Picture of the Celestion Redback installed in Mark V combo.
Best thing of all, no mods are required to install it as would be the case with any Celestion speaker in the 12 inch size.
The install of the EVM12L required front mounting. (removal of the 4 speaker screws or bolts) opening up the baffle board just a bit with a rotary sander drum (not much) and then using a router and carefully routing the grill frame to have clearance for the aluminum basket flange. I tried rear mounting the EV speaker but found that clearance between the magnet and power tubes was not sufficient, I could not remove any preamp tubes unless I removed the chassis from the shell. The extra work to front mount the speaker made life easier.
Since I had the 8 holes already drilled out, I used 8 bolts to mount the Redback. I bought the Mark V shell for about $245 used as the individual was converting their Mark V combo to a head. I went the other way.
This weekend I will be spending more time comparing the few guitars I have, as well as the other two channels. I did manage to run though the channel set but wanted to explore some time with the clean channel as that is what impressed me the most. Generally speakers when they are green do not perform their best on the distorted high gain channels. (actually it sounded good) but in light of the Alnico driven speakers I had to work my way there (Jensen Jet Blackbird) in fear of damaging the voice coil pushing the speaker too hard with a tight suspension just out of the box. I killed a WGS BlackHawk HP100 Alnico speaker that way. The case with the Celestion Crème was not as long and it performed well from the start. The same would apply to the Creambacks I installed in my RA100 Combo, the MC90 I bought as a replacement and the EV speaker. Just do not over do it for the first few hours of use.
Eventually I will get to my other amps and use the combo as an extension speaker. If I really like its performance I will get 4 more and rebuild my old OS Recto 412 cab. At the moment I do not miss the EV I took out of the Mark V. I did miss the Celestion Crème 90W alnico. I do not miss the MC90 either but at low volume playing to medium or moderate it is fine. The EV on the other hand just went beyond loud and never gave an inch in is performance but at lower volume levels it tends to sound sterile. the 90W Crème Alnico was also similar to the MC90 in respects to how loud you can drive the amp before you end up in breakup of the speaker. It could tolerate a bit more than the MC90 but do not run a JP-2C though it set to 100W (oops) thought I had set it to 60W but, oh well, I have made a $300 mistake. Speaker still works but fear the voice coil is done. Will have to check it out again later.
I will have more when I get the speaker broken in.... but I will relate how it sounds on the other channels before I get there.