I have been fortunate enough to have had much success in the upgrading of these units. They are a great idea to begin with, but the components in part of the circuits are old and outdate by 25 years! So, to improve and provide reliable service from these units, I have worked hard to make the necessary changes. Before I list the changes, I have to reiterate that, MY FEEDBACK HERE IS 147 ALL POSITIVE, AND I HAVE SOLD HERE FOR OVER 10 YEARS! AUDIOGON NEEDS TO CORRECT MY FEEDBACK SCORE! Now on to the list of upgrades:
1) All electrolytic capacitors have been changed out from 'standard' capacitors to Nichicon brand 'Fine Gold' or 'Muse' series capacitors. Specifically, in the output section of the audio circuit, the electrolytic caps have been replaced by bipolar caps. This in itself, provides a big improvement in audio performance. These bipolar caps are also bypassed with Mylar caps for even more impact on the performance of this unit.
2) The shamefully cheap steel RCA jacks on the rear of the unit have been replaced by high quality machined, chassis mount RCA jacks.
3) A ferrite sleeve was placed in the incoming AC line to help reject RFI noise.
4) The original hard rubber feet were replaced with Sorbothane feet, another major improvement for isolation from vibration.
5) Sorbothane was also used under the circuit board to isolate the circuit from vibration originating from the power transformer. Included is BLU-TACK placed between the power supply caps.
6) The top cover of the unit has a metal backed vibration dampening sheet. I did this after noting that the top cover rings like a bell when tapped with my finger.
7) The old convenience AC outlet was switched to an AC switch. Just made more sense to me to have a way of turning off the unit if you are on vacation.
8) The old AC cord was replaced with a cool dark red AC cord(hence the "RED DRAGON" name). More importantly, the AC plug was also changed to a much better solid brass plug, of which the inside of each prong was coated with SILCLEAR silver paste to maximize contact.
9) To enhance the appearance of the unit, I replace the cheap sheet metal screws with #6-32 threaded brass bolts on the side of the unit, and two 'acorn' brass nuts on top.
10) The unit comes with reprinted owners manual, encased in a decent folder. Also, is a paper written by me with set up tips, and experience with this unit over a 25 year period of time. I really should mention that this is the second version that Carver made of the C9, not the first. It has lower noise, and a better power supply arrangement. This is the unit that I use in my own audio system, and I own high quality equipment. This unit now keeps up with that demand. i list these units as a 7/10 due to age only. THIS LISTING IS ALSO ON EBAY WITH MORE PHOTOS. Thank you for your time.