Hearing is believing....WOW! - Page 8

For what it is worth, my own experience is that spiking the loudspeaker/stand through the carpet to ‘grip’ a wooden floor seems to have a noticeable effect when I have tried it, and I think I prefer it in the main audio system I use. However there is no guarantee this impression would be the same in every case, or that you would agree with my preference, or indeed that I am not imagining the change it made! I can't say that I have ever had the feeling that spikes which do not drive through the carpet had any audible effect. Where genuine vibration isolation or vibration absorption are required my experience (plus the analysis and measurements I have mentioned) make me doubt that cones/spikes of hard material are a good bet. My own experience is that something like soft rubber feet (bumper buttons), or felt feet are more effective for isolation purposes.

Originally Posted by 4DHD

At 80 htz, where most people have the XO set, there is not much difference (2~3 db). Certainly not enough to warrant the cost.
My first impression is those subtraps are more snake oil than anything else. Much like using "cable lifts" for speaker wire, or $5000 speaker cables.

"Rule of Thumb:

* An average home in the U.S. has a ceiling about 8ft high.
* Rule of 25: It is normally a good idea to put the sub approximately up to 25% away from the boundaries. For a riser, it means ceiling & floor.
* 8ft x 0.25 = 2ft.
* Raise your subwoofer approximately 2ft or less. You can also try to hang it 2ft away from the ceiling, but do it at your own risk. The WAF is waiting.

Rule of Thumb:

* An average home in the U.S. has a ceiling about 8ft high.
* Rule of 25: It is normally a good idea to put the sub approximately up to 25% away from the boundaries. For a riser, it means ceiling & floor.
* 8ft x 0.25 = 2ft.
* Raise your subwoofer approximately 2ft. You can also try to hang it 2ft away from the ceiling, but do it at your own risk. The WAF is waiting.

Originally Posted by A9X-308

Remember my graph back in post 23? 2' still isn't going to affect anything in the typical sub's operating BW.

Originally Posted by 4DHD

I just started reading this thread today. And my thought process was IF raising subs off the floor really worked, the likes of Harman would have mentioned it in their white papers concerning subs. And those papers were written by Dr. Floyd Toole and Sean Olive.

So as I mentioned earlier today, just more snake oil. And as is quite common, the people who spend tens of thousands of dollars, if not hundreds of thousands, buy into all this extra crap, like $5000 speaker wire or interconnects.

As far as do we sometimes hear what we WANT, at times, YES!

Originally Posted by aackthpt

I don't think they were going to try something that a reasonable person mightn't try anyway (or that they couldn't make a product large enough volume to sell at a profit). Because they do say to put a sub halfway across the width of the room to eliminate the first width mode, similarly with two subs at quarter points. A concept which is directly extensible to any dimension of the room. But the average person is not going to put a sub halfway up or higher in his room, not a chance.

Some enthusiasts aren't reasonable in that sense, and will do whatever it takes to improve their sound quality. Evidently Dr. Geddes isn't reasonable either, given his suggestion to place one of the three subs above the room centerline. I think he's one of us!

That said, placebo effect and expectation bias is powerful. Even Thomas Edison was known to say (related to his cheaty demonstrations of the audio quality of the phonograph) "People will hear what you tell them to hear."

One observation on testing: with modal issues, taking a measurement at a single point may not tell you if an improvement has been made. Imagine a listener at the center of the room in all three dimensions - it's a null for the first axial mode in every direction. It won't matter if you put the speaker where it drives those modes or not, the mic won't hear it. Therefore, to really know if you have changed anything you have to either place the mic in a corner, or else you need to measure in multiple locations. Though if all you care about is audio quality in one location, obviously you only need to measure in that one location. This is why one of the first things I do when analyzing a room is put a sub in a corner, put a mic in a different corner, and run a LF sweep. It tells you all of the modes you may find to be problematic anywhere in the room.

If you read Dr. Geddes' stuff, he used targets of both flat response on average AND how much deviation there was in FR between the different listening positions.

Originally Posted by Joe Skubinski

So let's get this straight. You place a sub 2.5 feet above the floor and expect the room and the sub to do new tricks with dramatic changes in the waterfall plot at the listening position? Think about this-- much of what you see in the plot is the room- you made no changes to the room.

There were changes in decay, dramatic, of course not, but a few hundred milliseconds here and there at various freq's that may be audible (no comment on how it sounds).

What if you had multiple subs, or even different subs, say in a room with a typical OSB floor? Would the effect be additive? You need to keep in mind that you have only tested one scenario, in one room, on concrete. You did not test the sub in an anechoic to see how it's output may be affected by a change in coupling, nor the floor for the same. It's quite possible that as a source of sound, a change in the coupling of it's cabinet changes the sound quality.

And where is the test correlation between this, and speaker wire or interconnects? 4DHD mentioned it twice as to make a connection with this test- there is no connection.