Thiel Owners

Hmmm...a pair of CS 7 available locally for $3k?  Cabinets appear fair...

I’m also looking at a Modwright KWI200 integrated which would give me an additional 100 watts @ 4 ohms.  

Damn you, Audiogon!

beetle, the actual combined cap value is important for proper tonal balance and phase addition thru the XO region. I like the CSA +, + with the 0.33 being a teflon or other ultra-grade cap if possible. Ultra bypasses are far less important on the woofer, put more value on the coax feeds with less value on the traps (where the electrolytics are.)

Mono is good for critical analysis, either from a mono source or summed in the preamp.

oblong, Rob might have an upgrade path for those CS7s. Note: 5' from the back wall gives you about 5ms reflection delay where the ear-brain identifies it as a reflection and not smear of the initial signal. That's where the big Thiels come to life.

Tom

I like the CSA +, + with the 0.33 being a teflon or other ultra-grade cap if possible. Ultra bypasses are far less important on the woofer, put more value on the coax feeds

Thanks for this, Tom!

I have yet to remove the passive radiator to take a look for myself but the pics I've found on the 'net suggest a problem I hadn't considered - there might not be enough room for double bypass on the coax feed. The extant 14 and 28uF caps are ~49 and ~65mm D, respectively. Replacing these two with six caps might not fit even if I stack them on the resistors and each other (BTW, are there sonic gains to be had by upgrading the resistors?).

It's tough to get the Thiel values (14 and 28 uF) in combos of two. Clarity makes a 27uF CSA, which would combine nicely with a 1uF ultra cap, but I can't find a retailer. I can get 18uF CSA and combine that with either 10uF CMR or Mundorf Supreme. The 14uF is tougher. I can get a 12uf MR and combine that with a 2uF CSA – is it deleterious or non-beneficial if the lower capacitance cap is lesser quality? Going with Mundorf mandates a double bypass, eg, 10uF CSA + 3.9uF Supreme + 0.1uF Supreme.

There appears to be much more room to replace the single 33uF woofer cap. Plenty of room to replace these with 15+18uF CSA or 33uF Mundorf Supreme EVO or, most inexpensively, 33 uF SA.

Obviously, I can’t make any purchase without first looking at the boards myself and seeing how much room there is.

Rob might have an upgrade path for those CS7s

Upgrading those to 7.2 and modding the XO could make those *really* sing! In my room, the speakers are 7' from the front wall . . .

7' from the wall is a great luxury. Do you also have a high ceiling? Ceiling bounce is a real issue.

XO layout space is a real issue that will have to be engineered as we go. Thiel used good resistors, I don't remember the facts. You might trace the specs of your actual resistors. But I do know that we chose those carefully, considering costs. There is a theoretical and audible improvement from more linear resistors, but I don't know where the present solution fits in that landscape.

The general answer to the mod / value / cost of caps is that the smaller values must be higher quality to get improvement. We are fudging to get the most gain for the least cost by using less expensive caps for the bulk of the work and tricking out the smaller values which we can more easily afford. 

The woofer cap deserves cost restraint, the impulse transient is far slower for lower frequencies. If the 33uF is a Solen film cap, that's probably OK. Upgrading to an SA seems plenty to me. Note that Jim bypassed 'lytics (etc) with a small value teflon for bigger sonic improvement than swapping the whole thing for a film type. Out of the blue (no real research yet), I would suggest a 32 ± SA bipassed  with 1uF ± teflon as a high likelihood of success. FYI: Gary Dayton worked with Jim on these issues and may be willing to share some insight if you (all) want to rattle his cage. 

As an ultimate 7.2 upgrade, I would imagine outboard XOs to reduce size / layout constraints and take the XO farther from driver EMF and microphonics. I always heard added congestion when packing the XO into the cabinet.