Apologies for resurrecting this ancient thread! But I am also looking for definitive circuit diagrams for TDL Studio 4s (or TDL Monitors) - I recently bought a pair and discovered that the crossovers had been replaced with something very home-made looking, (components soldered point to point to what look like nails on a piece of mdf) The bass drivers are playing roughly 6dB down compared to the mids and highs. As a temporary measure I am bi amping them, allowing me to attenuate the feed to the mid/high, which has been surprisingly successful! But I would be far happier to get hold of a couple of original crossovers, or at least a circuit diagram so I can build my own.
I've googled it to death and only found one source, from a blogger in Italy who was refurbing/modifying a pair - but it is not clear whether the circuit is the original design, or his own concoction. The Blog is very old, most of the links are dead, and there's no obvious way to contact the author.
http://www.cma4ch.org/chemo/image/hifi/TDL-Monitor-Studio4.png
The circuit is completely different in design and the values of the components compared to what is installed in mine. A helpful member on another forum forwarded the circuit diagram from a pair of TDL Monitors (a similar design in many ways, but a 4-way, with super-tweeters) but the circuit layout was completely different again, and unfortunately the values of many of the components was not indicated.
I have contacted Jerry at Falcon. He was as helpful as he could be but only had the same image as in the link from the Italian blog, and was not confident that it was correct either.
I have also contacted Axel at A.O.S. (who used to distribute a variation of the TDL Monitors in kit form) but so far he hasn't been able to find anything for me, although he did confirm that the crossover for the Studio 4 was initially based on the design for the Monitor.
Any help would be much appreciated!
Dan