Thiel Owners

That's 1-2 dB at 20k.

Tom D - welcome to the rabbit hole. Electrical and electromagnetic fields are a huge issue. In my opinion this issue deserved more attention than Jim gave it. As time went on, Jim's XO position moved farther from the drivers. Note the 3.7's location in a separate chamber in the bottom of the cabinet.

In the development of 1978's 03, we mounted the XO on the cabinet bottom, as far from the woofer field as possible. The interactions are significant. My clearest memory was noting the difference between the breadboarded 3 dimensional rat's nest crossover hanging in space / compared against the conglomerated XO on a board in relative proximity to the woofer (and other drivers) as well as closer to each other. The aural congestion was significant.

I had an aha similar to yours in my work on the CS2.2 a couple years ago using an EMF field meter which showed strong fields extending about 2' behind the woofer. I'm staying outboard when possible, and if not (such as a minimalist upgrade) it's going under or on the outside of the cabinet, in free air, far away from drivers.

Among the issues are vibration, which can be controlled via shock mounting.

Also, heat build-up changes circuit performance.

And there are proximity effects, both between components and in relation to the drivers. Those aspects interact because the coils (especially) must be positioned not only in relation to each other, but in relation to the flux lines of the driver fields, which can be a bigger deal than between the XO parts themselves.

MuMetal, etc. is quite technical and frequency and density related, generally requiring complete cages around components, which can exacerbate thermal considerations and reluctance interactions between the propagation fields in the coil wire. It's a jungle. I have found that physical distance and positioning geometry are more fertile avenues toward global solutions.

Regarding your preference for the sound of unbound coils - be very careful. Motion can induce various interactions with all other elements. Stillness is the goal (IMHO). As a generalization, many kinds of 'distortion' can be seductively appealing; sorting it out is a hard, complex problem. Where I've settled is that coils on rubber feet are strapped to the board. The feet increase and equalize thermal radiation , while mechanical motion is minimized as well as audio vibration frequency decreased to where the coils seem to not be stimulated into motion.

The position of coils can be optimized via listening to noise. The puzzle is hard because virtually all coils affect all others, and there are too many permutations to test (in a complex Jim Thiel crossover.)

There is another aspect that is real, but beyond my understanding, but here goes. Wire, at least new wire, has directional sonic properties. But I've found no reliable way (except Cardas wire) to track the directionality of wire. However, these effects seem to diminish with play-in time. I have chosen to ignore wire direction because I'm using played-in wire, and I can't do anything about it when re-using Thiel coils. In addition to spatial attitude, that leaves feed vs load of the coil. I have demonstrated to my own satisfaction (but contrary to common opinion) that coils are best fed from their circumference and tapped at their core with attention paid to lead wire dressing. I also note that as time passed, Thiel's crossovers tended to migrate toward this (outer to inner) feed direction.

Tom T.

Thanks, Tom Thiel, for your experienced and insightful response.

I have heard the sounds of Barkhausen noise generated by the rapid change in magnetic fields. I know this firsthand in my use and experiments with magnetic materials, varying field strength and geometric shapes within prototypes of my products for acoustic instruments.  

I will take what I learned in close quarters about my devices for acoustic instruments and expand into this speaker project. Hope it is no deeper than a rabbit hole and less than a Minute Man Silo.  Still learning after all these years. TomD

Tom, I'm glad you've experiened Barkhausen noise - it is baffling on first encounter. Actually hearing effects from change of state electron spin is mind-boggling, until you grasp that the audio cortex can hear practically everything. My first exposure was in developing an electric pickup for acoustic instruments which sense geo-location of the string rather than acceleration or electromagnetic changes. We worked it out and the insights gained have remained, as yours have with you.

Isn't audio a trip?

Hi fellow Thiel owners,

Finally, with a help of a very good and close friend (who is the previous owner of the Thiel CS 2.7), we managed to replace the previous pair of coaxial drivers with the newer pair of coaxial drivers from Rob, Coherent Source.

At this point of posting, I had them running in with my music playlist for about 8 hours continuously now and at approximately -6 dB from my usual listening volume.

I am happy to share with you all that these newer pairs of coaxial drivers sing more lively, more unveiling, transparent, yet almost laser-focused imaging in a 3-dimensional soundstage. I cannot wait to hear how it sounds after clocking in more hours on these.