Measuring, again...

David French · Post by **David French** » Mon May 08, 2006 3:59 pm

WTF?!? I swear I typed comments into each of these attachments! Oh well.

The ones that start with 'LF' show the decay in time of the low end of your speakers. The red line represents the response from about 0-300 msec, and the blue line represents time from about 200-500 msec, so basically, it's the response plot updated every 20 msec. The cooler the color, the later in time. This is useful for identifying resonances such as modes.

I'm sure you know 1/3 octave plots.

The last one is called the ETC (Energy Time Curve) It is another way of looking at the impulse response in the time domain (the other graphs were in the frequency domain). It shows that all the energy is at -60 dB afetr about 150 msec... a very short time.

moby · Post by **moby** » Tue May 09, 2006 12:13 pm

Cool

Of course I did this to check and improve my acoustics, so have to ask some questions about.

The ones that start with 'LF' show the decay in time of the low end of your speakers. The red line represents the response from about 0-300 msec, and the blue line represents time from about 200-500 msec, so basically, it's the response plot updated every 20 msec. The cooler the color, the later in time. This is useful for identifying resonances such as modes.

I see that some bass traps will be nice... But, what I have too look for? Is that 110.2hz fundamental freq. I have to treat or I have to go for every "null" and "peak? Not sure, is that 55.1 hz or maybe some other

I'm sure you know 1/3 octave plots.

Thats cool, I see that will be nice to adjust my HF response to "few db more". BTW, HF close measuring (from about 10cm) of my Tannoy's looks pretty close to the hot spot measuring. How the Tannoy guys measured hf response flat to 20khz +/-3db

The last one is called the ETC (Energy Time Curve) It is another way of looking at the impulse response in the time domain (the other graphs were in the frequency domain). It shows that all the energy is at -60 dB afetr about 150 msec

It's about rev. time?

It shows that all the energy is at -60 dB after about 150 msec... a very short time.

Is that good or bad?

David French · Post by **David French** » Tue May 09, 2006 3:49 pm

The bass in your room, with the exception of the 110 Hz slice, looks fantastic. From just looking at the graph, I assume that it sounds incredibly tight. Is that the case? I can't imagine that you need any bass trapping. I think that the slice is due to a single reflection somewhere, but it would be hard, at least for me, find the exact cause.

Yes, the ETC is related to reverb time, adn yes, it is IMO very good that your reverb time is as short as it is.

moby · Post by **moby** » Wed May 10, 2006 10:34 am

The bass in your room, with the exception of the 110 Hz slice, looks fantastic

Glad to hear that

From just looking at the graph, I assume that it sounds incredibly tight. Is that the case?

Yes, sounds very tight, except I not too happy with Tannoy AMS8 low end, but that's out of topic.

I think that the slice is due to a single reflection somewhere, but it would be hard, at least for me, find the exact cause.

I tried to "hide" the back of listening position with massive absorber, and that slice at 110.2 hz greatly improved, but when I move that "mass" a 1m into direction of rear wall slice comes agin. To be honest, will be very happy to solve this 110.2hz problem

Here's the pic what I'm talking about.

Yes, the ETC is related to reverb time, adn yes, it is IMO very good that your reverb time is as short as it is.

Great

Thanks a lot for helping

moby · Post by **moby** » Mon May 15, 2006 12:47 am

Bump

David French · Post by **David French** » Mon May 15, 2006 4:59 am

I don't see any question marks in your last post.

I suppose you're wanting help with the 110 Hz slice. I'm not sure just from looking. Older more experienced chaps might be. I will think more on this.

moby · Post by **moby** » Mon May 15, 2006 11:31 am

I suppose you're wanting help with the 110 Hz slice

Yee, I'm happy with my new studio, but will be more happy if i can do some fine tuning. Start can be to kill that 110hz slice... Unfortunately I don't have any experience about

knightfly · Post by **knightfly** » Tue May 16, 2006 11:25 am

What's the exact distance from your front wall, center, to the center of your rear wall? Also, where is the chair/mic in relation to these two points? Steve

moby · Post by **moby** » Tue May 16, 2006 12:09 pm

Steve, I presume that you are asking about distance fom one brick wall to another... Here's the pic. Distance is 5.20m and Mic was placed at hot spot, (chair) at 2.50m from front wall.
Thanks

moby · Post by **moby** » Fri Jun 02, 2006 1:09 am

Guys, is my description and drawing skimpy or you just in the middle of some business

knightfly · Post by **knightfly** » Fri Jun 02, 2006 9:22 pm

Just been buried for so long I can't remember having 10 minutes that weren't spoken for TWICE

It doesn't seem like your 110 hZ null is anything as simple as a front-to-back axial, although the effect of having the absorber right behind you is interesting; have you tried putting TWO such absorbers (or just a bunch of mineral wool slabs) in BOTH of the rear, outboard corners of the room, diagonally across the corners? Just a thought... Steve

moby · Post by **moby** » Wed Jun 28, 2006 12:10 am

have you tried putting TWO such absorbers (or just a bunch of mineral wool slabs) in BOTH of the rear, outboard corners of the room, diagonally across the corners? Just a thought... Steve

Thanks Steve. I will. Just tell me are you talking about corners of brick wall or inside c. room walls? To do that with "brick" (to me it's probably the position) corners I have to "fight" with lot of hangers behind false rear wall, but will do that