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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
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michaelgreenaudio's avatar
michaelgreenaudio OP
1,019 posts
 

Hi glupson

OK, Laminar flow, effect or line.

You & Geoff were on target for the name even though my use of the words had to be bent some as I looked at what to call the energy there. If you look on TuneLand you can see the drawings and more description but for the short version here laminar effect works like this. When a source produces the oscillatory motion in a room it stimulates the already established patterns of pressure. Meaning the info contained in the new motion may be different but the pattern has been in play since the enclosure (room, house, dissipative mingle) was built. Part of these mechanics is the room's walls, ceiling and floor. Your room is electronically charged by the Earth's fields. It's actually a continuum capacitor, not only because it is enclosed but also because most homes have electrical wiring surrounding the internal structure.

Geoff talks about "time of day" listening. This is a very real event that never stops. Not only does the cycle have certain shifts but also seasonal shifts change the Earth's fundamental interactions inside of every room. Your not hearing things, or should I say you are hearing things. Your hearing things and your feeling things all the time and even though you might think your standing or sitting still watch what happens when you have an inner ear infection, you loose your balance. That's all part of the power your system has. To listen to your particular laminar effect in your room is simple. Pick a wall with not much on it. If you start talking aloud in the center of the room and move toward that wall, when you get about 8" or so from the wall you will hear a sort of splashing sound that travels along the wall heading toward the intersections (seams) of the room. Back away and move forward a few times and you can pin point where the on coming sound pressure engages with the pressure coming back off the wall. This is called the laminar line. From the laminar line to the wall itself is called the laminar flow. Every suface in your room that is able to produce a reflection has a laminar effect. As I said earlier it's a continuum. You don't turn it on or off it's always there.

Walk inside of your house and listen to the different sounds of each of your rooms. They all sound different. That's because the materials and their structure (LxWxH) are all different. There's more but I usually break things down to 4 variables, size, material, gravity and charge. How much does the laminar effect play in this? Get 2 friends of yours and try this free experiment. Cut 2 pieces of cardboard out 5"x24". Place your ear about 5" from that wall we were listening to. Have your friends from either side approach you with the cardboards edge touching the wall (the cardboard will be out from the wall about 5"). If you look on TuneLand you will see this. As they approach you from either side you will hear the Laminar zone shrink and as they get right up to you it will sound like the rest of the room has somewhat disappeared. Have them move in the other direction and you will hear the zone open up again. Once you start playing with this you can make your own Sound Shutters out of cardboard or hobby wood and you will be shocked by the control you will gain over your walls.

Michael Green

www.michaelgreenaudio.net

amg56's avatar
amg56
887 posts
 

All this makes interesting, if not debatable reading. I have been to what is one of the acoustically greatest stages in the world, the Sydney Opera House. The magic that happens there is truly a wonder of the world. If I could get my music room to sound 10% of that I would be a happy man. If I could afford I could a worthy stereo, I'd be happy.

I read recently about the work Franck Tchang did with his static resonators with different metallic properties. Fascinating. Then there is the SOH with its phenomenal acoustic properties. I haven't travelled to the majestic concert hall of the world, but I will freely admit that acoustics can be changed using all sorts of materials and placement.

I would not think there is one spot where a stereo system is perfect in placement in a room. What does change though is the listeners perception of change. I can sit in one chair or another in my lounge and the same LP will sound perceptively different, or the hearing in my ears are way different. Probably the way the breeze passes from one and out the other... :)

michaelgreenaudio's avatar
michaelgreenaudio OP
1,019 posts
 

The Tunable Speakers

I’ve been making speakers a long time like many of you. Early on in my adventures I noticed a problem. Everytime I walked into a different recording studio the same speakers sounded different and I ended up spending all kinds of time playing with the EQ to try to find a reference point between the "Live Room" and the "Control Room" and than there was the playback or "Mastering Room". Guys would take the recordings and play them in their cars, and some used headphones and some just decided to suffer through the control room monitors. You’ve all seen pictures of the recording console with several different pairs of speakers. Many times JBL, NS10’s and one or two others on stand by.

In the late 70’s I finally got tired of having to deal with this when I was doing the setups, and I started playing with the idea of making a speaker that I could use with some kind of consistency. For years I would build custom speaker stands and speakers and speaker clamps until I finally landed on something that worked for me. The first tunable speakers were crude torture looking things, but they worked and studios started using them for main mix down monitors the "studio 5". Time went on and I was asked to be the acoustician for UMI (United Musical Instruments). This opened up the door to work more closely with the actual making of horns, wood winds, cellos, guitar, violins, violas and the coolest of cool, building rooms for Steinways.

Around 1989 or so I started to make my speakers out of instrument woods instead of MDF and found tons more tone to play with. This put into action the next 15 plus years in design hunting for the right drivers and parts and pieces so that I could make the most simple to drive speaker that I could (and low mass). For tweeters I used ribbons, silk domes, horns and pretty much the full range of everything I could find. Every time I went more complicated I ended up needing crossover work done and my goal was to go crossoverless. I had found the sound of the cap I wanted to use but drivers were a bugger. Finally I threw out everything and started from scratch. On the cabinet side I was doing pretty well as I got the inside tuning bar down to a science. The Tuning bar works like this. Instead of building heavy cabinets the tuning bar applies the force from the inside and the tuning bolt and washer on the outside supplies the inward force. Because the cabinet has both inside and outside force going on you can adjust the cabinets tone. Where most cabinet designs push outward mine equalize the pressure. The wood of the speaker is low mass compressed board treated with instrument finish. Except for the front baffle board which is a guitar body board. The whole speaker is then veneered in cherry.

The drivers however were a pain. I didn’t like anything I heard. There use to be some nice stamped drivers made in Europe but lately nothing that was what I wanted. I decided on modifying the standard Vifa D27 or ScanSpeak but still I wasn’t happy. Then it dawned on me to make my own baskets. This changed everything. I saw Kosst said I used 3.5" paper tweeters (stamped) as if that was a bad thing lol. Well it would be a bad thing except my baskets are redwood. Again the "walk" Kosst. All my drivers are redwood voiced drivers. The tone is out of this world. Ask the folks who have them. They’re pretty darn snappy pappy:)

The tuning is just as cool as the speaker. Lets say I’m playing cymbals and they are a little loose sounding. Lets say the halos are a tad too wooly. All you do is barely tighten the Tuning Bolt and the cymbal will tighten right up. The new Revs are pretty special. And yes if someone wants the ribbon or silks we do custom sets. We’re doing a set of ribbons right now.

Michael Green

www.michaelgreenaudio.net

tjbhuler's avatar
tjbhuler
55 posts
 
I can see some confusion that many people are facing concerning words like laminar flow or pressure zones. Well not to worry even initially I too had a though time trying to wrap my head around it. How would one define the meaning on laminar flow or pressure zones? Where are all these found in a given space or room? What is the first step should I do in order to have an understanding on them? Well these were all the questions that I was asking to myself again and again.

After years of practicing hopefully i could shed some light to those who are still not clear on them. It has got to do with pressure build up by your room itself. For an example if you walk out from a room to an open space your voice will sound open, less focussed and the loudness will be lesser as in comparison when you are in an enclosed space. This is a simple example on what a pressure in a room is causing towords our speakers when they are singing away and activiating or loading a given room. Of course speaker to room size ratio and thier placement is important as that will also determine how much of pressure zones will it activate in a room. Now what we are tuning here are these pressure zones. To give them a much more effective and organized way to work with our speaker and room itself. Pressure zones will be more towards acoustical space within the room itself and laminar flow are the pressure build up around the corners travelling along the walls of the room.

I tune them by using my voice which i hear and feel the resonance within me. Hearing a change of tone and openness in my voice dictates if the flow is moving away or concentrated in that one particular area. Now I'm not here to argue or prove myself at all. Bringing in physics and other methodological manner is not what im interested as what im doing is more than enough for me to understand and make it work for me. But what I would love to hear from others here is to give it a try by voicing yourself in your room and listen for the changes this itself should give you some idea on what is tuning all about. Now from what Michael has mentioned above concerning those simple cardboard excersises was exactly what I did a few years back which brought out a whole different way of thinking and mind set to me in this hobby.

Now onto what Bill has mention concerning on addressing mechanical and eletrical side this is another level of tuning that is equally important. I have removed most of my cable ties in my equipments that I can get my hands on and to be honest I was shocked with the improvments heard and it was a big improvment. As I said I came in with an open mind to what Michael has to offer and was very happy with the results. What got me thinking was how much of improvments I got just from listening to Michaels advise which was tottaly free. Of course knowing that he has such great depth of knowledge eventually gained my trust and of course I looked onto his products to augment my system more.


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