FWIW I have CS6's. Here's a few more points:
If you are interested in learning more than you ever wanted to know about Thiel speakers I recommend that you read the Thiel Owners thread on this forum. It takes several nights of reading but you will come away with a new appreciation for your speakers.
The main defining characteristic of Thiels is that Jim used first order crossovers on all of his later models. That means that each driver has to operate over an unusually broad frequency range which is a hard thing for a driver to do. By the time your speakers were produced Thiel was completely using custom drivers - many of them manufactured in house. This design decision was due to Jim's belief that phase and time coherence was critical to getting accurate sound.
For the reason above you will not be able to find non-Thiel drivers that will work in your speakers. They simply are not designed to work over the frequency range that Thiel designed his drivers for. The only company using first order crossovers that I know of is Vandersteen.
Regarding amplification I run a Krell KSA 300S which doubles power down into 2 ohms. You'll see in the Thiel thread that the company used high current amplifiers like the Krell to drive their speakers. Other users report good results with less robust amplifiers but I believe that one of the reason my CS6's sound so good is because my Krell can handle the difficult impedance curve with ease.
Rob Gillum, a former Thiel employee, has started a company called Coherent Source Service to repair and maintain Thiel speakers. I blew one of my woofers, for example, and Rob was able to rebuild it. He does have some hot rod crossover kits for various models but I don't know if the 3.6 is one of them. Before you email or call him you'll need to get the serial numbers of your speakers so you can let him know that info. I would ask him about the brightness you experience and see if he has any suggestions.
It's going to be really hard to improve on your 3.6's. I went to AXPONA and the Florida show a couple years ago and I came away amazed at how well my system compares to most of the megabuck systems. The one set of speakers that really impressed me (MBL 101E Mk II) were $70K. I won't be buying those anytime soon.
Finally, the brightness you are hearing may be an issue with room acoustics. It doesn't take much flutter echo to affect the sound. Also, you might be experiencing the effect of early reflections from the walls, ceiling, or floor. If you haven't done some serious work on your room I would work on that before messing with your speakers.
If you are interested in learning more than you ever wanted to know about Thiel speakers I recommend that you read the Thiel Owners thread on this forum. It takes several nights of reading but you will come away with a new appreciation for your speakers.
The main defining characteristic of Thiels is that Jim used first order crossovers on all of his later models. That means that each driver has to operate over an unusually broad frequency range which is a hard thing for a driver to do. By the time your speakers were produced Thiel was completely using custom drivers - many of them manufactured in house. This design decision was due to Jim's belief that phase and time coherence was critical to getting accurate sound.
For the reason above you will not be able to find non-Thiel drivers that will work in your speakers. They simply are not designed to work over the frequency range that Thiel designed his drivers for. The only company using first order crossovers that I know of is Vandersteen.
Regarding amplification I run a Krell KSA 300S which doubles power down into 2 ohms. You'll see in the Thiel thread that the company used high current amplifiers like the Krell to drive their speakers. Other users report good results with less robust amplifiers but I believe that one of the reason my CS6's sound so good is because my Krell can handle the difficult impedance curve with ease.
Rob Gillum, a former Thiel employee, has started a company called Coherent Source Service to repair and maintain Thiel speakers. I blew one of my woofers, for example, and Rob was able to rebuild it. He does have some hot rod crossover kits for various models but I don't know if the 3.6 is one of them. Before you email or call him you'll need to get the serial numbers of your speakers so you can let him know that info. I would ask him about the brightness you experience and see if he has any suggestions.
It's going to be really hard to improve on your 3.6's. I went to AXPONA and the Florida show a couple years ago and I came away amazed at how well my system compares to most of the megabuck systems. The one set of speakers that really impressed me (MBL 101E Mk II) were $70K. I won't be buying those anytime soon.
Finally, the brightness you are hearing may be an issue with room acoustics. It doesn't take much flutter echo to affect the sound. Also, you might be experiencing the effect of early reflections from the walls, ceiling, or floor. If you haven't done some serious work on your room I would work on that before messing with your speakers.