Thiel Owners

jon - I also enjoy the time I steal to write these messages.
Note that I am reconstructing history from various supplier records and so forth. What I believe is that the 3.6 was upgraded in Feb 1996 via XO component changes for smoother performance (3.6.1) and again in March 1999 to separate some film caps on the woofer/tweeter board from resistors to eliminate overheating (3.6.2). You have 3.6.1s, but may have hot caps. That upper board is behind the passive radiator. Cap damage would show as melted spots where touching white rectangular resistors. If you see no melted caps and the speakers sound good, you're OK. If there's trouble, Rob can help you.

Now for a little fun behind the curtain. My crossover modifications are specifically dealing with heat management, like in pro gear. All the layouts are modified to place all resistors along a central bar where the upgraded MRA resistors are mounted in metal clips screwed to the aluminum bar which is sunk to the input panel plus possibly a back-mounted heat sink. The result will preclude heat damage, but is also intended to introduce thermal stability to keep XO crosspoint behavior more stable during hard use. Congestion at FFF is mostly amplifier deficiency, but also includes value drift in hot components. Beetlemania's 2.4s will attach the hot bar to the SE input plate. Coils are also being elevated for 3D radiant cooling; likewise the caps are lifted from the board and the board is lifted from the cabinet wall for vibration isolation as well as thermal stability. Whew!

My 2.2s are getting real serious treatment of an additional chimney-spine: a square tube up the back and vented at the back center of the top. That chimney sucks cold air from the floor to exit at the top and sinks the XO hot bars as well as an aluminum tube from each driver to sink magnet heat plus provide additional recoil resistance for the drivers. If all unfolds as dreamt, such a modification could be available from Coherent Source Service as a Full Tilt Boogie Upgrade. My 2.2s include double bypassed caps and 4-9s foil coils in all series feed positions. The original 4-9s coils are retained in the shunts.

Good day all.
Tom

@tomthiel, wouldn’t an outboard cross-over be a simpler way to achieve the same results and reduce vibration issues at the same time?

unsound - there are real advantages for outboarding, and time may lead there. I have laid out the crossovers in outboard configuration.  However, there are problems along with advantages. The separate enclosure flunked the appeal census by a wide margin. The electromagnetic field interactions of coils would require a fairly large enclosure. And the wire-cable between the XO and the drivers is a critical link that invites unknowns because an external XO might be moved, adding additional cable of unknown parameters, which could seriously impact the signal at the drivers. That cable snake requires engineering-development that I am not presently prepared to provide. Many of those disadvantages could be overcome by piggy-backing the XO on the back of the cabinet, but that reintroduces some of the problems.

All things considered, including my limited time and resources, led to starting with the XOs remaining internal, which also preserves the classic Thiel value of simplicity of use.

For the CS2.4 owners, how does one have access to the XO?
Do the drivers have to be removed? Or can the XO be
accessed from the bottom of the cabinets?

The 2.4 XOs are accessed from the passive radiator.