I would like to share something that I found recently. Subs are normally rated +/- 3dB. Typically it means that the sub will go as low as that within a tolerance of +/- 3dB from reference. The normal reference is 75dB. This rating is done in a quasi anechoic chamber/room. This does not mean that the sub cannot reproduce below that. It only means that the volume will be lower than 72dB. Subs normally have a very steep rolloff below their rating.

My sub is rated at 26Hz (+/- 3dB). However, our room accoustics can lower or increase the frequency quite a bit. For example, if I use it in my dedicated stereo system I get +/- 3dB at 25Hz. However, if I were to change the sub phase to 0 from 180 I get a room response where my sub now is able to deliver 21Hz (+/-3dB).  However, with this lower there is a huge peak at 37Hz. If I were to hook up my CD player to the CD input of my AVR amp and use the stereo mode (Audyssey enabled) the peaks are much flatter and the 37Hz is reduced. The sub response at 180 is also now down to 20Hz (+/- 3dB). The 37Hz hump is there but very much smaller (the fronts are still pre-out to my dedicated Holfi amp).

I will try to post some graphs of my findings. At the moment, I am using a freeware (with a laptop), a USB soundcard and tripod mounted Radioshack SPL meter to show the response of the sub and mains at the lower frequencies. I am waiting for my new Galaxy Audio SPL meter that is calibrated tightly compared to the RS SPL that is known to be not as accurate. Also by moving my main speakers around, I get to see the flattest response with regards to my main listening position that improves the overall sound experience.

The importance of a sub in a home theater environment compared to a music environment is different. In a pure HT environment, you would like the bass to enable enjoyment of the LFE (boom, explosions, gun shots). However, in a music environment, you want the subwoofer to supplement the main speakers and not cause unnecessary boominess. The sub must not be felt, it needs to be blend in.

I wanted to point out that it is possible to go much lower than the sub is rated at depending on room placement and room accoustics.

I will try my best to post the charts here within the next few weeks when I get my Galaxy Audio SPL meter.

Contact Hi-Way Laser in SS2

I'm not from Kl, any contact number? TQ

Glad to see you're a calibration freak!  So you've got both the video and audio side covered. Your HT must look and sound fantastic!

Thanks for sharing your experience on the sub response. Didn't know phase and hook up can affect the response like that. If you have Audyssey (which I think is supposed to even out the response) is it still necessary to calibrate with SPL meter?

Yeah the sub ratings are important. At one point I was looking at the Audio Pro B1.36 sub and its freq response was listed as 25-100Hz, which I thought was quite good for a 10" driver. Then I decided to check on the limits and emailed them. They said the 25Hz was at -6 db. This turned me off.

For sound, your ears tell you something is not quite right, the measurements just confirm that. I know some guys, who have golden ears, came over to my house, heard the system, immediately moved the speakers to new position, adjusted the sub a little, lo and behold improvements in sound. If you do not have those ears, measurements help to see if you are in the right direction. You can also confirm that the changes you make are in the right direction.For most audio issues, the low to mid bass is the most problematic due to room issues. It causes loss of detail in other frequencies when it is wrongly set.

I am actually very pleased with Audyssey. I believe that Audyssey adjusts the filters quite right. However, after running Audyssey, it is important to check your speaker levels and correct it with a SPL meter. I found that it was off about 1-2dB, max 3dB.

You r right, some companies report the frequencies quite differently, lucky for you , you checked.

Wish I had 'golden ears' like that.

If, after running Audyssey, the speaker levels are still a little bit off then what else can you do to correct it? Use equalizer? Or do some adjustment to speaker position?

i got a quote for Velodyne CHT-12Q for Rm2900.  the other one I am considering is Klipsch RW-12d from HTkaki.

just want some opinions from the expert in here which is a better woofer.

TQ

2.9k quite high price for the 12Q

is it?  how much is it in KL?

I got one quote for RM2.7k from A&L Amcorp.

What do you think of this mpyw?