Thiel Owners

Thanks for all the information you share here, Tom!

Just to get on the right side of Thiele & Small, the term "critically damped" refers to a total system Q of .5, and "maximally flat" refers to the more commonly used .707 Butterworth configuration, which is slightly underdamped and is tuned to use a 3db hump in the bass response to lower the -3db point.

Tom, Thanks again for providing this forum for Thiel-philes! The schematic I found some time ago that says its for the 03A does have LF347 op amp(s) in it, so it must not be yours. Could you please provide the correct historical schematic for the 03a and/or any of the series you mentioned as equivalent?

I saw the recent references to the 03/03a Thiels, and had a question.  I have a pair of 03a speakers, which came to me without the equalizer.  My understanding is that they only provide a bass boost to lower the -3db point.  Would anyone know what the unequalized vs equalized response curves looked like?  Or at least the -3db points.  Did the equalizer return to flat at still lower frequencies (relying on the natural 12db/octave rolloff), or did it add additional rolloff at 6 or 12db/octave?

Also, I've seen the crossover schematic with the op amps.  Are there any hotrodded versions of the 03a equalizer?