1st graph-What next? Do I need eq?

Just measured my 1st graph with my new sub, and need help interpreting it... The 2 plots show the sub almost in the right hand corner of the room (purple), and almost in the left hand corner of the room (blue).

Room is 7m long by 4m width with a 1.25m width x2m length area taken out of the right hand side for a fireplace/chimney/next room.

Sub is a BK XLS-300PR.

I noticed significant boomy bass when watching a film, which is what prompted me to do a lot of reading over the last few days and try REW! I guess the boom is explained by the peak at around 65Hz on the purple plot?

Is the dip at 30Hz a limitation of the sub, or the room?

I am not sure if one of these plots is more desirable than the other!? Any comments would be appreciated. I have moving the sub around slightly but did not seem to make an appreciable difference.

What should I try next? Would cutting the peaks with a FBQ2496 be worthwhile?

Rest of the system is Onkyo 905, Monitor Audio RS8 fronts + RSLCR + 4 x RSFX

cheers!

[salvasol]

First of all ... Welcome

al_uk wrote:

Just measured my 1st graph with my new sub, and need help interpreting it...

cheers!

I will let the expert interpret your graph ...

Just a couple of questions: 1) Have you look for the best place for your sub using the "crawling method"??? ... 2) Have you used the autocalibration of your AVR??? ... 3) Do you have any accoustical treatments on your room???

Wow-quick response! Thanks...

1. No I have not come across crawling yet... Let me go and do some reading about it, then I'll come back!

2. Yes, I have auto calibrated as per the instructions, all processing & speakers except the sub disabled though for the REW measurements. Fronts are set as full range, and I have reset everything else as 80Hz.

3. No acoustical treatments. Carpet flooring. Listening point is approx in middle of the room, slightly to one side. TV/projection screen is parallel to the short edge of the room. Room is a living room.

[salvasol]

al_uk wrote:

Wow-quick response! Thanks...

That's a luxury that I have (time) ... I'm always in front of the computer, so I'm always checking the forum

1. No I have not come across crawling yet...

Is easy ... just place the sub where you seat, then crawl around to find the spot where the sub sounds better; that will be your best place

2. Yes, I have auto calibrated as per the instructions, all processing & speakers except the sub disabled though for the REW measurements. Fronts are set as full range, and I have reset everything else as 80Hz.

You're not confussing the AVR autocalibration with REW process, Right???
AVR autocalibration is when you use Audyssey (Onkyo); YPAO (Yamaha), etc. ...

Why did you disable the Sub during REW??? ... supossedly REW is used to calibrate the sub to get the best response; then you add the front speakers so they sound smooth

Maybe I'm missing or not reading something correctly

Most of the time the best settings are: speakers set to small (front can be large or small, but it will depend on their frequency response), crossover 80Hz, front speakers (L+R+C) at ear level and surrounds a little higher ... just to start

3. No acoustical treatments. Carpet flooring. Listening point is approx in middle of the room, slightly to one side. TV/projection screen is parallel to the short edge of the room. Room is a living room.

If you use accoustic panel it will help you a lot ...

As far as the seating position ... you're in a bad spot (I think is the worst)

It is recommended to have the seat 62% (4.34m) from front wall or 38% (2.66m) from back wall; that's the start point to find the best place. Also, avoid to have it next to the walls.

Will give crawling a try.

Sorry, I wasn't clear - I have run Audyssey, but for the REW measurements, I am using stereo out from the HTPC into a stereo aux in on the AVR, with Audyssey disabled. Also, I have unplugged the mains so that I am just getting the sub response.

The sub is set to bypass the internal lpf, and the avr lpf is set to 80Hz.

I will experiment with the listening spot, but I moved it around a bit, but couldnt get rid of of the 30Hz dip, or the 65 Hz peak on the graph.

[thewire]

Here is a calculation of the longest distance sound will travel in the room which is from one corner, to the opposite corner. Not the exact distance, but I think looks pretty close. Treating those corners would help I think.

[brucek]

but for the REW measurements, I am using stereo out from the HTPC into a stereo aux in on the AVR, with Audyssey disabled. Also, I have unplugged the mains so that I am just getting the sub response.
The sub is set to bypass the internal lpf, and the avr lpf is set to 80Hz.

Correct......

I am not sure if one of these plots is more desirable than the other!? Any comments would be appreciated. I have moving the sub around slightly but did not seem to make an appreciable difference.

Well, the response is not good. The dip at 30Hz is likely caused by the room. You need to move that sub around to remove the null. No amount of EQ will fix that response as it stands...

brucek

[JohnM]

Remember not to apply any smoothing to subwoofer measurements to get an accurate picture of the response.

Thanks for all the advice!

I've spent a happy hour with the sub at my listening spot and wandering around with the mic looking at the spectrum window on REW.

I couldn't get a reasonable plot with the sub at the front of the room, so I've now put the sub at the far back left of the room, and here is the result. To my eyes it looks much better?

[brucek]

Yeah, much better...............

[salvasol]

al_uk wrote:

... so I've now put the sub at the far back left of the room, and here is the result. To my eyes it looks much better?

Yes ... much better

Did you used Audessey to calibrate again after you moved the sub???

Yes, Audyssey run, but havent had a chance to test with a film yet...

Thanks :-)

[salvasol]

al_uk wrote:

Yes, Audyssey run, but havent had a chance to test with a film yet...

Thanks :-)

Which one will you use ... Transformers, War of The Worlds, Master and Commander, U-571, Jurassic Park, etc.

Watched Die Hard 4 and it sounded much better. Need to play with the phase a little.

Now I'm wondering whether I should have got a monolith!

Thanks for the help everyone.