Consonance Opera Cyber 211 mods

I had to get back into the amp last night to finally repair a ground hum when connecting the to XLR. Pictures can be found here:
http://www.flickr.com/photos/80136324@N02/

For those interested, I finally completed the mods to both Cyber amplifiers. Complete upgrade to the signal path - replaced all caps (2 vcap teflon and 2 blackgates), resistors (20 assorted and recommended by Nick at HiFi Collective), wiring (VHaudio teflon OC copper), Eichman binding posts and RCA), new balanced connector (Furutech), IEC (Furutech), and finally the bridge rectifier (4 diodes also recommended by Nick). I moved the RCA and Balanced inputs to a custom designed side panel to get away from the power at the rear.

I did not touch the power supply (other than the rectifier). As I mentioned before, I did these upgrades in three iterations, the improvements are stunning - with the biggest benefit from the resistors, recognizing that the vcaps are about 2/3 burned in, at about 300 hours or so.

As mentioned above re the psvanes, which I'm running now - I'm ready to find some GEs or RCAs.

Having just finished some extensive mods to my 211, I just thought I'd look here to see if anyone weighed in. Thanks David. It would appear that this amp has good design in need of much better parts.

I have been tackling my 211s one at a time. I first changed out the auricaps, internal wire, IEC, binding posts, and RCA with VCAPs, vhaudio copper air teflon, furutech IEC with an external fuse holder, and Eichman binding posts and RCAs. After about 100 hours of burn in the changes were remarkable - faster, more detail, more low end control, simply more engaging.

I then took the second amp and did the same thing, plus, with lots of advice from Nick at HiFi Collective, I changed all of the resistors along the signal path, in around the 5687 and 6922 tubes - 20 resistors in all. Lots of work. Oh, and I relocated the RCA input to the new side panel near the 6922 tube to eliminate the very long internal run past all the transformers and torroids.

After about 20 hours, this amp blows away the first one and keeps getting better - it's at about 60 hours now. I never imagined that resistors would make that kind of difference - a bigger improvement than the VCaps so far. Far more detail than I could imagine, makes the first amp sound like its playing through a towell.

My next step is to add the resistors etc to the first amp, plus build a new bridge rectifier, which converts the AC to DC driving the 211. The OEM part literally costs about 10cents. Nick tells me that this change should also be significant.

Assuming the rebuilt bridge rectifier is another big step I'll repeat that on the second amp, and then - not sure what else to do. Big bucks for new output transformers.

The improvement with the resistors is more dramatic than the vcaps, tho to be fair, the vcaps supposedly need 400 hours on them and I have about 150 or so. My 211 amp now has base that is controlled, deep, and rich. Voices etc. have lots of air. It's all very very musical now. Who is Ned Kelley?

Rather than drill through the stock wood side panels I just cut some nice teak 9-ply 3/8" plywood I got from a local hi-end wood place - they sold it 2' x 4' sections. So, it looks quite nice and gives the side some nice grain to look at instead of that that stock red stained stuff.

First, make sure the caps are drained so you don't kill yourself. I did not try to solder inside the amp and took out the two boards boards instead. The first amp was a tad scary and it took me awhile. You can manage to get both boards out of the amp and the wires will get a little wangled. You might have to desolder the one wire that goes to the power tube from the output transformer.

Then carefully draw a map where every wire goes to and from and check it like 5 times. Most locations on the power board are labeled - take lots of pictures. Then start removing and replacing the wires - and each wire I installed was maybe 1"-3" longer than the stock to make it easier to install the boards. The second amp was a lot easier to do - I found that installing everything on the tube board first made it easier, and then connecting it up to the power board. Oh, I did need to lengthen the wires from the torroid to the power board by about 2"-3" to make working with it all easier.

Mark some wires with tape and mark the board with black dot with permanent marker - leave these breadcrumbs. Use compressed air and solvent to clean up the flux and keep it all clean and pretty.

I actually did all the work with the boards on top of the (bottom of the) amp (of course, it's all upside down). The replacement wire is Chis Venhaus' solid core copper air teflon series. 24g for the rca connection, 21g for most of the wiring, and 18g for the higher current runs and to the speaker binding posts.

The only soldering inside the amp are the 5 wires from the output transformer to the binding posts. Do this with the boards removed. Everything else is external.

Wire from the IEC is Venhaus' 12g twisted pair soldered to the stock switch and I also installed a cryo'd fuse holder -but it stays under the bottom lid - no easy access to it.

The resistors are all recommended by Nick at HiFiCollective - enormously helpful and patient with my questions. I can give you that list, but they are all location and purpose specific. My list would only be helpful if your 845S is the same as my 211, which it likely is in most, if not all, areas. I found a schematic of the 211 amp online which Nick used for his recommendations - relating that schematic to the real thing was quite time consuming though. I don't know jack about circuits etc, I'm basically a solder by number guy.

I don't really know what to expect by replacing the bridge rectifier - Nick said it was a good idea and recommended some diodes for me and he has a build schematic on the website. I'll be doing that next.

If I had a complaint at this point it would be that the leading edge attack was soft - perhaps more time on the caps will help, and maybe the new rectifier will provide cleaner power. Oh, I also ran the twisted pair from the stock rectifier to the 211, replacing the crappy thin stock wire. The tubes should be now getting as much power as they want - perhaps that's the boost in base response I'm now getting.

I don't know how to post photos here and I did not take any of my finished product. I do have to venture back inside to install an XLR input connection - so I'll take some. And, I still need to install the resistors etc in the second amp. If you are in the SFBay area, let me know.

I don't know if 211 design is similar enough to the 800s - check with the distributor regarding similarities in design. It's likely that the 211 is similar to the 845 version because you can buy it to be compatible with both tubes, for an upcharge of course. Mine are straight 211 design.

At the moment I have completed the left monoblock with vcaps, connectors, and hookup wiring, and the right monoblock with all that plus the resistors - so I could hear the difference - which as I said is substantial. If you are interested in that let me know. I will post when I have completed both amps the same, including the pending bridge rectifier rebuild.

I don't know what the big deal with Agon is regarding urls to other sites with information directly related to Agon users. But here is another attempt to show the link to photo's so far.

flickr dot com slash photos slash 80136324@N02 slash