# Horrible results with REW and Sub.. help!



## Damo (Jan 4, 2010)

Well, its almost an exact opposite of what I should be getting, I suppose, but I am fairly new to the whole REW thing.

I trust the readings are correct, though!

There seems to be a huge notch just over 40Hz, and I have no idea if I can get any of it back, via movement of the sub - Would I be moving the sub further from the wall or closer to it to get better response below 30Hz from it, or is it as I suspect in that the sub probably cant reproduce the frequencies, no matter what I do?

It also looks like I may not have the crossover set properly on the sub, either, but Ill try getting some more readings tonight.

Man, I have some work ahead of me!

Any suggestions? Im running a smallish/crappish Yamaha YST-SW225








and expanded further...










Also, thanks to the makers for such a great program!


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## Wayne A. Pflughaupt (Apr 13, 2006)

Welcome to the Forum Damien!


> It also looks like I may not have the crossover set properly on the sub, either.


Correct. Actually, it looks like there is no crossover at all (unless the measurement includes your main speakers as well).




> There seems to be a huge notch just over 40Hz, and I have no idea if I can get any of it back, via movement of the sub -


It’s possible. Try some different locations, if that’s an option.




> Would I be moving the sub further from the wall or closer to it to get better response below 30Hz from it, or is it as I suspect in that the sub probably cant reproduce the frequencies, no matter what I do?


Yeah, budget 8” sub – 30 Hz is probably as good as it gets, but you might try a corner, if one's available. It’s only rated to 28 Hz to begin with, though...

Regards,
Wayne


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## glaufman (Nov 25, 2007)

Welcome Damien! +1 on what Wayne said, but even if you do get lower response in a corner, you can expect that to create more/deeper peaks/dips in the rest of the response. 

No harm in trying though. Sometimes it depends on your personal goals, whether you prefer boom at the expense of clean sound.

Without knowing the layout of your room, you can also try different listening positions.


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## Damo (Jan 4, 2010)

Thanks for the responses, guys.

Im investing in an SVS PB13 and some acoustic panelling at some point down the track, so Im not too concerned at this point, until that happens.

I know Ill be fighting with the wife for placement of the sub 

Any idea what the problem may be at 40Hz? Is it some sort of wave cancellation effect or something?


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## Wayne A. Pflughaupt (Apr 13, 2006)

Yeah, something like that. Those sharp, deep depressions like that - usually can't do anything about them except move the sub.

Regards,
Wayne


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## glaufman (Nov 25, 2007)

Somtimes moving the LP can help those too... the best placements should be the same regardless of the sub so you might want to try experimenting now just to put the bug in her head to fester...


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## Damo (Jan 4, 2010)

Forgive my n00biness, but LP stands for?

Ive got the guy down at my local HT store trying to get me onto a Velodyne SPL-1200 Ultra, but I'm reading better reports on the SVS PB13 Ultra. Both will make a huge difference in low end response compared to what I have, for sure, but still undecided which way to go there!


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## laser188139 (Sep 19, 2009)

LP is for listening position. 

Besides running sweeps, you can pursue Greg's suggestion to try different listening positions by using REW's RTA capability. This lets you enable the generator for subwoofer pink noise and move the microphone looking at changes in the spectrum. Then you can verify this with a sweep when you have found someplace interesting. 

Bill


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## glaufman (Nov 25, 2007)

Damo said:


> Forgive my n00biness, but LP stands for?


What Bill said! :T
Sorry... I tend to slip into lingo when I'm busy and multitasking... 
SVS has a very decent audition policy, so you can listen before you fully commit... perhaps you can talk your local guy into an in-house audition of the Velo also...
Check out our archives of some subwoofer tests done... 
http://www.hometheatershack.com/for...index-subwoofer-tests-manufacturer-model.html
The PB13U was done in all different tuning modes... the SPL1200 was done also, but the Mk2, which I assume is not the same as their Ultra. If it is, comparing to the SVS in "sealed" mode makes the comparison fair I think)...
Admittedly, some of the decision will come down to how you're going to use it. Music/Movies, open room vs sealed, etc...
One thing I love about the SVS is the different tuning configurations you can put it in. It could be argued that could increase the chances of you being happier over the longer haul. One thing that bothers me about the Velo that Ilkka tested is the size of the sealed enclosure as compared to the size of the driver.


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## Damo (Jan 4, 2010)

I suppose I should have clarified.

99.9% of the time we're using it for movies only, and within a sealed room.

The issue with the SVS is that the nearest dealer is over the other side of the COUNTRY


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## glaufman (Nov 25, 2007)

Ah, yes, I missed the fact of where you are... that most certainly can have an influence on your decision.
But alas, I do not know the ins and outs of these implications...


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## Damo (Jan 4, 2010)

Mind you, the SVS dealer has offered to take it back should I not like it.
Its just a freight cost I dont need. I still say Im more partial to doing this than getting the Velodyne locally though, Im not sure why!

SVS gets a good rap on this site!


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## paulspencer (May 11, 2007)

Probably a bit late, but actually that is not a bad measurement. Are you using your receiver for bass management but feeding the input direct for the measurement? That would explain the top end being unfiltered. The dip at 40 Hz is pretty minor as far as in-room measurement goes. Try third octave smoothing - it shows more like what you actually perceive and is a good reality check to keep visual chart perfectionism in check! Then switch it back off. 

When someone says "it looks terrible" that usually means they aren't used to seeing in-room measurements, not that yours is particularly bad. You would be lucky to get much better than that, although a more capable sub will extend down lower.


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