 876
Mitsubishi 73" DLP TV
Wii
PS3
Monster HTS 1600
Sony BDP-S350
Deftech CLR 2000 (Center)
Deftech BP 2004TL (Mains)
SVS PC12 Plus (Sub)
Deftech BP6 (Surrounds)
Deftech ProMonitor 1000 (Rear Surrounds)
Harmony One
AT&T Uverse for cable

So my question on the SVS sub is with the variable subsonic filter switch with 25Hz, 20Hz, 16Hz and sealed settings. Which setting is the preferred setting for other owners? I tried sealed and it wasn't enough bass output for me. I have also tried the 20 and 16Hz modes and I'm currently using the 16Hz setting. 20Hz seemed louder but at least in my mind the 16Hz seems to go noticeably lower. I know whatever sounds good to me is all that matters but curious of others choices. Thanks!
 

Robert_J

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The SSF setting should correspond with the tuning of the sub. Leave it at 25hz when all 3 ports are open. 20hz when you plug one port. 16hz when two ports are plugged. Finally, sealed when you plug all 3 ports. As with all subs, there is a trade-off. The 25hz tuning will allow you to turn up the volume and get more SPL. The 16hz tuning will give you the deepest bass but overall volume will be sacrificed. Sealed will give you the least amount of bass but you will not have any phase issues from the port. It should sound the cleanest.

I don't have an SVS sub but I do have 2 of their plus drivers and I'm building clones of their CS+ sub. I also have the SVS/Marchand black box with the variable SSF. My current sub is sealed. My last sub was ported. This will be my first variable tuning sub.

-Robert
Originally Posted by werty7777

Which setting is the preferred setting for other owners?
 

David Willow

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A lot depends on your room. With my smallish room (2000 or so cubic feet) I can tune my PB12 Ultra/2 to 16Hz and have plenty of headroom. In a larger room I would tune it up to 20Hz or even 25Hz. The fun part is trying it (and measuring the response). Placement in the room makes a big difference as well.
 

werty7777

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Yeah my room is rather large 22 by 13 or so with 9 feet ceilings. One of long sides is almost completely open to the kitchen. I have the sub in the corner of that open wall if that makes any sense. Which would make it over 2500 cuft without even figuring the kitchen.
I have been in to HT only for a few years so my subs are continually impressing me more. From the HTIB sub to the "better" Sony sub, then the Martin Logan and now the SVS. I guess I'm just trying to make sure I'm getting the most out of the sub as I'm not really sure how much better it can be. Any other owners out there?

Robert, FYI you should never plug two ports according to the manual in order to prevent port chuffing. 25 and 20Hz are with no plugs, 16Hz is with one, and sealed is all 3 obviously.
 

Robert_J

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So the version you have has an Fb of 20hz with all 3 ports open. Makes sense. But setting the SSF at 25hz is just limiting your driver from playing down to the natural resonant frequency of the enclosure.

If you want to get the most out of your sub you should plot the in-room frequency response with each setting. The resulting graphs will give you a very good indication of which is best and if you need to add an EQ to tame any room modes.

-Robert
 

werty7777

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Martin
I didn't quite see the purpose of the 25Hz setting either. Seems if you have a big room and only one sub your only options would be 20 or 16Hz. On the graph thing, I have no chance in the world to do that as I don't quite grasp that one. You have a link that could walk this slow kid through? There is a graph in the manual but I'm assuming that each room will react differently so that graph would be useless to me?
 

Robert_J

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Yes, the same sub sounds different in every room. It will even sound different when placed in different locations in the same room.

You need a Radio Shack analog SPL meter to start off with. Everything else is free. Download the PEQ spreadsheet (created by our own Tony Gomez aka Gomer) - http://www.pvconsultants.com/audio/eq/peq.htm

Create a test CD that has sine wave tones that match the frequencies on the spreadsheet. There are dozens of tone generators available on the web. My tones were 3 seconds long follwed by 10 seconds of silence. My files were burned with the highest frequency as track 1 and went down from there.

I used a tripod to set the SPL meter up in my listening position at head height and pointed up at a 45 degree angle. Only use the sub. All other speakers should be turned off. I played the first tone and adjusted the volume for 85db. Don't touch the volume control until the test is over. For track 1, I wrote down 85. Track 2 played and I wrote down what the SPL meter registered. Repeat until you have finished the disc. If the tones are higher or lower than the current setting on the meter, I would adjust the range and repeat the track until I got a good reading.

You have have a page full of numbers, you should enter them into the spreadsheet. The sheet has built in correction values for the inaccuracies of the meter. Hit the graph section and see how flat your response is. You can then play with the parametric EQ settings and see if you can flatten the response graph even more. If you only need a filter or two, then there are equalizers like the EQ-1 from Elemental Designs. I needed 6 different filters so I copied the exact settings into my Behringer Feedback Destroyer.

As a test, I re-measured the room with the EQ filters active. I then graphed them again and the result was very, very close to the software's prediction. Sound quality went from a boomy bass sub to one that was natural and will play flat down to 17hz.

-Robert
 

Mike Frezon

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Robert:

I've been reading your posts here for years. Most sub-graphing posts/threads have gone right over my head using verbiage I didn't understand.

But, that has to be one of the clearest "how to" posts I've ever read. Makes me think someday I should take the time and perform that exercise on my pissant little Sony SA WM-40 sub (I've got the SPL meter) and maybe I could tweak its settings some to improve it's performance. Anything I can do to improve performance on my little budget HT can go a long way.

Is it okay to use the tones on an Avia (or similar) test disc?
 

Robert_J

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Thanks for that. It took me a while go over the process in my head.

You should use your own test disc with sine waves to match the frequencies of the spreadsheet. I'll check tomorrow and see if I left the files on my other PC. It's either that or do real work during the day.

The SA-WM-40 is a heck of a sub for the price. My parents have one. You can't build a bargain sub for what those were selling for at the time. You can stuff it with a 20oz back of fiberfil from Wal-Mart though. That was the standard 'upgrade' to that sub back in the day. It makes the enclosure seem a little larger and shifts the Fb down a few Hz. Cuts down the boominess just a hair.

-Robert
 

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