[watermanpc]

I all mates!!, I'm here again since my last attempt to get my freq response with REW...well, now I finally have the RS SPL meter (analog model 33-4050), and I want to tell you how I did the measurement before nothing...

I set my meter in the listening position (with a tripod)...with an RCA-to-RCA cable, I connected the RS out to the right RCA-in of the jack-to-double RCA conversor like this one:

Then, the conversor to the mic-in (in the LINE-IN mode of course) of the laptop. Finally, the headphones-out of the laptop to the V-AUX-in of my Denon with a jack-to-double RCA cable (both RCA connectors fitted to the AVR but im not sure if I should connect just one¿?). Ok these are the connections, now the calibration...

With the calibration tone for subwoofers (and the speakers off in my amp) I set the volume in my Denon until the SPL meter measured 75db, in the 80db range(wich was very hard to do, because the needle of the meter was moving continously almost 3db up and down, due to fluctuations in the tone volume wich I could confirm just by ear and I think its a room problem). The meter was set in C and Slow. Once I had the sub at 75db I raised the meter range to 90db because I got some clip when calibrating, so I set the 90db range, then press calibrate again and finally I tell REW that the level was 75db for the new range.(I supose all that is correct)...then I had not any clipping. The crossover is at 80Hz from the receiver and REW...the sound card and the meter compensation files are loaded. Well this is the result:

and with 1/3 smoothing:

......looks really BAD!!!!! seems like I have a cancellation at 20Hz...¡¡¡20Hz!!!!...and nothing below that...what do you think guys???...do you recomend me to buy a FBQ-2496??? can it make any improvement in the response?? (specially in the lower zone??)


Many thanks!!!...and sorry for my bad english...

[Iron Man 2]

You might want to try moving it around the room. I had a very boomy sound with music and ran REW which showed a number of peaks and dips. Moving the sub around the room 1ft at a time improved the graphs and sound considerable.

Still not perfect but a work in progress.

[cribeiro]

Originally Posted by Iron Man 2

You might want to try moving it around the room. I had a very boomy sound with music and ran REW which showed a number of peaks and dips. [...]

Wait... you have a B&W PV1 and measure a in-room response extending down to 10Hz?

[watermanpc]

many thanks for your reply!!!...the problem is that I have a very, very limited space for moving the sub, almost nothing...maybe I can move it just a few inches, but nothing more...I cant believe it...I would never think that I could have a cancellation at such a low frequency, as every body seems to have a nice "flat" and "soft" response below that frequency...you for example dont have any problem in the low bass, indeed below 40Hz you dot have any problem, so in the worst case you only must to lower the crossover(or buying a bfd or fbq and you will have a brutal response), but I dont know what to do......I supose there is not any problem with my Monolith right???...it sounds well, but this brutal roll-off in 20Hz looks weird...

Many thanks and bye!!

[Iron Man 2]

Originally Posted by cribeiro

Wait... you have a B&W PV1 and measure a in-room response extending down to 10Hz?

As you can see it was rolling off at just 30hz before I started moving and then applying EQ. Most acoustic problems are the room not the speaker. The same REW sweeps were applied to all positions and the setup was reviewed by the guys on the REW forum.

[Iron Man 2]

Originally Posted by watermanpc

many thanks for your reply!!!...the problem is that I have a very, very limited space for moving the sub, almost nothing...maybe I can move it just a few inches, but nothing more...I cant believe it...I would never think that I could have a cancellation at such a low frequency, as every body seems to have a nice "flat" and "soft" response below that frequency...you for example dont have any problem in the low bass, indeed below 40Hz you dot have any problem, so in the worst case you only must to lower the crossover(or buying a bfd or fbq and you will have a brutal response), but I dont know what to do......I supose there is not any problem with my Monolith right???...it sounds well, but this brutal roll-off in 20Hz looks weird...

Many thanks and bye!!

to achieve that graph I simply twisted the sub approx 30 degrees. Before that there were some serious peaks. Even slight movements can make a big difference.

[Tyler Durden]

It's all fun and games. Moving the sub inches will make big differences, as will moving the SPL!

Enjoy!

[watermanpc]

Ok!, I will try moving it around a few inches...the SPL meter seems very sensible too...I set it in a tripod and in a horizontal plane, is that correct??.

Anyway, would you recomend me buying an eq?? the FBQ 2496 in this case, as I cant find the BFD now.


Bye

[cribeiro]

Originally Posted by Iron Man 2

As you can see it was rolling off at just 30hz before I started moving and then applying EQ. Most acoustic problems are the room not the speaker. The same REW sweeps were applied to all positions and the setup was reviewed by the guys on the REW forum.

It's not recommendable to apply EQ beyond the roll-off point of the subwoofer. It will simply struggle to produce some output that it can't. Of course, it won't be serious unless you want to go loud, but your headroom (how loud you can go) is strongly limited when you do that. I am surprised that the guys at the REW forum did not say anything about it , and I feel confident that I am not missing anything here

It would be interesting to see the response curves at 70, 80, 90 and 100dB. I guess you know this

B&W Pv1 - Home Theater Systems - Electronics and Forum - HomeTheaterShack

Which shows strong compression when reaching 100dB, and that's without lifting up the low-end. I understand you lifted it by 10dB, which leaves you with compression at 90dB

[Iron Man 2]

I didnt apply any eq beyond the roll off point. I only applied it in the range 65-85Hz. The amp only allows you to eq at 3 points. any other changes in the curve were due to moving it arround the room.

[cribeiro]

Originally Posted by Iron Man 2

I didnt apply any eq beyond the roll off point. I only applied it in the range 65-85Hz. The amp only allows you to eq at 3 points. any other changes in the curve were due to moving it arround the room.

Ok, then I misunderstood what you wrote previously That's quite an impressive response for a PV1, actually

[Iron Man 2]

Originally Posted by cribeiro

Ok, then I misunderstood what you wrote previously That's quite an impressive response for a PV1, actually

Cheers, I probably will still get a BFD to flatten it out further