Thiel Owners

Adding to Beetle’s excellent summary, here’s a cheapskate trick for the Thiel resistors that you might keep.

Turns out, a big part of those resistors’ ’sonic problem’ is the thermodynamics due to their mounting. They are non-inductive wire-wound with current flowing around their coil circumference, dissipating into the ceramic body. The bottom of that body is glued to the panel, creating a large differential in wire heat distribution. Solution is to mount that same resistor on an edge rather than a flat. Put the edge on Mortite / BluTac pads for even better results. Cheap fix, much of the improvement of Mills, suitable for woofer and midrange. Spend your savings on a Path, etc. for the 12Z tweeter feed.

pieper

try using parallel resistors 

http://www.sengpielaudio.com/calculator-parallel.htm

a 20 and a 30 = 12

Nice tweak, @tomthiel Curious to hear the back story on how you discovered that.

@pieper1973 you have CS2.4, right? Why do you want 12 ohms?

Also, I forgot to mention one of the Mundorf lines is comparable to Mills . . . It’s a re-badged Ohmite.

Beetle - I looked extensively at thermal dynamics as a source of 'aural congestion', drifting crosspoints, etc. That's where the new layouts came from, which have all the resistors separated from caps as well as positioned over ventilation holes in the board for natural convection, and moved either to the exterior of the cabinet or to separate XO enclosures. The hookup wire(s) also mount to pin-type heat exchangers close to each driver to drain voicecoil heat directly through the lead wires. Taken together the thermal management significantly improves dynamic range and 'sonic orderliness' during high-power use. The small-signal Thiel reputation got bigger.

My investigation began by remembering 'warranty claims' for melted caps and charred XO boards in the old days. In my power tests, some resistors got too hot to touch. Series coils also get hot - I put them on 3 rubber feet for all-round radiating and convection. My tool of choice is a non-contact infra-red thermometer to identify small scale/ local differentials. That led to some heat-sinks being added in-line on the XO board for dissipation before entering caps. I don't remember at what stage all that investigation stood when we hot-rodded your 2.4s. There's always more. 

@beetlemania 

Among others I have the 2.4 ..

The 12 Ohm is needed for my one point monitor with the SCS3-N Thiel coaxes.

Audi, I don't want to combine resistors to get to 12 Ohm. I'm just looking for a good substitute for the Mills, if anybody knows of one..