sub tuned in, now RT60?

[daxie]

hi everybody,

I recently finished my private ht and yesterday I integrated the sub.

This is the response (equalised using a BFD):



However, I would like to use the RT60-function to check if any further absorption is needed.
Currently the ceiling is absorbing and the carpet does a bit of a job too.

How do I proceed for a RT60-measurement?
Do I do a sweep? From where to where? After the sweep, do I just go to the RT60-tab and make it calculate?

Do I need to change any of the settings?

thanks,

Wouter

[Wayne A. Pflughaupt]

Graph looks great. A little too good, actually - hope you didn't go overboard with the equalization...

RT-60 is primarily for the upper frequencies, not the lower. There is some debate on the topic, but it's generally accepted that it's of little use in domestic systems because the rooms are too small.

For the low frequencies you want to use the waterfall function. Just take a sweep, then go to the Waterfall tab, set the window for something between 300-600 ms, and click the "generate" button. It will show you the time it takes for the signal to decay. If you feel decay times are too long, the primary "absorption" device for bass signals is bass traps.

Regards,
Wayne

[brucek]

I would like to use the RT60-function to check if any further absorption is needed.

RT-60 is really only meaningful in large rooms - not in a home environment.

In the HT room, below 200Hz we use waterfall and decay plots and above 200Hz ETC is useful for removing reflections.

But, if you use RT60, you require a full range sweep with the mains, and ignore any results below 200Hz. A good RT60 would be ~0.3 seconds, with higher numbers being worse.

brucek

[daxie]

Hello all,

I'm sorry I wasn't clear. I'm not looking into using the rt60 as a means of measuring bass decay time. I want to use it for mid/high absorption (therefor the question regarding the frequencies...).

As to my equalisation, there are 4 filters:
1 at 20Hz making the low end a bit milder (-3dB)
The other 3 are between 35 and 70 reducing that spectrum with about 7dB, all 3 bw 8 or more

*EDIT* The only freq where I have lower frequency decay issues is the are of 25Hz and lower... I have included the measurements file.
http://ht.deraeve.eu/melle/roomdata.mdat

So is the RT60 usable for small rooms?

And if not, what is the alternative? And if so, how do I use it?

[brucek]

I'm sorry I wasn't clear. I'm not looking into using the rt60 as a means of measuring bass decay time. I want to use it for mid/high absorption (therefor the question regarding the frequencies

As stated, RT60 is only suitable for large venues.... HT rooms do not qualify.

In the HT room, below 200Hz we use waterfall and decay plots and above 200Hz ETC is useful for removing reflections.

brucek