Thiel Owners

I understand Tom Thiel has been working with surface treatment of a speaker baffle to enhance laminar flow while also reducing interfering energy. This energy migrates back and forth on a vibrating surface and causes a pile up of noise that does return back down the speaker cone colliding with the next wave launch. Everything vibrates and everything that does generates shear waves of many types. Shear waves travel in 2 or more directions and their collision create an infinite amount of more collisions.  These shear waves only travel in solids and all materials have a different shear velocity. The music we hear is the result of air affected by the shear generated in these solids. The air contacts the solid surface, so the air vibrates, and we hear those vibrations as sounds. Shear wave velocity passing thru any carpet will be changed by the material and the density. Hardwood and glass both have their own unique velocity. Look at your room materials and shape that is why they sound different. The compressive wave upon impact creates shear wave and those in turn travel and impact other solids and make more shear and compressive waves. And the beat goes on...This is a regenerative process. Because these vibrations generate sound you don't want to kill them all. It's tough to be selective without causing more harm than good. 

The early work of Jon Dahlquist and his use of spray materials. Spray flocking on the baffle and spray Nextel on the cabinet was the first surface treatment that ever made a profound impact on the sound of a speaker cabinet with no woof tones just more refinement and clarity. I know this impact as I heard the same cabinet untreated and then months later returned to me as treated.

Bud Purvine's patent on the Enabl process probably achieves much the same but applied directly to the driver surfaces His method launches away polarities of shear and Raleigh waves so they reduce collisions with the next wave launch..Bud now considers these waves as Rayleigh waves. 

standingwaves (positive-feedback.com)

Over the last year I implemented laminar flow devices I have built and placed in strategic front locations of my 27/21/9 ft room. I also have for years used now 3 Natural wool panels on the front wall 1 each at the side reflection points. The laminar devices are inexpensive to make and are the biggest acoustic improvement I have made over the last 49 years. They are a wow factor.  Small in stature they seem to comb bass frequencies making my dueling 12s enhance the mid frequencies. With placement the vocal clarity now coming out of the rear mounted ports is nearly as clear as what comes out of the front mounted drivers. They clarify the instrument location all along the watchtower. The sound stage is panoramic even more so when the active device is engaged. Pretty much the room boundaries and its contents are gone. Looking forward to seeing and hearing the Pauley and Thiel front baffle treatment..Tom D

Tom - thanks for your comments. The entire arena fascinates me on multiple fronts. First is that "the problem" had been solved to our (Thiel's) satisfaction by 1983 with the CS3 contoured baffles that practically eliminated diffraction and baffle congestion. I didn't think a further problem existed.

My first hint was a demonstration that Doug Pauley did for a professional group (using a Tannoy speaker), that blew us away. We gathered further observational input from some leading audio industry luminaries, but the mechanics still remained mostly mysterious.

I pursued felt and flocking and Nextel, although I was unaware of Jon Dahlquist's explorations. Some of you beta-tested some of those solutions. They address the problem.

Then there was the CS3.6 thing that some of you reported where sometimes there was a screeching / pulsing / hashing, but no cause could be found. A couple months later I had narrowed down these so called 'sheer or propagation waves' on the baffle surface, primarily the flat area above the tweeter. 

The collaboration with Doug has applied his patented surface treatments for real advances toward mitigating a problem that had been unknown, unreported or otherwise invisible - but not inaudible.

BTW: you and I are on similar paths. I also ended up with genuine wool (F11) strategically placed on the walls. Also, there's a somewhat expensive addition via Ultrasuede - the real stuff - in the finest grade. US over F11 is where I was going before Doug came along and opened Pandora's Box. Thanks for the link and references.

All of this interference is nearly invisible and maybe at this point is not measurable but can certainly be seen in my mind's eye as myself and a friend have listened here and at his house. When I made my port treatment on my recent speaker rebuild, I couldn't believe the improved clarity of detail now coming out of the port everything improved. The tweaking of the bass frequencies was the catalyst, but what occurred was an enhancement of vocals and their placement.  So in search of a more specific solution, I may have found a solution to reduce some boundary interference which degenerates laminar flow. In a phone call about three years ago I mentioned my Dahlquist and Bud Purvine experience with you. Those 2 improvements I understand. The EnABL process by Bud Purvine took me a long time to figure out with the help of my geophysicist friend Debbie Miles. What I am doing now I cannot seem to measure but the improvements are pretty damn exciting. Tom D

tomthiel

Thank you very much for your response and wonderful history lesson on the CS3. I was 18 when my uncle purchased these and I learned most of what I know about jazz from him, and through the CS3's. Lovely memories.  

As I mentioned, the tweeter cavity is not deep enough for the Morel and I'm hoping for advice on the best method of modifying it. The long screw at the center of the cavity appears to be an important part of the structural integrity, so I imagine removing it and simply opening the cavity completely is not the best course. What would you advise? Also hoping for a couple suggestions on a repair technician for the bass equalizer.

Thanks again 

Jim - let's revisit your actual questions:

Tweeter cavity - I don't remember that tweeter mounting having a back in the cavity. It is possible that the early iterations, like yours, had it and it didn't stick or that you have an aftermarket tweak.

The first order of business is to make your tweeter fit, and if you lose that closed back, don't worry about it. If you keep it, a bolt  from there to the back would best be non-conductive and at least be non-magnetic. If yours is magnetic it may be causing more harm than good.

Onward to deepening the hole. Router bits are available with a flush-trim ball-bearing at the shaft end of the cutter. That bearing guides against the circumference of the mounting cavity and can be set to any depth. If you're not equipped, many woodworking shops would have such a setup.

Regarding repair of your EQ. I highly recommend Bill Thalmann of Music Technology in Springfield Virginia. He has the schematic and knowledge for repair. However, some parts are no longer available. We are working on an update. Meanwhile send me a PM to possibly trade yours for one I have here.