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Talk but not walk?

Hi Guys

This isn't meant to start a fight, but it is important to on lookers. As a qualifier, I have my own audio forum where we report on audio issues as we empirically test them. It helps us short cut on theories and developing methods of listening. We have a wide range of systems and they are all over the world adding their experiences to the mix. Some are engineers, some are artist and others are audiophiles both new and old. One question I am almost always asked while I am visiting other forums, from some of my members and also members of the forum I am visiting is, why do so many HEA hobbyist talk theory without any, or very limited, empirical testing or experience?

I have been around empirical testing labs since I was a kid, and one thing that is certain is, you can always tell if someone is talking without walking. Right now on this forum there are easily 20 threads going on where folks are talking theory and there is absolutely no doubt to any of us who have actually done the testing needed, that the guy talking has never done the actual empirical testing themselves. I've seen this happen with HEA reviewers and designers and a ton of hobbyist. My question is this, why?

You would think that this hobby would be about listening and experience, so why are there so many myths created and why, in this hobby in particular, do people claim they know something without ever experimenting or being part of a team of empirical science folks. It's not that hard to setup a real empirical testing ground, so why don't we see this happen?

I'm not asking for peoples credentials, and I'm not asking to be trolled, I'm simply asking why talk and not walk? In many ways HEA is on pause while the rest of audio innovation is moving forward. I'm also not asking you guys to defend HEA, we've all heard it been there done it. What I'm asking is a very simple question in a hobby that is suppose to be based on "doing", why fake it?

thanks, be polite

Michael Green

www.michaelgreenaudio.net


michaelgreenaudio
elizabeth
6,726 posts
 
(added ten minutes later: sorry about this rant. I just had to.. But it is nothing to do with the topic, other than thinking for yourself instead of just parroting other’s notions.)
I would comment on the 10ms delay thing.. If one ONLY looks at the single line (instead of endless ones all way) from the back directly behind the speaker. But the reality is the waves travel away in all directions. So my 20.7 being 42" nearest, and 58.5" (they are angled in a lot) farthest from direct back wall line, are actually an infinite variety of distances! The shortest being 45" from actual tweeter location, varying up to about ten feet to the opposite side back wall! I just take issue with using a single measurement, then claiming it is the theory answer. Well it is not. The distance of reflection is changing all across the back wall as the reflections of the sound hit all along the wall and bounce every which way..
Now I do have to say perhaps the ’main’ reflection is the angle from the rear of the speaker to the wall to the space between the speakers at the listener... However the percentage of the total surrounding sound from that tiny little line is pretty small. (if you calculate the actual space, vs all the space as a fraction.. Maybe 0.25% (guessing) of all the sound from the back.. and IMO is lost in the mix. So the made up rule of five feet is just that made up to fit a theory, which theory used in the rule of five feet... IMO is wrong. So the distance planar speaker should be from the back wall... may be anywhere from a few feet, to whatever sounds good... relying on made up theory is not good unless you think it through yourself. Way too often it is just repeated malarkey someone thought made sense.PS the ’five feet’ seemed to suddenly appear just a few years ago. Prior to that everyone was 2 to 3 with 3 being considered best. Then, suddenly the 10ms thing popped up and the five feet became the suggested distance. all based on the theory of 10ms and the first reflection. and nothing to do with actual use Like someone invented it and it suddenly became popular... Just whining.. feel free to "harrump" in disgust that anyone would dare to challenge a theory.
geoffkait's avatar
geoffkait
14,147 posts
 
Rather than just guessing, I don’t know why people don’t adopt a sure thing. The out of phase track on Test CDs like the XLO Test CD is just the ticket for finding the absolute best locations for any speaker in any room. And with any level of room treatment, from zero to $20,000. As you improve room acoustics over time the track will allow you keep track and find the best locations as you progress. It’s fool proof. Hel-loo! Trying to calculate or guesstimate or move a little/ listen a little will not work. They will provide only local maximums. You need a guaranteed method. Trial and error methods are like trying to solve x simultaneous equations in x + n unknowns.

Don’t be a cube, rube. Go ape! 🦍
elizabeth
6,726 posts
 
OK Geoff, explain how one uses the out of phase to position speakers... ???
geoffkait's avatar
geoffkait
14,147 posts
 
The best sound and best stereo imaging will occur for the case when the most diffuse sound is obtained using the out of phase track. Assuming your system is in Correct Polarity to begin with. See last sentence. You should hear the sound coming from all around you, from no particular direction. When you get as close as possible to that situation with the system out of phase, after carefully moving the speakers a little at a time from an initial position about 4 feet apart, that’s where the absolute best speaker locations will be. Of course the out of phase track will also highlight whether your system is in correct or reverse Polarity, also nice to know.

However, it might very well not be possible to obtain this magical case where the sound is coming at you equally from all directions, no matter where the speakers are. That’s because the room is not treated enough or not treated correctly. Fortunately, the out of phase track allows one to redo room treatments, as required, to have better success with the out of phase track.
bdp24's avatar
bdp24
4,908 posts
 

My 5’/10ms figure was suggested as the minimum distance a planar should be expected to need for anyone contemplating such a speaker. Of course reflections are more than a single line from the back of the speaker to the wall behind the speaker, and then theoretically back to the speaker, and then theoretically to the listener. The fact remains, however, that if you position a planar closer than 5’ from the wall behind it, there will be the very real possibility of negative consequences. If you have ten feet to spare, all the better! If you have less than five feet, you have been warned. I have had Maggies and QUADs 3’ from the wall, and have found 5’ to provide a definite improvement. I have never had 10’, but would sure like to!

But remember, it is the 10ms delay between the front and rear waves that is important, not the 5’ distance. You can create that 10ms delay by any means you choose; if heavy tow-in causes the rear wave to reflect off more surfaces, thereby delaying its arrival at your ears to 10ms or more in relation to the front wave, great! By the way, that 5’/10ms figure was not pulled out of thin air, it is the inevitable consequence of the behavior of sound---physics, and the brains processing of sound arriving at the ears from the same direction but at different times. "Toeing-in" a planar speaker provides benefits in a couple of ways, one of which is to decrease the direct reflection off the wall coming straight back at the speaker; toe-in scatters the rear wave, but not as effectively and predictably as do properly designed and built true diffusers (RPG, ASC, GIK, DIY, etc.).

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