So far, I have ordered and received Mills MRA-12 resistors from Sonic Craft (the only vendor that had all the correct values). Mills should be a step up from the ERSE resistors used in many Thiel models. All but one of the resistors on my SE boards were not labeled with manufacturer but they are probably ERSE (or Xicon). I considered every resistor I could find that met Thiel’s spec. Dueland and Path Audio are widely regarded as the best resistors available but these are crazy expensive (~$30 each compared to ~$5 for Mills) and subjective reviews suggest their sonic performance is not commensurate with their price (hey, that sounds like a LOT of things in audio!). Mills MRA, I think, represents a clear upgrade over Thiel’s OEM resistors while also representing good value. Tom agrees and these will probably be included in the forthcoming kits.
I have these installed only on one channel so far. It took me about 3 hours and a second pair of hands but the second speaker should go faster with my experience other than there’s no help for my soldering gun which is less than professional grade (Tom Thiel recommended at least 140 W for the lead-free solder on Thiel boards; my gun is 180 W). I did this just yesterday, so no burn in time tho’ Tom thinks this is not necessary for resistors. My initial impression is that lower-level “grunge” has been removed, ie, the noise floor seems lowered. This is subtle but is quite worthwhile for the sound I seek! I will listen/compare more before I upgrade the other speaker, including in mono one speaker at a time. Look for further updates in the coming days and weeks.
Tom has been researching the many options among capacitors, including bypasses. He is very close to a final parts list for his Power Points and CS2.2 as well as my CS2.4, and has the layouts worked out (apparently, the CS3.6 will also be among his first “hot-rods”). He is planning point-to-point connections. My SEs, built in 2012 around the time Kathy Gornik sold Thiel, have printed circuit boards so Tom thinks I will hear an improvement just from that simple change. Only the coils and styrene bypass caps will be salvaged from the original boards. Most of the new caps will be sourced from Clarity and are custom sizes so it will be a few more weeks before he has these (and another delay before the kits become available).
Mr. Thiel’s goal is to maintain Thiel Audio’s adherence to neutrality, high resolution and fidelity to the input signal while improving the overall sonics via superior passive parts. But he also is balancing value, so e$$$oteric parts may not be on his list. Instead, I expect to see/hear a well-considered crossover upgrade that should be a readily audible sonic improvement - even compared to my SEs - yet in line with Thiel Audio’s value-oriented approach.
Tom is still in the “hot-rod kit” development process but I want to get this out now because he is wondering about the demand for taking the new crossovers outboard, ie, the new boards would be in their own cabinet just behind each speaker. The advantage of outboard is maximized sonic performance via isolation from physical and microphonic resonances. This would also allow substantially better cooling which is important for those who listen loudly! I think this would also be easier to install for DIYers (I’m guessing the eventual kits will be DIY or send your speakers to Coherent Source for Rob Gillum to do the work). Tom has the shop to potentially match our cabinets (altho’ black would be easier and matches the front baffle of most Thiels). I imagine a XO cabinet would be the same width as our main cabinets, maybe a foot or so tall. Finally, an outboard solution would increase the options for new bracing to further reduce main cabinet resonances. The main (only?) downside of an outboard crossover is reduced WAF.
Tom would like input from the larger community as he finalizes his plans. So, please respond “yea” or “nay” regarding outboard crossovers so that he can gauge interest.
Here is an example of an outboard crossover (Avalon Ascent): https://usato.audiograffiti.com/annunci/diffusori-acustici/167157/
and: http://www.hifido.co.jp/KWB/G0201/E/400-10/C15-87521-47650-00/
Put me down for “yea”.