Thiel Owners

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.

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

I'm kidding about getting the 7s. The 7.2s were close to the best I've heard but I'd rather tweak out these 2.4s (for now!). My room is vaulted with the tall end at the listening position. I had fabric on the ceiling for a few years to reduce reflections but took it down to wash the dust and decided it really wasn't helping to a worthwhile extent. I think I'm saved by two openings on my rear wall including a ~5'W x 4'H just above my head behind me.

XO layout space is a real issue that will have to be engineered as we go.

I think i can fit the double bypass options by stacking the caps on each other and on the resistors. I will cut the extant leads close to the caps to make sure all the leads can tie together. Is it a no-no to place caps on the coils? I think this 3-D arrangement would extend the XO profile about 4 cm further into the cabinet.

the smaller values must be higher quality to get improvement.

Thanks for the warning!

I would suggest a 32 ± SA bipassed with 1uF ± teflon as a high likelihood of success.

Can't get a 32uF in a single cap. Could do a 20uF SA + 12uF CSA + 1uF CMR or Mundorf. What do you think about adding an ultra 0.01 to the 33 SA?

I would imagine outboard XOs to reduce size / layout constraints and take the XO farther from driver EMF and microphonics.

In an earlier post you warned about taking the XO outboard because the values are dialed-in for the within cabinet environment. Do you have a rule-of-thumb for how to modify for outboard?

I do not have a rule of thumb for how to account for changes in ourboard XO environment and I think any changes would be small enough to dismiss in the absence of research equipment and process.

0.01uF is very small for these voltage and current processes. It couldn't hurt, but . . .

I like your cascading scheme. I don't know the relative merits of CMR vs Mundorf.

Do not place caps on coils due to EMF field interaction. Keep the leads long enough for a heat sink while soldering. Use 4% silver x 96% tin solder or equivalent. I like mechanical / twisted connections under solder, flux the wire first. I don't think 40cm cabinet intrusion is enough to matter much. Do not change XO board orientation in the cabinet. Pay attention to potential wire buzzes when re-packing the cabinet.

Your room geometry accumulates pressure at the rear wall-floor intersection, and behind your head. That wall opening is great. If you can make some trap doors in those corners, you will clean up bass standing waves and flutter echo enormously.

Thank you *so* much for all this great info, Tom!

I think any changes would be small enough to dismiss

OK, I'll keep this as an option depending on space.

I don't know the relative merits of CMR vs Mundorf.

Reading the anonymous writer at humblehomemadehifi I've concluded that person is a careful listener and has credible thoughts on cap performance. Reading the descriptions literally and between the lines, the CMR appears to be the near equal of the upper range of Mundorf, perhaps a tad less transparent but a scotch more neutral. I think I would be happy with either. From that website and others, it seems that going further up the Supreme line to Oil, Silver Gold, and SGO have rapidly diminishing returns with equally rapid $$$ increase! He/she is a fan of coupling SA with Supreme:

Making a capacitor using about 90% Clarity Cap SA and about 10% Mundorf Supreme works very well, this tends to open up the top end just nicely without altering anything else.

As of now, I'm leaning 20uF SA + 12 CSA + 1 Supreme on the woofer; 15 uF CSA + 12 CSA + 1 CMR and 12 CSA + 1 CSA + 1 CMR on the coax. The double bypass to replace the 28uF cap seems the most challenging to stay away from the coil. Maybe I can get the 27uF CSA from a European supplier - that would really help.

If you can make some trap doors in those corners, you will clean up bass standing waves and flutter echo enormously.

The other opening on the rear wall is a large (5'W x 10'H) walkway into the next room, conveniently in the corner! I have a bookshelf in the other corner on the rear wall. I also have cloth window shades (the front wall is almost all glass) and plants on the floor and hanging along the front wall. One-half of the floor is tile, so I also added a rug on most of that. This room was *really* bright when I moved in but I'm pretty happy with it now. Running a tone sweep fails to reveal any unacceptable room modes.

I like where you are going. It might be possible to move the coil, if there is room in the cabinet. We could move the 0.15mH coil outboard past the end of the panel. That would require crimping and soldering lead extensions - not desirable, but possible. Damp all the caps with putty (BluTac, Mortite, etc.) especially if you stack the caps vertically, to damp microphonics. Note that the power capacity of the chosen caps matters-at least as much as original spec. And if the film-wrap direction is marked, match the original.