Thiel Owners

Rob and Erik - The 400uF electrolytic is in series feed to the midrange. Bummer.

Rob and Erik - The 400uF electrolytic is in series feed to the midrange. Bummer

Doh, then consider the Mundorf electrolytics:
https://www.partsconnexion.com/capacitors-ele-mundorf-e-cap-ac-series.html
or Axon film:

https://www.partsconnexion.com/axon-true-cap-film-capacitors.html

In either case, measure ESR of the original and be aware that reducing it significantly can result in more midrange output. :)

Best,
E

The 400uF electrolytic is in series feed to the midrange. 

Oh, wow! Welp, on the plus side there is more room for sonic improvement. But 400 uF of film caps will certainly need a new layout/board. And it looks like one of the other ELs is 220 uF. And not only much bigger but also $$$.

My new boards were much larger. I compensated in the passive radiator chamber by removing a similar volume of the fiberglass batt. But I only had two 100 uF ELs to replace. 400+ is probably still doable but complicates the issue and makes the upgrade spendy. Clarity CSA 250V is available in 100 uF for $68 each. PulseX 250V is more affordable and should be sonically superior to ELs. Lean on Tom’s Knowledge, Robert!

Question can you run a cap and resistor in series to equate the the esr of the original ? 

The best sounding resistors are the Vishay nude metal films. When I rebuilt my long gone Dunlavys years back..I had to build resistor bridges with several of these low wattage resistors to meet the power requirements. The improvement was almost staggering well that and sealing all the pores of the MDF inside of the cabinet with Cascade Vbloc..the formula now is a little different. Kinda like troweling on concrete. Sucks in and seals and kills the glue..Much more dynamic and open. I sealed 1 and kept quantity measurements, let dry for a few days and reassembled and compared..The treated one sounded like it went out the door and down the street..the other one was still in the box. The pair was amazing. My experience tells me not to replace inductors..go gently with the caps..and replace all the dime store resistors. Tom

Question can you run a cap and resistor in series to equate the the esr of the original ?

@theaudiotweak

Yes, you can, though ESR is not exactly a constant at all frequencies, you can definitely compensate with a little eye balling of the relevant graphs. :) 0.1 Ohm difference isn't as important as going from 1.5 Ohms to 0.3.  That in shunt can really drop the impedance of the next range.

Not as fancy, but I love Mills.  Small, very high power, extremely accurate and thermally stable.

Remember the same thing with inductors.  Keep the DCR the same, or you are changing the speaker.  There are a number of designs (including my own) which use the DCR as part of the baffle step compensation.

Best,
E