REW and BFD Results

[Kerbango]

First I must say Well Done on the BFD and REW Guides. I was able to set everything up and get measurements first time around!

My room is a family room with openings to the kitchen and hallways and an 8 ft ceiling. The sub is located next to the coach under the house plant. Placement recommended by Dr Hsu. Drawing not to scale.



My system:

Yamaha RX-V2500
Paradigm Monitor 11 v.4 Mains
Paradigm CC-370 v.4 Center
The Surrounds and Surround Back are umm... Bose Accoustimass 15
HSU VTF-3 Mk2 in Maximum Extension mode
Sony XBR 34" Direct View HDTV
Sony DVD player

I first mesured the sub response with an Analog Radio Shack SPL Meter using sine waves from this site and plotting manually on the New RS Analog Excel spreadsheet. This led me to REW.

I downloaded REW and purchased both a BFD and a Sound Blaster Live 24 bit sound card on eBay. With a few adapters from Radio Shack I was ready to begin. First I used YPAO to set up the levels, etc. Then I measured, set filters on the BFD and measured again, adjusted output on the sub, measured again...

I was able to achieve a pretty decent response with a gentle +8 dB house curve from 60 Hz to 20 Hz. This was achieved with 7 cuts and one 5 dB boost at 35 Hz. The best integration with the mains was achieved with a crossover of 90 Hz on the AVR and setting the crossover on the sub to IN also at 90 Hz. I've often read it is bad to have cascading crossovers but in my case it seems to work! The 90 Hz crossover also benefits the CC-370 (-2 dB @ 100 Hz) but is a little high for the Monitor 11s (-2 dB @ 48 Hz)

The measurements were taken at the center position of the couch. The results are even smoother on the right position. The left position has a very large null at 35 Hz. I will post graphs later today.

Now I can hear sounds I never heard before. The overall effect is smoother more defined bass without the 25 Hz and 50 Hz Mode excitement caused by the room.

[brucek]

I was able to set everything up and get measurements first time around!

Yep, when you read the guides first, it's really quite simple.

The sub is located next to the coach under the house plant. Placement recommended by Dr Hsu.

We have to agree to disagree on this one. The best position for a sub is usually in the corner left or right of the mains. You'll realize quite a bit of low end room gain this way.

The best integration with the mains was achieved with a crossover of 90 Hz on the AVR and setting the crossover on the sub to IN also at 90 Hz. I've often read it is bad to have cascading crossovers but in my case it seems to work!

Yeah, that's usually bad news, but if it works for you, that's great..

Hope you can post a before and after graph.....

brucek

[Kerbango]

brucek wrote:

Hope you can post a before and after graph.....

brucek

Here is the sub only, 90 Hz cutoff with BFD



Filters applied

12_1_06.req

Here is the sub plus mains, 90 Hz cutoff with BFD

[Kerbango]

brucek wrote:

Hope you can post a before and after graph.....

brucek

Here is the sub only no BFD crossover 90 Hz sub crossover out



Here is the sub and mains no BFD crossover 90 Hz sub crossover out

[Kerbango]

brucek wrote:

Hope you can post a before and after graph.....

brucek

Let's try the waterfall again

Sub Only with BFD



Sub plus mains with BFD

[Kerbango]

brucek wrote:

We have to agree to disagree on this one. The best position for a sub is usually in the corner left or right of the mains. You'll realize quite a bit of low end room gain this way.


brucek

Would it still apply given the wall is only 30" high and there is a very large opening to the kitchen at the only usable front corner?

The sub is currently near the only usable rear corner.

Chuck

[Kerbango]

brucek wrote:

Hope you can post a before and after graph.....

brucek

Waterfall sub only no BFD



Waterfall sub with mains no BFD

[brucek]

Would it still apply given the wall is only 30" high and there is a very large opening to the kitchen at the only usable front corner?

Mmm, that's a really good question. I don't have an answer for that one.
I wonder if anyone else here has experience or knowledge of that.

Great looking response - good job....

brucek

[Ayreonaut]

A couple of years ago I asked Dr. Hsu where to place my sub too. I think his recommendation is usually to put it in a corner farthest from unclosable openings in order to realize maximum corner gain.

Since then I've come to the conclusion that maximizing gain from corner placement shouldn't be your first concern, unless you are pushing the limits of the sub. Smoother frequency response, better directionality and more consistency from seat to seat can be obtained by moving the sub to the front and away from the corners.

Could you try it next to the TV?

[Kerbango]

Ayreonaut wrote:

A couple of years ago I asked Dr. Hsu where to place my sub too. I think his recommendation is usually to put it in a corner farthest from unclosable openings in order to realize maximum corner gain.

Since then I've come to the conclusion that maximizing gain from corner placement shouldn't be your first concern, unless you are pushing the limits of the sub. Smoother frequency response, better directionality and more consistency from seat to seat can be obtained by moving the sub to the front and away from the corners.

Could you try it next to the TV?

I moved the sub up front last night. Crossover in AVR set to 80 Hz - Crossover in sub set to OUT.

There is a steep 10 dB drop from about 23 Hz to 21 Hz. Then it levels out. I kept the peak at 80 Hz since it levels out with the mains. I haven't done any critical listening yet.





Chuck

[Kerbango]

I fine tuned the filters. Even though I lost some low end extension, the response is consistent across the viewing area. Any recommendations?

[Wayne A. Pflughaupt]

That’s a really tough room you have there. If you got response that good, and it’s reasonably consistent through most of the room, I’d say you’re done – stick a fork in it! Looks like you got good response down to about 24 Hz before response starts dropping – most people agree that’s low enough to deliver a satisfying home theater experience.

Regards,
Wayne

[brucek]

Looks like you got good response down to about 24 Hz before response starts dropping

Well, I'd say he has a decent response down lower than that, since it would appear he has added about a +10dB house curve from 80Hz down to 20Hz. If you compare the response to a normal target, the response is fine.

In fact, if it were me, I would do some more cutting and then raise the sub amp a bit and end up with a response that went down to ~18Hz.



brucek

[Kerbango]

brucek wrote:

In fact, if it were me, I would do some more cutting and then raise the sub amp a bit and end up with a response that went down to ~18Hz.

brucek

Thanks for the suggestion. I'll give it a try.

Chuck